The aim in this paper is the presentation of the influence of modification of polypropylene (PP) fibres on sorption capabilities of fibres. Modification of PP fibres were made with inorganic additives in the mass with a view to improving silicate composites – in construction. The prepared modified PP fibres were compared with pure PP fibres and their mechanical and thermomechanical properties were evaluated. And we wanted to evaluate and compare the sorption capabilities of these fibres using the Washburn method. However, the obtained results led us to the conclusion that the given method rather points to the excellent transport properties of PP fibres, as if it evaluated the sorption of the fibres.

In this work we present a study of impact of textile materials used in health care facilities on microbial colonization of textile surfaces. Polypropylene yarns doped with silver phosphate glass and zinc pyrithione were prepared and used for production of bed sheets and clothing for healthcare personnel. Subsequently measurements of airborne particles and viable microorganisms on given textiles were conducted in a private surgery clinic during 3 weeks comparing the counts of viable microorganisms before and after replacing of staff clothing and bedding on examination and surgical bed with said polypropylene cloth. In this study a significant reduction of viable airborne fungi and viable microorganisms on monitored textiles was observed by multiple methods.

Polypropylene (PP) is commonly used in the polymer processing industry. Its feature is a good chemical resistance, it is non-toxic and not harmful to people. Polypropylene is widely used in the manufacturing of food packages, laboratory and medical equipment, electric cables insulators, automotive parts, toys and furniture. The application of this material enables us to obtain complicated shapes of big surfaces. It is also highly recyclable. Polylactide (PLA) is a product of the so called “green chemistry” because it is obtained from the renewable raw materials (biomass). As its price is higher compared to the traditional polymers, its repeated use (recycling) is of high interest. Due to the same reason (cost) the mixtures of PLA with other polymers are applied. In this paper the results of testing the PP/PLA mixtures of various mass ratio of the components are presented. Technical terms of preparing and processing such mixtures have been practically tested. Also the mechanical strength was determined based on the static tensile tests. The results showed that those mixtures can be repeatedly processed. Even five-times reprocessing does not cause essential drop of mechanical properties

Increasing awareness of the potential health risks associated with microplastics (MPs) presence in the environment has led to significant rise in research focused on these particles over the past few years. This review focuses on research on MPs presence and spread, pathways of exposure and toxicological effects on human health and legal framework related to MP challenges. Several research projects have aimed to assess their potential harm to human health. Toxicological effects have been noticed at high concentrations of MPs, specifically polystyrene, the most widespread typical MP, but only short-term effects have been mostly studied. Significant quantities of consumed MP have been discovered to have diverse detrimental effects, posing a threat to human welfare. The exact concentrations of microplastics that are inhaled and swallowed and then build up in the human body are still not known. Further investigation is necessary to evaluate the impact of MP contamination at minimal concentrations and for prolonged durations.

The surface fluorination of polypropylene (PP) was performed using F2 and O2 gas mixtures with different F2 gas proportions at 25 °C and 13.3 kPa for 1 h. The surface roughness of the fluorinated PP samples was approximately 1.5 times higher than that of the untreated sample (5 nm). The Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results showed that the PP-derived bonds (-C-C- and -CHx) decreased because they were converted into polar groups (-C–O, -CHF-, and -CFx), which increased the surface electronegativity of PP. The variation in the F2 gas proportion in the gas mixture significantly affected the hydrophilicity and surface composition of PP. At F2 gas proportions of <70%, the hydrophilicity of the fluorinated PP samples improved. Notably, the hydrophilic and negatively charged PP surface enhanced the dyeing of the polymer with basic methylene blue (MB). In contrast, at F2 gas proportions of >90%, the PP surface became hydrophobic owing to increased hydrophobic -CF3 bonds. Thus, enhanced PP dyeing can be controlled based on the composition of the F2 and O2 gas mixture.

In order to obtain higher thermoelectric and mechanical properties in non-polar thermoplastic vulcanizates (TPVs), the Butyl rubber/Polypropylene (TPVs)/hydroxylated graphene (HGE) composites with nanosheet network were prepared through masterbatch technique and based on thermodynamic calculations, using polypropylene-graft-maleic anhydride (PP-MA) as a compatibilizer. The FTIR and Raman spectra revealed the introduced maleic anhydride group on PP-MA can form strong interfacial interaction with hydroxyl-containing functional groups on HGE. Morphology study indicated the rubber particles in the composites occupied the most volume of the PP phase, as expected to hinder the aggregation of HGE and form the effective nanosheet network. The nanosheet network can be combined with the IIR cross-linked particles during the dynamic vulcanization process to improve the interface bonding between PP and IIR, thus increasing the tensile strength of TPVs. When the content of HGE reached the percolation threshold (2 wt.%), the nanosheet network of HGE was formed, and the AC conductivity, dielectric permittivity and thermal conductivity increased sharply. The prepared TPVs/HGE nanocomposites have significantly improved in mechanical properties, thermal properties and dielectric properties, which provides a guarantee for their potential application as multifunctional TPVs polymers.

The preparation and thermal properties of polypropylene foils, filled with ceramic microparticles, talc or boron nitride, are described. A slow, linear increase of thermal conductivity with volume percent of filler up to 30 vol % is detected. Reduction of the foil thickness bellow 200 micrometers leads to a significant increase of thermal conductivity. Specific thermal capacities of foils are temperature dependent, they decrease with filler incorporation.

Polypropylene (PP) foam has a great deal of application since it normally exhibits non-uniform cell size distribution, low cell density, and cracked cells. In this study, a small amount of fluoroelastomer (FKM) was used as a nucleating agent to prepare well-defined microporous PP foam by supercritical CO₂. It was observed that solid FKM was present as the nanoscale independent phase in PP matrix and the FKM could induce a mass of CO₂ aggregation, which significantly enhanced the diffusion rate of CO₂ in PP. The resultant PP/FKM foams exhibited much smaller cell size (～24 μm), and more than 16 times cell density (3.2×10⁸ cells/cm³) as well as a much more uniform cell size distribution than that of the neat PP foam. PP/FKM foams possessed major concurrent enhancement in their tensile stress and compressive stress compared to neat PP foam. We believed that the added FKM played a key role in enhancing the heterogeneous nucleation, combined with the local strain field variation in the multiple-phase system, which was responsible for the considerably improved cell morphology of PP foaming. This paper provides a deep understanding of the scCO₂ foaming behavior of PP in the presence of FKM.

This study investigates by hybrid approach of classical calculations and numerical explicit FEM simulation the strain rate sensitive hardening of Polypropylene Sabic 83MF10 under dynamic tension loads. The Cowper-Symonds model is employed to characterize the non-linear increase in yield strength with strain rate, within the range of 0,01 to 1 [1⁄s]. For lower strain rates, a drastic decrease in yield strength is observed, suggesting the significant influence of creep and relaxation phenomena. The study proposes further research incorporating viscoelastic properties for a more comprehensive material model. Additionally, the study observes a disproportionate increase in yield strength for samples with smaller radius, indicating a dependency on triaxiality which suggests further research on the Drucker-Prager model for this material. The study concludes by recommending a broader range of input parameters for future studies, including the Johnson-Cook model and comparison of tensile test results with compression test results.

The effect of contamination of polypropylene (PP) with selected polymers is studied to simulate the effect of mis-sorting in recycling streams. Polystyrene (PS), polyethylene terephthalate (PET), polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS) and polylactic acid (PLA) were compounded with PP at different concentrations varying between 3 and 10%. Infrared spectroscopy proved the absence of chemical bonds between the constituents. The samples for mechanical testing were injection moulded and further tested for their tensile and impact properties. Critical behaviour was induced by the introduction of a weld line as a result of the application of multiple gating points during injection moulding. Results generally show the applicability of PP mixtures within the investigated range of inclusions, without much sacrifice in mechanical performance. However, in the case of ABS and PLA, more care should be taken when designing complex parts with weld lines, due to reduced toughness.

Background and Objectives: Impacted lower third molar extraction, is a common oral surgical pro-cedure. Pain, swelling and limitation of mouth opening that may occur in the postoperative pe-riod are factors that affect the daily routines of patients. In this study, it was aimed to evaluate the efficacy of polybutester and polypropylene sutures on postoperative complications after lower impacted third molar surgery. Materials and Methods: On 35 patients with bilateral impacted lower third molars included in the study; two different suture materials were used as polybutester suture in group 1 and polypro-lene suture in group 2. Measurements were made for the evaluation of edema and trismus be-fore the operation and on the 2nd and 7th day after the operation, and a visual analogue scale (VAS) was given to patients to fill in after the operation. Wound healing, suture related injury, and suture related discomfort in patients were noted. Results: According to the results of the study, the pain felt on the side using the polybutester su-ture on the 2nd postoperative day was less than the side using the polypropylene suture (p<0.05). On the 2nd postoperative day, it was observed that the suture on the side which the polybutester suture was used caused less discomfort to the patients than on the side which the polypropylene suture was used (p<0.05). It was observed that women experienced more pain (p<0.01) and more trismus (p<0.05) after the operation compared to men. Conclusions: On postoperative 2nd day, less pain was observed on the side where the polybutester suture was used and it was also found that the polybutester was better tolerated. These results support the use of polybutester suture in the surgery of im-pacted third molars.

To investigate the structural behavior of simply supported concrete beams with steel and polypropylene fiber under low velocity impact loading. In all twenty-four beams (150X200X1800 mm) with simply supported boundary condition were modeled and analyzed using ABAQUS software. Steel and polypropylene fibers of aspect ratio of 60 and 231 respectively are used. The total volumes of fibers are maintained at 1% by volume of specimen. A 100 kg hammer with tip diameter 16 mm (hemispherical contact area = 201 mm2) with four different velocities (3.13 m/s, 4.42 m/s, 5.43 m/s and 6.11 m/s) were used in the analysis. It is observed that with the addition of hybrid fibers the deflection in beams was reduced. The beams with 1% PP and 0% steel fiber shows the maximum deflection values due to low modulus of elasticity. Beams with 0.9% steel and 0.1% polypropylene fibers was less affected in terms of deflection as compared to all other beams, it is due to presence of high tensile strength fibers.

Polymers and their processing by engineering production technologies (injection, moulding or additive manufacturing) are being increasingly used. An explosive atmosphere can be created by the powder form of these polymer materials, and introduction of preventive safeguards to control safety is required for their use. Determination of the fire parameters of powder samples of Polyamide PA12, Polypropylene, and ultra-high molecular weight polyethylene (UHMW Polyethylene) is the subject of the current article. The results showed? that one of the samples used was not flammable and thus safe for use in terms of explosiveness. Two samples were flammable and explosive. The lower explosive limit was 30 g.m-3 (Polyamide PA12) and 60 g.m-3 (UHMW Polyethylene). The maximum explosion pressure of the samples was 6.47 (UHMW Polyethylene) and 6.76 bar (Polyamide PA 12). The explosion constant Kst of the samples was 116.6 bar.m.s-1 (Polyamide PA 12) and 97.1 bar.m.s-1 (UHMW Polyethylene). Therefore, when using polymers in production technologies, it is necessary to know their fire parameters, and to design effective explosion prevention measures for flammable and explosive polymers.

This manuscript investigates the dispersion of cetyltrimethylammonium bromide (CTAB) treated cellulose nanocrystals (CNCs) in polypropylene (PP) by melt mixing. FTIR spectra of CTAB-modified CNCs and unmodified CNCs in a PP matrix were used to evaluate the surface treatments. The surface energies and morphologies of CTAB surface modified CNCs in polypropylene (PP) were used to interpret the effects of nanoparticle dispersion on the crystallization and rheological and mechanical properties of the PP matrix.

In the preparation of polymer-clay nanocomposites the chemical incompatibility between the clay surface and polyolefins can be overcome by using clays organically modified with short chain organic cations. The compatibility can be further enhanced by using functionalized polymer that wets the clay surface while being miscible with the non-polar polymer matrix. In this work we tried to modify the host polymer polypropylene (PP) by irradiating it with gamma-rays in air knowing that it undergoes oxidation and chain scission simultaneously. Thus lower molecular weight PP with highly polar surface due to oxidation can be expected to play double role of clay modifier and functional compatibilizer. This has been observed to be the case. Finely ground PP granules were irradiated in air in a ⁶⁰Co γ-irradiator at the dose rate of 0.08 kGy/h (low dose rate to enhance oxidation) to 5, 10, and 20 kGy total doses. The extent of oxidation and change in molecular weight were determined by ATR-FTIR and Melt Flow Rate measurements respectively. PP/MMT nanocomposites were prepared by using 20% γ-PP, 1-5 % MMT and pristine PP to make up the total 100 in a torque rheometer. Maleated PP was also used in similar quantities to compare the effectiveness of γ-PP as a compatibilizing agent. Nanocomposites prepared with 10 kGy irradiated PP was found to show optimum mechanical properties among all formulations, with 26% increase in E-modulus and 10% increase in tensile strength as compared to pristine PP. Ternary PP nanocomposites were characterized by XRD, SAXS and PALS studies.

Microplastics (MPs) are plastic particles ranging from 1,000 to 5,000 µm in diameter, posing a growing environmental and health risk. Composting is an excellent way to add nutrient-rich humus to the soil to boost plant development, but it also pollutes agricultural soil with MPs. Previous research has shown that MPs can threaten plant development, production, and quality, hence they must be studied. This study examined how a mixture of three MP types—polyethylene (PE), polystyrene (PS), and polypropylene (PP)—affected greenhouse tomato plant development. MP types were spiked at 1% w/w (MPs/soil) in tomato pots, whereas non-spiked growth medium was the control. Statistical analysis was conducted using an analysis of variance (ANOVA) and Tukey test (95% confidence) to compare treatments and controls. Soil spiked with MPs increased chlorophyll content (SPAD), transpiration rate, photosynthetic rate, and stomata conductance by 5.16%, 16.71%, 25.81%, and 20.75%, respectively, compared to the control but decreased sub-stomata CO2 concentration by 3.23%. However, MPs did not significantly affect tomato plant morpho-physiological features (p > 0.05). Biochemical analysis of tomato fruits showed significant (p < 0.05) reduction effects of MPs on carotenoid, total flavonoid, and sugar but increased protein, ascorbate, and peroxidase activity. However, there was no significant difference (p > 0.05) in the effects of the combined MPs on total phenolic content. These data imply that whereas MPs did not influence tomato plant physiological and morphological properties, tomato fruit biochemistry was reduced. This raise concerns that an increase in MPs in soils may reduce antioxidant content and negatively affect human health contributing to a decrease in food security.

A new two-step method for developing a nanocomposite of polypropylene (PP) decorated with photocatalytically active TiO2 nanoparticles (nTiO2) is proposed. This method involves low-temperature plasma functionalization of polypropylene followed by ultrasound-assisted anchoring of nTiO2. The nanoparticles, polymeric substrate, and resultant nanocomposite were thoroughly characterized using nanoparticle tracking analysis (NTA), microscopic observations (SEM, TEM, EDX), spectroscopic investigations (XPS, FTIR), thermogravimetric analysis (TG/DTA), and water contact angle (WCA) measurements. The photocatalytic activity of the nanocomposites was evaluated through the degradation of methyl orange. The individual TiO2 nanoparticles ranged from 2-6 nm in size. Oxygen plasma treatment of PP generated surface functional groups (mainly -OH and -C=O), transforming the surface from hydrophobic to hydrophilic, which facilitated efficient deposition of nTiO2. Optimized plasma treatment and sonochemical deposition parameters resulted in an active photocatalytic nTiO2/PP system, degrading 80% of methyl orange under UVA irradiation in 200 minutes. The proposed approach is considered versatile for the functionalization of polymeric materials with photoactive nanoparticles and, in a broader perspective, can be utilized for the fabrication of self-cleaning surfaces.

Quality-changed behavior of ultraviolet light absorber (UVA: UV-326) in polymers (PP, HDPE, LDPE, PLA and PS) over time during degradation was studied with an enhanced degradation method (EDM) using sulfate ion radical in seawater. EDM was employed to homogeneously degrade the entire polymer samples containing the UVA. The PP and PS samples containing 5-phr UVA films whitened rapidly due to formation of numerous grooves or crushed particles. The UVA loss rate of PS with the higher Tg was much slower. The crystalline polymers, with the exception of PS, were similar in the behavior of the change in UVA loss rate with respect to degradation time. The significant increase in initial loss rate observed during EDM degradation was due to microplasticization. A similar increase in microplasticization rate occurred with the PS, but the intermolecular interaction between UVA and PS did not result in as pronounced its increase in loss rate as with other polymers. The UVA chemical structure was not altered by EDM degradation. These results revealed that the UVA leaching from the polymer matrix was the primary cause of the loss.

This paper uses polypropylene (PP) as the matrix and acrylic acid (AA) and maleic anhydride (MAH) as functional monomers to prepare PP-g-(AA-MAH) fibers by suspension grafting and melt-blown spinning technology that are easy to industrially scale-up. The fibers can be used to adsorb aniline from wastewaters. Results showed that the grafting ratio reached the maximum of 12.47%. The corresponding optimal conditions were grafting time of 3h, AA : MAH = 0.75, total monomer content of 55%, benzoyl peroxide 1.4%, xylene concentration of 6 mL/g PP, and deionized water content of 8 mL/g PP. Owing to its good fluidity and thermal stability, the product of suspension grafting can be used for melt-blown spinning. Infrared spectroscopic and nuclear magnetic resonance spectroscopic analyses indicated that AA and MAH were successfully grafted onto PP fibers. After grafting, the hydrophilicity of PP-g-(AA-MAH) fiber increased. Therefore, it had higher adsorptivity for aniline and the adsorption capacity could reach 42.2 mg/g at 45 min. Moreover, the PP-g-(AA-MAH) fibers showed good regeneration performance.

In the past decades, Fiber Reinforced Concrete has been gaining more attention in the concrete research development. There are many advantages of the inclusion of fiber into reinforced concrete structures. It was found that the inclusion of fibers in concrete, be it synthetic or natural, resulted in the improvement of the thermal properties of concrete, as well as its strength to some extent. However, the inclusion of fibers in concrete does affects its thermo-mechanical properties. The objective of this study is to identify the potential of the addition Polypropylene and Kenaf fibers in cement mortar at different compositions (0.1%, 0.2%, and 0.3%). Eight mixes were analyzed for this purpose. Upon investigating the flow ability, compressive strength, tensile strength, and thermal conductivity of the mortar samples, it was found that the incorporation of PP and Kenaf fibers reduced the flow ability. Cement mortar samples containing 0.1% addition of PP and Kenaf fibers show the highest compressive strength compared to other percentages, while samples containing 0.3% addition of PP and Kenaf fibers show the highest tensile strength compared to other percentages. The thermal conductivity of mortar samples shows reduction when high percentages of both fibers were used.

The goal of this study is to find out how some properties of wood-polymer nanocomposites are affected by the processing technology, the nanomaterials, and the ratio of coupling agents. To meet this objective, the extruded and dry blended samples are made from wood flour with MAPP, ZnO nanoparticles (0, 1, 3, and 5 wt%), and polypropylene. The mechanical properties of the nanocomposites improve significantly with ZnO and MAPP loading. Due to the more homogeneous structure of nanocomposites, better mechanical results are obtained with the extrusion method. With ZnO and MAPP loading, the thermal stability of nanocomposites improves. The storage and loss modulus values indicate that the processing technology of nanocomposites could be a key factor in the resistance of the materials obtained by extrusion. The storage and loss modulus of nanocomposites manufactured by the extrusion technology are determined to be higher than those of the samples produced by the dry blending method.

Expansive soil shows dual swell-shrink which is not suitable for the construction. Several mitigating techniques exist to counteract the problem promulgate by expansive clayey soils. This paper explored the penitential mecho-chemical reinforcement of expansive clayey soil to mitigate the effect of upward swelling pressure and heave. The polypropylene fiber is randomly distributed in the soil for mechanical stabilization, and the industrial residual silica fume is used as a chemical stabilizer. The experimental analysis is made in three phases which involved the tests on mechanical reinforced expansive soil using randomly distributed polypropylene fibers with different percentages (0.25%, 0.50%, and 1.00%), and 12mm length. The second phase of experiments carried out on chemical stabilized expansive soil with different percentages (2%, 4% and 8%) of silica and next phase of the experimental focused in the combination of mecho-chemical stabilization of the expansive soil with different combination of silica (i.e., 2%, 4% and 8%) and polypropylene fibers (i.e., 0.25%, 0.50% and 1.00%). Maximum dry density (MDD), optimum moisture content (OMC), liquid limit (LL), plastic limit (PL), plastic index (PI) grain size, and constant volume swelling pressure test were performed on unreinforced and reinforced expansive soil to investigate the effect of polypropylene fiber and silica fume on the engineering properties of expansive clayey soil. The experimental results illustrate that the inclusion of polypropylene fiber has a significant effect on the upward swelling pressure and expansion property of expansive soil. The reduction in the upward swelling pressure and expansion is a function of fiber content. These results also indicated that the use of silica fume caused a reduction in upward swelling potential, and its effect was considerably more than the influence of fiber.

The effect of reprocessing on the quasi-static uniaxial tensile behavior of two commercial polypropylene (PP) based composites is experimentally investigated and modeled. In particular, the studied materials consist of an unfilled high-impact PP and a talc-filled high-impact PP. These PP composites are subjected to repeated processing cycles including a grinding step and an extrusion step to simulate recycling at the laboratory level, the selected reprocessing numbers for this study being 0, 3, 6, 9 and 12. Because the repeated reprocessing leads to thermo-mechanical degradation by chain scission mechanisms, the tensile behavior of the two materials exhibits a continuous decrease of elastic modulus and failure strain with increasing number of reprocessing. A physically consistent three-dimensional constitutive model is used to predict the tensile response of non-recycled materials with strain rate dependence. For the recycled materials, the reprocessing effect is accounted by incorporating the reprocessing sensitive coefficient into the constitutive model for Young’s modulus, failure strain, softening and hardening equations. Our predictions of true stress - true strain curves for non-recycled and recycled 108MF97 and 7510 are in a good agreement with experimental data.

The application of solvent method in the preparation of polypropylene powders was investigated, including the influence of various technological conditions, such as the raw material melt index of polypropylene, processing temperature, dosage of the solvent and the packing pressure. The experimental data show that using solvent method can effectively produce polypropylene powder, and the optimal technological conditions are: melt index of polypropylene being about 17.8 g/10min, processing temperature being about 166.0 ℃, dosage of the solvent being about 0.067g/ml and the packing pressure being about 0.7MPa.Under this technological conditions, polypropylene powder with excellent sphericity could be prepared, the apparent density of powder can reach 0.40 g/cm3 and the prepared powder displayed a narrow size distribution with the mean size of about 42.7 µm.

This article raise a topic of critical examination of polypropylene, a key polymeric material, and its extensive application within the automotive industry, particularly focusing on the manufacturing of brake fluid reservoirs. The study aims to enhance the understanding of polypropylene's behavior under mechanical stresses through a series of laboratory destruction tests and numerical simulations, emphasizing the Finite Element Method (FEM). A novel aspect of this research is the introduction of the PEAK parameter, a groundbreaking approach designed to assess the material's resilience against varying states of strain, known as triaxiality. This parameter facilitates the identification of critical areas prone to crack initiation, thereby enabling the optimization of component design with a minimized safety margin, which is crucial for cost-effective production. The methodology involves conducting burst tests to locate crack initiation sites, followed by FEM simulations to determine the PEAK threshold value for the Sabic 83MF10 polypropylene material. The study successfully validates the predictive capability of the PEAK parameter, demonstrating a high correlation between simulated results and actual laboratory tests. This validation underscores the potential of the PEAK parameter as a predictive tool for enhancing the reliability and safety of polypropylene automotive components. The research presented in this article contributes significantly to the field of material science and engineering by providing a deeper insight into the mechanical behavior of polypropylene and introducing an effective tool for predicting crack initiation in automotive components. The findings hold promise for advancing the design and manufacturing processes in the automotive industry, with potential applications extending to other sectors.

This paper presents the results of investigations into the pyrolysis of waste polypropylene in a laboratory fixed-bed batch reactor. The experiments were designed and verified in such a way as to allow the application of the Response Surface Methodology (RSM) in the development of an empirical mathematical model that quantifies the impacts mentioned above. The influence of the mass of the raw material (50, 100 and 150 g), together with the reactor temperature (450, 475 and 500 °C) and the reaction time (45, 50 and 75 min) was examined. It has been shown that the mass of the raw material, i.e. the filling volume of the reactor, has a significant influence on the pyrolysis oil yield. This influence exceeds the influence of reactor temperature and reaction time. This was explained by observing the temperature change inside the reactor at three different spots at the bottom, middle and top of the reactor. Recorded temperature diagrams show that with greater masses of feedstock, local overheating occurs in the middle part of the reactor, which leads to overcracking of vapor products, and from there to an increased formation of non-condensable gases, i.e. reduced yield of pyrolytic oil.

Thermoplastic pultrusion is a suitable process for fabricating continuous unidirectional thermoplastics with a uniform cross-section, high mechanical properties due to continuous fiber reinforcement, low cost, and suitability for mass production. In this paper, jute and glass fibers were reinforced with a polypropylene matrix and fabricated using the thermoplastic pultrusion process. The volumetric fraction of the composite was designed by controlling the filling ratio of the reinforcing fiber and matrix. The effects of molding parameters were investigated, such as pulling speed and molding temperature, on the mechanical properties and microstructure of the final rectangular profile composite. The pulling speed and molding temperature were varied from 40 to 140 mm/min and 190 to 220°C, respectively. The results show that an increase in molding temperature initially led to an increase in mechanical properties, up to a certain point. Beyond that point, they started to decrease. The increase in molding temperature also led to an increase in void content. Meanwhile, un-impregnation decreased with the increase in molding temperature, and the jute fiber began to degrade at high temperatures. In the next step, with varying pulling speed, the mechanical properties decreased as the pulling speed increased, with a corresponding increase in void content and un-impregnation. The decrease in mechanical properties was influenced by the increase in void content and un-impregnation, as the jute fiber degraded at higher temperatures.

We have recently introduced the possibility of performing operando small-angle X-ray scattering measurements using a novel industrially relevant injection moulding system for plastics. We show that useful time-resolving measurements can be performed with a time-cycle of 1s and we highlight the possible steps to reduce this to 0.5s. We show how we can use the transmission measurements to provide a time-marker when plastic first enters the mould cavity in the region probed by the incident X-ray beam. We show the opportunities provided by this experimental stage mounted on the NCD-SWEET beamline at ALBA to probe the reproducibility of the injection moulding system on different scales. The design of the equipment allows the development of the structure and the morphology to be evaluated in different parts of mould cavity and we evaluate any differences in a rectangular mould cavity. We identify future prospects for this equipment in terms of novel mould heating and cooling systems and the opportunities for quantitatively evaluating radical approaches to injection moulding technology.

This paper presents the values of several mechanical characteristics for two blends: H (60% PP + 12% PA6 + 8% EPDM + 20% Polybond 3200) and G (20% PP + 42% PA6 + 28% EPDM + 10% Polybond 3200) (%wt), comparing them to those of PP (polypropylene) and PA6 (polyamide 6). The adding of EPDM (ethylene propylene diene monomer rubber) and Polybond 3200 help reducing the disadvantages of simple blends made of PP+PA6, when the PA6 concentration allows for having a PA6 matrix with droplets of PP. SEM analysis helps for understanding the performance of material G as compared to the neat polymers. EDX analysis proved that there was a matrix inversion, material H having a PP matrix and material G a matrix made of PA6 with droplets of PP. Strain at break for PP and material H were proved to be insensitive to test speed, but materials G and PA6 had large value for strain at break and energy at break for v = 10 mm/min. Taking at basis the values for polyamide 6 (PA6), material G has greater values for energy at break: with 97.8% for v = 10 mm/min, with 29.5% for v= 250 mm/min and with 98% for 1000 mm/min, without exhibiting the micro and macro cavitation of PA6. This means that the recipe, the technology and the mechanical characteristics make material G a potential candidate for applications where a low and moderate impact resistant material is required.

Modified ammonium polyphosphate (MAPP) as a novel mono-component intumescent flame retardant (IFR) was prepared via the ionic exchange between ammonium polyphosphate (APP) and piperazine sulfonate, which is synthesized by self-assembly using 1-(2-Amioethyl) piperazine (AEP) and p-amino benzene sulfonic acid (ASC) as raw materials. This all-in-one IFR integrating three functional elements (carbon, acid, and gas source) showed more efficient flame retardancy and excellent smoke suppression as well as better mechanical properties than the conventional APP. The incorporation of 22.5 wt.% MAPP into polypropylene (PP) eliminated the melt dripping phenomenon and passed the UL-94 V-0 rating. The results of the cone calorimetry test (CCT) revealed that the release of heat, smoke, and CO is significantly decreased, demonstrating that this novel IFR endows PP with excellent fire safety more effectively. For PP/MAPP composites, a possible IFR mechanism was proposed based on the analysis of the pyrolysis gas and char residues.

The automotive industry is under growing pressure from regulatory agencies to improve the recyclability of their plastic components. Simultaneously, manufacturers are adopting natural fiber composites in vehicles to reduce carbon footprints and decrease reliance on petroleum-based materials. This presents a challenge at vehicle end-of-life however, as natural fiber-reinforced polymers are substantially more difficult to recycle than their unreinforced counterparts. This study investigated the development of a mechanical recycling process for paper fiber-reinforced polypropylene composites, focusing on the impact of injection molding parameters—specifically, injection temperature and rate—on the thermal, mechanical, and water uptake properties of the composites. The results showed that processing temperature had a greater influence on composite performance than injection rate, with some limited interaction effects between the two. Higher processing intensity damaged the paper fibers, increasing the number of nucleation sites and resulting in greater polypropylene crystallinity. These structural changes reduced tensile properties at higher intensities, while flexural properties improved. Objective function analysis was applied to identify optimal processing conditions, balancing these competing trends. Overall, the findings demonstrate that paper fiber-reinforced polypropylene composites can be recycled into automotive relevant injection molding compounds using conventional plastic manufacturing techniques, though careful tuning of processing parameters is essential to achieve optimal performance.

The extensive use of polypropylene (PP) in various industries has heightened interest in devel-oping efficient methods for recycling and optimising its mixtures. This study focuses on formu-lating predictive models for the Melt Flow Rate (MFR) and shear viscosity of PP blends. The in-vestigation involved characterising various grades, including virgin homopolymers, copolymers, and post-consumer recyclates, in accordance with ISO 1133 standards. The research examined both binary and ternary blends, utilising traditional mixing rules and symbolic regression to predict rheological properties. High accuracy was achieved with the Arrhenius and Cragoe models, at-taining R² values over 0.99. Symbolic regression further enhanced these models, offering signif-icant improvements. To mitigate overfitting, empirical noise and variable swapping were in-troduced, increasing the models' robustness and generalisability. The results demonstrated that the developed models could reliably predict MFR and shear viscosity, providing a valuable tool for improving the quality and consistency of PP mixtures. These advancements support the de-velopment of recycling technologies and sustainable practices in the polymer industry by opti-mising processing and enhancing the use of recycled materials.

We describe the design and fabrication of an industrial injection moulding system which can be mounted and used on the NCD-SWEET Small-angle X-Ray Scattering Beamline at ALBA. We show how highly useful time-resolved data can be obtained using this system. We are able to evaluate the fraction of material in the mould cavity and identify the first material to solidify and how this varies with the injection tem-perature. The design follows current industrial practice and provides opportunities to collect time-resolved data at several points within the mould cavity so we can build up a 4D perspective of the morphology and its temporal development. The quantitative data obtained will prove invaluable for the optimisation of the next generation of in-jection moulding techniques. This preliminary work used results from the injection moulding of a general purpose isotactic polypropylene.

The bending performance of a basalt-polypropylene fiber-reinforced concrete (HBPFRC) was characterized by testing 24 400×100×100 mm3 prismatic specimens in a four-point bending test JSCE-SF4 configuration. The type and content of both fibers was varied in order to guarantee different target levels of post-cracking flexural performance. The results evidenced that mono-micro basalt fiber reinforced concrete (BFRC) allows the increase of the flexural strength (pre-cracking stage), while macro polypropylene fiber reinforced concrete can effectively improve both bearing capacity and ductility of the composite for a wide crack width range. Compared with the plain concrete specimens, flexural toughness and equivalent flexural strength of macro polypropylene fiber-reinforced concrete (PPFRC) and the hybrid fiber-reinforced concrete (HFRC) increased by 3.7~7.1 times and 10%~42.5%, respectively. From both technical and economic points of view, the optimal mass ratio of basalt fiber to polypropylene fiber resulted to be 1:2, with a total content of 6 kg/m3. This HFRC is seen as a suitable material to be used in sewerage pipes where cracking control (crack formation and crack width control) is of paramount importance to guarantee the durability and functionality of the pipeline as well as the ductility of the system in case of local failures.

Microplastics (MPs) pollution has become a persisting problem over the last decades and a critical issue for environmental protection and human health. In this context any scientific data able to reveal the MPs presence and to improve the characterization and identification in different systems is valuable. The aim of this paper was to assess available techniques for determining MPs in real freshwater samples and subsequently to highlight the occurrence and type of MPs in the study case area (Somesul Mic River). The specific objectives of the study were: i) MPs separation and visual characterization; ii) microscopic analyses and morphological characterization of MPs; iii) Raman and FT-IR spectroscopic identification of MPs. MPs sampling was performed from the fresh water and sediment using planktonic nets and sieves with different mesh sizes (20 to 500µm). After digestion with hydrogen peroxide, the MPs characterization was performed using both classical microscopic techniques as well as scanning electron microscopy (SEM). For the MPs identification, Raman and FT-IR spectrometry techniques were used. Large (1-5 mm) and small (1 µm to 1 mm) MPs were observed in the shape of fibers, fragments, foam, foils and spheres in various colors (red, green, blue, purple, pink, white, black, transparent, opaque). Polymers were identified related to scientific literature and reference spectra. The presence of polyethylene (PE), polypropylene (PP) and polystyrene (PS) was registered for all sampling point. The MPs laboratory investigations have raised some issues regarding the identification of MPs particles with the size smaller than 500µm, being characterized especially under microscope. Small MPs particle dispersed on cellulose filter were identified using micro-Raman spectroscopy highlighting the same type of polymers. The results showed that both spectrometric methods Raman or FT-IR confirm the identification of the same type of polymers. No differences were registered between the sampling points due to the widespread presence of MPs. The sediments samples presented a greater abundance compared to the water samples. Overall, it is necessary to continue the optimization of the MPs separation protocol and identification according to the complexity of samples, mainly due to the limitation and lack of spectral databases.

In this work, a simple and environmentally friendly process combining low pressure (vacuum) and mechanical compression is proposed to convert recycled polypropylene (PP) foams (28 kg/m3) into low density foams (90-131 kg/m3) having negative tensile and compressive Poisson's ratios (NPR). The effect of processing conditions (vacuum time, temperature, and mechanical pressure) was studied. Based on the optimized conditions, the tensile Poisson’s ratio of the resulting auxetic foams reached −1.50, while the minimum compressive Poisson's ratios was −0.32 for the same sample. The foam structure was characterized via morphological analysis (SEM) to determine any changes related to the treatment applied. Finally, tensile and compressive properties (Young's modulus, strain energy, energy dissipation and damping capacity) are also presented and discussed. It was observed that the mechanical properties of the resulting auxetic foams were improved compared to the original PP foam (PP-O) for all tensile properties in terms of modulus (19.9 to 59.8 kPa), strength (0.298 to 1.43 kPa) elongation at break (28 to 77%), energy dissipation (14.4 to 56.3 mJ/cm3) and damping capacity (12 to 19%). Nevertheless, improvements were also observed under compression in terms of energy dissipation (1.6 to 3.6 mJ/cm3) and damping capacity (13 to 19%). These auxetic foams can find applications in sport and military protective equipment, as well as any energy mitigation system.

Surface modification of polypropylene (PP) films is achieved using gamma-irradiation-induced grafting to proffer with antimicrobial activity. The copolymer was obtained through a versatile two-step route; pristine PP is exposed to gamma rays and grafted using methyl methacrylate (MMA), then N-vinylimidazole (NVI) is grafted onto the copolymer PP-g-MMA by simultaneous irradiation. The characterization included Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Thermogravimetric Analysis (TGA), X-ray Photoelectron Spectroscopy (XPS), and physicochemical analysis of swelling and contact angle. The copolymer (PP-g-MMA)-g-NVI was loaded with vancomycin, and the drug released was quantified by UV-vis spectrophotometry at different pH. The surface of (PP-g-MMA)-g-NVI exhibited pH-responsiveness and moderate hydrophilicity, suitable properties for controlled drug release.

Up to 13 million tons of plastic waste are estimated to enter the oceans every year. A generally accepted picture based on an increasing number of environmental studies suggests that the largest fraction of it consists or is rapidly degraded into microplastics (MPs). Most of the analytical studies focused on MPs are based on the detection and identification of the polymers. On the other hand, plastic debris in the environment undergo chemical (mainly photoxidative) and physical degradation processes leading not only to fragmentation but also to the formation of leachable, soluble and/or volatile degradation products that are released in the environment. The formation of such low molecular weight species is generally neglected in the studies on MPs even if these compounds, released in the environment from the plastics debris, may pose even higher risks for the environment and for the biota than the MPs particles themselves, risks that are far from being understood and assessed. In this study we performed the analysis of reference MPs - polymer micropowders obtained by grinding a set of five polymer types down to final size in the 857-509 μm range, namely high- and low-density polyethylene (HDPE and LDPE, respectively), polystyrene (PS), polypropylene (PP), and polyethylene terephthalate (PET). The reference MPs were artificially aged in a Solar-Box and their degradation products were analyzed to investigate their degradation processes. In particular, a systematic and thorough characterization of the aged (photo-oxidized) MPs and of their low molecular weight and/or highly oxidized fraction extractable in polar organic solvents was performed. For this purpose, the artificially aged MPs were subjected to selective extraction with organic solvent that are non-solvents for the virgin polymers, targeting selective recovery of the low molecular weight fractions generated during the artificial aging. Analysis of both the extractable fractions and the residues was carried out by a multi-technique approach combining evolved gas analysis-mass spectrometry (EGA-MS) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). Up to 18 wt% of newly extractable, low molecular weight fraction was recovered from the photo-aged MPs, depending on the polymer type. The results highlight the need for more extensive studies about the potential harmfulness of the oxidation products (molecular and oxidized oligomeric species) that may leach out from plastic debris during their permanence in the environment.

Experimental measurement of porous polypropylene (PP) using the DTC-25 TA laboratory equipment and hot box test has been compared. The thermal conductivity of materials indicates the insulation capability of building materials. Excellent building materials will have a lower thermal conductivities value as well as other building insulator performance metrics. While results show that increasing the volume fraction of fluid in the porous PP has an inverse association with the thermal conductivity of the material as predicted by porous media theories, there is a marked difference in the measured values of the thermal conductivity using the two methods. The thermal conductivity values of porous from DTC-25 and hot box test were 0.21 and 0.0033 W/mK, respectively. The difference in the thermal conductivity values was due to the misapplication of the Fourier’s guarded heat flow model in the DTC-25 device to a convective fluid porous medium material.

Tire wear particles (TWP) are among the most relevant sources of microplastic pollution of the environment. Nevertheless, common analytical methods like IR- and Raman spectroscopy are highly impaired by additives and filler materials, leaving only thermo-gravimetric methods for chemical analysis of TWP in most cases. We herein present quantitative NMR spectroscopy (qNMR) as an alternative tool for the quantification of the polymeric material used for the production of tires including natural rubber (NR), styrene-butadiene-copolymer (SBR), polyethylene-polypropylene-copolymer (EPR) and polybutadiene (BR). Limits of quantification between 3 µg and 43 µg per sample and recovery rates of 72-92% are achieved for all tested polymer types. The first results of combining these measurements with Soxhlet extraction as a sample preparation tool are presented alongside the qNMR experiments.

The sound and heat insulation are among the most important concerns in modern life and nonwoven composite structures are highly effective in noise reduction and heat insulation. In this study, three layered nonwoven composite structures composed of recycled polyester (r-Pet) based thermo bonded nonwoven outer layer and meltblown nonwovens from PP and PBT as inner layers were formed to provide heat and sound insulation. Fiber fineness and cross section of thermo bonded outer layer, fiber type (PP/PBT), areal weight (100/200g/m2) and process conditions (calendared/non-calendared) of meltblown inner layer have changed systematically and the influence of these parameters on thickness, bulk density, air permeability, sound absorption coefficient and thermal resistance of composite structures were analyzed statistically. Also; the results were compared with composite structures including electrospun nano fiber web inner layer and with structures without inner layer. It was determined that sound absorption coefficients ranging between 0.77-0.98 for moderate sound frequencies and 0.99-1 for higher sound frequencies were acquired with developed nonwoven composite structures. Besides, higher sound absorption coefficients were obtained as 0.71 and 0.74 for low sound frequencies such as 800 and 1000Hz, respectively. As a result of this study it can be concluded that developed nonwoven composite structures that provides better sound absorption coefficients and similar thermal conductivity values compared to previous studies and materials in the market can be used as insulation material in required areas.

The use of commodity polymers such as polypropylene (PP) is key to open new market segments and applications for the additive manufacturing industry. Technologies such as powder-bed fusion (PBF) can process PP powder; however, much is still to learn concerning process parameters for reliable manufacturing. This study focusses in the process-property relationships of PP using laser-based PBF. The research presents an overview of the intrinsic and the extrinsic characteristic of a commercial PP powder as well as fabrication of tensile specimens with varying process parameters to characterize tensile, elongation at break, and porosity properties. The impact of key process parameters, such as power and scanning speed are systematically modified in a controlled design of experiment. The results were compared to the existing body of knowledge; the outcome is to present a process window and optimal process parameters for industrial use of PP. The computer tomography data revealed a highly porous structure inside specimens ranging between 8.46% and 10.08%, with porosity concentrated in the interlayer planes in the build direction. The results of the design of experiment for this commercial material show a narrow window of 0.122 ≥ Ev ≥ 0.138 J/mm³ led to increased mechanical properties while maintaining geometrical stability.

The rotational correlation times of a small compact spin probe (2,2,6,6-tetramethylpiperidin-1-yl)oxyl in isotactic polypropylene were obtained over a wide temperature range by EPR spectra simulation taking into account anisotropic rotation as well as distribution of probe molecules by rotational mobility. The averaged values of rotational correlation times were compared with the corresponding values calculated using well-known approximated formulas based on the intensities and widths of the spectral lines. It was shown that the calculated values can be used as effective parameters to characterize rotational mobility of the spin probe in the polymer matrix in a wide range of rotational correlation times.

Natural Fibre Composites (NFC) are eco-friendly, sustainable alternatives to synthetic polymers. However, some intrinsic natural fillers´ properties hinder their widespread implementation as re-inforcement in polymeric matrices and require further investigation. In the scope of this study, the thermal, rheologic, mechanical (tension and flexural modes), morphological properties, water ab-sorption and dimensional stability of the NF polypropylene (PP) based injection moulded compo-sites with the rice husk (rh) and olive pits (op) of 20 wt% and 30% wt%, were investigated. The results suggest that the higher content of the rice husk and olive pits led to a similar reduction of the Melt Flow Index (MFI), independent of the additive type compared to virgin polypropylene (PPv). The melting and crystallization temperatures of the PPrh and PPop composites did not change with statistical significance. The composites are stiffer than the PP matrix by up to 49% and possess higher mechanical strength in what concerns the tension mode at the expense of de-creased ductility. PPrh and PPop have superior flexural modulus in the bending mode, while the flexural strength improvement was accomplished for the PP30%rh. The dimensional stability of the composites was improved as the linear shrinkage in the flow direction was decreased by 49% for PPrh and 30% for PPop, positively correlating with an increase in the filler content and stiff-ness. PPop was less susceptible to water sorption than PPrh due to fibres' composition and larger surface-to-area volume ratios.

The strength of laser joined metal and plastic hybrids is based purely on adhesion. Unpolar plastics like polypropylene depend solely on the mechanical adhesion while polar plastics like polyamide 6.6 develop covalent bonds with the metal. In this research the influence of different surface metallizations on the lap shear strength of laser joined hybrids was investigated. Sandblasted AISI 304 was used as base metal and reference. Aluminum and titanium coatings were deposited by the means of Arc-PVD. Polypropylene and polyamide 6.6 were utilized as polar und unpolar plastics. The lap shear strength of all hybrids with polyamide 6.6 was higher than the polypropylene samples. For all investigated variations of the laser power, scanning speed and the cohesive and adhesive failure modes, the samples joined with the sandblasted AISI 304 showed the highest lap shear strength. The reduction in lap shear strength for the coated samples was due to the increased difference in thermal conductivity between the plastics and the coating materials. This lead to increased warping and residual stresses. It can be concluded that the thermal properties of the metallization in laser joined metal and plastic hybrids has a high impact on the lap shear strength.

Post-industrial recycling (PIR) and post-consumer recycling (PCR) are measures to sustain re-sources by improving materials’ circularity and sustainability. Currently, circularity is mostly measured as the degree of reutilization of a material from 0 to 100 % at product or company lev-el. This lacks in assessing the resources’ usage over multiple product life cycles. Therefore, we propose to assess circularity as (i) the frequency resources are used in products (effective circu-larity eC) and (ii) a vehicle to reduce virgin resource use and environmental impacts (environ-mentally efficient circularity eeC). Besides, to compare the environmental impacts of using recy-cled materials from PIR or PCR, we analyse their impact reduction potential (IRP) indicating the environmental benefits of recycling in relation to virgin material put onto the market. We demonstrate the suggested indicators for a case study material: polypropylene. For this polymer type, the eC ranges between 0.93 and 9.08 uses of the resource on average depending on collec-tion, sorting, and recycling rates. Likewise, the eeC ranges between 0.31 and 1.50 uses per kg of CO2 equivalents emitted. PCR has a higher IRP regarding climate change impacts than PIR in all analysed scenarios. The results reveal the relevance of PCR and PIR beyond the product life cycle.

This paper investigates if the polar groups induced by a plasma treatment can increase the lap shear strength of laser joined metal and plastic hybrids. Optimal laser joining parameters for cold-rolled AISI304 – Polyamide 6.6 and sandblasted AISI304 - Polypropylene hybrids are developed. The OWRK-method was utilized to identify the change in surface free energy of a low-pressure plasma treatment. Plasma treated samples were joined and tested. The fractured surfaces were investigated via light microscopy and SEM. The arithmetic means of the plasma treated hybrids lap shear strength with polyamide 6.6 varied slightly but all measured values were within the range of the untreated samples. The lap shear strengths of the polypropylene hybrids were significantly reduced. This was attributed to an overaging and the development of low molecular weight oxidized materials which lead to a weak boundary layer. No correlation between surface free energy and the lap shear strength could be found.