Polypropylene Research Articles

The Effect of Microplastics with Different Types, Particle Sizes, and Concentrations on the Germination of Non-Heading Chinese Cabbage Seed

Microplastics (MPs) are a new type of pollutant widely distributed in the environment. The ecological risks caused by MPs are becoming increasingly serious, especially in cultivated land where pollution is more likely to accumulate. In this paper, the effects of different types, particle sizes, and concentrations of MPs on the seed germination of non-heading Chinese cabbage were analyzed to reveal their potential mechanisms. Five types of MPs, polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and polystyrene (PS), were used for correlation analysis. The results showed that the effect of PVC and PET on seed germination was greater than that of PP, PS, and PE. PVC and PP promoted the growth of germinated seeds, while PET and PS showed a certain degree of inhibition. The effect of MPs with a particle size of 6.5–150 μm on seed germination was obvious. Low-concentration MPs (<1 g/L) had a weak inhibitory effect on seed germination. When the concentration was 1 g/L, 75 μm-PP, 75 μm-PVC, and 150 μm-PS promoted the growth of germinated seeds, while 48 μm PET showed inhibition. At high concentration, PP and PS inhibited amylase activity. In general, MPs’ effects showed significant differences according to different types, particle sizes, and concentrations.

Influence of Talc in Polypropylene on Total Fluorine Measurements Used as an Indicator of Per- and Polyfluoroalkyl Substances (PFAS).

Increasing restrictions for chemicals of concern in plastic packaging materials have created an urgent need to accurately detect and quantify these chemicals. Total fluorine measurements have been utilized to screen for highly scrutinized per and poly-fluorinated substances (PFAS) in food packaging materials. Inorganic contributions to the total fluorine signal can result in false positive signals exceeding regulatory limits. The purpose of this study is to develop a method for determining the contribution of talc inorganic filler to the total fluorine signal. The influence of talc on total fluorine measurements of plastics was evaluated by compounding talc with virgin polypropylene (PP) then measuring the total fluorine concentration using oxidative pyrohydrolytic combustion ion chromatography. This study provides a framework to predict the contribution of talc in plastic samples to the total fluorine signal. A near infrared spectroscopy method was developed by employing the full width half height (FWHH) of the interstitial fluorine characteristic band of talc. The FWHH signal of the processed puck specimens was determined to be linearly increase with the measured total fluorine difference as a function of talc concentration (R2 = 0.9619). This study developed a method to predict contribution of talc fillers to the total fluorine signal of plastic samples. This method is critical for accurately determining the regulatory compliance of talc filled plastic samples for PFAS using total fluorine. Total fluorine is a common regulatory compliance technique as an indicator of PFAS. Talc is a common plastic filler that contains fluorine as a contaminant. The fluorine in talc contributes to the total fluorine signal, which can falsely elevate the total fluorine signal, potentially resulting in the lack of regulatory compliance. The developed method serves as a framework of how to identify the fluorine contribution of inorganic fillers in plastics.

Microplastics Meet Metoprolol in Natural Water: Sorption Behavior and Mechanism

As an ideal carrier for the spread of pollutants in the aquatic environment, microplastics (MPs) can adsorb pharmaceutical β-blockers, which can affect their migration and lead to some unpredictable adverse consequences. In this paper, the sorption behaviors and mechanism of MPs (polyvinyl chloride (PVC) and polypropylene (PP)) for typical β-blocker metoprolol (MTL) were investigated. The effects of pH, salinity and humic acids (HAs) on the sorption were studied, which proved that the sorption behavior was different under different environmental conditions. Both low pH and high salinity inhibited the sorption of MTL by the MPs. Specifically, the sorption capacity of MTL increased, with pH increase from 3 to 10. When pH = 10, the sorption capacities of MTL on PVC (1.75 mg/g) and PP (3.34 mg/g) reached the maximum. After pH > 10, the amount of MTL adsorbed on PVC was slightly decreased, while that on PP was essentially the same. The addition of salt ions inhibited the sorption in the concentration range of 5–250 mg/g for both NaCl and CaCl2, with the inhibitory effect of Ca2+ being stronger than that of Na+. Moreover, the presence of HAs promoted the sorption of MPs for MTL. In the absence of HAs, the sorption capacities of PP and PVC for MTL were 0.34 mg/g and 0.79 mg/g, respectively. When HA concentration was 100 mg/L, the highest sorption capacities of PP and PVC reached 0.79 mg/g and 1.37 mg/g, respectively. This indicated that the promoting effect of HAs on PP was stronger than that on PVC. In general, based on the study of the sorption behavior of MTL and the characterization of the MPs, the sorption mechanism was speculated to consist mainly of electrostatic interactions, cation exchange, hydrophobic interaction and halogen bonding. The sorption kinetics of MTL on the two MPs were well-fitted by the pseudo-second-order model with R2 > 0.99. The sorption isotherms both fitted the Freundlich model, which substantiated that the sorption of MTL on the MPs (PVC and PP) was multilayered and heterogeneous. Collectively, these findings provided a theoretical basis for revealing the complex interactions between MPs and MTL in natural water and a new insight into the fate and migration of MPs and β-blockers in the environment.

Hybrid Supports for Oligonucleotide Synthesis: Controlled Pore Glass Derivatives with Branched Amine-Ended Polyether or Polyimine.

Controlled pore glass (CPG), differing in pore size and subsequent specific surface, was chemically modified by: (1) increasing surface susceptibility for amine functionalization via reaction with oxirane-type (active) and alkyl/aryl-type (inactive towards amine compounds) silane pro-adhesive compounds, and (2) immobilization of trimethylolpropane tris[poly(propylene glycol), amine terminated] ether, comb-like 8-arm octa[poly(ethylene glycol) amine] with each branch amine terminated, and a poly(propylene imine) amine-terminated second-generation dendrimer. The increase in surface density of amine functions-monitored by UV-Vis technique adopted for quantitative measurements of Ruhemann's purple intensity-improved final loading capacity, characterized by dimethoxytrityl cation absorption. Obtained materials proved their applicability in automatic oligonucleotide (ON) synthesis, especially when silanized 2000 Å CPG modified with 8-arm octa[poly(ethylene glycol) amine], with deduced empirical formula CPG-silane-(NH)5.7PEG-(NH2)2.3, was used for long-chain (150 nucleotides) ONs synthesis. This can be regarded as a good CPG support for this purpose. Moreover, hybrid supports with different porosity allowed the synthesis of shorter ONs with satisfactory yield and purity, monitored by RP-HPLC and MALDI-TOF. On the molecular level, two competitive mechanisms seem to influence the utility of the final hybrid support: spatial availability of active sites and the propensity of the functionalizer to bond with the CPG surface.

Modification of Poly(3-Hydroxybutyrate) with a Linear Polyurethane Modifier and Organic Nanofiller—Preparation and Structure–Property Relationship

The growing demand for products made of polymeric materials, including the commonly used polypropylene (PP), is accompanied by the problem of storing and disposing of non-biodegradable waste, increasing greenhouse gas emissions, climate change and the creation of toxic products that constitute a health hazard of all living organisms. Moreover, most of the synthetic polymers used are made from petrochemical feedstocks from non-renewable resources. The use of petrochemical raw materials also causes degradation of the natural environment. A potential solution to these problems is the use of biopolymers. Biopolymers include biodegradable or biosynthesizable polymers, i.e., obtained from renewable sources or produced synthetically but from raw materials of natural origin. One of them is the poly(3-hydroxybutyrate) (P3HB) biopolymer, whose properties are comparable to PP. Unfortunately, it is necessary to modify its properties to improve its processing and operational properties. In the work, hybrid polymer nanobiocomposites based on P3HB, with the addition of chain, uncross-linked polyurethane (PU) and layered aluminosilicate modified with organic salts (Cloisite®30B) were produced by extrusion process. The introduction of PU and Cloisite®30B to the polymer matrix (P3HB) influenced the processing parameters beneficially and resulted in a decrease in the extrusion temperature of more than 10 °C. The influence of the simultaneous addition of a constant amount of PU (10 m/m%) and the different amounts of nanoadditives (1, 2 and 3 m/m%) on the compatibility, morphology and static mechanical properties of the resulted nanobiocomposites were examined. The component interactions by Fourier transformation infrared spectroscopy (FTIR) analysis, nano- and microscale structure studies using small-angle X-ray scattering (SAXS) and morphology by scanning electron microscopy (SEM) were carried out, and the hardness and tensile strength of the obtained polymer nanobiocomposites were determined. FTIR analysis identified the compatibility of the polyester matrix, PU, and organomodified montmorillonite, the greatest being 3 m/m% Cloisite30B content. The addition of PU to the polyester elasticizes the material and decreases the material’s strength and ductility. The presence of nanoclay enhanced the mechanical properties of nanobiocomposites. The resulting nanobiocomposites can be used in the production of short-life materials applied in gardening or agriculture.

Evaluation of Microplastic Toxicity in Drinking Water Using Different Test Systems

Microplastic pollution poses a significant threat to environmental and human health. This study investigated the toxicological and genotoxic effects of various microplastic types (polystyrene (PS), polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE)) on plant and animal models. Aqueous extracts of microplastics in different size fractions (0.175 mm, 0.3 mm, 1 mm, 2 mm, and 3 mm) were evaluated for their impact on barley seed germination and cell division. Results indicated that smaller microplastic fractions exhibited higher toxicity, particularly for PP and PE. Significant reductions in germination rates and root growth were observed, along with increased chromosomal aberrations in barley cells. Furthermore, the migration of formaldehyde, a known toxicant, from microplastics exceeded permissible limits. These findings highlight the potential risks associated with microplastic pollution, particularly in drinking water sources. Future research should focus on the long-term health impacts of microplastic exposure, including carcinogenic potential, and explore the synergistic effects with other pollutants. Stricter regulations on microplastic pollution and advancements in water treatment technologies are urgently needed to mitigate these risks.

Poly (Propylene Carbonate) with Extremely Alternating Structure Used as Binders for High-Loading Cathodes by Solvent-Free Method in High-Performance NCM811 Batteries

The cathode affects the capacity, working voltage, and cost of lithium-ion batteries. Although the binder is a small part of the cathode material, it is particularly important to the performance of the batteries. Therefore, the design and development of polymer binders with different structures and characteristics is an important topic. In this paper, an NCM811 cathode (PPC-NCM) was prepared by a solvent-free method using poly (propylene carbonate) (PPC) as the binder, with an active substance loading of 10 mg/cm2. To explore the effect of the PPC binder on the electrochemical performance of the NCM811 cathode, the discharge capacity was 112.2 mAh/g with a 76.1% capacity retention after cycling more than 200 cycles at 1 C, which has a significantly better cycling performance than that of a PVDF-NCM/Li battery. The PPC/NCM/graphite full cells were also assembled to demonstrate the practical application potential of this work. It was shown that PPC as a binder can improve the cycling stability of NCM811/Li and NCM811/graphite full cells. The PPC binder used in the NCM811 cathode not only makes it extremely easy to prepare dry electrodes, but also makes it very simple to recover the electrode material by heating in the case of battery failure. This paper provides a new idea for the industrialization and development of a novel binder.

Understanding Separation of Oil-Water Emulsions by High Surface Area Polymer Gels Using Experimental and Simulation Techniques.

This work examines the functional dependence of the efficiency of separation of oil-water emulsions on surfactant adsorption abilities of high surface area polymer gels. The work also develops an understanding of the factors and steps that are involved in emulsion separation processes using polymer gels. The work considers four polymer gels offering different surface energy values, namely, syndiotactic polystyrene (sPS), polyimide (PI), polyurea (PUA), and silica. The data reveal that surfactant adsorption abilities directly control the emulsion separation performance. The gels of sPS and PI destabilize the emulsions due to significant surfactant adsorption. The surfactant-lean oil droplets are then absorbed in the pores of sPS and PI gels due to the preferential wettability of the oil phase. The PUA and silica gels are more hydrophilic and show a lower surfactant adsorption ability. These gels cannot effectively remove the surfactant molecules from the emulsions, leading to a poor emulsion separation performance. The study uses simulation data to understand the adsorption characteristics of two poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer surfactants. The simulation results are used for the interpretation of emulsion separation performance by the gels.

Impact of statistical poly(propylene co-ethylene) on the thermo-mechanical properties of high-density polyethylene

A series of high-density polyethylene and a statistical copolymer of poly(propylene-co-ethylene) blends in a wide range, namely (0, 10, 20, 30, 40, 50, 60,70, 80, 90, 100) abbreviated as HDPE/VM were systematically investigated by using a rheometer, differential scanning calorimetry (DSC) measurements, polarized optical microscopy (POM) and tensile tests. Rheometer results show that adding VM decreases dynamic viscosity, storage, and loss modulus. Han plot shows that HDPE and VM are compatible and miscible in the range from 20 to 60 VM % in the molten state. DSC results show little nucleation effect of VM on HDPE (HDPE’s melt crystallization temperature shifts 2 °C higher). Moreover, a linear composition dependence of ∆cp ∆Hc, ∆Hm shows that PE and VM are most probably compatible in the molten state in composition range from 20 to 60%. However, upon crystallization, the VM and PE domains occur distinctively. The results of the tensile tests demonstrated a decrease in elastic modulus, yield stress, and ultimate tensile strength as VM content increased. At low VM content (less than 20%), high elongation at break was detected for the blends, and very fine spherulites of HDPE were found across the sample by POM.

Interaction Parameters of Some Polymers Used in Nuclear Power Plants with Ionizing Radiation, Produced Secondary Radiations and Radiation Damages

AbstractThe primary interactions of polypropylene (PP), poly(vinyl acetate) (PVA), ethylene‐vinyl acetate (EVA), polyvinyl chloride (PVC), polychloroprene (CR) and polyurethane (PUR) polymers preferred in the nuclear industry with gamma and neutron radiations, secondary radiations formed after neutron interactions and damages given to polymers by these ionizing radiations are investigated. The gamma interaction parameters Were determined in the photon energy range of 0.03‐20 MeV using WinXCOM, GEANT4 and FLUKA methods. Also, energy absorption and exposure buildup factors and Kerma parameters are calculated at different photon energies. To investigate the interactions of the studied polymers with neutron, the effective removal cross‐section for fast neutrons with theoretical and the partial neutron rates passing through the studied polymer at 4.5 MeV, 100 eV and 0.025 eV energies are determined with simulation codes. The numbers of secondary gamma‐rays and neutrons Were obtained with GEANT4. The Total Ionizing Dose and Displacements per Atom parameters are studied with the help of FLUKA simulation. It is observed that the interaction of PVC polymer with gamma radiation and PP polymer with neutron particles is higher than the others. The secondary radiation from PVC and CR is less. The PP, PVA, and EVA exhibit superior resistance to radiation damage.

Wastewater-associated plastispheres: A hidden habitat for microbial pathogens?

Wastewater treatment plants (WWTPs) receive wastewater from various sources. Despite wastewater treatment aiming to remove contaminants, microplastics persist. Plastic surfaces are quickly colonized by microbial biofilm ("plastispheres"). Plastisphere communities are suggested to promote the spread and survival of potential human pathogens, suggesting that the transfer of plastispheres from wastewater to the environment could pose a risk to human and environmental health. The study aimed to identify pathogens in wastewater plastispheres, specifically food-borne pathogens, in addition to characterizing the taxonomic diversity and composition of the wastewater plastispheres. Plastispheres that accumulated on polypropylene (PP), polyvinyl chloride (PVC), and high-density polyethylene propylene (HDPE) surfaces exposed to raw and treated wastewater were analyzed via cultivation methods, quantitative reverse transcription PCR (RT‒qPCR) and 16S rRNA amplicon sequencing. RT‒qPCR revealed the presence of potential foodborne pathogenic bacteria and viruses, such as Listeria monocytogenes, Escherichia coli, norovirus, and adenovirus. Viable isolates of the emerging pathogenic species Klebsiella pneumoniae and Acinetobacter spp. were identified in the plastispheres from raw and treated wastewater, indicating that potential pathogenic bacteria might survive in the plastispheres during the wastewater treatment. These findings underscore the potential of plastispheres to harbor and disseminate pathogenic species, posing challenges to water reuse initiatives. The taxonomic diversity and composition of the plastispheres, as explored through 16S rRNA amplicon sequencing, were significantly influenced by the wastewater environment and the duration of time the plastic spent in the wastewater. In contrast, the specific plastic material did not influence the bacterial composition, while the bacterial diversity was affected. Without efficient wastewater treatment and proper plastic waste management, wastewater could act as a source of transferring plastic-associated pathogens into the food chain and possibly pose a threat to human health. Continued research and innovation are essential to improve the removal of microplastics and associated pathogenic microorganisms in wastewater.

New Horizons in Micro/Nanoplastic-Induced Oxidative Stress: Overlooked Free Radical Contributions and Microbial Metabolic Dysregulations in Anaerobic Digestion.

Excessive production of reactive oxygen species (ROS) induced by micro/nanoplastics (MPs/NPs) is highly toxic to microbes. However, the mechanisms underlying ROS generation and metabolic regulation within anaerobic guilds remain poorly understood. In this study, we investigated the effects of environmentally relevant levels of polypropylene (PP)-MPs/NPs on oxidative stress and microbial ecology during anaerobic digestion (AD). Electron paramagnetic resonance spectroscopy revealed that PP-MPs/NPs elevated the concentrations of environmentally persistent free radicals (EPFRs) and derived hydroxyl radicals (•OH). EPFRs were identified as the primary contributors to •OH generation, as evidenced by a high Spearman correlation coefficient (r = 0.884, p < 0.001) and free radical-quenching studies. The formation of •OH enhanced ROS production by 86.2-100.9%, resulting in decreased cellular viability and methane production (by 37.5-50.5%) at 100 mg/g TS PP-MPs/NPs. Genome-centric metagenomic and metatranscriptomic analyses suggested that PP-MPs/NPs induced the reassembly of community structures, re-evolution of functional traits, and remodeling of interspecies interactions. Specifically, PP-MPs/NPs induced a shift in methanogen consortia from hydrogenotrophic Methanofollis sp. to acetoclastic and hydrogenotrophic Methanothrix soehngenii, primarily because of the latter's diverse ingestion patterns, electron bifurcation complexes, and ROS-scavenging abilities. Downregulation of genes associated with antioxidative defense systems (i.e., sodN, katA, and osmC) and ROS-driven redox signal transduction pathways (c-di-AMP and phosphorylation signaling pathways) provided insights into the mechanisms underlying ROS-induced microbial metabolic dysregulation. Our findings enhance the understanding of microbial ecological and metabolic traits under MPs/NPs stressors, facilitating the control of MPs/NPs toxicity and the stabilization of AD processes.

Preliminary Research to Assess the Possibility of Grinding Selected Plastics Using Crushers

This study aims to investigate the effect of the shredding machine used on the recyclability of plastic fractions after primary crushing. This work presents a method for producing aggregates that has yet to be used in the plastics industry. This study included crushing of polymethylmethacrylate (PMMA), polyamide (PA-6), acrylonitrile butadiene-styrene (ABS), polycarbonate (PC), polystyrene (PS), and polypropylene (PP) waste in a jaw, a hammer, and a cone crusher. An analysis of the grain composition was carried out to characterize the obtained crushing products. The influence of feed size on the grain composition of the product and, only on the jaw crusher, the influence of the material used on the parameters of the crushing process was studied. This paper proposes a method to evaluate the grain composition and a way to assess plastic shredding capabilities based on machine kinematics and mechanical properties of a given material.

Sonochemical synthesis characterization and biocompatibility studies of polymeric composites for biomedical applications

In this work the in situ synthesis of mixtures of Polymethylmethacrylate (PMMA), High Density Polyethylene (HDPE) and Polypropylene (PP) with biocompatible ceramics was carried out, using high frequency ultrasound as an energy source. Starting from calcium hydroxide and ammonium hydrogen phosphate, two different crystalline phases were obtained: hydroxyapatite (HA) and calcite (CaCO3). FTIR and XRD studies showed that for the materials prepared with HDPE, only CaCO3 was formed during the synthesis process. When Polypropylene used, mixtures of HA with CaCO3 were obtained, while for the materials synthesized with Polymethylmethacrylate, only pure HA was obtained. DSC analyses did not reveal any significant changes in the melting temperatures of HDPE and PP, nor in the glass transition temperature of PMMA with the incorporation of HA and CaCO3, in the polymeric matrices. TGA, showed that the decomposition temperatures of these materials increased with respect to those of the polymers alone, indicating a significant thermal stability. Biocompatibility tests with osteoblastic cells and Scanning Electron Microscopy (SEM) studies showed that the composites of PMMA with HA, PP with HA/CaCO3 and HDPE with CaCO3, are capable of promoting cell adhesion and proliferation mechanisms, revealing potential applications as biomaterials for bone replacement.

Mechanical, Thermal, and Morphological Analysis of Himalayan Agave Fiber /GO Coated Fly Ash Hybrid Polypropylene Composites.

Composites containing two different types of reinforcements offer a wide range of possibilities and synergistic properties. This study investigates the hybridization effect of chemically active fly ash (FA) (5 wt.%) on the composites made from alkali (1 wt.%) - APTES silane (2 wt.%) treated Himalayan agave fibers (HAF) (25 wt.%) and polypropylene (PP). Prior to FA activation, the planetary ball mill was used to suitably reduce the particle size of the FA with was confirmed by the dynamic light scattering approach. Secondary reinforcement FA was modified with APTES silane (1 wt.%), followed by treatment with graphene oxide (GO) (0.5, 0.75, and 1 wt.%). The highest tensile strength of 40.47 MPa and modulus of 1.49 GPa were observed for the hybrid composites fabricated from 0.75 and 1.0 wt.% GO treated fly ash. Interestingly, this trend differed for flexural properties, and the highest flexural strength of 53.52 MPa was demonstrated by 0.5 wt.% GO treated FA hybrid composite. Thermal characterization revealed that addition of fiber increased crystallinity but decreased thermal stability, whereas a good wettability of the fiber and FA in matrix was demonstrated through morphological characterization.

A systematic review on sustainable utilization of plastic waste in asphalt: assessing environmental and health impact, performance, and economic viability.

Increasing amount of plastic waste (PW) poses a global challenge that necessitates multifaceted strategies. Repurposing PW in asphalt pavement is a sustainable strategy with extensive benefits, but there are several challenges that need to be overcome. This systematic review aims to examine three significant aspects associated with plastic-modified asphalt: environmental and health considerations, performance and technical properties, and cost.-effectiveness and economic feasibility. The environmental and health impacts of using PW in asphalt were particularly focused on the release of carcinogenic compounds and harmful fumes like polyaromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs), microplastic pollution, and climate impact. Environmental challenges and potential health risks associated with the use of PW in asphalt production were analyzed and indicated. Afterwards, the effects of different plastic types on the fatigue and rutting resistance of asphalt pavement are investigated. While many types of PWs show potential for enhancing rutting and fatigue performance, conflicting results have been observed for certain plastics. Some PW types, such as polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), low-density polyethylene (LDPE), and high-density polyethylene (HDPE), have been shown to yield inconsistent results. Lastly, factors that are recognized to have an impact on the cost-effectiveness of plastic-modified asphalt include the collection and processing costs, asphalt materials price and availability, incorporation method, and possible changes in the asphalt's lifespan. The findings of this review help researchers to identify current gaps and aid stakeholders in making informed decisions towards more environmentally friendly, high-performance, and economically viable approaches to asphalt production.

Modification of polyolefins utilizing C–H insertion of azides: Azidoformate end-functionalized polystyrene for modifying polypropylene

Polyolefins dominate the global plastics industry, constituting roughly 60% of all commercial plastics. However, their limited chemical functionality restricts their applicability in adhesion, printability, and compatibility-dependent applications. To overcome these limitations, this study investigated metal-free, melt-process post-polymerization modification of polypropylene (PP) via C-H insertion of azidoformate (AF) groups. We investigated grafting of AF end-functionalized polystyrene (PS) onto PP and demonstrated the successful preparation of novel PP hybrids with interesting properties, including enhanced compatibility between PP and PS components due to grafting, smaller PP crystallite size, high Young's modulus, and elastic rheological behaviors likely attributable to the presence of PS branches. Importantly, the presented approach avoids chain scission of PP and undesirable coloration of the product, offering a promising avenue for industrial transformations of conventional polyolefins. This research paves the way for developing polyolefin-based hybrid materials with enhanced properties and environmental benefits.

Durability and hardened characteristics of cement mortar incorporating waste plastic and Polypropylene exposed to MgSO4 attack

Annual waste plastic disposal has grown, harming nature. Utilising this waste in concrete production may help preserve building resources. This study tested cement mortar with polyvinyl chloride (PVC) and polypropylene (PP) substituted for sand aggregate at 0, 5, 10, 15, and 20%. The samples were nevertheless exposed to a 10% and 20% MgSO4 solution for a month. The properties of both fresh and hardened materials under these circumstances have been evaluated and contrasted with those evaluated under typical circumstances. For mixes including PP and PVC, the flow diameter increased. The rounded plastic particles provided fewer contact surfaces and less friction among mixtures, which reduced water consumption and improved workability, leading to an increase in slump flow. As the amount of plastic aggregate increases, the compressive strength decreased. Moreover, this pattern might be explained by the weakening of the bond between the surfaces of the plastic aggregate and cement paste. The hydration of cement may also be hampered by the hydrophobic properties of plastic aggregate. Like compressive strength, the splitting tensile strength decreased as the replacement level of plastic ratio increased regardless of its type under all conditions (normal and exposing to MgSO4). PP and PVC fine aggregate in mortar increases sorptivity under all situations. Following screening, those circumstances and PVC have the most impact on compressive strength. increasing PVC and PP at 10% for each of them leads to lower values of compressive and tensile strength. An optimization process was implemented to determine the optimum value of PVC, PP, and MgSO4. It shows that using PVC of 3.9%, PP of 10.1%, and MgSO4 of 19.59% leads to maximum compressive and tensile strength with the minimum cost and CO2 emissions.

Fabrication of high performance polypropylene based blends from ethylene vinyl acetate-based sole waste via solid-state shear Co-milling

Ethylene vinyl acetate copolymer (EVA) foam products with cross-linked structure are now widely used in the fields of functional footwear. However, due to their cross-linked structure and complex composition, they are quite difficult to be recovered in large scale after disposal, causing serious environmental pollution. Based on our self-designed solid-state shear milling (S3M) equipment, a novel co-milling technology was established to recycle ethylene vinyl acetate-based sole waste (ESW) and reuse it to strengthen and toughen polypropylene (PP). The effects of co-milling on PP/ESW powders as well as blends were studied, and the results showed that the existence of PP promoted the solid pulverization of ESW, so formed the powders with smaller size and wider distribution. Ascribing to the partial de-crosslinking of ESW during co-milling process, the contact area and the molecular entanglements at their interfaces increased, effectively improving the compatibility between PP and ESW. In this way, the simultaneous enhancement and toughening of ESW on PP were achieved. After co-milling, ESW phase in blends significantly decreased and no visible phase interface was observed. With 20 co-milling cycles, the tensile strength and impact toughness of PP/20 wt% ESW blend respectively increased from 21.9 MPa to 3.79 kJ/m2 to 25.4 MPa and 5.83 kJ/m2, both higher than most other similar PP based materials. This work provides a new strategy for high-quality and efficient recycling of ESW in large scale, and fabrication of high-performance PP based materials.

Ecofriendly hybrid natural fiber reinforced polypropylene composites from biowastes

The used ground coffee waste (GCW) and tea leaf waste (TLW), the large wastes from the beverage process, were selected as natural reinforcement and natural pigment in the polypropylene (PP) matrix. In this work, the maleic anhydride polypropylene (MAPP) was added to the composites to develop the compatibility between fillers, fibers, and polymer matrix. The TLW/PP composites, GCW/PP composites, and GCW/TLW/PP hybrid composites were prepared in the ratio of TLW and GCW ranging from 0 to 30 wt% with the addition of MAPP at 5 wt% of fillers. The presence of GCW and TLW in the PP matrix decreased tensile properties and impact resistance but increased flexural modulus and hardness of PP at high concentrations of GCW and TLW. The increase in GCW and TLW concentration slightly reduced melting temperature but it enhanced the tensile and flexural modulus. Furthermore, it enhanced the hardness, thermal and rheological properties of the composites. The TLW/PP composites had better mechanical properties, and rheological properties than GCW/PP composites but thermal properties were quite similar. The mechanical properties of GCW/TLW/PP hybrid composites were better than those of GCW/PP composites but lower than those of TLW/PP composites. The rheological and thermal behaviour of hybrid composites were like that of TLW/PP composites. Incorporating MAPP improves the mechanical and rheological behavior of PP composites by enhancing the interaction among PP, GCW, and TLW. However, this addition does not significantly enhance the composites’ thermal properties. The optimum composite was hybrid composites of GCW/TLW/PP consisting of GCW of 10 wt%, TLW of 20 wt%, and MAPP of 1.5 wt% which presented good mechanical, thermal, and rheological properties. The mechanical properties of this hybrid composites were as follows: a tensile strength of 26.35 MPa, elongation at break of 10.91%, tensile modulus of 636.69 MPa, flexural strength of 45.57 MPa, flexural modulus of 3632.86 MPa, impact resistance of 12.72 kJ/m2, and a Shore D hardness of 76.15. The overall results showed that GCW and TLW can be used as reinforcement material and natural pigment in the polymer matrix.