Polypropylene Composites Research Articles

Enhanced mechanical, thermal, barrier, and antibacterial properties of polypropylene nanocomposites reinforced with nano‐silver carbon black

AbstractThis study investigates the incorporation of nano‐silver carbon black (AgCB) into polypropylene (PP) to develop nanocomposites with enhanced mechanical, thermal, barrier, and antibacterial properties. AgCB, synthesized with a carbon black‐to‐silver ratio of 19:1, was incorporated into PP at 0.5–5 wt% via melt blending. At 1 wt%, AgCB improved tensile strength by 21.5%, enhanced thermal stability, and reduced water vapor and oxygen permeability, achieving optimal performance with uniform dispersion. With increasing AgCB content, antibacterial activity improved significantly, achieving a sterilization rate exceeding 99.7%, although higher concentrations led to agglomeration, reducing mechanical and barrier performance. The dual function of AgCB as a nucleating agent and functional additive was demonstrated through DSC, WAXRD, and antibacterial tests. This work highlights the potential of AgCB as a cost‐effective filler for PP composites, suitable for applications requiring enhanced durability, barrier properties, and antimicrobial efficacy.Highlights Nano‐silver carbon black improves PP crystallinity and barrier performance. Optimal 1 wt% AgCB enhances PP's tensile strength and thermal stability. AgCB creates tortuous pathways, reducing water vapor and oxygen permeability. Low‐cost AgCB (CB:Ag = 19:1) achieves strong antibacterial activity (>99% efficacy). AgCB mitigates nanoparticle agglomeration, enhancing filler dispersion in PP.

Synergistic effect of tannic acid/stearic acid/calcium carbonate/recycled polypropylene polymer composites and molecular dynamics simulation study

AbstractDeveloping high‐toughness recycled polypropylene (REPP) composites using non‐polluting and cost‐effective methods remains a major challenge. In this study, we propose a novel modification scheme using tannic acid (TA)/stearic acid (SA) synergistically modified CC as a filler to prepare composites by blending with REPP. Characterizations, such as mechanical tests and thermodynamic tests, verified that the CC‐TA‐SA modified composites presented higher tensile and impact strengths as well as crystallinity. The tensile strength of the composites was increased from 27.44 to 30.53 MPa and similarly the impact strength was increased from 10.63 to 24.81 MPa. The thermal stability and melt fluidity of the modified composites also improved. This phenomenon is further investigated through the use of molecular dynamics (MD) simulations. This research expands the promise of REPP composites for industrial applications with stringent toughness requirements.Highlights Tannic/stearic acids modulate the surface properties of calcium carbonate. Polymer composite reinforced with synergistically modified calcium carbonate. Molecular dynamics simulations to predict composite properties.

Fabrication of High-Strength Waste-Wind-Turbine-Blade-Powder-Reinforced Polypropylene Composite via Solid-State Stretching

In recent years, wind energy has emerged as one of the fastest-growing green technologies globally, with projections indicating that decommissioned wind turbine blades (WTBs) will accumulate to millions of tons by the 2030s. Due to their thermosetting nature and high glass/carbon fiber content, the efficient recycling of WTBs remains a challenge. In this study, we utilized solid-state shear milling (S3M) to produce a fine WTB powder, which then underwent surface modification with a silane coupling agent (KH550), and we subsequently fabricated WTB-reinforced polypropylene (PP) composites with enhanced mechanical performance through solid-state stretching. The stretching-process-induced orientation of the PP molecular chains and glass fibers led to orientation-induced crystallization of PP and significant improvements in the mechanical properties of the PP/WTB@550 composites. With 30 wt. % WTB content, the PP/WTB@550 composite achieved a tensile strength of 142.61 MPa and a Young’s modulus of 3991.19 MPa at a solid-state stretching temperature of 110 °C and a stretching ratio of 3, representing increases of 268% and 471%, respectively, compared to the unstretched sample. This work offers both theoretical insights and experimental evidence supporting the high-value recycling and reuse of WTBs through a cost-effective, environmentally friendly, and scalable approach. Due to the enhanced mechanical properties of the PP/WTB composite and the intrinsic waterproofing and corrosion resistance of PP, it is hoped that such a composite would be used in road engineering and building materials, such as geogrids, wall panels, floor boards, and floor tiles.

Multiscale analysis of the mechanical properties and interface damage mechanisms of carbon fiber reinforced polypropylene composites

AbstractIn this article, the mechanical properties of carbon fiber reinforced polypropylene (CF/PP) composites at different carbon fiber (CF) mass fractions were systematically investigated. A comprehensive examination is provided through the integration of experimental testing, numerical simulation, and theoretical analysis, revealing the enhancement effects of CF on the polypropylene (PP) matrix across multiple scales. Experimental results demonstrated that the incorporation of CF significantly impedes crack propagation and enhances the fracture resistance of the composites. Specifically, at a CF mass fraction of 15%, the elastic modulus of the composites is enhanced by 21.7% compared with pure PP, while the tensile strength increases by 40.9%–43.2%. The addition of maleic anhydride grafted polypropylene (MAH‐g‐PP) as a compatibilizer significantly improves the interfacial compatibility between CF/PP. Furthermore, finite element simulations revealed the damage evolution process at the CF/PP interface during tensile loading. Based on the Mori‐Tanaka model, the elastic modulus was predicted, aligning well with experimental and simulated results. This research offers a scientific basis for the design and application of CF/PP composites and contributes to the advancement of high‐performance composites.Highlights CF/PP composites show enhancements in mechanical properties with CF addition MAH improves interfacial adhesion between CF and PP, boosting tensile strength Multiscale experimental and FEA studies reveal CF/PP interface damage mechanisms Mori‐Tanaka model accurately predicts the elastic modulus of CF/PP composites

Flame Retardancy and Heat Shielding in Green Polypropylene Composites Using Biohybrid Fibers and Agro-Waste Fillers.

The current work presents the flame-retardant performance of hybrid polypropylene composites, reinforced with specific short woven flax fabrics (SWFs), short basalt fibers (BFs), and rice husk powder (RHP), using polypropylene grafted maleic anhydride (MAPP) as the coupling agent. Horizontal burning test (HBT), microcalorimeter test (MCT), and cone calorimeter test (CCT) were conducted on these composites. The formulations used were 25% SWF/PP, 25% SWF/20% BF/PP, and 25% SWF/20% BF/PP with 6% RHP and 25% SWF/20% BF/PP with varying RHP contents (6, 12, and 18%) in combination with 6% MAPP. A peak heat release rate (pHRR) reduction of 14.42% was recorded in microcalorimeter test results. However, cone calorimeter test results indicated a reduction of 80.95% in pHRR and 23.84% in total heat release rate (THR). Furthermore, the emissions of CO and CO2 were reduced by 68 and 67%, respectively, in the 25SWF/20BF/PP.6MAPP-18RHP composite compared to pure PP, indicating an overall improvement in combustion efficiency. Fire performance index (FPI) also improved remarkably: FPI increased by 130% and fire growth index (FGI) improved by 81.34%. Moreover, the horizontal burning test showed an improved performance, with the burning rate further reduced by 11.10% compared to that of the 25% SWF/PP composite. These results highlight the synergy among natural fibers, agro-waste fillers, and MAPP in improving flame retardancy of polypropylene composites, and hence their potential application in automobiles and construction, where the demand for fire safety is very high.

Enhancement of Thermal, Mechanical, and Oxidative Properties of Polypropylene Composites with Exfoliated Hexagonal Boron Nitride Nanosheets.

This study investigates the enhancement of polypropylene (PP) composites through the incorporation of exfoliated hexagonal boron nitride (h-BN) nanosheets. The preparation process involved exfoliating h-BN in a liquid phase using a high-pressure homogenizer, followed by the coating of PP pellets with the exfoliated nanosheets using an acoustic mixer. Melt extrusion was then employed to fabricate h-BN-reinforced PP composite films. Characterization techniques, including scanning electron microscopy, confirmed the uniform dispersion of exfoliated h-BN within the PP matrix, which is crucial for improving thermal conductivity, mechanical strength, and oxidative stability. Tensile testing demonstrated that exfoliated h-BN significantly enhanced the strength and toughness of homopolymer PP, while the improvements in impact copolymer PP were more modest. Thermal analysis revealed no significant change in the decomposition temperatures of PP but indicated improved oxidative stability with the incorporation of h-BN nanosheets. Notably, the oxidation resistance of PP was enhanced, as evidenced by reduced carbonyl index values in thermally aged samples. Overall, exfoliated h-BN nanosheets significantly improve the performance of PP composites, demonstrating their potential for diverse industrial applications that require superior thermal and mechanical properties, as well as enhanced oxidation resistance.

Biomimetic flow field flame retardant modification of sisal fiber and its polypropylene composites

The lumen of sisal fiber provides a good space for loading flame retardants and constructing a three-dimensional flame-retardant network, effectively improving the flame retardancy of their polymer composites. In this study, we combined water/nutrient transport mechanism of plant fiber with layer-by-layer self-assembly technology, innovated a biomimetic flow field flame retardant modification method and successfully deposited ammonium polyphosphate (APP) and polyethyleneimine (PEI) into sisal fiber lumen. After 20 cycles modification, the flame retardants in fiber increased to 18.36wt%. Its TG residue achieved to 43.23% from 17.35% (unmodified) and its limited oxygen index (LOI) value achieved to 39.1% from 20.7% (unmodified). Compared to directly immersing fiber in APP/PEI solution, this method mitigated the blockage of flame retardants at lumen entrance and realized a uniformly deposition in lumen interior. When blending this modified fiber with polypropylene (PP) at 30wt% (the flame retardant content is only about 4.65wt%), the composite TG residue increased from 3.10% (unmodified) to 15.77%, and its LOI value increased from 19.4% (unmodified) to 23.2%. This composites also has better flame retardancy than APP/PEI directly dispersed in PP matrix (TG residues 11.10%, LOI value 21.1%). For sisal fiber polymer composites, employing fiber lumen as flame retardant carrier could improve its flame retardancy efficiently. The carried flame retardants inhibit the combustion of flammable sisal fiber, and the constructed flame-retardant network restrict PP matrix combustion.

Investigation of mechanical, morphological and thermal properties of waste glass powder and wood flour reinforced polypropylene composite

Investigation of mechanical, morphological and thermal properties of waste glass powder and wood flour reinforced polypropylene composite

Tensile performance of bamboo fibre reinforced recycled polypropylene composites produced via injection moulding technique

Tensile performance of bamboo fibre reinforced recycled polypropylene composites produced via injection moulding technique

Preparation of APP@CNCSi-DA and its application in intumescent flame retardant polypropylene.

A Silicon-containing Oligomeric Charring Agent (CNCSi-DA) containing triazine rings and silicon was designed, synthesized and characterized. CNCSi-DA was chosen as macromolecular coating agent to modify Ammonium Polyphosphate (APP) to be core-shell coating-mixture (APP@CNCSi-DA). The synergistic effects of APP@CNCSi-DA on hydrophobicity, mechanical and flame retardant properties, and mechanism of flame-retardant polypropylene (PP) were studied. It was obvious that when the mass ration of APP to CNCSi-DA in APP@CNCSi-DA ranged from 15:15 to 0:30, the water contact angle meter (WCA) value of PP composites were higher than 90°. The CNCSi-DA reinforced the compatibility and improved the flexible and impact strength. APP@CNCSi-DA was highly effective in enhancing the flame retardancy of PP. When the weight ratio of APP to CNCSi-DA was 2:1 with 30% content, the limited oxygen index (LOI) of the composite reached the peak of 35.9%, which achieved UL-94 V-0. The IFR lowered flammability parameters significantly analyzed by cone calorimeter test.

Flame-retardant effects of NH2-MIL-53(Al) in combination with phosphorus-containing and nitrogen-containing flame retardants on polypropylene

Polypropylene (PP) flammability poses great fire risks for its application. A metal-organic framework (MOF), NH2-MIL-53(Al), was synthesized and subsequently integrated into PP, the flame-retardant efficacy in conjunction with piperazine pyrophosphate (PAPP) and melamine cyanurate (MCA) was additionally examined. When the total mass fraction of the additives was 25 %, the limiting oxygen index (LOI) of PP composite reached 31.1 %, it also passed the UL-94 test with a V-0 rating. The peak heat release rate (pHRR) and the total heat release rate (THR) was reduced by 88.55 % and 79.75 %, respectively, compared with the pure PP. The char residual char percentage increased to 8.02 %. The Tensile Strength reached 30.1 MPa. The results indicate that adding NH2-MIL-53(Al) significantly enhanced the flame retardancy and thermal stability of PP composites, without significantly affecting their mechanical properties, which offers a novel potential direction for the advancement of polymer flame retardants (FRs).

In English

Iron-containing polypropylene (PP) composites were synthesized by precipitating iron(III) nitrate from aqueous solutions of varying concentrations onto a polypropylene matrix, followed by drying at ≤110°C and heating at ≤230°C temperatures. The resulting composites were characterized using scanning electron microscopy combined with energy-dispersive elemental analysis (SEM/EDS), X-ray diffractometry (XRD), and electron magnetic resonance (EMR).The study revealed that the composites obtained through thermal decomposition of iron(III) nitrate from aqueous solutions on a polypropylene matrix, with subsequent heat treatment at 220°C, form a two-phase system consisting of isotactic polypropylene and magnetite. SEM/EDS data showed a non-uniform distribution of the iron-containing component on the PP surface, even in samples with less than 1% by weight of the iron component. FMR spectra indicated the formation of superparamagnetic and ferromagnetic particles within the polypropylene matrix, attributed to nanosized magnetite particles of varying dimensions.Theoretical spectra were calculated using the Landau-Lifshitz-Gilbert equation, considering Lorentzian, Gaussian, and Dyson resonance signal shapes. These theoretical spectra, which accounted for the dependence of g-factor values and line widths of the FMR spectra on particle size, were adjusted to match the experimental data to clarify the magnetic resonance characteristics of the iron-containing particles.The study concluded that magnetite particles formed during the thermal decomposition of iron(III) nitrate deposited from an aqueous solution onto the polypropylene matrix do not interact significantly with the polypropylene. These particles remain mobile on the polymer surface and are prone to aggregation, posing challenges for achieving a uniform composite material.

Comparative Effects of Carbon Fiber Reinforcement on Polypropylene and Polylactic Acid Composites in Fused Deposition Modeling.

Comparative Effects of Carbon Fiber Reinforcement on Polypropylene and Polylactic Acid Composites in Fused Deposition Modeling.

Effects of Consolidation Parameters on Flexural Behavior of Polypropylene/Glass Fiber Thermoplastic Composites

In this study, the flexural behavior of glass fiber-reinforced polypropylene (GFR-PP) composites was systematically investigated under three-point bending conditions to evaluate the impact of key production parameters. Composite plates with a thickness of 4 mm were fabricated using a stepped mold under varying pressure levels (10, 20, and 30 bar) and durations under pressure (5, 10, and 20 minutes). The specimens were prepared according to ASTM standards to ensure consistency and reliability. The primary objective of this study was to understand how production parameters influence the mechanical properties of GFR-PP composites. The results indicated that the combination of low pressure (10 bar) and longer durations (20 minutes) led to superior flexural strength and enhanced fiber-matrix adhesion due to optimized consolidation, with a maximum flexural strength exceeding 500 MPa. In contrast, higher pressure levels (30 bar) resulted in fiber deformation and reduced mechanical performance. This work provides critical insights into the optimization of production parameters to achieve high-performance GFR-PP composites, with potential applications in aerospace and other lightweight structural components requiring high mechanical strength and durability.

Effect of particle size and loading of cherry tree branch fillers on the mechanical and viscoelastic properties of polypropylene composites

Effect of particle size and loading of cherry tree branch fillers on the mechanical and viscoelastic properties of polypropylene composites

Improved fracture toughness of glass fibers reinforced polypropylene composites through hybridization with polyolefin elastomers and polymeric fibers for automotive applications

AbstractPolypropylene‐reinforced composites mostly exhibit a trade‐off between stiffness and toughness. In this study, the impact of incorporating polyolefin elastomer (POE) and Polyvinyl Alcohol (PVA) fibers as individual and hybrid reinforcement to glass fiber‐reinforced polypropylene composite in the presence of a compatibilizer was explored. The main focus was on achieving an optimal stiffness/toughness balance. Several ternary and quaternary hybrid composite systems were developed and analyzed. All components were melt‐blended using a twin‐screw extruder and then injection molded for subsequent mechanical and morphological analysis. A significant stiffness of approximately 2.4 GPa Young's modulus, and notched izod impact strength ranges between 250 and 400 J/m can be attained with the quaternary hybrid system, PP/GF/POE/PVA fibers. Its performance can be controlled by altering the POE/PVA fibers ratio to achieve the targeted stiffness/toughness balance. These values represent a remarkable increase, with Young's modulus being 120% higher and the izod impact strength surpassing that of the control sample by over 800%. The achieved results aligned with the requirements of the automotive industry, so the developed composites could have a high potential for automotive parts.Highlights Ternary and quaternary hybrid systems were fabricated by a twin‐screw extruder. An improvement of 120% in stiffness and 800% in toughness was observed. Distinct micromechanical deformation mechanisms were identified. Remarkable stiffness‐toughness balance was achieved. Reduction in weight makes the system suitable for automotive applications.

Rotomolded polypropylene‐ignimbrite composites: Giving a second life to mineral dust wastes

AbstractThe possibility of rotomolding polypropylene (PP) composites with high loadings of a silica‐based dust of ignimbrite, a byproduct of volcanic stone extraction is demonstrated. This study aims to establish the properties of composites with various ratios of mineral dust as a filler in PP matrices at loadings from 5 to 30 wt%, ultimately transforming mining residues into a valuable resource for composite production and creating a value chain around the traditional mining industry. Once the composites were obtained, they were subjected to several characterization techniques to comprehensively assess their mechanical and thermal properties. In general, a high percentage of ignimbrite powder has resulted in a reduction in the mechanical properties of neat PP, although no significant changes were observed for composites at lower loadings. Furthermore, the incorporation of this mineral material modified the thermal properties of the PP, enhancing its thermal stability. The blending of the matrix and filler resulted in a reduction in both the melting crystallization temperatures for highly‐filled composites. Rotomolded items with good aesthetics, with stone‐like appearance, were obtained without any modification on the mineral dust or even without any melt compounding, therefore not increasing the energy consumption during the composites production.Highlights Composites production is a suitable strategy for valorization of mineral residues. Welded ignimbrite residual dust has been used for the first time in composites. Mineral dust has been successfully used in composites obtained by rotomolding. Polypropylene with up to 30% of the stone dust can be processed. Good aesthetics and mechanical features can be obtained with mineral wastes.

Development of an Automotive-Relevant Recycling Process for Paper Fiber-Reinforced Polypropylene Composites

The automotive industry is under growing pressure from regulatory agencies to improve the recyclability of its plastic components. Simultaneously, manufacturers are adopting natural fiber composites in vehicles to reduce their carbon footprint 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.

Effect of soft and hard segments ratio of waterborne polyurethane on the properties of modified basalt fiber reinforced polypropylene composites

Effect of soft and hard segments ratio of waterborne polyurethane on the properties of modified basalt fiber reinforced polypropylene composites

Fabrication of microfibrillated cellulose reinforced polypropylene composites assisted by a synergistic strategy of pre‐quaternization and paper‐making process

AbstractTo tackle the ease of aggregation issue of highly hydrophilic microfibrillated cellulose (MFC) in polypropylene (PP) that thus results in an undesired reinforcing effect, this work developed an effective and industrially feasible strategy combining pre‐quaternization of pulp fibers with paper‐making process to fabricate PP/MFC composite with enhanced performance. Effects of MFC consistency, maleic anhydride grafted polypropylene (MAPP) content, and plasma treatment of chopped PP fibers on the mechanical and thermal properties of resultant composites were systematically investigated. The surface‐quaternized MFC obtained by a low‐consistency refiner (L‐MFC) exhibited a higher aspect ratio and degree of fibrillation than the corresponding surface‐quaternized MFC obtained by a high‐consistency one (H‐MFC). It was found that there existed a synergistic effect between pre‐quaternization and the paper‐making process in promoting the dispersion of MFC in PP. As compared with L‐MFC, a higher reinforcing efficiency on PP was achieved for H‐MFC, which was because the former one was more prone to form the fibril aggregates in the PP matrix. Due to both the entangled network of MFC and its nucleation effect on PP, the heat deflection temperature (HDT) of resulting composites was largely increased up to 159.9°C, an increase of 68.7°C with respect to that of PP.Highlights The H‐MFC yielded a superior reinforcement on PP than L‐MFC. The optimum mechanical properties of PP/composites were achieved at 15% MAPP. Interfacial bonding between PP and H‐MFC was enhanced by plasma treatment. An increase in Tc of the PP matrix was noted for PP/MFC. A maximum increase of 159.9°C in HDT was achieved for PP/MFC.