Maleic Anhydride-grafted Polyethylene Research Articles

Improving the antibacterial properties of polyethylene food packaging films with Ajwain essential oil adsorbed on chitosan particles

The aim of this research is to develop a composite antibacterial film for food packaging using low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polyethylene-graft-maleic anhydride (PE-g-MA), and incorporating chitosan (CS) particles onto which ajwan essential oil (AEO) is adsorbed. The films were characterized using various techniques, including Fourier-transform infrared spectroscopy (FTIR), Gas chromatography/mass spectroscopy (GC-MS), X-ray diffraction (XRD), tensile testing, oxygen transmission rate (OTR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and antibacterial assays. FTIR results confirmed the presence of CS and/or AEO in the films. Mechanical testing indicated a decrease in tensile strength and an increase in elongation at break with the addition of AEO, while CS reduced elongation. In the sample containing only 7.5% chitosan (PE-7.5-0), the oxygen permeability was reduced to 910 cm2/m2·day·bar due to the presence of CS. However, the inclusion of AEO in the sample (PE-0-10) increased the oxygen permeability to 2200 cm2/m2·day·bar, which is higher than that of the control sample (PE-0-0) with an oxygen permeability of 1680 cm2/m2·day·bar. The antibacterial activity results demonstrated a synergistic inhibitory effect of CS and AEO. Data from GC-MS and inhibition zone (IZ) tests indicated that while chitosan alone does not exhibit significant antibacterial activity due to its incorporation in the bulk of the film, its combination with AEO enhances antibacterial efficacy. This enhancement occurs as the oil is adsorbed and protected from evaporation during the film formation process. Overall, the findings from this research suggest that the composite film PE-7.5-10, which possesses suitable mechanical properties and significant antibacterial activity, could be an effective candidate for food packaging applications.

Impact of Surface Modification of Hemp Fibers Using a Coupling Agent in Solvent on the Properties of Polyethylene Composites

This study investigates the grafting of a coupling agent, maleic anhydride-grafted polyethylene (MAPE), onto hemp fibers in a 1,2,4-trichlorobenzene (TCB) solution, followed by an evaluation of the morphological, rheological, and mechanical properties of the resulting polyethylene composites containing 30% hemp. The SEM analysis revealed that a thin layer of MAPE formed on the surface of the modified fibers. This was further confirmed by the appearance of a MAPE degradation peak at 448°C, observed in the modified fibers but absent in the unmodified counterparts. Composites made with unmodified hemp fibers (UT30) showed a significant increase in modulus but not in tensile strength. In contrast, the modification of hemp in solution significantly enhanced the tensile strength of the composites (UTE3S) without significantly affecting the modulus. Increasing the amount of coupling agent (in UTE6S and UTE9S) reinforced this trend, indicating that the thin polymer layer on the surface of the modified hemp fibers notably improved interfacial bonding, with minimal impact on the tensile modulus of the composites.

Interfacial properties of polyethylene/poly(lactic acid)/maleic anhydride-grafted polyethylene ternary blends and its relationship with rheology, morphology and mechanical properties

Interfacial properties of polyethylene/poly(lactic acid)/maleic anhydride-grafted polyethylene ternary blends and its relationship with rheology, morphology and mechanical properties

Amide wax-assisted interfacial compatibilization of maleic anhydride-grafted polyethylene for high-performance wood-plastic composites

ABSTRACT The interfacial compatibility between wood fibers and plastics is one of the key problems in the preparation of high-performance wood-plastic composites (WPCs). However, the current compatibilization strategy primarily relies on a single compatibilizer, but the resulting effect is less than ideal. In this study, the combination of maleic anhydride-grafted polyethylene (MAPE) and amide wax (AW) was adopted for the synergistic compatibilization of WPCs. This approach enabled the high mobility of AW to fully penetrate the surfaces and voids of wood fibers, facilitating the interfacial migration of MAPE and resulting in strong compatibilization effects. The dual compatibilization mechanism was revealed based on the results of polarized light microscope (PLM), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). As a consequence, the WPCs compatibilized by MAPE and AW compounds possessed better thermal stability, as well as slightly higher dynamic modulus and complex viscosity. The tensile strength and flexural strength of the WPCs reached to 55 and 45 MPa, increased by approximately 26% compared to the WPCs compatibilized by single MAPE. The dual compatibilization strategy can effectively solve poor interfacial adhesion of WPCs, enabling the preparation of high-performance and environmental-friendly WPCs, and also be readily extended to other composites.

Thermorheological complexity in Nylon12‐Cork composites: Role of interfacial compatibilizer

AbstractHerein, we demonstrate how compatibilizers affect the thermorheological properties and morphology of engineering thermoplastic composites based on nylon and cork. Nylon12 was melt‐mixed with cork treated with four distinct compatibilizers with radically different chemical structures and compositions, respectively: (i) Octadecanamide (ODA), (ii) polyethylene‐graft‐maleic anhydride (PE‐g‐MA), (iii) polypropylene‐graft‐maleic anhydride (PP‐g‐MA), and (iv) (3‐aminopropyl)triethoxysilane (APTS). The rheological behavior was assessed using an oscillatory rheometer and the morphology was visualized using a scanning electron microscope. The rheological data were thoroughly analyzed using different formalisms based on empirical, phenomenological, and molecular origin, including the Carreau‐model, time–temperature superposition (TTS), Han plot, and van Gurp–Palmen (vGP) plot. It is observed that rheological data of neat nylon can be treated as themorheologically simple. However, the inclusion of cork makes the composite thermorheologically complex and increases the relaxation time (τ) by >50‐fold when compared to the neat polymer. As compatibilizers, ODA and PP‐g‐MA significantly lower τ, improve internal flow behavior, and demonstrate good cork distribution and dispersion. However, PE‐g‐MA does not affect the τ of composites significantly. The application of APTS as a compatibilizer enhances the interfacial interaction between Nylon12 and cork most significantly, which leads to a notable rise in τ, and the composite's elastic modulus surges by two orders in magnitude compared to neat Nylon. Additionally, the polymer melt flow becomes elastically dominant. Finally, it is observed that the Han plot offers a better insight into the correlation between changes in the thermorheological behavior and the microstructural modifications to the composites.Highlights Utilizing cork particles as a sustainable raw material for engineering thermoplastics. Quantifying compatibilizer's impact on rheological properties of polymer composite. Illustrating how interfacial interaction affects thermorheological complexity in composites. Visualizing morphological change in nylon‐cork composite with interfacial interaction. Producing lightweight engineering polymer composites using cork as a filler.

Fabrication of biopolyethylene-based biocomposites with coffee ground waste: Effect of polyethylene-graft-maleic anhydride

The production of plastic products from non-renewable raw materials, such as petroleum, damages the environment. Consequently, biocomposites have aroused interest from industry and researchers due to their ecologically correct characteristics, mainly because they come from renewable sources. Therefore, this study aimed to produce biopolyethylene/coffee ground waste (BioPE/CGW) biocomposites and analyze the impact of CGW and polyethylene-graft-maleic anhydride (PE-g-MA) on BioPE. The biocomposites were prepared in a co-rotational twin-screw extruder equipped with a side feeder to feed the CGW. The materials were subsequently injection molded to produce the impact, tensile, and HDT samples. The temperature profiles used during extrusion and injection were between 170 and 180°C. The BioPE and biocomposites were investigated for the vibrational (Infrared Spectroscopy - FTIR), thermal (differential scanning calorimetry), mechanical (tensile, impact, and hardness), thermomechanical (heat deflection temperature (HDT) and Vicat softening temperature (VST)), and morphological (scanning electron microscopy (SEM)) properties. The compatibilizer improved the interface between phases, promoting mechanical and thermomechanical improvements in the biocomposites. PE-g-MA promoted increments in tensile strength and elastic modulus of up to 38% and 25% in the BioPE/CGW30 and an increase of 44% in the elastic modulus compared to BioPE. The thermomechanical investigations showed that HDT increased by 8.8 and 3.3°C and VST increased by 2.5 and 6.6°C compared to BioPE and the BioPE/CGW30, respectively. Biocomposites from renewable and biodegradable sources align with a sustainable development concept.

Multi-approach synthesis of functionalized graphene oxide as reinforcement for polyethylene: Make a strong interaction

Nanoparticles need to be well dispersed in a polymer matrix to employ their advantages. Their agglomeration may cause defects and stress concentrations, deteriorating the final properties of polymer/graphene nanocomposite. Here graphene oxide (GO) was functionalized in several ways to improve its interaction with polyethylene and dispersion. Polyethylene-grafted maleic anhydride (PE-g-MA) with strong polar groups was used as the matrix to consider a high potential of enhanced interaction with the GO nanoparticles and therefore obtain a high-performance polyolefin composite. First, GO was produced by modified Hammer’s method from graphite. The GO was aminated by phenylene diamine and named FGO. Also GO was reduced chemically to obtain CRGO and thermally to obtain TRGO and then the recent ones were amino functionalized, named FCRGO and FTRGO, respectively. In another route GO was first amino functionalized and then was reduced chemically and named FCRGO+. The synthesized nanoparticles were characterized by visual tests, FTIR, XRD, SEM, and TGA analysis. Subsequently, the study investigates the fabrication of nanocomposites using these nanoparticles at 2 wt% in the PE-g-MA matrix by solution-casting method. The nanocomposites were characterized by optical microscopy, tensile and rheometric tests, FTIR, DSC, and SEM analysis. Based on the results, FCRGO+ was identified as the optimum nanoparticle having better dispersion, improved interfacial interaction, and stronger mechanical properties. The GO functionalized nanocomposites showed up to 36% in tensile modulus, 56% in tensile strength and 70% in elongation at break as compared to those of GO nanocomposites without functionalization of GO.

Thermo-mechanical performance characteristics of glass reinforced HDPE composites: A comprehensive review

Millions of tonnes of plastic and glass waste is produced worldwide, with only a limited quantity being recycled with the majority ending up in landfill, our oceans or in stockpiles. Even though current applications exist for recycled glass and plastic, there is still a need to introduce recyclate to different industries. This review presents an investigation aimed at mechanical and thermal property improvements by the incorporation of reinforcement material into a polymeric matrix. The performance of high-density polyethylene (HDPE) and glass composites manufactured with different levels of glass, additives and surface treatments have been evaluated by analysing several past investigations. The critical parameters influencing the mechanical and thermal performance of HDPE-Glass composites were identified to be the type of reinforcement, glass content, additives utilised, and the different manufacturing methods employed. Optimised mix designs proposed by researchers have been analysed along with reaction mechanisms. This review has identified a composite material to be further refined and optimised with the potential to be improved by integrating reclaimed waste to manufacture composites by promoting a zero-waste economy. Improvements in tensile strength up to 71% can be observed with the implementation of 20% by weight of glass reinforcement in HDPE composites. The use of maleic anhydride grafted polyethylene (MAgPE) as a compatibilizer facilitates the stress transfer between the two phases by improving their bonding with tensile and flexural strength increments up to 85% and 25%, respectively. This review is a valuable resource for future researchers as it identifies crucial research gaps in HDPE-Glass composite manufacturing and synthesises key findings in existing literature.

Synthesis of polyethylene-based covalent adaptable networks including 1,2,3-triazolium or imine dynamic cross-links by reactive processing

Polyethylene-based covalent adaptable networks (PE CANs) are obtained by reactive extrusion in a micro-compounder of a commercial maleic anhydride-grafted polyethylene (PE-g-MA) with two tailor-made α,ω-diamine cross-linkers carrying either imine or 1,2,3-triazolium groups as dissociative covalent dynamic bonds. Depending on the chemical nature of the exchangeable bonds, drastically different properties are demonstrated by FTIR, swelling/extractible, reactive dissolution and rheological experiments. The imine-containing PE CAN yields a high gel fraction but rheology and reactive dissolution experiments demonstrate the lack of dynamicity due to side-reactions promoting the formation of non-dynamic covalent cross-links. Such undesirable reaction occurs already during the processing stage from the premature cleavage of the imine bonds into amines, and further formation of permanent imide cross-links by reaction with pendent maleic anhydrides. Conversely, the 1,2,3-triazolium-containing PE CAN presents a lower gel fraction but exhibits viscoelastic properties typical of dissociative CANs. While this material is easily reprocessable by compression moulding, the evolution of the rheological properties at high temperatures (160–200 °C) points toward the occurrence of side reactions slowing down the relaxation dynamics which we attribute to the chemical rearrangement of the 1,2,3-triazolium cross-links. These two examples illustrate the difficulty of using amine-functionalized dynamic cross-links in the synthesis of PE CANs by reactive extrusion using PE-g-MA.

Optimization of the performance of CsPbI2Br perovskite solar cells in air by adding polyethylene-graft-maleic anhydride and its mechanism

In this study, by adding Polyethylene-graft-maleic anhydride (PGMA) to the inorganic CsPbI2Br perovskite film, the coordination bonds and hydrogen bonds between PGMA and CsPbI2Br cooperate to passivate defects, regulate energy level and stabilize the perovskite structure and eventually improve the device performance. We systematically study the effects of PGMA addition on the morphology, structure, light absorption, defect concentration and carrier lifetime, hydrophobicity, and optical stability and room temperature black phase stability of CsPbI2Br films, and the photoelectric performance and air stability of PSCs, as well as their mechanism. The experimental results show that the addition of 3 wt% of PGMA greatly improves the photoelectric conversion efficiency (PCE) of CsPbI2Br PSCs by 40.19 % because of the synergistic passivation effects and energy level tuning. The hydrogen bonds between –CH2 in PGMA and I−/Br− in CsPbI2Br, along with the coordination of carbonyl groups with Cs+/Pb2+, improve carrier transport and collection by inactivating flaw and managing the level, reducing the non-radiative recombination losses. In addition, the PSCs with 3 wt% of PGMA maintain 80 % of their initial efficiency even after 600 h in high humidity air environment due to the synergistic effect of coordination bonds and hydrogen bonds. Our study provides valuable insights into the use of PGMA to improve the performance of all-inorganic CsPbI2Br PSCs and the practicality of perovskite solar cells.

Compatibilization of Polyamide 6/Cyclic Olefinic Copolymer Blends for the Development of Multifunctional Thermoplastic Composites with Self-Healing Capability.

This study investigated the self-healing properties of PA6/COC blends, in particular, the impact of three compatibilizers on the rheological, microstructural, and thermomechanical properties. Dynamic rheological analysis revealed that ethylene glycidyl methacrylate (E-GMA) played a crucial role in reducing interfacial tension and promoting PA6 chain entanglement with COC domains. Mechanical tests showed that poly(ethylene)-graft-maleic anhydride (PE-g-MAH) and polyolefin elastomer-graft-maleic anhydride (POE-g-MAH) compatibilizers enhanced elongation at break, while E-GMA had a milder effect. A thermal healing process at 140 °C for 1 h was carried out on specimens broken in fracture toughness tests, performed under quasi-static and impact conditions, and healing efficiency (HE) was evaluated as the ratio of critical stress intensity factors of healed and virgin samples. All the compatibilizers increased HE, especially E-GMA, achieving 28.5% and 68% in quasi-static and impact conditions, respectively. SEM images of specimens tested in quasi-static conditions showed that all the compatibilizers induced PA6 plasticization and crack corrugation, thus hindering COC flow in the crack zone. Conversely, under impact conditions, E-GMA led to the formation of brittle fractures with planar surfaces, promoting COC flow and thus higher HE values. This study demonstrated that compatibilizers, loading mode, and fracture surface morphologies strongly influenced self-healing performance.

Olive stone as a filler for recycled high-density polyethylene: A promising valorization of solid wastes from olive oil industry

The valorization of solid residues generated from olive oil production is a challenging issue for olive oil-producing countries such as Greece, Italy, Spain, etc. Olive stone waste is a type of lignocellulosic biomass with potential use as a natural additive in polymeric composites. In the present study, olive stone waste was compounded with recycled high-density polyethylene (rHDPE) via melt mixing in 5 %, 10 %, and 20 % wt. Additionally, the effect of Joncryl (JC) and polyethylene-grafted maleic anhydride (PE-g-MA) as compatibilizers on the properties of the green composites was also investigated. It is worth mentioning that JC was employed for the first time as a compatibilizer for polyolefin composites with olive stone. The materials underwent structural, thermal, and mechanical characterization using multiple complementary techniques. Scanning electron microscopy showed good dispersion of the filler for all composites, while in the compatibilized samples a markedly better adhesion was observed. Tensile tests revealed an increase in the elastic modulus for the composite with 10 % wt. olive stone. Furthermore, all materials demonstrated a strong antioxidant activity, rendering them interesting for active packaging applications. Overall, the solid residue from olive processing can enhance the properties of rHDPE, paving the way to promote circular economy.

Assessing the recycling potential of thermosetting polymer waste in high-density polyethylene composites for safety helmet applications

Abstract The rising demand for thermosetting polymers has resulted in the production of large amounts of industrial waste. Environmental issues due to waste landfills and increased raw material costs for new product development have led to the development of innovative recycling methods. This study focuses on the development of a product (helmet shell) by reinforcing thermosetting polymer waste (TPW) as a filler in a high-density polyethylene (HDPE) matrix. The HDPE and TPW were converted into extrudates using a twin-screw extruder. Then, the extrudate was pelletized to use as raw material for the injection molding machine. The HDPE/TPW composites were fabricated using injection molding. Maleic anhydride-grafted polyethylene was employed as a compatibilizer. In the composite, the TPW volume was reinforced at various weight percentages, ranging from 0 to 35 wt%. The mechanical, thermal, and viscoelastic properties of the composites can be enhanced by uniformly dispersing TPW in the HDPE matrix. However, it is difficult to achieve uniform dispersion at higher TPW volumes owing to the agglomeration effect. According to these findings, the mechanical properties were enhanced by up to 30 wt% addition of TPW. The findings suggest that the proposed composite has sufficient mechanical properties to be suitable for the fabrication of helmet shells.

Green Bionanocomposites of Poly(Lactic Acid) (PLA) and Linear Low-Density Polyethylene (LLDPE): Fabrication and Properties

This study utilizes a polymer matrix made from a combination of Poly (Lactic Acid) (PLA) and Linear Low-Density Polyethylene (LLDPE). The polymer matrix is then improved by adding a compatibilizer, Polyethylene-graft-maleic anhydride (PE-g-MA), a filler, Recycled Tyre Waste (RTW), and a nano-scale filler, Graphene nanoplatelets (GNPs). Examining how PE-g-MA, RTW, and GNPs influence the binary blend's (PLA/RTW) chemical and thermo-mechanical characteristics is the focus of this study. A twin-screw extruder is used for the melting and intercalating processes. The binary mixture consists of 5% PE-g-MA, five percent RTW, and 3% GNPs. The samples are then pelletized after being cooled to room temperature. Analysis and characterization of the pelletized samples thermal and chemical characteristics follow. After including a compatibilizer, filler, and nanofiller into the bionanocomposite, improved qualities are anticipated.

Avocado Pruning Residues for the Formulation of Bio‐Based Polyethylene/Fiber‐Based Biocomposites for Sustainable Food Packaging

AbstractThe extensive use of non‐biodegradable bioplastics and fossil‐based plastics in food packaging presents a significant environmental challenge. Consequently, there has been a growing interest in exploring agricultural biomass as a potential source for formulating biocomposites for packaging due to the substantial amount of lignocellulosic residue generated. This study explores the utilization of avocado pruning residue (APR) for isolating lignocellulose fibers and their application as replacement and reinforcement material for bio‐based polyethylene (BioPE) composites. The results obtained reveal that a concentration of 9% (w/w) of maleic anhydride‐grafted‐polyethylene (MAPE) shows the most effective fiber–polymer interaction, resulting in a significant improvement of 25.47% in the mechanical properties. Biocomposites with varying fiber concentrations, ranging from 10% to 40% (w/w), are prepared and assessed for their macro‐ and micromechanical properties. The results demonstrate a substantial 49% increase in tensile strength and a remarkable 325% enhancement in Young's modulus for biocomposites containing 40% (w/w) fiber content. Furthermore, micromechanical analysis provides insights into the intrinsic strength and modulus of avocado fibers, with values of ≈437 MPa and 33 GPa, respectively. This research contributes to the development of sustainable and eco‐friendly alternatives for food packaging, reducing the reliance on fossil‐based plastics, and promoting the utilization of agricultural waste.

A polyamide and polyethylene multilayer composite with enhanced barrier and mechanical properties at high temperature

An advanced multilayer thermoplastic composite, composed of Polyethylene of Raised Temperature (PERT), Polyamide 12 (PA12), and Maleic Anhydride Grafted Polyethylene (MA), has been developed for high-temperature, high-pressure applications.

On the Mechanical, Thermal, and Rheological Properties of Polyethylene/Ultra-High Molecular Weight Polypropylene Blends.

The novel ultra-high molecular weight polypropylene (UHMWPP) as a dispersed component was melt blended with conventional high-density polyethylene (PE) and maleic anhydride grafted-polyethylene (mPE) in different proportions through a kneader. Ultra-high molecular weight polypropylene is a high-performance polymer material that has excellent mechanical properties and toughness compared to other polymers. Mechanical, thermal, and rheological properties were presented for various UHMWPP loadings, and correlations between mechanical and rheological properties were examined. Optimal comprehensive mechanical properties are achieved when the UHMWPP content reaches approximately 50 wt%, although the elongation properties do not match those of pure PE or mPE. However, it is worth noting that the elongation properties of these blends did not match those of PE or mPE. Particularly, for the PE/UHMWPP blends, a significant drop in tensile strength was observed as the UHMWPP content decreased (from 30.24 MPa for P50U50 to 13.12 MPa for P90U10). In contrast, the mPE/UHMWPP blends demonstrated only minimal changes in tensile strength (ranging from 29 MPa for mP50U50 to 24.64 MPa for mP90U10) as UHMWPP content varied. The storage modulus of the PE/UHMWPP blends increased drastically with the UHMWPP content due to the UHMWPP chain entanglements and rigidity. Additionally, we noted a substantial reduction in the melt index of the blend system when the UHMWPP content exceeded 10% by weight.

Effect of different modifiers on tobacco stalk fiber/high‐density polyethylene composites

AbstractAgricultural waste fiber has huge utilization potential due to its abundant sources, renewability, and low recycling costs. In this process, up to 30 wt% tobacco stalk fiber (TSF) was compounded with high‐density polyethylene (HDPE) and interfacial modifiers using a grinder, melting‐blending mixer, and injection molding machine to prepare environmentally friendly TSF/HDPE composites, which have excellent mechanical properties and good water resistance. On this basis, the interfacial compatibility between TSF and HDPE was enhanced by adding a silane coupling agent KH550, titanate coupling agent 201, and maleic anhydride grafted polyethylene (MA‐g‐PE), which led to the improvement of mechanical properties of composites. The mechanical properties of the composites with 2% MA‐g‐PE were the best, while the tensile strength and flexural strength increased by 72% and 38%, respectively, compared with the unmodified composites. Fourier transform infrared (FTIR) spectroscopy showed that TSF was modified by different coupling agents and new chemical bonds were formed. The scanning electron microscopy images showed that the interfacial compatibility between TSF and HDPE was improved by the interface modifiers. This work confirms that it is possible to use TSF to prepare composites and provides a new way for resource utilization of tobacco stalk fiber.Highlights TSF was incorporated into composites, boosting material sustainability. The interface compatibility between TSF and HDPE was greatly improved. Thermal and water absorption analysis can be used for composites design. Composites modified by 2 wt% MA‐g‐PE had optimal comprehensive properties.

Replacing Harmful Flame Retardants with Biodegradable Starch-Based Materials in Polyethylene Formulations.

The addition of toxic flame retardants to commercially available polymers is often required for safety reasons due to the high flammability of these materials. In this work, the preparation and incorporation of efficient biodegradable starch-based flame retardants into a low-density polyethylene (LDPE) matrix was investigated. Thermoplastic starch was first obtained by plasticizing starch with glycerol/water or glycerol/water/choline phytate to obtain TPS-G and TPS-G-CPA, respectively. Various LDPE/TPS blends were prepared by means of melt blending using polyethylene graft maleic anhydride as a compatibilizer and by varying the content of TPS and a halogenated commercial flame retardant. By replacing 38% and 76% of the harmful commercial flame retardant with safe TPS-G-CPA and TPS-G, respectively, blends with promising fire behavior were obtained, while the limiting oxygen index (LOI ≈ 28%) remained the same. The presence of choline phytate improved both the charring ability and fire retardancy of starch and resulted in a 43% reduction in fire growth index compared to the blend with commercial flame retardant only, as confirmed by means of cone calorimetry. Standard UL 94 vertical tests showed that blends containing TPS exhibited dripping behavior (rated V2), while those with commercial flame retardant were rated V0. Overall, this work demonstrates the potential of starch as a natural flame retardant that could reduce the cost and increase the safety of polymer-based materials.

Effect of Rice Husk and Wood Flour on the Structural, Mechanical, and Fire-Retardant Characteristics of Recycled High-Density Polyethylene.

Given the rising consumption of plastic products, it is becoming imperative to prioritize the recycling of plastic items as a solution to reducing plastic waste and environmental pollution. In this context, this research focuses on assessing the impact of incorporating rice husk and wood flour into recycled high-density polyethylene (rec-HDPE) to analyze its mechanical properties, flammability, and thermal stability. The combined rec-HDPE content of wood flour and rice husk varied between 0% and 20%. The rec-HDPE content of maleic anhydride grafted polyethylene (MAPE) was fixed at 3%. Mechanical characteristics such as flexural, tensile, and impact strengths were assessed. Cone calorimetry (CC) tests, limited oxygen index (LOI) tests, and horizontal and vertical burning tests were performed to determine the flammability or fire retardancy of these composites. On the other hand, to characterize the thermal characteristics of these composites, thermogravimetric analysis (TGA) was used. To further characterize the fluctuation in these characteristics, scanning electron microscopy (SEM) and infrared spectroscopy (FTIR) studies were carried out. The mechanical characteristics were found to be increased in response to adding rice husk or wood flour. An 8% increase in tensile strength and a 20% increase in elastic modulus enhancement were recorded for a 20% rice husk-added composite. SEM revealed the reason for the variation in tensile properties, based on the extent of agglomeration and the extent of uniform distribution of fillers in rec-HDPE. Following these lines, the 20% rice husk-added composite also showed a maximum increase of around 6% in its flexural strength and a maximum increase of 50% in its flexural modulus. A decrease in impact strength was recorded for rice husk and wood flour-reinforced composites, compared with unreinforced rec-HDPE. Hybrid composites displayed a lack of mechanical strength due to changes in their nature. FTIR tests were performed for a much more elaborate analysis to confirm these results. Twenty percent of rice husk-added rec-HDPE displayed the best thermal properties that were tested, based on TGA and derivative thermogravimetric (DTG) analysis. This 20% composite also displayed the best fire-retardancy characteristics according to UL 94 tests, cone calorimetry tests, and limited oxygen index tests, due to the barrier created by the silica protective layer. These tests demonstrated that the incorporation of both fillers-rice husk and wood flour-effectively enhanced the thermal, mechanical, and fire-retardant attributes of recycled HDPE.