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This study compares the mechanical properties of recycled high-density polyethylene (r-HDPE)/rice husk (RH) composites from a twin-screw extruder and a heated two-roll mill, and the effect of different filler loadings using different melt blending processes on the mechanical properties of r-HDPE/RH composites. Polyethylene-graft-maleic anhydride (MAPE) acts as the coupling agent to enhance interfacial bonding between the fibre and the polymer matrix. The filler loading used was in the range of 10-40 wt. %. In this work, r-HDPE/RH blends were prepared using a twin-screw extruder and a heated two-roll mill. The ratio of 70/30 twin-screw extruder compounded composites significantly showed higher tensile based on improved to about 45.5% at 11 MPa compared to those compounded in the heated two-roll mill. The same ratio showed an increment almost up to 9% of elongation at break. It has also been verified that the higher filler loading used reduced the tensile strength and elongation at break, while the Young's modulus increased. The result was evidenced by the increase in water absorption and longer burning time as the filler loading increased. [ABSTRACT FROM AUTHOR]

The research on the polymer silicate layer nanocomposites is currently focusing on maximizing the polymer‐filler interface interaction. This study aimed to elucidate the effect of two different types of montmorillonite (MMT), which were Cloisite sodium (CNa) and Cloisite 10A (C10A), on the thermal, water absorption, and mechanical performances of polylactide (PLA) nanocomposites. Nanocomposites with different clay loadings from 1 to 7 wt% were fabricated by melt intercalation in a twin‐screw extruder. XRD analysis showed an intercalated structure for PLA/C10A at 1 and 3 wt% loadings. From TGA analysis, the initial thermal degradation temperature for PLA/C10A at 1 and 3 wt% showed promising enhancement in thermal stability. DSC results also confirmed that both nanocomposites at clay loadings less than 5 wt% improved thermal properties and crystallinity compared to neat PLA. Storage modulus and tan δ for PLA/C10A shifted towards higher temperature. Water absorption intakes of PLA/C10A at 1 and 3 wt% loadings were reduced by 42% and 39%, respectively. For PLA/C10A at the optimum loading of 3 wt%, tensile strength improved by 21% and strain by 17%. This loading exhibited the finest morphological structure. [ABSTRACT FROM AUTHOR]

In this study, graphene nanoplatelets (GNP) of 0.2%–1.0% by weight were introduced to the rubber toughened epoxy matrix with via a direct method. The effect of GNP loadings on the mechanical (tensile and impact properties) and thermal properties of the rubber toughened epoxy/GNP nanocomposites were evaluated. The results showed that the incorporation of GNP had optimally improved the tensile strength and tensile modulus by 70% and 74%, respectively, at 0.6 wt% filler loading. Thermogravimetric analysis (TGA) and Tg increment result proved the barrier effect via delaying decomposition process which induced by the layered structure of GNP and thus significantly enhanced the thermal stability of epoxy‐based resin, irrespective of GNP loadings (insignificant difference in the decomposition temperature). The fractured surfaces of these nanocomposites showed the good interfacial interaction between the matrix and the GNP nanofiller. X‐ray diffraction (XRD) analysis demonstrated the exfoliation and intercalation states of GNP dispersion in epoxy/LENR. [ABSTRACT FROM AUTHOR]

A high loading rice husk fibre (RHF) incorporated polyolefin blend of recycled polyethylene high-density/poly(ethylene terephthalate) (rPEHD/rPET) biocomposite was produced through extrusion and hot/cold press process. Interfacial modification of biocomposites was conducted through alkalization (sodium hydroxide solution) of fibres, compatibilization (using E-GMA) and/or coupling agent (MA -g -PE) to improve the interaction between components and the homogeneity of materials blending. Alkalization of fibres had improved the impact strength of biocomposites. The compatibilization and coupling effects on immiscible rPEHD/rPET blend and recycled polymer/RH filler, respectively, had led to an enhancement of mechanical performance and morphological stability. Scanning electron microscope micrograph revealed the improved matrix–matrix and filler–matrix interaction through interfacial modification. This investigation had shown that RHF mixed well with rPEHD/rPET/RHF to produce eco-friendly biocomposite products. [ABSTRACT FROM AUTHOR]

Conventional polymer blending has a shortcoming in conductivity characteristic. This research addresses the preparation of conductive thermoplastic natural rubber (TPNR) blends with graphene nanoplates (GNPs)/polyaniline (PANI) through melt blending using an internal mixer. The effect of PANI content (10, 20, 30, and 40 wt %) on the mechanical and thermal properties, thermal and electrical conductivities, and morphology observation of the TPNR/GNPs/PANI nanocomposites was investigated. The results showed that the tensile and impact properties as well as thermal conductivity of nanocomposite had improved with the incorporation of 3 wt % of GNPs and 20 wt % of PANI as compared to neat TPNR and reduced with further increase of the PANI content. It was observed that the GNPs and PANI acted as a critical component to improve the thermal stability and electrical conductivity of the TPNR/GNPs/PANI nanocomposites. The most improved conductivity of 5.22 E‐5 S/cm was observed at 3 wt % GNPs and 40 wt % PANI. Variable‐pressure scanning electron microscopy micrograph revealed the good interaction and distribution of GNPs and PANI within TPNR matrix at PANI loadings lower than 30 wt %. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48873. [ABSTRACT FROM AUTHOR]

High-fiber loading green composites were prepared from recycled high-density polyethylene (rHDPE)/recycled polyethylene terephthalate (rPET) blend matrix and rice husk (RH) as filler (from 40 wt% up to 80 wt%) via corotating twin-screw extruder and compression molding. The water absorption (WA) upon immersion in sea water, mechanical behavior, and combustion enthalpy of green composites were examined. The WA mechanisms obeyed the Fickian diffusion. The computed diffusion coefficient (D), thermodynamic solubility (S), permeability (P), and orthotropic swelling were generally increased as a function of RH filler. The increment of tensile strength and modulus of composites were maximized up to 16% and 121%, respectively, which was achieved at 70 wt% RH filler. The theoretical prediction of tensile strength and Young's modulus from micromechanical models for random oriented RH fiber/blend composites were compared with the experimental results. As the RH weight fraction increased, the combustion enthalpy decreased (by approximately 30–48%) and thereby the enhancing the fire retardancy of green composite. [ABSTRACT FROM AUTHOR]

The thermal conductivity and mechanical performance of a hybrid multi‐walled carbon nanotubes/silicon carbide (MWCNTs/SiC)‐reinforced thermoplastic natural rubber (TPNR) nanocomposite were investigated. TPNR was fabricated from polypropylene, natural rubber (NR) and liquid NR at a volume ratio of 70:20:10, respectively. The Young's modulus, the tensile strength, and the storage and loss modulus of the nanocomposites with a single filler of MWCNTs or SiC were enhanced compared with those of neat TPNR. The greatest improvements in these properties were achieved at a composition of 1.5 wt% SiC‐1.5 wt% MWCNTs‐reinforced nanocomposite. In addition, the thermal conductivity and specific heat capacity of the nanocomposites, determined using a laser flash technique, were improved in the 3 wt% SiC‐reinforced nanocomposite sample relative to those of the pure sample and the other reinforced nanocomposites. Based on these findings, MWCNTs and SiC could serve as suitable percolated networks of hybrid reinforcement fillers to achieve optimal thermal and mechanical properties in the TPNR matrix. POLYM. COMPOS., 40:E695–E703, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Green composite materials were made from agricultural and plastic wastes which were rice husk (RH), recycled high‐density polyethylene (rHDPE), and recycled polyethylene terephthalate (rPET), by twin‐screw extrusion and hot/cold pressing molding. The dimensional stability, orthotropic swelling, and mechanical performance of the green composites were determined as a function of bio‐filler concentration for neat (uncompatibilized) and compatbilized rHDPE/rPET blend based composites. Water absorption and swelling results showed a linear increase with the RH concentration. The highest swelling occurred in the thickness of the composites, followed by the width and length, respectively. Water absorption and dimensional instability of compatibilized recycled polymer blend (rPB)‐based composites were lower than those of neat rPB‐based composites. As RH concentration increased, the flexural properties increased significantly. The optimum tensile strength and modulus were achieved at 70 wt% RH. It is interesting to note that compatibilization of polymer blend matrix had further increased the strength and elongation properties of composites. POLYM. COMPOS., 39:2695–2704, 2018. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The use of rice husks (RH) to reinforce polymers in biocomposites are increasing tremendously. However, the incompatibility between the hydrophilic RH fibers and the hydrophobic thermoplastic matrices leads to unsatisfactory biocomposites. Surface modification of the fiber surface was carried out to improve the adhesion between fiber and matrix. In this study, the effect of surface modification of RH via alkali, acid and ultraviolet-ozonolysis (UV/O3) treatments on the properties of composites recycled high density polyethylene (rHDPE) composites was investigated. The untreated and treated RH were characterized by Fourier Transform Infrared (FTIR) and Scanning Electron Microscope (SEM). The composites containing 30 wt% of RH (treated and untreated) were then prepared via extrusion and followed by compression molding. As compared to untreated RH, all surface treated RH exhibited rougher surface and showed improved adhesion with rHDPE matrix. Tensile strength of UV/O3-treated RH composites showed an optimum result at 18.37 MPa which improved about 5% in comparison to the composites filled with untreated RH. UV/O3 treatment promotes shorter processing time and lesser raw material waste during treatment process where this is beneficial for commercialization in the future developments of wood plastic composites (WPCs). Therefore, UV/O3 treatment can be served as an alternative new method to modify RH surface in order to improve the adhesion between hydrophilic RH fibre and hydrophobic rHDPE polymer matrix. [ABSTRACT FROM AUTHOR]

This article studies the enhancement in the properties of thermoplastic natural rubber (TPNR) reinforced by graphene oxide (GnO) and multiwalled carbon nanotubes (MWCNTs). TPNR is a blend of polypropylene and liquid natural rubber (NR), which is used as a compatibilizer and NR at a percentage of volume ratio 70:10:20, respectively. Using TPNR as the host matrix, a number of TPNR/carbon nanotubes (CNTs), TPNR/GnO, and hybrid TPNR/GnO/CNTs nanocomposites are processed and their mechanical, thermal, and electrical properties are characterized. The results extracted from tensile and impact test showed that tensile strength, Young’s modulus, and storage modulus of TPNR/GnO/MWCNTs hybrid nanocomposite increased as compared with TPNR composite and TPNR/GnO nanocomposite but lower than TPNR/MWCNTs nanocomposite. On the other hand, the elongation at break considerably decreased with increasing the content of both types of nanoparticles. Based on the experimental results, the thermal, electrical conductivity of a 0.5 wt% MWCNTs-reinforced sample increased as compared with a pure TPNR and other MWCNTs/GnO-reinforced composites. The improved dispersion properties of the nanocomposites can be due to altered interparticle interactions. MWCNTs, GnO, and MWCNTs–GnO networks are well combined to generate a synergistic effect that is shown by scanning electron microscopy micrographs. With the existence of this network, the mechanical, thermal, and electrical properties of the nanocomposite were improved significantly. [ABSTRACT FROM AUTHOR]