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Developments of lignocellulosic natural fibers reinforced hybrid thermosetting composites (LNFRHTCs) are essential in the current scenario as far as the environmental safety is concerned. The hybrid composites develop from this type of materials are aiming to introduce new dimensions for sustainability. LNFRHTCs exhibit a wide range of high-end properties suitable for structural applications. Moreover, the improvement of hybrid composites by incorporation of natural fibers is economical and possesses several advantages including recyclability, cost-effectiveness, biodegradability, and their abundant availability. Presently, LNFRHTCs are one of the developing materials that have been found in current researches that are gaining attention for structural applications in various sectors such as automobiles, marines, defense military, aircraft, buildings, and constructions etc. In this review paper, we present several recently published studies associated with physical, mechanical, thermal, properties and processing techniques of natural fibers, their hybrids with thermosetting matrix materials. This paper will illustrate the importance of hybridization of natural/synthetic fiber and their hybrid composites as well ensuing to enhanced desired properties for high-end structural applications.

The major roadblock for recycling of waste electrical and electronic equipments (WEEE) depends on the viability of sorting process, which is a complex task, involving various techniques such as sink float, froth flotation, optical separation and manual separation, etc. This makes the sorting process highly time consuming and expensive. The primary aim of this investigation is to study the properties of polymeric blends formulated from computer keyboards, by avoiding high end sorting procedure to avoid manpower and instrumental cost. The major polymers recovered from waste keyboards were identified as acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS) and polystyrene (PS), using fourier transform infrared (FTIR) spectroscopy. These polymers were subjected to mechanical recycling by employing melt blending technique, followed by injection moulding. A ternary blend was prepared utilizing various percentages of ABS, HIPS and PS. The mechanical test of the blends revealed an optimum tensile strength of 35 ± 3 MPa, flexural strength of 65 ± 3 MPa, and impact strength of 45 ± 3 J/m. The homogeneity of the blends was determined through thermal analysis and morphological analysis of impact fractured specimens. The thermogravimetry analysis (TGA) showed a narrow peak with degradation of 98% of the blends at 700 °C. It was observed that, the properties of blends were similar to each other, which allows to eliminate multiple sorting process reducing cost aspect with improve performance characteristics.

In current study the blends prepared by utilizing recycled poly(vinyl chloride) (r-PVC) as well as recycled acrylonitrile butadiene styrene (r-ABS) material recovered from e-waste are investigated with respect to property enhancement. Also, nitrile rubber (NBR) was added to prepared blends of r-(PVC/ABS) as a bridging agent between the optimized blends composition. The blends was prepared by means of the melt-mixing process and further tensile sample prepared using micro-compounding process. The superior properties on compatibility between NBR-modified r-(PVC/ABS) blends were successfully studied using rheological, mechanical, morphological, thermal, and water absorption analysis studies. The primary analysis of r-PVC and r-ABS was employed using FTIR analysis. The thermal stability of blends containing 10 wt% NBR was stable up to 253 ºC. In addition, significant enhancement on impact strength of r-(PVC/ABS) blends having 10 wt.% of NBR content. Morphological properties of NBR added based blends presented proper homogenization and properly mixed recycled polymer-rubber phase in prepared r-(PVC/ABS) blends. The water absorption test results showed rapid ingress of water with an increase in NBR content in prepared blends. This study provides a novel way towards reuse the polymer from electronic waste with its improved properties by preparing blends.

The primary aim of this study was to identify the polymers recovered from keyboard waste, and formulate a ternary blend from the recovered polymers, with improved mechanical, thermal and morphological characteristics, and encouraging product-based recycling. The recycling and reuse of polymers recovered from E-waste is one of the prime topics in solid waste management. The major drawbacks of utilizing recycled polymers are its lower mechanical strength. This was majorly evidenced in styrene based polymers such as acrylonitrile butadiene styrene (ABS) and high impact polystyrene (HIPS). In our case, the polymers ABS, HIPS and polystyrene (PS) were recovered from waste keyboards, and their impact strength was 29 J/m, 42 J/m and 20 J/m respectively. After formulating a ternary blend with PS as a major phase, the impact strength observed was 66 J/m. The thermal stability of the blends also improved from 380℃ to 396℃, after the addition of PS to the blends, but the glass transition temperature had negligible effect. The morphology of ternary blend shows salami structures after the addition of ABS/HIPS blends. This shows that the r-PS morphology had a brittle to ductile transition which leads to the improvement of impact properties.

The recent work evaluates the effect of ethylene methacrylate (EMA) as an impact modifier and the hybrid filler constitutes graphite flakes (GF), multiwalled carbon nanotubes (MWCNT), and steel fibers (SF) for the development of polycarbonate (PC) based conducting composite with high thermal conductivity and EMI shielding. The samples were initially optimized based on their mechanical properties, which were further characterized by thermal conductivity (TC) and electromagnetic interference shielding effectiveness (EMI SE). The thermal conductivity of the polycarbonate (PC) nanocomposites was found to increase by ~ 451% and ~ 602% at a significantly higher filler loading of 20 wt% and 30 wt% respectively without any processing difficulties. Further, the EMI SE values of the same have been enhanced in the range of -40.2 dB and -46.4 dB respectively, which falls within the range of commercially acceptable limits. Nonetheless, the results were indicative of the creation of a conductive network through the matrix, the electron microscopic and diffractometric studies confirmed the optimum dispersion of the hybrid filler system within the PC matrix.

The use of biodegradable polymers in agricultural sector has gained considerable interests over the last decade. Biopolymers like polylactic acid (PLA), polybutylene adipate co-terepthalate (PBAT) and its blend with starch have been widely employed in agricultural field to eliminate the difficulties faced during the incineration of petroleum-based polymers like polyethylene (PE) or polypropylene (PP) after use. The biopolymers are more vulnerable to be attacked by microorganisms in the field which also increases their usability. In the current study, blown film of biodegradable aliphatic polyester PLA blended with three different types of thermoplastic starch (TPS): rice starch (RS), corn starch (CS), and potato starch (PS), was taken for on field trials as agricultural mulching films. A comparative account of PLA/TPS blend-based mulching films with the commercially available polyethylene films was undertaken with respect to the performance characteristics on the field. Various tropical plants like banana ( Musa acuminate ), papaya ( Carica papaya ), chilli ( Capsicum frutescens ), brinjal, ( Solanummelongena ), hibiscus ( Hibiscus rosa-sinensis ) and table rose ( Portulacagrandiflora ) were taken for study on growth of the plants over six month field trial. Further, post 6-month field trials, the mulching films were evaluated for aerobic biodegradation study under thermophilic conditions to confirm their compostability characteristics. Graphical abstract

The effect of surface treated sisal fiber on the mechanical, thermal, flammability, and morphological properties of sisal fiber (SF) reinforced recycled polypropylene (RPP) composites was investigated. The surface of sisal fiber was modified with different chemical reagent such as silane, glycidyl methacrylate (GMA), and O-hydroxybenzene diazonium chloride (OBDC) to improve the compatibility with the matrix polymer. The experimental results revealed an improvement in the tensile strength to 11%, 20%, and 31.36% and impact strength to 78.72%, 77%, and 81% for silane, GMA, and OBDC treated sisal fiber reinforced recycled Polypropylene (RPP/SF) composites, respectively, as compared to RPP. The thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), and heat deflection temperature (HDT) results revealed improved thermal stability as compared with RPP. The flammability behaviour of silane, GMA, and OBDC treated SF/RPP composites was studied by the horizontal burning rate by UL-94. The morphological analysis through scanning electron micrograph (SEM) supports improves surface interaction between fiber surface and polymer matrix.

Aluminum trihydrate (ATH) of different sizes is added to polypropylene (PP) to prepare a composite which will have both good fire-retardant and mechanical properties. PP/ATH (nano or micro) composites are more fire-resistant and having appreciable mechanical properties as compared to virgin PP. Addition of maleic anhydride-functionalized polypropylene (MAPP) to the composite to increase the compatibility between PP and ATH (nano or micro). The need for developing the mechanical properties of flame-retardant composites is discussed in this paper. The influence of concentration of ATH (nano or micro) in PP/ATH (nano or micro)/MAPP composites is presented. The mechanical, thermal, morphological and flame-retardant properties were studied and discussed. The tensile modulus, hardness and flame-retardant properties increase, while elongation at break and tensile strength decreases with the increase in ATH (nano or micro) content. Graphical abstract

Aluminum trihydrate (ATH) of different sizes is added to polypropylene (PP) to prepare a composite which will have both good fire-retardant and mechanical properties. PP/ATH (nano or micro) composites are more fire-resistant and having appreciable mechanical properties as compared to virgin PP. Addition of maleic anhydride-functionalized polypropylene (MAPP) to the composite to increase the compatibility between PP and ATH (nano or micro). The need for developing the mechanical properties of flame-retardant composites is discussed in this paper. The influence of concentration of ATH (nano or micro) in PP/ATH (nano or micro)/MAPP composites is presented. The mechanical, thermal, morphological and flame-retardant properties were studied and discussed. The tensile modulus, hardness and flame-retardant properties increase, while elongation at break and tensile strength decreases with the increase in ATH (nano or micro) content.

Natural fiber‐reinforced nanocomposites based on polypropylene/nanoclay/banana fibers were fabricated by melt mixing in a twin‐screw extruder followed by compression molding in this current study. Maleic anhydride polypropylene copolymer (MA‐g‐PP) was used as a compatibilizer to increase the compatibility between the PP matrix, clay, and banana fiber to enhance exfoliation of organoclay and dispersion of fibers into the polymer matrix. Variation in mechanical, thermal, and physico‐mechanical properties with the addition of banana fiber into the PP nanocomposites was investigated. It was observed that 3 wt% of nanoclay and 5 wt% of MA‐g‐PP within PP matrix resulted in an increase in tensile and flexural strength by 41.3% and 45.6% as compared with virgin PP. Further, incorporation of 30 wt% banana fiber in PP nanocomposites system increases the tensile and flexural strength to the tune of 27.1% and 15.8%, respectively. The morphology of fiber reinforced PP nanocomposites has been examined by using scanning electron microscopy and transmission electron microscopy. Significant enhancement in the thermal stability of nanocomposites was also observed due to the presence of nanoclay under thermogravimetric analysis. Dynamic mechanical analysis tests revealed an increase in storage modulus (E′) and damping factor (tan δ), conforming the strong interaction between nanoclay/banana fiberand MA‐g‐PP in the fiber‐reinforced nanocomposites systems. POLYM. COMPOS., © 2011 Society of Plastics Engineers.