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A reciprocating screw, showing the feeding zone, compressing (or transition) zone, and metering zone
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The interest in natural fiber-reinforced polymer composites is growing rapidly due to their high performance in terms of mechanical properties, significant processing advantages, excellent chemical resistance, low cost and low density. In this study, the compression and injection molding of polypropylene (PP) and polylactic acid (PLA) based composi...
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Citations
... KC et al. [4] did injection molding using pellets from sisal fiber and polypropylene. Srebrenkoska et al. [5] recycled polymer processing with kenaf fiber and rice husk printed using an injection mold-ing machine. ...
... Results of electron microscopy showed brittle failure of jute fibres under tension and void spaces between fibre and polymer matrix, indicating that the strength of the PLA/jute interface could be improved. Authors [84] developed the biodegradable composites with maleic anhydride-grafted PLA reinforced with rice husks and kenaf fibres and concluded that compressive strength and compressive modulus of PLA/kenaf (345 + 3.11 MPa and 174 + 0.11 GPa, respectively) was higher than that of PLA/rice hull (216 + 2.67 MPa and 146 + 0.07 GPa, ...
... Other studies have also been carried out with the injection molding process using pellets derived from kenaf and polypropylene fibers [5]. Furthermore, research on the injection molding process of recycled polymers mixed with two natural fibers, namely kenaf fiber and rice husk has also been carried out [6]. ...
... The beneficial impact of anhydride containing modifiers on the compatibility of PE-based materials was previously reported by other researchers [73]. The beneficial effects of maleic anhydride on polymer composites' compatibility were repeatedly reported in the literature, both for lignocellulose [74,75] and mineral [76] fillers. Such an effect is associated with the partial "crosslinking" of material due to generation of covalent bonds [77]. ...
The recycling of plastics is currently one of the most significant industrial challenges. Due to the enormous amounts of plastic wastes generated by various industry branches, it is essential to look for potential methods for their utilization. In the presented work, we investigated the recycling potential of wastes originated from the agricultural films recycling line. Their structure and properties were analyzed, and they were modified with 2.5 wt % of commercially available compatibilizers. The mechanical and thermal performance of modified wastes were evaluated by tensile tests, thermogravimetric analysis, and differential scanning calorimetry. It was found that incorporation of such a small amount of modifiers may overcome the drawbacks caused by the presence of impurities. The incorporation of maleic anhydride-grafted compounds enhanced the tensile strength of wastes by 13–25%. The use of more ductile compatibilizers—ethylene-vinyl acetate and paraffin increased the elongation at break by 55–64%. The presence of compatibilizers also reduced the stiffness of materials resulting from the presence of solid particles. It was particularly emphasized for styrene-ethylene-butadiene-styrene and ethylene-vinyl acetate copolymers, which caused up to a 20% drop of Young’s modulus. Such effects may facilitate the further applications of analyzed wastes, e.g., in polymer film production. Thermal performance was only slightly affected by compatibilization. It caused a slight reduction in polyethylene melting temperatures (up to 2.8 °C) and crystallinity degree (up to 16%). For more contaminated materials, the addition of compatibilizers caused a minor reduction in the decomposition onset (up to 6 °C). At the same time, for the waste after three washing cycles, thermal stability was improved. Moreover, depending on the desired properties and application, materials do not have to go through the whole recycling line, simplifying the process, reducing energy and water consumption. The presented results indicate that it is possible to efficiently use the materials, which do not have to undergo the whole recycling process. Despite the presence of impurities, they could be applied in the manufacturing of products which do not require exceptional mechanical performance.
... It is evident also from the figure that the HDPE/PALP composites processed through extrusion moulding technique gave slightly higher tensile strength than those processed through injection moulding technique for all the filler contents investigated. This result is similar to the findings of Vineta [14]. Vineta [14] prepared eco-composites using compression, and injection moulded techniques and reported that the flexural, impact, compression and tensile strengths of the injection moulded composites decreased by about 25 % when compared to the strengths of samples prepared by compression moulded technique. ...
... This result is similar to the findings of Vineta [14]. Vineta [14] prepared eco-composites using compression, and injection moulded techniques and reported that the flexural, impact, compression and tensile strengths of the injection moulded composites decreased by about 25 % when compared to the strengths of samples prepared by compression moulded technique. The processing technique of polymers has profound effect on the properties of the polymer product. ...
... It can also be observed from Fig. 2 that the extrusion moulded HDPE/PALP composites produced very slight increase in tensile modulus for all the filler contents investigated when compared to the samples processed through injection moulding technique. Vineta [14] reported that the techniques used for producing eco-composites under certain processing conditions induced slight changes on the composites mechanical properties. This result is similar to the ones reported by Avella et al [18], and Siaotong et al [19]. ...
... Green agro-fibre thermoplastic biocomposites, also known as agro-plastics, where agro-fibres are bond with bioplastics, were developed in different researches on lab-scales, including rice straw -poly hydroxybutyrate-co-hydroxyvalerate (PHBV) biocomposites [3], rice straw-PLA [1] and rice husk-PLA [23] Wheat straw -recycled petro-based HDPE and rice husk bonded by recycled PVC biocomposites are available on the market. Otherwise, the available green thermoplastic-NFRP on the market are mainly household products, depending on kenaf-PLA, hemp-PLA and cellulose-lignin biocomposites [4]. ...
Natural fibres retrieved from annual agricultural by-products offer diverse advantages, when applied as a main ingredient in biocomposite building materials. These fibres, such as straw and other non-wood fibres are annually renewable and are worldwide available having the lowest cost, in comparison to other natural fibres available in the industrial fibre market. In this paper, the author presents three case studies of natural fibre reinforced polymers (NFRP), discussing the agro-fibre densification, different architectural designs for customized applications and fabrication stages. The natural fibres were compounded with three different biopolymers: a thermoplastic, a thermoset and an elastic thermoplastic one. This allowed variations in the final designs and geometries that can be reached, but caused a necessity of changing the fabrication technique in each case accordingly. To prove the applicability of the developed products, mechanical properties and environmental assessment were analyzed.
... PLA has been found to be biodegradable in composting environment: proper temperature , bacteria content etc., and at the end of life cycle it degrades into CO 2 , CH 4 and water in humid environment. Recently high molecular weight PLA has been developed with advanced polymerization techniques which can stand for lifetime while maintaining its mechanical properties under humid environment616263. The resultant products of banana fibre reinforced with polylactic acid is a biodegradable composites and its mechanical properties are reported inTable 5 [43,64,65]. ...
... Rice Husk (RH) was applied, accompanied by the conventional coupling agent maleic anhydride (MA) with the typical ratio (5%) with grafted PLA, and the examination revealed the possibility of applying the rice husk as an effective eco-filler as well, (Srebrenkoska, et al., 2009). ...
... The mechanical properties of PLA have been extensively studied as a biomaterial in the medicine, but only recently has it been used as a polymer matrix in eco-composites [8], although its application is still limited by its relatively high price when compared with some other biodegradable polymers. Kenaf fibers have already been tested as natural reinforcement for polyolefins, but there is a growing interest in the preparation of biocomposites [14,15]. Xia et al. [9] investigated the use of PLA resin reinforced with kenaf fibers for the interior parts of its Prins hybrid car. ...
p>In this study, rice-hull-filled poly(lactic acid) (PLA) biocomposites were prepared through the addition of 5 wt.% PLA-grafted-MA (CA) for the enhancement of adhesion between the polymer matrix and natural filler. The composites containing 30 wt.% rice hulls (RH) were prepared by compression molding, with particular attention given to the introduction of recycled PLA matrix, as well as to the possibility of the recycling and reuse of PLA/RH biocomposites. For all biocomposites, produced from neat polymer and RH and those produced after the recycling of PLA/RH composites, the mechanical and thermal properties were analyzed and compared to those of a commonly used thermoplastic based-polymer, polypropylene (PP), containing the same reinforcement. Thermal stability of biocomposites based on recycled PLA matrix and of the new composites produced from recycled ones was practically unchanged. Introduction of the recycled PLA matrix into biocomposites resulted in decreased flexural modulus and strengths of about 50%. Utilization of the mixture obtained after the thermal-mechanical recycling of the whole biocomposite resulted in a composite with slightly increased flexural modulus and decreased flexural strength.
The obtained results have shown that rice-hull-filled poly(lactic acid) biocomposites could be recycled and utilized for the production of new eco-materials with acceptable thermal and mechanical properties. Namely, the results for flexural strength and modulus of the recycled biocomposite samples are comparable to those of conventional formaldehyde wood medium density fiberboards used as construction elements for indoor applications.
Keywords: biocomposites, polylactic acid, polypropylene, rice hulls, compression moulding.</p
... [1][2][3][4][5][6][7][8][9] Among the disadvantages, the low temperature resistance of PLA and its brittle behavior has to be mentioned. Efforts have been carried out to modify the properties of PLA using various fillers and fibers, for example, starch, [10] montmorillonite, [11][12][13][14][15] silica, [16] kaolinite, [17] bentonite and hectorite, [18] talc, [19] nano-calcium carbonate, [20,21] graphene, [22] carbon nanotube, [23,24] titanium dioxide, [25,26] natural fibers, [27][28][29] and cellulose whiskers. [30] Another common strategy is via thermoplastic blending, for example, PLA/poly(vinyl alcohol) [4] and PLA/poly(trimethylene terephthalate). ...
Poly(lactic acid) (PLA)/halloysite composites were prepared using melt compounding followed by compression molding. Maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH) was used to toughen the PLA composites. The mechanical properties of the PLA composites were studied through tensile, flexural, and impact tests. The thermal properties were characterized by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The fracture surfaces of the composites were assessed by using field emission scanning electron microscopy (FESEM). The impact strength and thermal properties of the PLA/halloysite composites were increased by addition of SEBS-g-MAH.
