A foamed starch-based biomass composite was prepared by the extrusion foaming method with starch, wood fiber and polyvinyl alcohol (PVA) as raw materials. The effects of three additives (plasticizer, cross-linking agent, and blowing agent) on the mechanical performance of the foamed starch-based biomass composite were studied, and a three-layer back-propagation (BP) artificial neural network model was established for mechanical property prediction. The orthogonal experiment results were used as samples to train the network and predict the mechanical performance of foamed composite. The results show that the proposed BP network model is effective in forecasting the mechanical performance of foamed composite. The appropriate amount of composite plasticizer (glycerin/ NaOH) can reduce the crystallinity of the starch; increase the compatibility of the starch,wood fiber and PVA, and increase the tensile strength of the composite to 5.91 MPa. Crosslink reaction occurs between PVA molecular under the reaction of cross-linking agent borax. The tensile strength of the composite increases up to 6.12 MPa. The tensile strength lowers down as a result of the decrease of the contact area caused emerging bubbles with the help of the blowing agent NaHCO 3 . POLYM. COMPOS., 40:3923-3928, 2019.
In this work, a novel functional polylactic acid (PLA) was prepared by melt blending using epoxy Joncryl ADR 4468 (ADR) as chain extender. The effects of the epoxy chain expander ADR on the molecular structure, crystallization properties, rheological properties, and mechanical properties of PLA were studied. Furthermore, the chain expansion mechanism was analyzed. It was found that the epoxy group of the epoxy chain extender reacted with the terminal hydroxyl and terminal carboxyl groups of PLA in the molten state, thus significantly increasing the molecular weight of PLA. Meanwhile, the weight average molecular weight of PLA increased by 42.51% when the maximum additional amount of epoxy chain extender was 1.2 wt%. The dynamic rheological experiments also confirmed that ADR can effectively improve the storage modulus, loss modulus and complex viscosity of PLA systems and the Cole‐Cole diagram reveals the branched structure of PLA chain expansion systems. The formation of this branched structure will destroy the regularity of the PLA chain, reduce the crystallization capacity of PLA, and increase the cold crystallization temperature of the PLA system. Through SEM and mechanical property tests, it is found that the addition of ADR makes the molecular chain form a micro‐crosslinked structure, thereby improving the tensile strength of PLA. Therefore, the molecular structure of PLA was effectively regulated and exhibited a promising performance, which greatly expands the potential applications of PLA.
The aim of this study was to fabricate highly filled wood plastic composite pallets with extrusion‐compression molding technique and investigate the effects of processing parameters on mechanical performance and production stability. The composites were blended in twin‐screw extruder and subsequently measured by weight with an electronic scale. Before compression, it was divided into pieces and rearranged in the cavities of compression mould according to the mass distribution. The effects of compression pressure and mould temperature on flexure strength, density, water absorption, and dimensional deviation were investigated. The results show that both the flexure strength and density of the pallets increased with compression pressure and remained higher than that of extruded deck when compression pressure exceeded 6.5 MPa. Water absorption and dimensional deviation decreased with compression pressure and remained lower than that of extruded deck after the compression pressure exceeded 6.0 MPa. Compression pressure could increase the final passed yield by improving the composite melt filling state and lowering the buckling deformation, but further increase above 6.7 MPa would result in a decline in final passed yield. Increase in mould temperature contributed to the production stability but an excessive value would extend the molding cycle. The insights gained from this study may be of assistance in optimizing extrusion‐compression processing parameters and expanding the application of highly filled wood plastic composites in complicated and irregular products.
Demand for natural fibers reinforced composites is growing as an alternative to synthetic fiber reinforced plastic composites. However, poor compatibility between natural fiber and matrix has limited its development. Therefore, it is necessary to improve their interfacial adhesion to improve the comprehensive properties of composites. In this work, sisal fibers were subjected to an alkali/polyvinyl alcohol coating treatment by an ultrasonic impregnation method, and the sisal/high-density polyethylene composite was prepared by a twin-screw extruder. The Fourier transform infrared spectroscopy was used to characterize the modification effect of sisal fiber. The surface morphology of sisal fiber and the interfacial morphology of sisal/high-density polyethylene composites were observed. The mechanical properties and water absorption of sisal/ high-density polyethylene composites were also studied. The results show that alkali/polyvinyl alcohol coating compound treatment can effectively improve the interfacial adhesion between sisal fiber and high-density polyethylene, improve the mechanical properties of composite, and reduce water absorption. Alkali/polyvinyl alcohol coating compound treatment is a very environment-friendly, cost-effective fiber modification method when compared with traditional modification methods. It is helpful for the development and application of natural fibers reinforced composites.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.