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31.
Yingni Yang Yao Pang Weiye Zhang Rongqi Xia Yanchen Li Yi Liu Hongwu Guo 《Polymer Composites》2021,42(3):1429-1439
Rice husk (RH) is a productive agricultural residue; however, its materialization is limited by its inherent properties. The comprehensive utilization of RH can be improved via pretreatment using physical and chemical methods. In this study, we explored the effect of pretreatment (shearing, grinding, and alkaline) on the properties of RH, as well as the bio-composites developed using RH and high-density polyethylene (HDPE). Further, the surface morphology, chemical structure, water absorption, thermal stability, and dynamic viscoelasticity of the pretreated RH and RH/HDPE composites were investigated. The results denoted that the surface roughness of RH increased and that the silicon content partially decreased. The water absorption of the RH/HDPE composites pretreated by physical pretreatment was <2%. The occurrence of dynamic viscoelasticity indicated that the RH/HDPE composites pretreated by alkaline exhibited improved rigidity and mechanical properties. In the composites prepared using the RH pretreated by grinding, a strong bonding could be observed between the interfaces of HDPE and RH. Hence, the efficiency of RH utilization can be improved by pretreatment, and the prepared bio-composites can increase the value of RH. 相似文献
32.
The feasibility of tailoring the moisture resistance of bioadhesives by activating relaxation-controlled diffusion mechanisms is demonstrated herein using gelatin, a hydrophilic biopolymer, as a model biobased resin for engineered wood products. The effect of gelatin-to-water concentration and tannin addition on the governing kinetics of water transport in gelatin-based bioadhesives was investigated in this work. Time-dependent flexural mechanical properties of laminated (a) gelatin and (b) gelatin–tannin wood veneer composites conditioned at both moderate and high humidity were characterized and compared to oriented strand board and plywood. Results indicate that increases in both gelatin and tannin content not only decrease rates of water uptake, volumetric swelling, and maximum moisture contents of gelatin-based resins, but also increasingly induce relaxation-controlled moisture diffusion behavior, which implies short-term moisture resistance and long-term moisture affinity. This behavior could be leveraged to address both in-service (i.e., strength, stiffness) and out-of-service (i.e., rapid biodegradation) requirements for engineered wood products. 相似文献
33.
Yu Xian Cuicui Wang Ge Wang Leemiller Smith Hai Tao Cheng 《Iranian Polymer Journal》2017,26(3):169-178
To analyze quantitatively the interface of core–shell structural bamboo plastic composites (BPCs) surface, the relationship between the microstructure of composite surface and the macroscopic impact performance was investigated. The effect of shell layer on the interface and impact strength of the core–shell BPCs was studied by scanning electron microscope (SEM) images, computer image processing technique and fractal theory. The fractal dimensions of the core–shell BPCs were calculated and the relationship between the measured impact strength and the fractal dimensions of the core–shell BPCs fracture surface was discussed. The results showed that the fractal dimensions of the interface and fracture surface were within the range of about 2.1725 to 2.1970 and 2.2075 to 2.2204, respectively. All the correlative coefficients were higher than 0.99, therefore, the strong linear correlation indicated that the fractal characterization of the interface and impact fracture surface for the BPCs was possible, and also proved that the interface could be analyzed quantitatively depending on the feature parameters of the fractal dimension. The relationship between the fractal dimension and the measured impact strength was linear. The bigger the fractal dimension of surface, the bigger the impact strength and stronger the interfacial bond were. Thus, using the fractal dimensions the surface morphology of core–shell structural BPCs can be described and it may provide a new approach to investigate the inherent rules of fractal characteristics and Charpy impact strength of the BPCs with core–shell structure. 相似文献
34.
《Carbon》2014
Multifunctional designs of biomimetic layered materials are in great demand for broadening their applications. Artificial hybrid films are fabricated using a simple evaporation-induced assembly method, using nacre as the structural model, two-dimensional reduced graphene oxide (RGO) and magnetic graphene (MG) as inorganic building blocks and poly(vinyl alcohol) (PVA) as glue. The nacre-like films exhibit good mechanical performance, such as high stiffness, strength and toughness. The biomimetic materials possess the shielding properties of electromagnetic pollution. MG based nacre-like films present more significant electromagnetic interference (EMI) shielding performance than RGO film, because of a synergism between dielectric loss of graphene and magnetic loss of magnetic nanoparticles. Average EMI shielding effectiveness (SE) reaches ∼20.3 dB over the frequency range of 8.2–12.4 GHz (X band) for MG hybrid film only 0.36 mm thick. The lightweight, flexible and thin MG artificial hybrid films possess good potential for EMI shielding applications. 相似文献
35.
Tannin from larch (Larix gmelini) bark extracts, as a natural renewable resource, was used to prepare tannin–urea–formaldehyde (TUF) resin. The chemical structures of larch tannin and TUF resin were characterized by matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry and 13C nuclear magnetic resonance. The thermal behaviors of TUF resin were evaluated by differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). The performances of TUF resin were investigated by measuring the bond strength and formaldehyde emission of its bonded plywood. It was clearly shown that larch tannin is mainly composed of prodelphinidin repeating units. Phenolic groups were introduced into TUF resin mainly linked by methylene bond. Larch tannin has an adverse effect on the resin curing. However, it promoted the rigidity and flexibility of the glued system and upgraded the properties of plywood. Therefore, larch tannin could be applied in the modification of urea–formaldehyde resin. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41064. 相似文献
36.
The techniques for denaturing defatted soy flour (DSF) for the production of high performance soy-based bio-adhesives (SBA) have been developed. The developed soy based products from various stages of process were characterized using FTIR and XPS to examine the denaturing mechanisms. The results from the orthogonal statistics [L9(34)] showed that the optimized ratio of DSF:H2O was 2:8 by weight and the best combination of acid:salt:alkali was 2.38:0.002:7.98% total mass of DSF and H2O. The FTIR and XPS spectra illustrated the change of chemical groups and conversion of the protonized products: the amide link hydrolysis and decarboxylation have taken place when DSF was denaturized by acid and salt with the active groups, –NH2, –COOH and –OH, increased. The alkali modification caused some aminolysis with the active groups increased further. Curing SBA made amide links reestablished and hence caused amination, resulting in the improvement of cross-linkage of soy-protein and hence water-resistance. 相似文献
37.
易钊;李城;李炯炯;张伟;李建章 《中国人造板》2016,23(2):5-7
防眩板是高速公路重要安全防眩形式之一,本文介绍了防眩板的发展现状、我国现有高速公路用防眩板的种类以及木质复合材料防眩板的开发与性能,并展望了木质复合材料防眩板发展前景。 相似文献
38.
《Fuel》2006,85(12-13):1743-1749
Biodiesel is a clean alternative fuel, which can be used to reduce the emission pollution from diesel engines. The improvement of fuel properties of biodiesel through production technique was investigated in this study. A chemical production procedure of transesterification reaction combined with an additional peroxidation process was applied to produce the biodiesel. It was shown that the biodiesel produced by this method has a larger weight proportion of saturated carbon bonds, higher kinematic viscosity, and a higher flash point with less fuel residue collected after the fuel burning, than the biodiesel without the additional peroxidation process. Moreover, the peroxide value and the acid number increased while the thiobarbituric acid value, iodine value, combined relative oxidation rate, and number of double bonds of fatty acids reduced for the biodiesel produced with the additional peroxidation process. Therefore, it was concluded that the peroxidation process for biodiesel production can be used to improve the fuel properties of biodiesel. 相似文献
39.
Carbon nanofibers (CNFs) were functionalized with 3-glycidoxypropyltrimethoxysilane and dispersed into epoxy resin. The chemical modification of CNFs was confirmed by FTIR, SEM, EDX and TGA measurements. After silanization, FTIR showed the existance of epoxy ring; EDX detected Si element; while TGA indicated 1.1 wt.% Si on CNFs. Mechanical properties were analyzed by DMA. Silanized CNFs/epoxy composites demonstrated improved dispersion of CNFs in the matrix, and an enhancement of storage modulus for about 20% compared to the neat matrix, which indicated that the modification of CNFs improved the adhesion between fillers and matrices. DC electrical conductivity of CNFs was reduced about 7-fold compared to the original CNFs due to the silane coating. Accordingly, the composites containing silanized CNFs also had lower electrical conductivity than those containing original CNFs. In spite of decreased electrical conductivity, thermal conductivity of silanized CNFs/epoxy composites was increased due to the surface modification of CNFs. 相似文献
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