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991.
我国主要合成橡胶的进口情况 总被引:1,自引:0,他引:1
介绍2012年我国丁苯橡胶(SBR)、聚丁二烯橡胶(BR)、丁基橡胶(IIR)、丁腈橡胶(NBR)、氯丁橡胶(CR)、乙丙橡胶(EPR)、异戊二烯橡胶(IR)和丁苯热塑性弹性体(SBCs)8种主要合成橡胶的进口情况。2012年我国合成橡胶进口量略有减小,进口主要来源国家和地区为韩国、美国、日本、俄罗斯和我国台湾省,进口贸易方式以一般贸易和进料加工贸易为主,进口地集中在我国轮胎和制鞋行业发达的山东省、上海市、广东省、浙江省、江苏省和福建省等。 相似文献
992.
993.
Combination of microwave-vacuum drying and conventional vacuum drying was investigated as a potential method for drying concentrated Ganoderma lucidum extraction. The Ganoderma lucidum was extracted by hot water (60–65°C) and then concentrated to moisture of about 70% (wet basis) in a rising-film evaporator. The concentrated sample was dried by microwave-vacuum until the moisture content reached 10% (wet basis), and then by conventional vacuum drying at the temperature of 55–60°C to final moisture content about 6% (wet basis). The retention of polysaccharide and triterpenes of Ganoderma lucidum dried by this method were evaluated and compared with those dried by freeze drying and conventional vacuum drying alone. The comparison showed that the quality of extraction dried by the current method was close to that of freeze-dried extraction and much better than that of conventional vacuum-dried ones. 相似文献
994.
Four different drying methods, namely, air drying (AD), microwave-assisted vacuum drying (MWVD), coupled microwave–hot air drying (MWAD), and freeze drying (FD), were studied, in terms of drying time, color, reducing sugar content, shrinkage, microstructure, and sensory evaluation. The drying rate of MWVD and MWAD were notably faster than that of AD and FD. The highest reducing sugar content was observed in MWAD, followed by MWVD. No significant differences were observed in reducing sugar between air-dried and freeze-dried products. FD had the best color and shrinkage among the other drying methods. The color and shrinkage of MWVD drying is close to the fresh litchis and much better than hot air and MWAD. Scanning electron microscopy (SEM) images showed that the MWVD and FD litchis have a porous structure, whereas AD and MWAD litchis have a compact structure. The sensory evaluation suggests that peeled litchis dried by the four studied drying methods are of a quality that is accepted by consumers. 相似文献
995.
In this study, five different flexibilizers were added into a matrix resin to improve the flexibility of electrically conductive adhesives (ECAs). The flexible ECAs were fabricated from the matrix resin and electrically conductive fillers. Their curing was fixed at 150 °C for 30 min. Of the five flexibilizers, 1,3‐propanediol bis(4‐aminobenzoate) (PBA) had the best effect on the electrical, mechanical and thermal properties of the ECAs. During curing, PBA reacted with the functional epoxy in the matrix resin. The soft ether segments in PBA were grafted into the crosslinked epoxy network to form an orderly spaced mesh structure. This led to high‐temperature stability, with the pyrolysis temperature being above 350 °C. Flexible ECAs with a 10% weight ratio of PBA in the matrix resin had the best properties. Their viscosity and bulk resistivity were the lowest. Their flexibility and electrical conductivity were the highest. They also had low storage modulus which could effectively dissipate or reduce the residual shear stress generated by the mismatch of thermal expansion coefficient between chip and substrate. Their impact strength was the lowest, and the toughening effect was so significant that the improvement was about 48% compared to ECAs. © 2013 Society of Chemical Industry 相似文献
996.
In order to enhance the interfacial adhesion between wood fiber and an unsaturated polyester matrix (UPE), acrylic acid (acrylic acid)/poly(methyl methacrylate), and (acrylic acid)/silanization (AAS) were used to treat the wood fibers. The mechanical properties and the impact fracture surfaces of the prepared composites were measured and characterized, and the fracture mechanism of these kinds of composites was analyzed. The results showed that the AAS composites possessed the optimum comprehensive mechanical properties. When the weight fraction of wood fiber was 16%, the flexural strength and flexural modulus of the AAS composites were increased by 28.9 and 51.8%, respectively, compared to those of untreated composites. The highest tensile strength and lowest water absorption were also noted for AAS composites. These composites possessed the strongest interfacial adhesion between wood fiber and the UPE matrix. J. VINYL ADDIT. TECHNOL., 19:18–24, 2013. © 2013 Society of Plastics Engineers 相似文献
997.
Bai Cui Eugenio Zapata‐Solvas Michael J. Reece Chang‐an Wang William E. Lee 《Journal of the American Ceramic Society》2013,96(2):584-591
Using spark plasma sintering, Ti3AlC2/W composites were prepared at 1300°C. They contained “core‐shell” microstructures in which a TixW1?x “shell” surrounded a W “core”, in a Ti3AlC2 matrix. The composite hardness increased with W addition, and the hardening effect is likely achieved by the TixW1?x interfacial layer providing strong bonding between Ti3AlC2 and W, and by the presence of hard W. Microstructural development during high‐temperature oxidation of Ti3AlC2/W composites involves α‐Al2O3 and rutile (TiO2) formation ≥1000°C and Al2TiO5 formation at ~1400°C while tungsten oxides appear to have volatilized above 800°C. Likely due to exaggerated, secondary grain growth of TiO2‐doped alumina and the effect of W addition, fine (<1 μm) Al2O3 grains formed dense, anisomorphic laths on Ti3AlC2/5 wt%W surfaces ≥1200°C and coarsened to large (>5 μm), dense, TiO2‐doped Al2O3 clusters on Ti3AlC2/10 wt%W surfaces ≥1400°C. W potentially affects the oxidation behavior of Ti3AlC2/W composites beneficially by causing formation of TixW1?x thus altering the defect structure of Ti3AlC2, resulting in Al having a higher activity and by changing the scale morphology by forming dense Al2O3 laths in a thinner oxide coating, and detrimentally through release of volatile tungsten oxides generating cavities in the oxide scale. For Ti3AlC2/5 wt%W oxidation, the former beneficial effects appear to dominate over the latter detrimental effect. 相似文献
998.
Min Jia Hongmin Cui Weiqun Jin Lili Zhu Yu Liu Ji Chen 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(3):437-443
BACKGROUND: Rhenium is a rare and valuable metal coexisting with molybdenum in molybdenite and sulfide copper ores and is hard to separate. Methods such as solvent extraction, ion exchange, adsorption, precipitation, etc. have been used to separate and purify Re(VII), and resin ion exchange has been widely investigated and used owing to its convenient operation and relatively low‐cost. The main challenge comes from the preparation of resins having high performance and stability. In an earlier study, an N‐methylimidazolium functionalized strong basic anion exchange resin was successfully synthesized and used for Cr(IV) extraction. This paper, reports on further synthesis and application of this resin for adsorption and separation of Re(VII) and Mo(VI), especially from copper arsenic filter cake. RESULTS: At pH 6.25, Re(VII) and Mo(VI) can be effectively separated with the N‐methylimidazolium functionalized strong basic anion exchange resin, giving a Re(VII) recovery of up to 93.3%, but only 5.1% for Mo(VI). When using the copper arsenic filter cake sample 89.1% Re(VII) recovery was achieved. CONCLUSION: The N‐methylimidazolium functionalized strong basic anion exchange resin exhibited high selectivity and recovery for Re(VII) in a mixed system. © 2012 Society of Chemical Industry 相似文献
999.
Qi Wang Susana M. Olhero José M. F. Ferreira Wei Cui Kexin Chen Zhipeng Xie 《Journal of the American Ceramic Society》2013,96(5):1383-1389
Spherical granules of aluminum nitride (AlN) with an average particle size of about 50 μm were produced from aqueous suspensions using an AlN powder surface treated against hydrolysis with aluminum dihydrogenphosphate [Al(H2PO4)3]. Two different amounts of Al(H2PO4)3 were tested and the effects of surface treatment and aging time were evaluated by various techniques (XRD, TG‐DTA, zeta potential and pH measurements). The treated powder exhibited antihydrolytic property and good dispersing behavior, enabling the preparation of low‐viscosity and high‐concentration aqueous AlN slurries for freeze granulation. The spherical AlN granules were sintered in a boron nitride (BN) powder bed followed by ultrasonic washing of the AlN granulates/BN mixture to remove BN. The sintered spherical AlN granules present excellent crystallinity and high sphericity as observed from SEM micrographs. 相似文献
1000.
A sandwich element can be isolated in all two-dimensional adhesive joints, thereby simplifying the analysis of strain and stress. An adhesive sandwich model has been developed that accommodates arbitrary loading, a bilinear adherend stress-strain response, and any form of nonlinear adhesive behavior. The model accounts for both the bending deformation and the shear deformation of the adherends. Stress and strain distributions in the adhesive were obtained by solving a system of six differential equations using a finite-difference method. For a sample adhesive sandwich, the adhesive strains and stresses from the new model were compared with those of other models. Finally, the model was coupled with an analytical solution for the detached section of an adhesive joint in peel. The stress and strain distributions in the adhesive and the root curvature of the peel adherend were then compared with finite element results. An accompanying article in this issue uses the model with experimental peel data to investigate the suitability of various adhesive failure criteria. 相似文献