Natural fiber‐reinforced biodegradable polyester composites were prepared from biodegradable polyesters and surface‐untreated or ‐treated abaca fibers (length ca. 5 mm) by melt mixing and subsequent injection molding. Poly(butylene succinate)(PBS), polyestercarbonate (PEC)/poly(lactic acid)(PLA) blend, and PLA were used as biodegradable polyesters. Esterifications using acetic anhydride and butyric anhydride, alkali treatment, and cyanoethylation were performed as surface treatments on the fiber. The flexural moduli of all the fiber‐reinforced composites increased with fiber content. The effect of the surface treatment on the flexural modulus of the fiber‐reinforced composites was not so pronounced. The flexural strength of PBS composites increased with fiber content, and esterification of the fiber by butyric anhydride gave the best result. For the PEC/PLA composites, flexural strength increased slightly with increased fiber content (0–20 wt.‐%) in the case of using untreated fiber, while it increased considerably in the case of using the fiber esterified by butyric anhydride. For the PLA composite, flexural strength did not increase with the fiber reinforcement. The result of soil‐burial tests showed that the composites using untreated fiber have a higher weight loss than both the neat resin and the composites made using acetylated fiber.
Flexural modulus of PBS composites as a function of fiber content. 相似文献
The objective of this research was to evaluate the effectiveness of several different methods for controlling the pore size and pore size distribution in activated carbon fibers. Variables studied included fiber shape, activation time, and the addition of small amounts of silver nitrate. Pure isotropic pitch and the same isotropic pitch containing 1 wt.% silver were melt spun to form fibers with round and trilobal cross sections. These fibers were then stabilized, carbonized, and activated in carbon dioxide. Field emission scanning electron microscopy (FE SEM), electron dispersive spectra (EDS), and wavelength dispersive spectra (WDS) were used to monitor the size and distribution of the silver particles in the fibers before and after activation. Each of these analyses showed that the distribution of silver particles was extremely uniform before and after activation. The fibers were also weighed before and after activation to determine the percent burn-off. The BET specific surface areas of the activated fibers were determined from N2 adsorption isotherms measured at −196 °C. The results showed that round and trilobal fibers with equivalent cross-sectional areas yielded similar burn-off values and specific surface areas after activation. Also, activation rates were found to be independent of CO2 flow rate. The porosity of the activated fibers depended on the total time of activation and the cross-sectional area of fibers. The N2 adsorption measurements showed that the activated fibers had extremely high specific surface areas (greater than 3000 m2/g) and high degrees of meso- and macro-porosity. FE SEM was also used to investigate surface texture and size of pore openings on the surfaces of the activated fibers. The photos showed that silver particles generated surface macro- and mesopores, in agreement with the inferences from N2 adsorption measurements. 相似文献
Three-dimensional (3D) long range well ordered macroporous SiCN ceramics were prepared by infiltrating sacrificial colloidal silica templates with the low molecular weight preceramic polymer, polysilazane. This was followed by a thermal curing step, pyrolysis at 1250 °C in a N2 atmosphere, and finally the removal of the templates by etching with dilute HF. The produced macroporous SiCN ceramics showed high BET surface areas (pore volume) in the range 455 m2/g (0.31 cm3/g)–250 m2/g (0.16 cm3/g) with the pore sizes of 98–578 nm, which could be tailored by controlling the sizes of the sacrificial silica spheres in the range 112–650 nm. The sphere-inversed macropores were interconnected by 50 ± 30 nm windows and 3–5 nm mesopores embedded in the porous SiCN ceramic frameworks, which resulted in a trimodal pore size distribution. The surface of the achieved porous SiCN ceramic was then modified by Pt–Ru nanoparticle depositing under mild chemical conditions. 相似文献
For the first time, graphite fibers have been electrochemically intercalated with Br− that have the same structure and properties as those intercalated from vapor phase Br2. This was accomplished by intercalating pitch-based Thornel® K-1100 graphite fibers at low temperature (near 0 °C) and high currents (2 A) for long times (6 h). The mechanism appears to be that Br− is oxidized to aqueous Br2 which, when sufficient local concentration builds up, intercalates the fiber. This was confirmed by intercalating K-1100 fiber in a saturated aqueous Br2 solution without passing an electrical current. The applied voltage does apparently lower the activation energy of the reaction as evidenced by the observation that P-120 and P-100 fibers will not intercalate in aqueous Br2 unless a voltage is applied. 相似文献
Molecular sieve properties of activated carbon fibers modified by cracking treatment with methane are studied herein. The effect of methane treatment on the porous texture of the samples has been studied while varying temperature and time. These materials have been evaluated for their selectivity during CO2 and CH4 separation; their uptakes have been compared with non-treated activated carbon fibers (studied previously), which were considered suitable to be used as molecular sieves. Kinetics of CO2 and CH4 uptake have also been investigated in this research. The treatment produced materials exhibiting fast kinetics and high selectivity during CO2 and CH4 separation; at the same time however, the CO2 uptake capacity was diminished. 相似文献