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51.
The transitions and reactions involved in the thermal processing of binary mixtures of polyethylene and poly(ethylene‐co‐vinyl acetate) copolymers with different concentrations of a foaming agent (azodicarbonamide) were studied using differential scanning calorimetry (DSC). The effect of ZnO as a kicker also was discussed. The temperature at the maximum rate and the heat evolved were measured for all the processes—melting, transitions, and reactions—all the mixtures prepared were measured and compared. Azodicarbonamide decomposed differently depending on the polymeric matrix. These data can be very useful for the plastic processing industry. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2015–2025, 2006 相似文献
52.
将纳米LDH有机化改性后,与PE进行插层复合,制得复合材料,经挤出吹塑制备纳米复合热封膜,并对其阻隔性及热封性进行测试。结果表明:纳米LDH提高了热封膜对氧气和有机溶剂的阻隔性,并且其用量约3%时,达到最大;同时还提高了热封膜的热封温度;而对水蒸气的阻隔性及热封强度则略有降低。要提高纳米复合封膜的热封强度可适当提高热封温度。 相似文献
53.
The effect of ultrasonic vibration and binary processing aid in improving the processability of metallocene linear low‐density polyethylene (mLLDPE) was investigated. During extrusion, ultrasonic vibration clearly reduced the die pressure and apparent viscosity of mLLDPE but had only a slight effect on its melt fracture. The effect of diatomite/PEG binary processing aid (BPA) was excellent in reducing the viscosity and eliminating the sharkskin fracture of mLLDPE. The effect of ultrasonic vibration and binary processing aid in improving the processability of mLLDPE was synergetic. With a combination of ultrasonic vibration and a small amount of processing aid, the flowability of mLLDPE was further improved, and the critical shear rate for the onset of sharkskin fracture was increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1927–1935, 2007 相似文献
54.
Mostafa Rezaei Azadeh Shirzad Nadereh Golshan Ebrahimi Marianna Kontopoulou 《应用聚合物科学杂志》2006,99(5):2352-2358
We performed surface modification of ultra‐high‐molecular‐weight polyethylene (UHMWPE) through chromic acid etching, with the aim of improving the performance of its composites with poly(ethylene terephthalate) (PET) fibers. In this article, we report on the morphology and physicomechanical and tribological properties of modified UHMWPE/PET composites. Composites containing chemically modified UHMWPE had higher impact properties than those based on unmodified UHMWPE because of improved interfacial bonding between the polymer matrix and the fibers and better dispersion of the fibers within the modified UHMWPE matrix. Chemical modification of UHMWPE before the introduction of PET fibers resulted in composites exhibiting improved wear resistance compared to the base material and compared to unmodified UHMWPE/PET composites. On the basis of the morphological studies of worn samples, microploughing and fatigue failure associated with microcracking were identified as the principle wear mechanisms. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006 相似文献
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Blending a crosslinked high‐density polyethylene (xHDPE) enhances melt strength and strain hardening behavior in elongational viscosity of high‐density polyethylene (HDPE) to a great degree. Gel fraction of xHDPE has a stronger effect on the strain hardening than sol fraction, although sol fraction also enhances the strain hardening to some degree. Further, the xHDPE crosslinked by peroxide in a compression mold exhibits more pronounced effect than xHDPE by radiation, which is attributed to the difference in the amount of the gel fraction. The xHDPE, which enhances the strain hardening, has sparse crosslink points in the network. Moreover, it was found from linear viscoelastic measurements, such as oscillatory modulus and relaxation modulus, that the xHDPE is characterized as a critical gel, which was also supported by the result of tensile testing. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 73–78, 2002 相似文献
57.
对非均相液—液两相的聚结分离机理进行了阐述,以纤维类聚结介质为例,将聚结过程分为液滴捕集、液滴聚结和液滴沉降三个阶段。在聚结原理基础之上,对液—液聚结分离用的聚结材料进行分类,在此基础之上,详细介绍了目前应用比较广泛的液—液两相分离设备。最后指出液—液两相聚结分离技术及设备的发展方向。 相似文献
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59.
This paper deals with in situ compatibilization of PE/PS blends via Friedel-Crafts reaction, performed at the interphase. Two polyethylenes having different molecular weights, and the same PS, were used along a wide range of catalyst concentration. The influence of the graft copolymer architecture and content on the efficiency of blend compatibilization was studied. The emulsifying effect, morphological aspects and mechanical behavior were also assessed for these blends. The amount of copolymer formed increases with catalyst concentration and the short chain length fraction of the homopolymers. The high molecular weight (MW) copolymers behaved as better compatibilizers as they showed, at the cmc, greater graft copolymer concentration than the low MW ones. A substantial increase in interfacial adhesion and particle size reduction was observed, even at catalyst concentrations as low as 0.3 wt%. In correspondence, mechanical properties, like ductility and yield strength, were enhanced by the effect of this Friedel-Crafts reaction's compatibilization. 相似文献
60.