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151.
Wen‐xiong Shi Yun‐yan Li Jun Xu Gui‐qiu Ma 《Journal of Macromolecular Science: Physics》2013,52(6):1115-1126
The relationship of the phase morphology of polypropylene/polyethylene‐terephthalate (PP/PET) blends and their corresponding compatibilized blends with composition was investigated using digital image analysis. A diameter, d g , was defined and calculated to discuss the phase morphology of this polymer blend system. A figure‐estimation method was introduced to determine the width of the distribution of d g . Based on the method, it is proven that the distribution of d g obeys a log‐normal distribution and consequently, the distribution width, σ was calculated. Further, a fractal dimension, D f , was introduced to describe the distribution of main sizes of the particles of the dispersed phase. The results showed that, while d g increased with the concentration of the dispersed phase, σ and D f show different dependence relations on composition;σ increases monotonously but D f shows a maximum at a PET content of 30%, indicating that, even though the whole size distribution is much broader, the distribution of the main body of size becomes more uniform when the content of PET is less than 30%. 相似文献
152.
Binary blends of unbranched polyethylene (PE) and 5-10% model ethylene-butene random copolymers are used to determine the effects of composition heterogeneity on phase separation in the melt, semicrystalline morphology, plane strain fracture toughness JC and tensile modulus and yield strength. Slowly cooled samples of melt-miscible blends are appreciably tougher (JC = 5.2 kJ/m2) than unblended PE (JC = 2.7 kJ/m2). A blend with the same average short chain branch concentration, but which is phase separated in the melt state, has JC= 3.3 kJ/m2; dispersed domains of amorphous polymer have little effect on toughness. Enhanced toughness is associated with nonuniform morphology formed on slow cooling “one phase” melts composed of chains with different amounts of branching. The relative number of chemically different chains, as opposed to absolute branch concentrations, seems most important. Tensile properties are relatively unaffected by blending at these levels. Results from these model blends are used to consider the properties of compositionally heterogeneous ethylene copolymers. © 1994 John Wiley & Sons, Inc. 相似文献
153.
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155.
The functions of the main indices of refraction n(ν) and absorption κ(ν) of uniaxial thin polyethylene terephthalate films
have been calculated by the experimental spectra of frustrated total reflection of s-and p-polarized radiation in the 700–760-cm−1 range. The κo(ν) maximum falls at the the 727-cm−1 frequency and the maximum of κe(ν) falls at the the 724-and 732-cm− 1 frequencies.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 756–759, November–December, 2005. 相似文献
156.
Stick-slip flow of high density polyethylene in a transparent slit die investigated by laser Doppler velocimetry 总被引:1,自引:0,他引:1
The oscillating flow instability of a molten linear high-density polyethylene is carefully studied using a single screw extruder equipped with a transparent slit die. Experiments are performed using laser Doppler velocimetry in order to obtain the local velocities field across the entire die width. At low flow rate, the extrusion is stable and steady state velocity profiles are obtained. During the instability, the velocity oscillates between two steady state limits, suggesting a periodic stick-slip transition mechanism. At high flow rate, the flow is mainly characterized by a pronounced wall slip. We show that wall slip occurs all along the die land. An investigation of the slip flow conditions shows that wall slip is not homogeneous in a cross section of the slit die, and that pure plug flow occurs only for very high flow rates. A numerical computation of the profile assuming wall slip boundary conditions is done to obtain the true local wall slip velocity. It confirms that slip velocities are of the same order of magnitude as those measured with a capillary rheometer. 相似文献
157.
Merijs Meri R. Jablonskis I. Zicans J. Kalnins M. Bledzki A. K. 《Mechanics of Composite Materials》2004,40(3):247-252
Considering the wide applicability of polymeric composite materials, heterogeneous blends of poly(ethylene terephtalate) (PET) and polyethylenes of high and low densities (HDPE and LDPE, respectively) were investigated. Rheological (the flow-behavior index), mechanical (the yield strength and the Charpy impact strength), and morphological (crystallinity and the melting temperature) properties were detected for individual blend components and different blend compositions. A radiation treatment (-rays) was applied to improve certain characteristics of the heterogeneous blends. The results of this investigation show that the radiation modification can be successfully used to improve some physical properties of the PET-based blends and to choose individual blend components, optimum irradiation conditions, and desirable blend compositions, which allows producing materials with a predictable set of mechanical properties. 相似文献
158.
The structure of XLPE and the distribution of space charge 总被引:1,自引:0,他引:1
The formation and accumulation of space charge under charge treatment are investigated using PWP method. The interaction between space charge and the structure of XLPE is measured using infrared spectroscopy (IR) method. The related mechanism about space charge distribution and the structure of XLPE are discussed. 相似文献
159.
160.
Hua Zhu Xiaoping Xu Wei Cui Yuanqing Zhang Huaping Mo Yu‐Mei Shen 《Journal of polymer science. Part A, Polymer chemistry》2011,49(8):1745-1752
This article describes the synthesis and characterization of hydroxyl tailored, molecularly defined biodegradable cooligomers capable of chelating rhenium for potential radiopharmaceuticals. New insights were gained during the synthesis of lactide based on dimethylaminopyridine‐catalyzed transesterification. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献