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91.
The method to prepare microporous chitosan membrane by selective dissolution of its blend was evaluated. Two synthetic polymers, e.g. polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG), were chosen to be the counterpart polymers. Results of Fourier transform infrared (FTIR) characterization, differential scanning calorimeter (DSC) analysis, wide angle X-ray diffraction (WAXD) measurements showed that there are special interactions between chitosan and the counterpart polymers. The pore structure induced by this method is controlled by the compatibility of the chitosan and the counterpart polymers. No pore structure was induced in the case of chitosan/polyvinyl pyrrolidone because of their molecule level miscibility and strong interaction. Highly porous structure was induced in the case of chitosan/polyethylene glycol because of their poor compatibility and multiphase structure. 相似文献
92.
Matthias Ballauff 《先进技术聚合物》1990,1(1):109-116
Polymer blends can be either composed of mixtures of flexible components, of a stiff chain and a flexible macromolecule, or of two stiff-chain polymers. All three cases may be dealt with in terms of the Flory lattice model. Special attention is paid to the influence of liquid crystalline order on the miscibility of the two polymers. For isotropic mixtures all three cases may be described in terms of the usual Flory–Huggins approximation. If a nematic phase is formed the miscibility of blends of rigid rods with flexible macromolecules (molecular composites) is strongly reduced because of entropic reasons. Highly ordered mixture of two stiff-chain polymers in melt can be described in terms of the regular solution theory leading to the same miscibility criterion as is valid for two flexible polymers. All deductions are compared to recent experimental work. 相似文献
93.
聚氯乙烯(PVC)用作阻尼材料时多作成与高聚物的共混物,也有采用IPN的方法改善PVC的阻尼性能,前巳报导PVC-丁腈羟低聚物共混物有较佳的阻尼性质。本工作考察了PVC-PIB(聚异丁烯)组成及添加剂对共混物力学性能和动态力学性质的影响。 相似文献
94.
<正> 二苯甲酰甲烷(DBM)由于其互变异构平衡强烈地趋向烯醇,因而存在着稳定的分子内六元环氢键结构,具有较强吸收紫外辐射的能力。 相似文献
95.
96.
Fatemeh Samadi Bernhard A. Wolf Francisco-J. López-Villanueva 《European Polymer Journal》2007,43(10):4236-4243
Branched polyisoprene (PI) was prepared from PI-macromonomers. Linear byproducts of the synthesized polymer were removed by means of inverse spin fractionation, using the solvent cyclohexane (CH) and the precipitant acetone (AC). A well-defined fraction (Mw = 17.5 kg/mol, Mw/Mn = 1.8) of the branched polyisoprene obtained in this manner was used to determine different phase diagrams with branched and/or linear PI in the mixed solvent CH/AC at 25 °C. For comparable molar masses of the polymers the two-phase area is smallest for the branched PI and slightly larger for the linear PI; in the case of the unfractionated original sample of the branched polymer one observes a pronounced peninsula of immiscibility extending into the region of high CH concentrations. This feature is attributed to a large miscibility gap between the branched and the linear polymer, which was studied in more detail for the ternary system CH/branched PI/linear PI. 相似文献
97.
Ilya Kuselman Maria Belli Stephen L. R. Ellison Ales Fajgelj Umberto Sansone Wolfhard Wegscheider 《Accreditation and quality assurance》2007,12(11):563-567
Comparability and compatibility of proficiency testing (PT) results are discussed for schemes with a limited number of participants
(less than 20–30) based on the use of reference materials (RMs) as test items. Since PT results are a kind of measurement/analysis/test
result, their comparability is a property conditioned by traceability to measurement standards applied in the measurement
process. At the same time, metrological traceability of the certified value of the RM (sent to PT participants as test items)
is also important, since the PT results are compared with the RM certified value. The RM position in the calibration hierarchy
of measurement standards sets the degree of comparability for PT results, which can be assessed in the scheme. However, this
assessment is influenced by commutability (adequacy or match) of the matrix RM used for PT and routine samples. Compatibility
of PT results is a characteristic of the collective (group) performance of the laboratories participating in PT that can be
expressed as closeness of the distribution of the PT results to the distribution of the RM data. Achieving quality-of-measurement/analysis/test
results in the framework of the concept “tested once, accepted everywhere” requires both comparability and compatibility of
the test results. 相似文献
98.
99.
In this Letter we study a class of symmetries of the new translational extended shape invariant potentials. It is proved that a generalization of a compatibility condition introduced in a previous article is equivalent to the usual shape invariance condition. We focus on the recent examples of Odake and Sasaki (infinitely many polynomial, continuous l and multi-index rational extensions). As a byproduct, we obtain new relations, to the best of our knowledge, for Laguerre, Jacobi polynomials and (confluent) hypergeometric functions. 相似文献
100.
HIPS-g-GMA相容剂对PC/HIPS共混物相容性的影响* 总被引:3,自引:0,他引:3
将两种或两种以上聚合物进行共混是获得性能优异合金材料的简单而有效的途径[1,2 ] .但是大多数聚合物共混时 ,由于混合焓ΔH >0且混合熵ΔS非常小 ,导致混合自由能大于零 ,故大多数共混体系是不相容的 .而对于不相容的共混 ,由于两相间的界面张力大 ,两相间形成锐形界面 ,两相之间的界面粘结力低 ,导致材料性能很差 .为了改善两相间的相容性 ,需要加入相容剂[3 ,4 ] .绝大多数增容剂是嵌段或接枝共聚物 .这类增容剂分子量较大 ,在加工条件下 ,由于其粘度较大往往难于迁移到两相的界面处 ,起不到应有的增容作用 .聚合物反应加工技术是近 2… 相似文献