Thermal and crystallization characteristics of poly(ethylene terephthalate) with poly(oxybenzoate‐p‐trimethylene terephthalate) copolymer

Poly(ethylene terephthalate) (PET) was blended with two different poly(oxybenzoate‐p‐trimethylene terephthalate) copolymers, designated T28 and T64, with the level of copolymer varying from 1 to 15 wt %. All samples were prepared by solution blending in a 60/40 (by weight) phenol/tetrachloroethane solvent at 50°C. The crystallization behavior of the samples was studied by DSC. The results indicate that both T28 and T64 accelerated the crystallization rate of PET in a manner similar to that of a nucleating agent. The acceleration of PET crystallization rate was most pronounced in the PET/T64 blends with a maximum level at 5 wt % of T64. The melting temperatures for the blends are comparable to that of pure PET. The observed changes in crystallization behavior are explained by the effect of the physical state of the copolyester during PET crystallization as well as the amount of copolymer in the blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1599–1606, 2002     

护肤品的功效性评价方法综述

现代科学技术,尤其是生物技术和计算机技术的飞速发展和广泛应用,给化妆品行业带来了全新的发展机遇,赋予化妆品以一定的功效性是新世纪化妆品发展的重要趋势.近20年来,人们对化妆品的要求已从洁肤、润肤为目的的基础护肤品向美白、祛皱为目的的功效性化妆品方向发展.     

The kinetics of B‐a and P‐a type copolybenzoxazine via the ring opening process

The structure of benzoxazines is similar to that of phenolic resin through thermal self‐curing of the heterocyclic ring opening reaction that neither requires catalyst nor releases any condensation byproduct. These polybenzoxazine resins have several outstanding properties such as high thermal stability and high glass transition temperature. To better understand the curing kinetics of this copolybenzoxazine thermosetting resin, dynamic and isothermal differential scanning calorimetry measurements were performed. Three models, the Kissinger method, the Flynn–Wall–Osawa method, and the Kamal method, were used to describe the curing process. Dynamic kinetic activation energies based on Kissinger and Flynn–Wall–Osawa methods are 72.11 and 84.06 KJ/mol, respectively. The Kamal method based on an autocatalytic model results in a total order of reaction between 2.66 and 3.03, depending on curing temperature. Its activation energy and Arrhenius preexponential are 50.3 KJ/mol and 7959, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 730–737, 2005     

浅析实践论视角下的马克思主义真理观

从实践论的视角分析马克思主义真理观.通过对真理的属性及其检验标准、真理和价值的关系问题的讨论,阐述了实践在马克思主义真理观中的作用和地位.     

江苏省泗洪县湿地公园雕塑创作浅析

江苏省泗洪县有着悠久的历史底蕴和深厚的文化背景,泗洪湿地公园是国家级湿地保护区.笔者受当地县政府委托在湿地公园入口处设计制作一幅大型浮雕壁画,前景是两尊立体的2.8米圆雕人物,照壁30米长,2.8米高,记载历史故事和民俗风情.以当地的泗洪湿地的特色飞禽白鹭贯穿始终,将不同时期的人物与景观自然地连贯穿插.并以文武两位名士的圆雕塑像为主要历史文脉,提升湿地公园的历史和人文内涵.湿地公园的雕塑寓意深刻、内涵丰富、品味高雅.雕塑紧扣泗洪县当地的自然环境和历史文化,为泗洪湿地公园增添了风采和神韵.     

MC(Mid-Century)催化氧化过程的研究进展

介绍了MC催化氧化过程规律；从催化荆体系的改进、新型溶剂体系的开发、反应器构型和配套设施的改进、富氧氧化技术的开发等方面综述了近年来MC技术的发展；探讨了MC液相催化氧化技术应用范围的拓展以及MC液相催化氧化过程的发展方向。     

乳胶制品生产的工序能力分析及质量控制

本文分析了乳胶制品的生产过程，并对工序能力指数进行了分析，从而推断出产品的质量。     

Crystallization behavior,mechanical properties,and environmental biodegradability of poly(β‐hydroxybutyrate)/cellulose acetate butyrate blends

The miscibility, crystallization behavior, tensile properties, and environmental biodegradability of poly(β‐hydroxybutyrate) (PHB)/cellulose acetate butyrate (CAB) blends were studied with differential scanning calorimetry, scanning electron microscopy, wide‐angle X‐ray diffraction, and polarizing optical microscopy. The results indicated that PHB and CAB were miscible in the melt state. With an increase in the CAB content, the degree of crystallinity and melting temperature of the PHB phase decreased, and this broadened the narrow processability window of PHB. As the elongation at break increased from 2.2 to 7.3%, the toughness and ductility of PHB improved. From the degradation test, it could be concluded that degradation occurred gradually from the surface to the inside and that the degradation rate could be adjusted by the addition of the CAB content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2116–2122, 2003     

Reaction mechanism and microstructure evolution of reaction sintered <Emphasis Type="Italic">h</Emphasis>-BN

Hexagonal boron nitride ceramic (h-BN) based on the nitridation of B powders was obtained by reaction sintering method. The effects of sintering temperature on the mechanical properties and microstructure of the resultant products were investigated and the reaction mechanism was discussed. Results showed that the reaction between B and N₂ occurred vigorously at temperatures ranging from 1 000 °C to 1 300 °C, which resulted in the generation of t-BN. When the temperature exceeded 1 450 °C, transformation from t-BN to h-BN began to occur. As the sintering temperature increased, the spherical particles of t-BN gradually transformed into fine sheet particles of h-BN. These particles subsequently displayed a compact arrangement to achieve a more uniform microstructure, thereby increasing the strength.