动态热机械分析仪测试条件对轮胎胎面胶动态力学性能分析的影响

研究动态热机械分析仪测试条件对胎面胶动态力学性能测试结果的影响。结果表明:升温速率过快,会导致玻璃化转变温度和损耗因子(tanδ)测试值偏大;预拉伸形变(静态形变)过大,会导致tanδ测试值偏差变大;动态形变过大,会导致胶料滞后效应明显,tanδ测试值偏大;测试胎面胶性能时,应选择较小动态形变;测试胎侧胶性能时,应选择较大动态形变。     

双基推进剂的玻璃化温度

评述了双基推进剂的分子结构松弛和玻璃化转变过程,简介了玻璃化转变过程的检测方法,分析了影响双基推进剂玻璃化温度测定的主要因素.提出以动态热机械分析(DMA)测定的α松弛tanδ峰温为双基推进剂玻璃化温度的建议.     

PVC及PMMA在CO_2环境中玻璃化转变特性的研究

对聚合物在CO2环境中的玻璃化转变特性进行了研究。利用蠕变柔量法,在自建的实验装置上,对聚氯乙烯和聚甲基丙烯酸甲酯在CO2环境中不同压力下的玻璃化转变温度进行了测定,并利用间接法测定了对应状态下聚合物中CO2的质量分数。结果表明,在CO2环境中2种材料的玻璃化转变温度显著降低。利用基于经典热力学与统计热力学理论构建的模型,对聚合物中不同的CO2质量分数对应的玻璃化转变温度值进行了计算,得到的计算结果与实验结果较吻合。     

测试方法对聚合物玻璃化温度的影响

选取环氧树脂固化物为样品,分别采用DSC法和DMA法测定了其玻璃化转变温度。结果表明,玻璃化转变温度随测定方法和条件的不同而变化,因此,在给出某种材料的玻璃化转变温度时,必须注明测定方法和条件。     

静态热机械分析法测定液晶聚合物负荷变形温度的研究

建立静态热机械分析法(TMA)测定液晶聚合物负荷变形温度的方法。通过热重(TG)测试确定差示扫描量热法(DSC)测试的终止温度,通过DSC测试确定负荷变形温度测试的终止温度,由分析结果可知,负荷变形温度测试的终止温度不能超过样品的起始熔融温度;样品宽度比负荷杆的截面小,可得到所需的结果,而样品长度会对结果产生较大影响;负荷变形温度测试的起始温度应不高于27℃。此方法操作简单,所得结果重现性较好,具有良好的推广应用价值,还可以扩展热机械分析仪的应用范围。     

粉末涂料聚酯树脂玻璃化温度的研究

探讨了在合成粉末涂料聚酯树脂中，酸，醇等因素对玻璃化温度的影响。合成产品与国外同类产品做ＩＲ图对比，结果相同。     

粉末涂料聚酯树脂玻璃化温度的研究

探讨了在合成粉末涂料聚酯树脂中，酸、醇等因素对玻璃化温度的影响。合成产品与国外同类产品做ＩＲ图对比，结果相同。     

丙烯酸系乳液共聚物玻璃化温度的研究

论述了丙烯酸系乳液聚合物设计中玻璃化温度（Ｔｇ）的预测。低水溶性的单体、带羧基或羟基官能团的单体和阴离子型乳化剂使共聚物Ｔｇ升高；非离子型乳化剂使共聚物Ｔｇ降低。     

A Rapid Method of Measuring the Glass Transition Temperature Using a Novel Dynamic Mechanical Analysis Method

This paper describes a method of measuring the glass transition temperature, by dynamic mechanical analysis, in which the glass transition temperature can be obtained by determining the temperature at which the peak value of damping is observed. The novelty of the method reported here is to use a fast heating technique with a feedback circuit that maintains the specimen at resonance. By doing the test in about a minute, polymer cure is not altered significantly by the heating cycle.     

PPO/EP复合材料的玻璃化转变温度及其测试方法

介绍了玻璃化转变温度(Tg)的内涵及其主要测试方法;以聚苯醚/环氧树脂(PPO/EP)为研究对象,分别采用DSC法和DMA法测定其Tg值,并讨论了两种测试方法的异同。结果表明:两种测试方法的测试条件、测试精度及影响测试结果的因素是不同的。在给出某一种高聚物的Tg时须注明测试方法和条件。     

Glass Transition Temperature and the Nature of the Amorphous Phase in Semicrystalline Polymers: Effects of Drawing,Annealing and Hydration in Polyamide 6

Abstract

The influence of the organization of the amorphous chains segments on the glass transition temperature (T_g) in semicrystalline polymers is analysed by studying the effects of drawing, annealing and hydration in polyamide 6 fibers. We consider the role of three of the features of the amorphous phase: orientation (configurational entropy), density (free volume) and confinement (segmental mobility). Three classes of amorphous phases are identified; two of these are constrained in the intercrystaline regions, at the fold surfaces (between the lamellae within the lamellar stack) and at the stem surface (growth surface of the lamellae or between the fibrils). The third species is the bulk amorphous phase outside the lamellar stacks, and constitutes a large fraction of the amorphous phase especially at low crystallinities. Because the small fraction of the amorphous chain segments in the intercrystalline regions, and because they are in confined spaces, we suggest that these interlamellar and the interfibrillar components do not contribute significantly to the observed major glass transition peak. Rather, it is the amorphous region outside the lamellar stack that determines the T_g. T_g increases upon drawing and decreases upon annealing (heat setting). Our data suggest that orientation has a direct influence on T_g and can easily be measured whereas the influence of crystallinity is more complex. The influence of orientation of T_g can be understood in terms of a two T_g model in which the oriented amorphous component has a higher T_g than the unoriented component.     

Glass transition temperature enhancement of PMMA through copolymerization with PMAAM and PTCM mediated by hydrogen bonding

A series of poly(methyl methacrylate-co-methacrylamide-co-tricyclodecyl methacrylate) (PMMA-co-PMAAM-co-PTCM) copolymers possessing high glass transition temperatures and high transparency are prepared. By incorporating the aliphatic tricyclodecyl methacrylate moiety into the PMMA-co-PMAA main chain results in high glass transition temperature and high transparency of PMMA-based polymeric material. The TCM content affects the fraction of hydrogen bonding in these terpolymers, small content of TCM does not sacrifice the fraction of hydrogen-bonded association in and does not cause T_g decrease. The extent of free amide group plays the major role in dictating moisture absorption of terpolymers. The incorporation of TCM significantly reduces the moisture absorption of terpolymers due to its hydrophobic and bulky tricyclodecyl group. In addition, the TCM plays the role of inert diluent to convert portion of the strong self-associated hydrogen bonded amide groups into inter-associated hydrogen bonding between carbonyl groups of ester units and MAAM.     

生物高聚物玻璃化转变温度计算

目前玻璃化转变温度一般都通过实验获得．但是同一样品采取不同方法,结果有较大差别。采用传统测量方法,既浪费时间又很繁琐,并且测量仪器昂贵。应用基因贡献法计算生物高聚物及共混、共聚的玻璃化转变温度,计算结果与实验值吻合较好。介绍塑性方程如Gordon-Taylor和Couchman-Karasz方程。这些信息有利于食品科学研究及冷冻食品加工和储藏。     

HAN-H_2O 二元体系玻璃化转变温度的依数性及其突变

用ＤＳＣ研究了ＨＡＮ－Ｈ２Ｏ二元体系的玻璃化转变温度Ｔｇ与Ｈ２Ｏ含量的关系,发现在一定的Ｈ２Ｏ含量范围内,玻璃化转变温度具有依数性。根据Ｔｇ的变化规律初步推测该二元体系的分子结构,认为ＨＡＮ－Ｈ２Ｏ二元体系可随Ｈ２Ｏ含量的不同而形成ＨＡＮ／Ｈ２Ｏ摩尔比不同的分子簇,而一个ＨＡＮ分子最多能与三个Ｈ２Ｏ分子形成分子簇,当Ｈ２Ｏ含量８超过７５ｍｏｌ％（ＨＡＮ／Ｈ２Ｏ摩尔比为１／３）时,只能形成ＨＡＮ／Ｈ２Ｏ摩尔比为２／３的稳定分子簇。     

液体发射药的玻璃化转变温度及其体积弛豫活化焓

用ＤＳＣ测定了三种硝酸羟胺－三乙醇胺硝酸盐－水（ＨＡＮ－ＴＥＡＮ－Ｈ２Ｏ）为主成分的液体发射药的玻璃化转变温度，研究了玻璃化转变温度与升温速率的关系，导出了玻璃化转变时体积弛豫的活化焓的表达式，并计算得到了这种活化焓，为改进预测液体发射药低温粘度的方法打下了基础。     

Water Sorption and Glass Transition Temperature of Spray-Dried Mussel Meat Protein Hydrolysate

The water sorption behavior at 25°C and glass transition temperature (T _g ) of mussel meat protein hydrolysate powder without and with maltodextrin 10 DE or gum arabic at 15 and 30% (w/w) were studied in this work. The sorption isotherms were determined by the gravimetric method, and the glass transition temperature was obtained by differential scanning calorimetry (DSC) after powder conditioning at various water activities. Sorption isotherms data were well fitted by a modified Brunauer-Emmett-Teller (BET) model. Powder without additives showed the highest water adsorption followed by those produced with 15 and 30% of carrier agent, respectively. The Gordon-Taylor model was able to predict the effect of water on the glass transition temperature. At 25°C, the critical water content that ensured the glassy state of the mussel hydrolysate powder during storage increased from 0.05 to 0.12 g water/g product and the critical water activity increased from 0.24 to 0.60 when the concentration of carrier agents was increased to 30%.     

玻璃化转变温度测试方法对测试结果的影响

以玻纤增强尼龙66、高密度聚乙烯为样品,分别采用差示扫描量热法和热膨胀法测试了样品的玻璃化转变温度(Tg)。结果表明,材料的Tg随测试方法、测试条件的不同而变化,采用不同的测试方法所得的Tg结果之间不具有可比性,在说明某种材料的Tg时,应注明所采用的测试方法和测试条件。