不同端基及分子量聚氧乙烯的结晶行为研究

通过偏光显微镜和DSC技术，较为详细地研究了不同端基及分子量PEO的结晶行为，当PEO的分子量大于6000g/mol时，分子量对其结晶行为的影响逐渐变得很小，当分子量介于6000g/mol-2000g/mol时，为一临界分子量区，分子量变化对其结晶能力有很大的影响。氯乙基酯端基PEO链的折叠结晶受限较大，结晶度损失较大，而且，当分子量降至临界分子量区时，PEO结晶受限对端基体积更加敏感，结晶能力大大降低，羟基端基对结晶熔融焓（ΔHf)的影响与分子量的大小有强烈的关系，Tm仅随着端基体积的变大而下降。     

分子量及其分布对聚丙烯力学性能和结晶行为的影响

通过机械共混的方法制备一系列不同分子量及其分布的聚丙烯，并对其力学性能和结晶行为进行了表征，研究了分子量及其分布对这些性能的影响以及力学性能和结晶行为的对应关系。通过实验发现，分子量及其分布对聚丙烯的结晶速率，结晶温度，结晶度，冲击强度，拉伸屈服强度，断裂伸长率等均有较大影响。     

蓖麻油-聚醚基聚氨酯弹性体的制备和表征

以可再生资源-蓖麻油作为起始荆,环氧丙烷开环聚合制备了不同分子量的蓖麻油-聚醚多元醇,并通过1HNMR 和 FTIR 等手段来分析蓖麻油-聚醚多元醇的结构.以不同分子量的蓖麻油-聚醚多元醇作为原料制备了一系列聚氨酯弹性体,并对其进行物理机械性能和热性能分析.研究结果表明:随着蓖麻油聚醚多元醇分子量的增加,其聚氨酯弹性体的扯断伸长率逐渐增加,拉伸强度、撕裂强度和硬度逐渐降低;同时,热稳定性提高,硬段的结晶熔融温度和结晶度降低.     

聚酰胺6接枝线性聚磷腈的结晶行为研究

以聚(对苯氧基羧酸)磷腈和己内酰胺为原料，合成了聚酰胺6接枝线性聚磷腈(PA6-g-PPZ)树脂。研究了不同磷含量PA6-g-PPZ树脂的非等温结晶行为，并采用Avrami方程分析了其非等温结晶动力学。研究结果表明，PA6-g-PPZ的结晶速率随着冷却速率的增加而增加；在相同的冷却速率下，PA6-g-PPZ的结晶速率随其磷含量的增加而降低。进一步采用Kissinger法计算出了不同磷含量PA6-g-PPZ的结晶活化能，发现其结晶活化能随磷含量的增加而增加，表明其结晶能力降低。通过X射线衍射分析了PA6-g-PPZ树脂的晶型，发现其γ晶型随着磷含量的增加而增加。     

PA1212-b-PEG嵌段共聚物的组成对结晶和熔融行为的影响

研究以双端羧基尼龙1212为硬段,以双端氨基聚乙二醇为软段的聚酰胺-聚醚分嵌段共聚物的结晶行为。用偏光显微镜、差示扫描量热法研究了不同组成共聚物的结晶形态、熔融结晶温度的影响。PLM观察到共聚物的结晶形态随硬段分子量的增大趋于完善,软硬段相容性随软硬段分子量增大而变差;DSC扫描表明共聚物的熔融温度随着硬段分子量增大而增大,软硬段分子量较大时软硬段相容性较差。     

滑石粉粒径对聚乳酸的结晶行为和力学性能研究

本文研究了不同粒径的滑石粉对聚乳酸(PLA)结晶性能和力学性能的影响。通过差示扫描量热仪研究了不同比例的PLA/滑石粉体系的结晶熔融行为,并使用热台偏光显微镜对PLA/滑石粉体系的结晶形态进行了表征。通过实验分析得出,滑石粉添加量相同时,其粒径越小,PLA的结晶度越高,成核效果越好。且随结晶度增大,其拉伸强度提高,但是断裂伸长率有所下降;滑石粉粒径大小相同时,随滑石粉添加量的增加,PLA结晶度增加,拉伸强度提高。     

固相缩聚共聚酯的熔融行为和结晶速率研究

通过固相缩聚合成了两种不同结构的高分子量共聚酯，研究了样品的熔融行为和结晶速率。研究发现，共聚酯的熔融峰随着固相聚合温度和时间的变化而与纯ＰＥＴ有明显的差别，共聚酯泊结晶速率与慢于纯ＰＥＴ的结晶速率。     

间规聚苯乙烯/高抗冲聚苯乙烯共混物的结晶行为

用双螺杆挤出机制备了间规聚苯乙烯/高抗冲聚苯乙烯(sPS/HIPS)共混物,用差示扫描量热仪和X射线衍射仪研究了HIPS对sPS熔体结晶和冷结晶行为、晶型的影响。结果表明,熔融温度为290℃时,少量HIPS提高sPS熔体结晶温度,但HIPS含量增加降低sPS熔体结晶温度。熔融温度高于300℃时,sPS熔体结晶温度随HIPS含量的增加而降低。熔融温度从290℃提高到300℃,sPS结晶温度降低,结晶热明显增加。sPS冷结晶峰温随HIPS含量增加和扫描速率加快而提高,HIPS对sPS的结晶主要起阻碍作用。退火处理使得sPS和sPS/HIPS生成α和β晶,且随着HIPS含量的增加,α晶含量增大。     

PLA/HNTs纳米复合材料的制备、性能及其发泡行为

采用熔融共混炼法制备交联改性聚乳酸(PLA)/埃洛石(HNTs)纳米复合材料,利用热重分析、差示扫描量热分析、偏光显微镜和流变仪对其热学性能、结晶、流变行为进行了研究,并采用超临界CO2流体技术进行微孔发泡,利用扫描电镜对泡孔形态进行了表征。结果表明:随着HNTs含量的增加,PLA/HNTs复合体系在高温下的热稳定性下降,结晶度由37.4%下降为28.0%,但异相成核效果明显,结晶速率提高,结晶时间由2h缩短为10min。同时,加入HNTs后,PLA/HNTs的熔体粘度显著增加,但随着HNTs含量的增多,PLA/HNTs纳米复合材料粘度增加的趋势逐渐趋缓。当HNTs含量为0.5wt%时,体系粘度达到最大值且发泡效果最佳,泡孔平均直径为21.23μm,泡孔密度达到1.08×109个/cm3。     

表面接枝处理的n-HA充填PLGA等温结晶行为的研究

应用示差扫描量热计（DSC）研究了用低分子量聚乳酸（PDLLA）接枝与未接枝两种处理的纳米羟基磷灰石（n-HA）对聚乙丙交酯（PLGA）等温结晶行为及熔融行为的影响,采用Avrami方程处理其等温结晶过程,计算结晶动力学参数;同时用配带热台的偏光显微镜（POM）研究了其结晶的晶核形态。结果表明该体系等温结晶行为可以用Avrami方程来描述;加入n-HA的两种复合材料及PLGA其结晶最快的温度都是110℃,且都是随着结晶温度的提高结晶速率变慢,但接枝的n-HA对提高PLGA基体的结晶速率、熔点及结晶活化能都比未接枝处理的要小。偏光显微镜研究得出加入n-HA的两种复合材料及PL-GA其球径形态相似,且都随温度升高而使结晶速度降低,但加入未接枝的n-HA比接枝后的结晶更快。以上结果说明接枝处理后的n-HA提高了两相界面结合,因而n-HA的异相成核能力比未接枝处理的要差。     

Immobilization behavior of methyl tert-butyl ether by cyclodextrins

The immobilization behavior of methyl tert-butyl ether (MTBE) by various cyclodextrins (CDs) was studied. Although it has a low hydrophobic character and high polarity compared to other organics, MTBE was effectively immobilized by CDs. The immobilization isotherm was a type of Freundlich isotherm. The immobilization capacity of beta-CDs was the largest of the natural CDs. The initial apparent association constant for MTBE-CD complex follows the order: gamma = beta > methyl-beta > hydroxypropyl beta > alpha. The difference in these constants is related to the size of MTBE and CDs. The size of beta- and gamma-CD is large enough to encapsulate MTBE molecule into the cavity, which that of alpha-CD is too small to encapsulate MTBE.     

Effect of carbon nanotubes on the mechanical properties and crystallization behavior of poly(ether ether ketone)

Pristine carbon nanotubes (CNTs) and noncovalently functionalized carbon nanotubes (f-CNTs) were used to prepare poly(ether ether ketone) (PEEK) composites (CNTs/PEEK and f-CNTs/PEEK) via melt blending. Noncovalently functionalized multiwalled nanotubes were synthesized using hydrogen-bonding interactions between sulfonic groups of sulfonated poly(ether ether ketone) (SPEEK) and carboxylic groups of nanotubes treated by acid (CNTs–COOH). The effects of these two kinds of nanotubes on the mechanical properties and crystallization behavior of PEEK were investigated. CNTs improved mechanical properties and promoted the crystallization rate of PEEK as a result of heterogeneous nucleation. Better enhancement of mechanical properties appeared in the f-CNTs/PEEK composites, which is ascribed to the good interaction between f-CNTs and PEEK. However, the strong interaction of f-CNTs and PEEK chains decreased the crystallization rate of PEEK for high content of f-CNTs.     

Accelerated weathering behavior of poly(phenylene ether)-based TPE

In this report accelerated weathering characteristics of a novel poly(phenylene ether) (PPE)-based thermoplastic elastomer (TPE), i.e. a blend of styrene–ethylene–butylenes–styrene (SEBS)/ethylene vinyl acetate (EVA) and PPE-polystyrene (PS), were studied in detail. Exterior and interior accelerated weathering protocols were followed during photooxidative weathering to simulate outdoor and indoor (behind window glass) applications, respectively. Photooxidative degradation was monitored through optical and mechanical property measurements on the injection molded TPE. The effects of titanium dioxide and carbon black at variable loadings were also studied during the photooxidation process. Attempt was made to analyze the surface mechanical properties through nanoscratch/nanoindentation measurement. Using atomic force microscopy, surface roughness and erosion of the exposed material were investigated. Changes in chemical functionalities due to photooxidative degradation were monitored using attenuated total reflection (ATR)-FTIR. Structure property correlation was established through mechanical (surface and bulk), optical, chemical, and morphological analyses.     

新型聚芳醚酮/SiO2杂化薄膜的制备和摩擦性能

在玻璃基片上制备了含硅氧烷官能团聚芳醚酮(PPEK)/SiO2杂化薄膜.通过对PPEK进行化学改性,得到了含硅氧烷官能团功能性树脂,对其进行了结构表征和性能测量.结果表明,在异腈酸酯基硅烷偶联剂的作用下,含硅氧烷官能团PPEK与正硅酸乙酯经溶胶一凝胶过程形成了共价型有机/无机杂化薄膜材料,用杂化薄膜修饰的基底具有很好的减摩抗磨效果,当载荷为50 mN及100 mN时,杂化薄膜的稳定摩擦系数为0.1左右,且摩擦5 h后摩擦系数变化不大.薄膜的摩擦失效机理主要为疲劳磨损.     

Carbon-nanofibre-reinforced poly(ether ether ketone) composites

Poly(ether ether ketone) nanocomposites containing vapour-grown carbon nanofibres (CNF) were produced using standard polymer processing techniques. Evaluation of the mechanical composite properties revealed a linear increase in tensile stiffness and strength with nanofibre loading fractions up to 15 wt% while matrix ductility was maintained up to 10 wt%. Electron microscopy confirmed the homogeneous dispersion and alignment of nanofibres. An interpretation of the composite performance by short-fibre theory resulted in rather low intrinsic stiffness properties of the vapour-grown CNF. Differential scanning calorimetry showed that an interaction between matrix and the nanoscale filler could occur during processing. Such changes in polymer morphology due to the presence of a nanoscale filler need to be considered when evaluating the mechanical properties of such nanocomposites.     

Carbon-nanofibre-reinforced poly(ether ether ketone) fibres

Nano-reinforced fibres were spun from a semicrystalline high-performance poly(ether ether ketone) containing up to 10 wt% vapour-grown carbon nanofibres using conventional polymer processing equipment. Mechanical tensile testing revealed increases in nanocomposite stiffness, yield stress, and fracture strength for both as-spun and heat-treated fibres. X-ray and differential scanning calorimetry analyses were performed in order to investigate both the orientation of nanofibres within the polymer matrix and the matrix morphology. The carbon nanofibres were found to be well aligned with the direction of flow during processing. Significantly, the degree of crystallinity of the poly(ether ether ketone) matrix was found to increase with the initial addition of nanofibres although the crystal structure was not affected. The measured increase in composite tensile modulus is compared to injection-moulded nanocomposite samples made from the same blends. The results highlight the need to characterise the matrix morphology when evaluating nanocomposite performance and hence deducing the intrinsic properties of the nanoscale reinforcement.     

聚醚醚酮改性研究进展

聚醚醚酮(PEEK)作为一种新型高性能热塑性工程塑料,在许多工程领域有着广泛的应用.采用不同手段增强PEEK,改善其加工性能和力学性能、热性能、摩擦学性能,有利于降低材料成本和进一步拓展应用范围.本文从纤维增强PEEK、颗粒填充PEEK、PEEK表面改性、与聚合物共混等方面综述了PEEK改性研究的进展情况.     

Phase behaviour and mechanical properties of poly(ether ether ketone)-poly(ether sulphone) blends

The phase behaviour and the mechanical properties of binary blends composed of poly(ether ether ketone) and poly(ether sulphone) have been studied both in the amorphous state and after crystallization of poly(ether ether ketone).Differential scanning calorimetry and dynamical mechanical analysis clearly show the existence of phase separation in the blends. Density measurements confirm the absence of strong interactions between the blend components, as well as the slight effect of PES on the crystallization of PEEK.The mechanical properties of the quenched, amorphous blends remain surprisingly good in spite of the observed immiscibility, however, slowly cooled, crystalline blends appear as brittle materials.