尼龙6,6(PA_(6,6)及其共混物结晶性能的研究

<正> 尼龙6,6(PA_(6,6))是一种典型的结晶性工程塑料,被广泛应用于纺织、机械制造等行业,但其加工温度范围较窄,耐热性差。聚醚砜(PES)具有较高的玻璃化转变温度,是非晶聚合物,可以诱发某些结晶聚合物结晶。PES与PA_(6,6)共混体系的研究报道较少,本文用熔融法将PES与PA_(6,6)制成共混物,企图改善PA_(6,6)的结晶性,以提高其耐热性,取得了较理想的结果。     

聚氧化乙烯(PEO)/聚双酚A羟基醚(PBHE)共混体系的非等温结晶动力学

本文联系Avrami方程和Ozawa方程,得出一个适合于非等温结晶动力学过程的新的基本方程,由这个方程可获得描述非等温结晶动力学过程的某些参数,并用DSC方法,对PEO/PBHE共混体系的非等温结晶动力学进行了研究,对实验结果进行了讨论.     

聚丙烯-聚乙烯嵌段共聚物的分子结构及性能的研究

本工作用核磁共振(~(13)C-NMR)、示差扫描量热(DSC)、动态力学分析(DMA)和扫描电子显微镜(SEM)等技术研究了将丙烯、乙烯单体两步分段共聚、预期为聚丙烯-聚乙烯嵌段共聚物的合成物(简称为聚丙烯-聚乙烯嵌段共聚物或嵌段共聚物)。结果表明,在嵌段共聚物中含有一定量的、能为正庚烷抽提出来的乙丙无规共聚物(EPR);分段共聚的产物并非预想的PP-b-PE两嵌段共聚物,而是含有多种组分的共混物;形态表征的结果表明了嵌段共聚物为多相体系,EPR和PE形成分散相以球形无规分布于PP基体中。     

聚乙炔热氧化过程的研究

本文测定了聚乙炔在氮气、空气和氧气中的等速升温热重曲线,测定了不同聚乙炔样品热氧化的恒温热重曲线,比较了聚合体系和顺反结构等对热氧化行为的影响。观察到钕催化聚乙炔的热氧化诱导现象。动力学分析表明,氧化反应对聚乙炔和氧气浓度都接近表观一级反应,顺式聚乙炔的表观活化能为42±6ki/mol,反式聚乙炔为51±6kJ/mol。用红外光谱跟踪氧化过程,表明含氧基团可分两类,分属于中间和最终产物,由此推断了可能的氧化反应。     

热处理过程中非晶态聚芳酯超分子结构的变化

本文采用TEM、SAXS及DSC等方法研究了经WAXD证明的芳香族聚酯在T_g,附近退火过程中形成的区域结构,在TEM观察中采用了金装饰制样技术,使形态观察更为清晰,在SAXS测量中采用了Kratky准直系统而提高了分辨率,在DSC测量中,从剩余焓(△H)对升温速率作图,求得热力学平衡态时的(△H)_0。结果证明,聚芳酯在T_g以下长时间退火时,可以形成40—60nm的区域结构。     

结晶聚合物的辐射效应 Ⅰ.γ-辐照尼龙1010的聚集态结构

本文通过WAXD和DSC等方法研究了γ-辐照尼龙1010聚集态结构的变化,结晶损伤和无定形化的过程。这些过程和结晶与非晶界面原子参与化学反应密切相关,结晶损伤从结晶表面开始,随着辐照剂量增加逐渐向结晶内伸展,直到完全无定形化。     

IONIC CONDUCTIVITY OF EPOXY NETWORK/POLYETHYLENE GLYCOL- LITHIUM PERCHLORATE COMPLEX IPN SYSTEM

In an attempt to prepare a polymeric solid electrolyte with both high ionic conductivity at ambient temperature and adequate mechanical strength, an ionic conducting IPN composed of bisphenol A epoxy resin/polyethylene glycol containing LiClO_4 was synthesized. The dependence of conductivity was investigated as a function of salt content, composition and temperature. It has been revealed that a maximum of conductivity appeared when EO/Li=25, where EO denotes the—(CH_2CH_2O)-unit in polyethylene glycol, and that the temperature dependence of conductivity followed VTF equation, suggesting that the motion of ionic carriers resulted from the segmental motion of the polymer. When glycerol epoxy resin was used instead of bisphenol A epoxy, the ambient temperature (25℃) conductivity could somewhat further be raised up to 3×10~(-5) S/cm.     

结晶聚合物的辐照效应——Ⅰ.尼龙-1010的聚集态结构对其辐射化学反应的影响

本文用DSC,WAXD,ESR和介电谱以及凝胶分数测定等技术,研究Nylon-1010的聚集态对γ-辐射化学反应以及辐照后热处理结果的影响。结果表明,辐照Nylon-1010的交联与裂解反应主要发生在非晶区或结晶表面,进一步证明了非晶区也是辐射后交联和后裂解主要反应区。     

HEAT SHRINKING BEHAVIOUR OF γ-RADIATION CROSSLINKED POLYETHYLENE

Heat shrinking material of γ-radiation erosslinked polyethylene is widely used for various application in industry. In this study, DSC, TMA, WAXD and density measurement techniques were used to investigate the influence of MI and thermal history of LDPE on the effectiveness of network formation. Based on the results of heat stretching and heat shrinkage tests, it is found that the formation of a network as perfect as possible is indispensable to the irradiated material if good heat shrinkage property is desired. To this end, quenching technique and polyethylene with appropriate MI must be used so that an effective radiation effect will be obtained with a minimum amount of radiation dose. In spite of that the mechanical property of the irradiated polyethylene in the rubbery state is basically in agreement with the classical expression of the theory of high elasticity, only about 90% shrinkage can be reached. Besides, the heat shrinkage temperature T_s and the % shrinkage Sare both related to the radiation dose.     

THERMAL ANALYSIS OF POLYPROPYLENE-b-POLYETHYLENE DIBLOCK COPOLYMERS AND CORRESPONDING BLENDS

Difference in thermal behavior of presumed polypropylene-b-polyethylene block copolymers(PP-PE) and corresponding PP+PE blends was studied. Different views in the literature were unified in our observation that faster cooling rate yielded only one exothermal peak for the blends, while slower cooling rates revealed both PP and PE exothermal peaks. Further details on when a single or double exothermal peaks would appear are discussed. Melting and crystallization temperatures for both PP and PE in blends were found to be a few degrees higher than for PP and PE in block copolymers. Thus, thermal analysis can be used to identify PP-PE block copolymers. These phenomena and the lower △H_f-values of PP and PE in block copolymers than the △H_f-values of pure homo-PP and -PE (for PE even more so) are explained in terms of restricted block movement due to covalent bond between blocks and of crystallization processes in block copolymers. The presence of block structure in the PP-PE samples studied is inferred.