STRUCTURE AND PROPERTIES OF SEQUENTIALLY POLYMERIZED PROPYLENE-B-[ETHYLENE-CO-PROPYLENE]-B-PROPYLENE COPOLYMERS

The structure and properties of presumed block copolymers of polypropylene (PP) with ethylene-propylene random copolymers (EPR), i.e., PP-EPR and PP-EPR-PP, have been investigated by viscometry, transmission electron microscopy, dynamic mechanical analysis, differential scanning calorimetry, gel permeation chromatography, wide-angle x-ray diffraction, and other techniques testing various mechanical properties. PP-EPR and PP-EPR-PP were synthesized using delta-TiCl3-Et2AlCl as a catalyst system. The results indicate that the intrinsic viscosity of these polymers increases with each block-building step, whereas the intrinsic viscosity of those prepared by chain transfer reaction (strong chain-transfer reagent hydrogen was introduced between block-building steps during polymerization) hardly changes with the reaction time. Compared with PP / EPR blends, PP-EPR-PP block copolymers have lower PP and polyethylene crystallinity, and lower melting and crystallization temperatures of crystalline EPR. Two relaxation peaks of PP and EPR appear in the dynamic spectra of blends. They merge into a very broad relaxation peak with block sequence products of the same composition, indicating good compatibility between PP and EPR in the presence of block copolymers. Varying the PP and EPR content affects the crystallinity, density, and morphological structure of the products, which in turn affects the tensile strength and elongation at break. Because of their superior mechanical properties, sequential polymerization products containing PP-EPR and PP-EPR-PP block copolymers may have potential as compatibilizing agents for isotactic polypropylene and polyethylene blends or as potential heat-resistant thermoplastic elastomers.

COMPATIBILIZING EFFECT OF POLY(ETHYLENE OXIDE)-B-POLYSTYRENE-B-POLY(ETHYLENE OXIDE) IN PHENOLPHTHALEIN POLY(ETHER ETHER KETONE) POLY(2,6-DIMETHYL-1,4-PHENYLENE OXIDE) BLENDS

The morphology and mechanical behaviour of phenolphthalein poly(ether ether ketone) (PEK-C)/poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) blends has been investigated. A poly(ethylene oxide)-b-polystyrene-b-poly(ethylene oxide) (PEO-PS-PEO) triblock copolymer was used as compatibilizer. It was found that PEO-PS-PEO has a compatibilizing effect on the PEK-C/PPO blends. The addition of PEO-PS-PEO to the blends greatly improves phase dispersion and interfacial interfacial adhesion and also enhances the ultimate tensile strength and Young's modulus at compositions ranging from 30 to 70% PEK-C. However, all the values of the ultimate tensile strength within the whole composition range are lower than those expected by simple additivity, probably owing to the poor mechanical properties of PEO-PS-PEO copolymer.

PMMA-b-PTHF/PTHF共混体系中共聚物结晶能力的增强

结晶嵌段共聚物具有一般均聚物所没有的许多特殊结晶行为。虽然,人们很早就已开始对聚氧化乙烯/聚苯乙烯诸类嵌段共聚物的结晶行为进行研究,但对这类体系相分离规律及结晶行为的认识仍很不够。这主要是因为已研究的体系非常有限,此外,大都为对体系非平衡态结构的研究。所以,尽管Whitmore和Noolandi最近提出了结晶嵌段共聚物及其共混物的平衡形态理论,但缺乏实验数据与之比较。

罗丹明B-硫氰酸盐分光光度法测定微量金

本文研究了Au(Ⅲ)-KSCN-罗丹明B-阿拉伯树胶水相显色体系和光度特性。缔合物的λ_(max)为595nm,表现摩尔吸光系数ε=1.23×10~5L mol~(-1).cm~(-1).Au(Ⅲ)浓度在0.0～8.0μg/25mL时服从比耳定律。所制定的测金光度法,结合巯基棉分离技术,已试用于金精矿的分析,获得了较好结果

L-B膜

L-B膜即 Langmuir-Blodgett单分子膜,它是人为地利用分子间相互作用而建立起来的特殊分子体系。在L-B膜中分子是有序的准晶体排列,其性质有别于固体和晶体,因而有人将其称为物质的第五相。用米制备L-B膜的技术称为L-B技术。

碱性染料杂多酸多元配合物显色反应的研究 Ⅶ.丁基罗丹明B-磷钼杂多酸-聚乙烯醇_(124)体系

本文研究了丁基罗丹明 B-磷钼杂多酸-PVA_124超高灵敏显色反应,提出了测定痕量磷新的分光光度法,缔合物的最大吸收波长位于588nm 处,表观摩尔吸光系数ε值为1.1×10~6L·mol~(-1)·cm,研究了缔合物的组成比和红外光谱,并初步讨论了反应机理,本法直接用于钢、试剂和水样的分析,结果较为满意,测定下限分别可达4ppb(10ml 水)和2×10~(-6)％(1g 试剂)。

RE_(1-x)B_xF_(3-y)(RE=Y、La、Ce、Gd;B=Ca、Ba)的敏感性质的研究

LaF_3作为离子选择性电极和对气体的敏感性质已进行了一定的研究,但其他稀土氟化物的敏感性质却未见报道。本文合成了RE_(1-x)B_xF_(3-y),研究了它们的结构、电学性质及敏感性质,得到有可能在150℃使用的固体电解质氧敏材料。 (一) RE_(1-x)B_xF_(3-y)的结构分析 结构分析表明,Ca、Ba置换RE的含量少时,如La_(0.95)Ba_(0.05)F_(3-y)、Ce_(0.95)Ca_(0.05)F_(3-y)的X射线衍射分析结果与LaF_3、CeF_3相似,说明它们是固溶体。而Ca置换RE含量较多时,如Y_(0.71)Ca_(0.29)F_(3-y)、Gd_(0.85)Ca_(0.15)F_(3-主)的X射线衍射分析结果却与相应的YF_3和GdF_3完全不

碱性染料杂多酸多元配合物显色反应的研究——Ⅵ.丁基罗丹明B-砷钼杂多酸-聚乙烯醇-124体系

本文研究了丁基罗丹明B-砷钼杂多酸-PVA-124体系,由于形成高取代氢原子的杂多酸而使反应灵敏度大增,ε值高达6.9×10~5 L·mol~(-1)·cm~(-1)。缔合物的组成比As(V):BRB=1:7。红外光谱研究证明,染料和杂多酸形成了离子对缔合物。本法可成功地用于水样和试剂中痕量砷的测定。测定下限分别为2.0ppb(水样)和2×10~(-6)％(试剂)。

超高灵敏显色反应及其应用的研究——Ⅴ.钨(Ⅴ)-SCN~--乙基罗丹明B-PVA-124体系

本文研究了在聚乙烯醇-124存在下,钨(V)-SCN~--乙基罗丹明B超高灵敏显色体系。缔合物λ_(max)=585nm,表观摩尔吸光系数ε_(585)=1.9×10~6L·mol~(-1)·cm~(-1)。钨浓度在0.1～1.5μg/25ml范围内符合比尔定律,方法曾用于水样及钢样中痕量钨的测定,结果较满意。

超高灵敏显色反应及其应用的研究Ⅲ.锑(Ⅲ)—乙基罗丹明B—碘化物体系

本文研究了在聚乙烯醇-124存在下,锑(Ⅲ)—乙基罗丹明B—碘化物的显色反应。缔合物λ_(max)=605nm表观摩尔吸光系数为7.0×10~3。锑浓度在0.1～2.5μg/25ml时服从比尔定律。藉氢化物分离技术,本法可用于地球化学标样中痕量锑的测定。

Nd-Fe-B-Si合金的研究

为了探索提高Nd-Fe-B磁性材料的居里温度T_C,我们采用了与文献不同的组成和制 条件,研究了Si对合金的物相、T_C等的影响,得出Nd-Fe-B-Si是一种有希望的非钴高居里温度合金体系. 试样系以钕铁、硅铁、硼铁和还原铁粉为原料,按 Nd_(15)Fe_(77-x)Si_xB_8(x=4、8、16、18 at％)配比,在石墨电阻炉内于Ar气保护下熔炼而成.T-σ曲线在日本MB-2型磁天平上测得;微区分析和x-射线衍射分别用JXA-840扫描电镜和日本理学2028x-射线衍射仪进行.

碱性染料杂多酸多元配合物显色反应的研究 Ⅴ.乙基罗丹明B-磷钼杂多酸-聚乙烯醇体系

本文研究了乙基罗丹明B-磷钼杂多酸-聚乙烯醇(PVA)显色体系,提出了高灵敏度的测磷分光光度法。缔合物最大吸收λ_(max)=584nm。表观摩尔吸光系数ε_(586)为3.2×10~5L·mol~(-1)·cm~(-1)。提高介质酸度和添加还原剂可消除SiO_3~(2-)、AsO_4~(3-)等的干扰。缔合物中P(V):ERB~+=1:4。红外光谱研究证明,染料阳离子与杂多酸阴离子形成了离子对缔合物。本法可用于钢样及试剂中磷的测定,测定下限达1×10~(-5)％(1g试样)。

超高灵敏显色反应及其应用的研究——镉-乙基罗丹明B-碘化物体系

本文介绍了镉-乙基罗丹明B-碘化物超高灵敏显色体系,确定了分光光度测定痕量镉的条件,时反应机理作了初步讨论。方法的灵敏度很高,表观摩尔吸光系数可达1.3×10~6。拟定了直接测定水样和硫酸锌试剂中镉的方法,检测下限分别为0.5ppb和1×10~(-5)％。