高透明耐冲击聚氯乙烯接枝聚合研究

研究高透明耐冲击聚氯乙烯接枝聚合工艺，讨论了加料顺序、复合分散体系以及采用聚集粒子乳液、并用碱性物质调节其ｐＨ值等对接枝聚合物性能的影响，确定了接枝聚合最佳工艺条件。     

苯乙烯与1-(2-叔丁基过氧异丙基)-3-异丙烯基苯共聚行为研究

苯乙烯与1－（2－叔丁基过氧异丙基）－3－异丙烯基苯（D120）能进行自由基共聚合反应，聚合后过氧基团以侧基的形成被保留在共聚物大分子链上，凝胶色谱分析发现，随原料单体中D120比例增加，共聚物的分子量减小，分子量分布变窄，DSC分析发现共聚物中过氧基团的分解温度随D120结构单元含量的增加而下降，但仍高于D120单体过氧基团的分解温度，苯乙烯与D120的竞聚率为：rD120=0.700,rSt=0.714。     

Methacryloxyethyl phosphate‐grafted expanded polytetrafluoroethylene membranes for biomedical applications

Expanded polytetrafluoroethylene (ePTFE) membranes were modified by graft copolymerization with methacryloxyethyl phosphate (MOEP) in methanol and 2‐butanone (methyl ethyl ketone (MEK)) at ambient temperature using gamma irradiation. The effect of dose rate (0.46 and 4.6 kGy h^?1), monomer concentration (1–40 %) and solvent were studied and the modified membranes were characterized by weight increase, X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). XPS was used to determine the % degree of surface coverage using the C? F (ePTFE membrane) and the C? C (MOEP graft copolymer) peaks. Grafting yield, as well as surface coverage, were found to increase with increasing monomer concentration and were significantly higher for samples grafted in MEK than in methanol solution. SEM images showed distinctly different surface morphologies for the membranes grafted in methanol (smooth) and MEK (globular), hence indicating phase separation of the homopolymer in MEK. We propose that in our system, the non‐solvent properties of MEK for the homopolymer play a more important role than solvent chain transfer reactions in determining grafting outcomes. Copyright © 2005 Society of Chemical Industry     

Copolymerization of bromophenylmaleimide with ethyl or butyl methacrylate

N‐p‐Bromophenylmaleimide (BrPMI) does not polymerize in solution by conventional free radical mechanism. However, it readily polymerized in bulk when mixed with a free radical initiator and heated in a microwave oven for 7–8 min. Copolymerization of ethyl methacrylate or butyl methacrylate with BrPMI was conducted in dioxane. The copolymers were characterized by IR and ¹H NMR spectroscopy and gel permeation chromatography. The monomer reactivity ratios were calculated by a non‐linear least‐square analysis. Thermal analysis indicated a great improvement in thermal stability of the copolymers compared with the methacrylate homopolymers. BrPMI was also polymerized in bulk in the DSC pan, which allowed the calculation of the activation energy of its polymerization. Copyright © 2003 Society of Chemical Industry     

Preparation of ion‐exchange membranes by hydrolysis of radiation‐grafted polyethylene‐g‐polyacrylamide membranes

Polyethylene‐g‐polyacrylamide membranes were prepared by graft polymerization of acrylamide onto polyethylene films using a preirradiation method. The ion‐exchange membranes were obtained by the hydrolysis of grafted films so as to transform amide groups into carboxyl groups. The fraction of amide groups transformed into carboxyl groups was limited to ～0.5. The characterization and thermal behavior of membranes with different degrees of grafting were evaluated by FTIR, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) measurements. The heat of fusion and the crystallinity of polyethylene decreased considerably in the hydrolyzed membranes depending on the degree of grafting. It was found that the grafting of acrylamide led to the reduction in crystallinity due to disruption of the crystallites (crystal defects) and dilution of the inherent crystallinity (dilution effect). The contribution of the hydrolysis step to the crystallinity decrease was negligible. The thermal stability of the membranes as obtained from TGA showed considerable enhancement after hydrolysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 149–154, 2003     

高分子材料辐射接枝苯乙烯的研究进展

对各高分子材料辐射接枝苯乙烯的动力学，接枝方法及接枝材料的应用进行了综述，讨论限辐射剂量，剂量率，温度，后效应，溶剂，添加剂和高分子材料厚度及结晶性等方面对接枝反应的影响。     

In-chain functionalization by alternating anionic copolymerization of styrene and 1-(4-dimethylaminophenyl)-1-phenylethylene

Anionic copolymerizations of styrene (M₁) with excess 1-(4-dimethyl-aminophenyl)-1-phenylethylene (M₂) were conducted in benzene at 25°C for 24h, using sec-butyllithium as initiator. Narrow molecular weight distribution copolymers with M?;_n = 16.1 × 10³ g/mol (M?_w/M?_n = 1.04) and 38.2 × 10³g/mol (M?_w/M?_n = 1.05), and 24 and 38 moles of M₂ per macromolecule, respectively, were characterized by size exclusion chromatography, ¹H NMR spectroscopy and DSC. The monomer reactivity ratio, r₁ = 5.6, was obtained from the copolymer composition at complete consumption of M₁, assuming that the rate constant k₂₂ =0,i.e. r₂ =0. The polymers exhibited T_g values of 128 and 119°C, respectively, which correspond to an estimated T_g = 217°C for the hypothetical homopolymer of M₂.     

天然竹芋淀粉及其接枝共聚

分析了竹芋淀粉的伴生物组成，粒径分布及直链淀粉的含量，研究了竹芋淀粉与甲基丙烯酸甲酯的接枝共聚，用偏光显微镜，Ｘ射线衍射等方法研究了淀粉接枝共聚反应前后的结构与形态，认为淀粉的结晶区和非晶区均为接权共聚反应的场所。