PVC/EVA-g-VC共混物的形态与加工条件和性能的关系

PVC/EVA(-14)及 PVC/EVA(-14)-g-VC的等速升温Brabender塑化曲线上有两个扭矩峰,分别标志着EVA和PVC的塑化,对应着共混形态经历的三个变化:(1)EVA塑化——PVC粉粒破碎;(2)EVA呈连续相——PVC集结粒子解体;(3)EVA呈分散相——PVC初级粒子熔化。聚合投料比(VC/EVA)越小,EVA-g-VC的塑化温度和熔体粘性越高,两个扭矩峰靠得越近。实验结果表明,EVA-g-VC与EVA相比,不仅与PVC有更好的相容性,而且有较好的均匀可混性。冲击强度的测定结果表明:EVA连续网——PVC初级粒子结构具有较高的冲击强度。VC/EVA较小时所得EVA-g-VC改性的PVC可在较宽的加工温度范围保持EVA连续网结构和较高的冲击强度。     

氯乙烯在高聚物中的溶解度

本文进行了氯乙烯在氯相/高聚物 (PVC,EVA,EVA-g-VC) 间相平衡的研究。实验数据用三种数学模型作了处理:Flory-Huggins 经典模型、Prigogine-Flory 自由容积模型和本文作者提出的线性模型。氯乙烯在高聚物中的溶解度按三种模型的计算值与实验结果都符合得很好。而且,结果表明,线性模型具有精确易用的优点,Prigogine-Flory 模型完全适用于 VC/PVC体系,VC在EVA-g-VC接枝共聚树脂中的溶解度服从加和性规律。     

化学交联聚氯乙烯树脂的合成和结构

研究了氯乙烯/交联单体悬浮共聚时,交联单体种类、浓度和聚合温度对化学交联聚氯乙烯树脂结构的影响.对于氯乙烯/邻苯二甲酸二烯丙基酯(VC/DAP)悬浮共聚体系,凝胶含量和凝胶交联密度随DAP起始浓度的增加而增大;DAP浓度相同时,凝胶含量和凝胶交联密度随聚合温度上升而下降;当凝胶含量较高时,分子链物理缠结对凝胶交联密度有较大贡献,凝胶交联密度随凝胶含量增加而快速上升.在相同交联单体浓度下,氯乙烯/马来酸二烯丙基酯(VC/DAM)共聚物的凝胶含量最大,VC/DAP共聚物次之,氯乙烯/乙二醇二甲基丙烯酸酯(VC/EGDMA)共聚物最小,这是由于DAM单体的竞聚率小于1,且含有马来酸双键,EGDMA单体的竞聚率远大于1.     

丙烯酸丁酯/4-乙烯基吡啶共聚物与聚氯乙烯共混相容性的研究

合成了系列丙烯酸丁酯/4-乙烯基吡啶共聚物[P(BAVP)].以四氢呋喃为溶剂,用溶剂浇铸法制备了一系列P(BAVP)与聚氯乙烯(PVC)的共混物.动态力学性能测试表明:共混物中吡啶环含量高于1%(摩尔百分含量)的共混物呈均相,即共聚物与PVC相容.P(BAVP)/PVC共混物的T_g随PVC含量和乙烯基吡啶链段含量增加而提高.由红外光谱分析推论出:P(BAVP)分子间的作用力比PBA分子间作用力弱,从而使P(BAVP)与PVC的相容性提高.     

17R4/F127混合水溶液的凝胶结构

结合流变学频率扫描和同步辐射小角X射线散射(SAXS), 研究了17R4(PO₁₄-EO₂₄-PO₁₄)含量和温度对17R4/F127(EO₉₉-PO₆₅-EO₉₉)混合水溶液凝胶结构的影响. 结果表明, 溶胶、 软凝胶和硬凝胶分别对应无序结构、 无序与立方相共存结构以及立方相结构. 对于F127水溶液体系, 可以将F127形成的胶束看作硬球, 随着温度的升高, 胶束的硬球半径和胶束中F127链的聚集数随之减小, 这是因为17R4在较低温度下很难形成胶束, 当温度升高时, 17R4链参与胶束的形成, 从而使胶束数目增加, 因此每个胶束中的F127链数也随之减小. 当17R4含量较高时, 胶束外壳中F127部分的PEO链段数随着温度升高而减小, 胶束外壳变得更软, 因此, 当17R4/F127摩尔比为2: 1时, 混合溶液在高温下呈现面心立方(fcc)到体心立方(bcc)的结构转变.     

EPR-g-PS热塑弹性体的形态结构

电子显微镜观察表明,以乙丙橡胶(EPR)为主干,聚苯乙烯(PS)为支链的接枝共聚物EPR-g-PS的基本形态是高度分散的聚苯乙烯微区(约几百?)存在于乙丙橡胶连续相中的两相体系,随接枝共聚物中聚苯乙烯含量增加,微区形态发生变化,少量的接枝共聚物在PS与EPR共混物中起“增容剂”作用,使分散相微区变得小而均匀,多重玻璃化转变的存在进一步证实了接枝共聚物相分离的形态结构。     

SAN共聚物组成对PVC/ABS共混物相容性的影响

采用乳液聚合技术通过改变共聚单体的投料比(St/AN)合成了一系列不同AN结合量的ABS接枝共聚物粉料和SAN共聚物.将其与聚氯乙烯(PVC)和邻苯二甲酸二辛酯(DOP)熔融共混分别制得了PVC/ABS、PVC/SAN、PVC/ABS/DOP和PVC/SAN/DOP共混物,利用SEM、TEM和动态力学粘弹谱仪(DMA)对共混物的相容性和相结构进行了表征.结果发现,在PVC/ABS共混体系中,尽管改变接枝SAN共聚物的AN结合量,PVC和SAN共聚物均为不相容体系;在该共混物中引入增塑剂DOP后,虽然当SAN共聚物AN结合量小于23.4 wt%时,共混物在室温以上只存在一个tanδ峰,但形态结构研究结果表明共混物仍为不相容体系,共混物的相区尺寸明显地依赖于SAN共聚物中的AN结合量,当AN结合量为23.4 wt%时相区尺寸最小.     

PP-g-MAH对聚丙烯/滑石粉复合材料的性能影响

研究了两种马来酸酐接枝聚丙烯（PP-g-MAH）在不同含量时对聚丙烯（PP）/滑石粉复合材料的力学性能、雾化性能和线性膨胀系数的影响.结果表明,接枝物的加入能提高复合材料的拉伸性能、冲击性能和弯曲性能,但随着含量的增加拉伸强度、冲击强度和弯曲强度及弯曲模量有所降低.在含量相同时,接枝物1对冷凝组份的影响更小.复合材料的线性膨胀系数随接枝物含量的增加先减小后增加.     

PVC/ACR共混物微观结构与性能

本文研究了聚氯乙烯/丙烯酸酯类共聚物(PVC/ACR)共混物的应力-应变行为和冲击强度对ACR 用量的依赖关系。ACR对 PVC有良好的增韧作用,提高了PVC抗冲击性能。考察了三盐基性硫酸铅和硬脂酸钡-硬脂酸镉稳定剂对共混体系的影响,实验结果说明不同的热稳定体系对ACR改性PVC的效果有差别。动态力学性能测定结果表明PVC/ACR共混物存在两个玻璃化转变温度,证明PVC与ACR不相容性;而两个转变温度随共混物组成改变而变化,说明PVC与ACR之间存在着相互作用,PVC/ACR为部分相容体系。通过透射电子显微镜观察PVC/ACR共混物的微观结构形态表明:PVC与 ACR为两相体系,ACR呈粒状分布在PVC连续相中。但是,采用硬脂酸钡-硬脂酸镉稳定体系时,随着ACR用量增加,ACR的分散形态由粒状分散逐渐形成网络结构形态,与此相对应的共混物具有更好的抗冲击性能。     

环氧树脂/聚砜共混体系相结构的调控研究——环氧预聚物分子量的影响

研究了不同分子量的环氧预聚物对双酚A型双官能团环氧树脂 /聚砜 (PSF) /固化剂 (二氨基二苯基砜 ,DDS)体系相分离结构的影响 .通过红外光谱 (FTIR)和动态热机械分析 (TMA)对反应转化率、玻璃化温度以及固化温度的关系的研究 ,表明环氧预聚物分子量较小时 ,凝胶点和玻璃化是影响相结构的关键因素 ;环氧分子量较大时 ,环氧扩链后粘度的变化则成为抑制相分离的重要因素 .电子显微镜 (SEM)结果表明改变环氧预聚物分子量可以达到调控相结构的目的 ,随着预聚物分子量的增大 ,体系的微区尺寸减小 .     

聚氯乙烯-丙烯酸丁酯接枝共聚物的结构表征

以通用聚氯乙烯(PVC)和脱氯化氢PVC树脂为基体,采用悬浮溶胀接枝共聚法合成聚氯乙烯-丙烯酸丁酯接枝共聚物,对脱氯化氢PVC和接枝共聚物的结构进行了表征.结果表明,以碱液为介质加热PVC能脱除少量氯化氢,得到以链节数为2,3,4的共轭双键为主的不饱和结构,而树脂的分子量变化不大;在相同接枝反应条件下,采用脱氯化氢PVC与丙烯酸丁酯接枝共聚可以提高接枝率和接枝效率;PVC接枝共聚物的特性粘度随接枝率增加而增加,其重均分子量和分子量分布指数均大于接枝所用的PVC树脂.     

Broad line NMR investigation of compatibility using powdered and milled samples of PVC and EVA, and the effects of heat-treatment

The limited miscibility of poly(vinyl chloride) (PVC) and ethylene-vinyl acetate copolymer (EVA) observed for milled samples has now been demonstrated for samples in powdered form by means of broad line NMR. The changes in the phase relations are mainly dependent on two processes, viz. the phase separation and the development of the interactions between PVC and EVA chains. The stable level of the phase relations is dependent upon the thermal history. We assume this to be an effect of the varying degrees of entanglement between PVC and EVA chains. It has also been demonstrated that the fraction of EVA staying in the free phase increases both for the milled and powdered samples when the degree of grafting between PVC and EVA decreases. A method for the quantitative investigation of the solubility conditions of polymer two-phase systems in bulk is also presented.     

聚氯乙烯-g-聚甲基丙烯酸-2-羟乙酯共聚物的合成和表征

聚氯乙烯 (ＰＶＣ)是常用医用高分子材料之一 ,可以制作储血袋、导液管、人工尿道等 .ＰＶＣ亲水性差 ,影响其生物相容性 .采用亲水性单体与ＰＶＣ接枝共聚是提高ＰＶＣ亲水性的重要方法[1] .Ｋｒｉｓｈｎａｎ等[2 ] 对Ｃｏ60 辐照下ＰＶＣ接枝Ｎ 乙烯基吡咯烷酮进行了研究 .Ｓｉｎｇｈ等[3～ 5] 采用辐照引发甲基丙烯酸在ＰＶＣ薄膜的接枝反应 ,对接枝动力学、接枝后薄膜表面形态、溶胀和抗凝血性等进行了研究 .Ｇｏｌｄｂｅｒｇ等[6] 采用辐照引发甲基丙烯酸2 羟乙酯 (ＨＥＭＡ)在ＰＶＣ薄膜上的接枝 .Ｌｅｅ等[7]采用溶液接枝共聚制备了…     

Grafting of polymethyl methacrylate from poly(ethylene-co-vinylacetate) copolymer using atom transfer radical polymerization

Atom transfer radical polymerization was employed for the first time to prepare graft copolymer having by ethylene-vinyl acetate (EVA) copolymer as backbone and poly(methyl methacrylate) (PMMA) as branches. The polymerization of MMA was initiated by EVA carrying chloropropionate groups as macroinitiator, in the presence of copper chloride (CuCl) and bipyridine (bpy) at 80 °C. The macroinitiator was prepared by esterification of partially hydrolyzed EVA with 2-chloropropionyl chloride. Successful graft copolymerizations were performed both in toluene/γ-butyrolactone mixed solvent and in toluene solution, with grafting efficiency of 12% and 6%, respectively. Molecular weight distribution of the PMMA segments around 1.2 has been achieved with pure toluene solution. The ATRP graft copolymerization was supported by an increase of the molecular weight of the graft copolymers, as compared to that of the macroinitiator and also by their monomodal molecular weight distribution.     

Radiation-Induced Grafting of Ethyl Vinyl Ether onto Polyvinyl Chloride)

The radiation-induced graft polymerization of ethyl vinyl ether (EVE) onto polyvinyl chloride) (PVC) was studied under a variety of conditions. Graft copolymer and homopoly(EVE) were formed in all cases. The presence of water reduced overall polymerization rates, percentage grafting, and homopoly(EVE) molecular weights. With “superdry” EVE, grafting reached 29% at a total dose of 6.9 Mrad. Grafting to PVC films was less efficient than grafting to PVC powder. Application of a relatively poor swelling agent for PVC resulted in an increase in the efficiency of grafting. From a comparison of studies of radiation-induced EVE homopolymerization and the present work, it was concluded that dry and superdry EVE are grafted to PVC by a cationic mechanism and wet EVE is grafted mainly by a free-radical mechanism.     

The influence of nano‐PS particle on structure evolution and electrical properties of PP/PS

The polypropylene‐g‐polystyrene (PP‐g‐PS) copolymers with different grafting ratios are used as compatibilizers to control the size of polystyrene (PS) particles at nanometer scale in polypropylene (PP) matrix. Then the PP/PS insulating nanocomposites (containing 10 wt % PS calculated from PS and PP‐g‐PS) are manufactured. With the increase in grafting ratio of PP‐g‐PS, the size of PS particle is reduced and the interfacial adhesion is enhanced. Meanwhile, the dielectric properties, DC breakdown strength and volume resistivity are increased with the decreasing of PS particle size. The spherulite size of PP is decreased and the boundary between crystals and amorphous regions is blurred or even disappears due to the presence of PS nanoparticles. This evolution of PP structure is attributed to the serious entanglements of PP and PS molecular chains. Finally, the correlation between morphological structure and electrical properties is ultimately established based on the in‐depth understanding of the molecular chain movement, crystal structure, and phase morphology. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 706–717     

微波辐照实现PVC-PS之间的Friedel-Crafts接枝反应

在四氢呋喃、环己酮等溶液中实现了聚氯乙烯(PVC)与聚苯乙烯(PS)的Friedel-Crafts接枝反应,考察了加热方式、反应温度、催化剂种类、催化剂用量对接枝反应的影响,通过FTIR表征了PVC-g-PS接枝物的结构,探讨了反应的机理和特点.研究发现,油浴加热和微波辐照都能使PVC和PS发生接枝反应,但微波辐照效果更好,油浴加热,接枝率仅0.27%,而微波辐照接枝率高达23%;油浴加热时产物少且多为间位,微波辐照时产物多且多为对位和邻位.无水AlCl3、无水FeCl3、无水SnCl4皆对PVC与PS之间的Friedel-Crafts反应具有催化活性,其中无水AlCl3的催化活性最高,其最佳用量为质量分数3%,此时,接枝率达到29%.当无水AlCl3过高时,PVC降解,产生双键,接枝率下降.表明微波辐照是实现PVC与PS之间Friedel-Crafts接枝反应的有效途径.     

The co-continuous morphology of biocompatible ethylene-vinyl acetate copolymers/poly(��-caprolactone) blend: effect of viscosity ratio and vinyl acetate content

The phase behavior and its linear viscoelastic responses of a biocompatible blend based on ethylene-vinyl acetate copolymers and poly(??-caprolactone) (EVA/PCL) were studied in this work in terms of blending ratios and annealing. The effects of viscosity ratios and vinyl acetate contents of the EVA on the co-continuous morphology were addressed. The results show that EVA/PCL is a typical immiscible blend due to the high interfacial tension between the two polymers. Thus, the blend shows a wide percolation range with a narrow fully co-continuous region. Although the phase inversion point can be well predicted by the viscous Utracki model, the dynamic viscoelastic responses of the blend cannot be well described by the emulsion model. The elasticity ratio was proposed to play an important role together with the viscosity ratio on the phase inversions. During dynamic annealing, the phase size of both the sea?Cisland and the co-continuous structures increases evidently, but the principle of time?Ctemperature superposition is only valid for the co-continuous blend while fails with that with the sea?Cisland phase structure. Beside, the phase size of the co-continuous structure is dependent strongly on the viscosity ratio between EVA and PCL. With reduced viscosity ratio, the phase size increases remarkably. However, vinyl acetate (VA) contents of the EVA have little influences on the interfacial properties and phase size of the co-continuous blends in the experimental content ranges (28?C12?wt.%).