天然橡胶/氯化聚氯乙烯热塑性弹性体的性能与结构

采用动态硫化法制备天然橡胶(NR)/氯化聚氯乙烯(CPVC)热塑性弹性体(TPV),并研究甲基丙烯酸缩水甘油酯(GMA)/苯乙烯(St)双单体熔融接枝NR[NR-g-(GMA-co-St)]与白炭黑复配增容补强NR/CPVC TPV的物理性能、耐溶剂性能和微观形态结构。结果表明:当NR-g-(GMA-co-St)和白炭黑的用量分别为7和3份时,交联NR分散相在CPVC基体中的分散度和均一性得到明显改善,相界面的结合强度显著提高,达到良好的复配增容补强效果。与未改性NR/CPVC TPV相比,改性NR/CPVC TPV的拉伸强度、拉断伸长率和撕裂强度增大,耐溶剂性能明显改善。     

多单体熔融接枝天然橡胶及其性能的研究

以甲基丙烯酸缩水甘油酯（GMA）为接枝单体，苯乙烯（St）为接枝共单体，过氧化二异丙苯（DCP）为引发剂，通过熔融接枝法制备接枝天然橡胶[NR-g-（GMA-co-St）]。研究了GMA、St及DCP用量和接枝温度对NR的接枝率及其力学性能的影响。结果表明，GMA、St和DCP质量分数分别为8％、4％和0．3％，接枝温度为160℃时，NR-g-（GMA—co—St）的接枝率最高，综合力学性能最好；St的加入能明显提高NR的接枝率，并能减轻NR的降解；红外光谱的分析证实了GMA已接枝到天然橡胶分子链上。     

硫化型吸水膨胀天然橡胶的制备研究

采用原位聚合法在天然胶乳中制备出吸水膨胀天然橡胶,并硫化制得硫化型吸水橡胶（WSNR）。傅立叶红外谱图分析发现该原位聚合法能使聚丙烯酸钠接枝到天然橡胶的分子链上;TG和DTG分析表明接枝了聚丙烯酸钠的天然橡胶的热稳定性能有一定的提高;不同硫化体系对吸水橡胶的硫化性能影响考查结果表明：随着硫黄用量的增加,WSNR的吸水性能降低、力学性能得到提高。     

AC/MMA接枝改性天然胶乳的制备及性能研究

以丙烯基氯（AC）和甲基丙烯酸甲酯（MMA）接技改性天然胶乳，采用正交试验方法研究引发剂用量，反应温度，单体配比，胶乳浓度等对接枝聚合反应中单体转化率和接枝率的影响，测试了改性天然胶乳的粘度，粘接性能及其硫化胶膜的力学性能，耐溶剂性和阻燃性，结果表明，适宜的接枝聚合反应条件为：引发剂异丙苯过氧化氢（CHP）和四乙烯五胺（TEP）的质量分数分别为0．58％和0．36％－0．72％（占橡胶质量的百分率）、反应温度为30℃、单体体积配比v（MMA）：v(AC）＝1．5：1、胶乳质量分数为53．3％，所得接枝胶乳粘度较高，粘结性能较好，耐溶剂性能剂，且有较好阻燃性。     

辐射接枝粉末橡胶/聚氨酯复合泡沫的制备及性能研究

首先利用辐射接枝改性方法研制了与聚氨酯相容性较好、颗粒大小为3.5~22.7μm的接枝粉末橡胶(甲基丙烯酸甲酯接枝天然橡胶,NR-MMA)。然后,将粉末橡胶作为填料加入聚氨酯发泡组分中制得复合泡沫。测试结果表明,粉末橡胶/聚氨酯复合泡沫具有比较均匀的泡孔结构和较好的声学、力学性能。     

不同协助技术固相接枝改性聚丙烯的研究

分别采用有机分散剂、溶液浸渍和超临界二氧化碳(SC CO2)协助技术对聚丙烯(PP)进行固相接枝改性。通过自由基聚合制备了PP与马来酸酐(MAH)、丙烯酸(AA)的接枝共聚物(PP-g-MAH/AA),考察了单体投料量、反应时间、反应温度对接枝反应的影响,用傅里叶变换红外光谱(FTIR)对PP-g-MAH/AA进行了表征,并测试了接枝产物的水接触角、热稳定性、熔体流动速率和力学性能。实验结果表明,当单体投料量为6%,100℃下反应2h时,三种协助方法的接枝效率均达到最大值,SC CO2协助技术对PP接枝改性的接枝率和接枝效率较最高,可达5.33%和88.83%。测试结果表明,SC CO2协助技术制得PP接枝产物热稳定性最好、水接触角最小。     

聚合物接枝改性及接枝率的表征

综述了聚合物接枝改性的几种常见方法。如溶液接枝聚合、悬浮接枝聚合、超声波引发接枝聚合、超临界流体技术引发接枝聚合等,介绍了接枝聚合原理、研究和应用,并总结了接枝改性聚合物接枝率的表征方法,包括酸碱滴定法、傅里叶红外光谱（FTIR）、X射线衍射图谱分析（XRD）和元素分析法等。     

“胶乳共混法”制备天然橡胶／二氧化硅纳米复合材料及其性能

采用γ-甲基丙烯酰氧基丙基三甲氧基硅烷（KH570）改性纳米二氧化硅（SiO2）,然后通过乳液聚合接枝上聚甲基丙烯酸甲酯（PMMA）,再将其与甲基丙烯酸甲酯（MMA）改性的天然胶乳,通过胶乳共混法制备天然橡胶／二氧化硅纳米复合材料,结果显示,纳米二氧化硅表面接枝上了PMMA,二氧化硅在橡胶基体中分散良好,粒径在60～100nm之间,得到的胶膜力学性能有很大的提高。     

化学交联模压法制备NR-g-(GMA-co-St)/PVC共混泡沫材料

采用化学交联模压法制备甲基丙烯酸缩水甘油酯/苯乙烯（GMA/St）熔融接枝天然橡胶[NR-g-（GMA-co-St）]和聚氯乙烯（PVC）共混泡沫材料。研究了橡塑比、增塑剂邻苯二甲酸二辛酯（DOP）用量、发泡剂种类及用量对泡沫材料性能的影响以及泡沫材料的微孔结构。结果表明,当橡塑共混比为70/30、DOP和复合发泡剂的质量分数分别为30%和8%时,可制得密度较小,具有较好综合力学性能的NR-g-（GMA-co-St）/PVC泡沫材料。NR/PVC泡沫材料的泡孔尺寸稳定性较差且以开孔为主,而NR-g-（GMA-co-St）/PVC泡沫材料以闭孔为主,且泡孔小、分布均匀。     

酶催化合成脂肪族聚酯的研究进展

酶催化合成生物可降解脂肪族聚酯是一种新型聚合方法,可以在温和条件下高效合成,有着传统方法难以比拟的优势,但该方法所合成的产物仍存在生物相容性低、力学性能差、分子量低等不足。本文综述了近十年来酶催化合成脂肪族聚酯的研究进展,分别介绍了开环聚合法、共聚法和缩合聚合法的聚合机理,并且简述了通过酶的固定化、功能化改性、调节支链等方法来提高酶的催化效率和活性、降低反应能耗和材料中残留有毒物质、提高原料转化率和产物分子量、增强产物亲水性及开发材料新用途的相关研究报道。并且总结了酶催化聚合法在不同介质中的优势和不足,并指出酶催化合成脂肪族聚酯在超临界二氧化碳、水、离子液体等环保介质中进行将成为绿色化学发展的趋势。     

超临界CO_2夹带乙醚协助三单体固相接枝改性聚丙烯

采用超临界CO2作为溶剂和溶胀剂,乙醚作为共溶剂,通过自由基聚合作用进行三单体BMA/St/MAH固相接枝改性聚丙烯。在43℃,8.2 MPa的超临界CO2流体作用下用三单体及引发剂AIBN溶胀PP,卸压后转移至圆底烧瓶中,在氮气保护下于85℃进行固相接枝,接枝率为2.99%。考察了溶胀时间、溶胀压力、溶胀温度以及共溶剂的用量对接枝率的影响。结果表明,通过改变溶胀压力、溶胀时间以及共溶剂的用量可以控制接枝的效果,共溶剂的加入有利于缩短溶胀时间。     

高抗冲聚苯乙烯(HIPS)连续生产的模拟

根据热引发连续本体聚合生产高抗冲聚苯乙烯 (HIPS)的动力学机理 ,建立了苯乙烯 /顺丁二烯橡胶本体聚合过程的多釜串联 (CSTR)数学模型 ,并由两个不同品牌的实际工业生产数据对模型进行了验证。得到了各釜出口苯乙烯单体的转化率、HIPS的接枝效率、接枝率以及自由PS的重均分子量及其分布     

Modification of Polychloroprene Rubber Latex by Grafting Polymerization and Its Application as a Waterborne Contact Adhesive

Grafting of methyl methacrylate (MMA) onto polychloroprene rubber latex (CRL) was carried out by emulsion polymerization using a redox initiator. The effects of the principal factors such as emulsifier, initiator and their concentrations and monomer/polymer ratio on monomer conversion, and grafting efficiency were studied. Infrared (FTIR) spectra, proton nuclear magnetic resonance (HNMR), and differential scanning calorimetry (DSC) analysis of the graft copolymer showed the occurrence of grafting. The surface-diffusion controlled process model was proposed to describe the grafting mechanism. The graft copolymer was blended with tackifier and filler for waterborne contact adhesive applications. The 180 degree peel strength of the above adhesive for canvas to other decoration materials was investigated.     

等离子体引发炭黑 接枝聚合的溶剂效应

用等离子体处理炭黑发现,这些等离子体黑颗粒经辉发放电后会产生不同种类的活性种,如高能电子、光子、自由基等,这些活性能引发乙烯基单体进行接枝聚合反应。等离子体炭黑对不同的乙烯基单体具有较强的选择性,当选用不同的溶剂时会产生明显的溶剂效应,产生溶剂效应的原因与等离子体引发聚合的机理有关。等离子体的位阻排斥引发机理会对乙烯基单体的接枝聚合产生较强的选择性。等离子体的溶剂化活性引发机理会对乙烯基单体的接枝聚合产生较强的溶剂效应。当等离子体炭黑与甲基丙烯酸甲脂、甲基丙烯酸丁酯接枝聚合时,溶剂采用二甲基甲酰胺,可得到较高的树枝率。同时讨论了接枝反应的的影响因素。在炭黑颗粒上接枝不同的乙烯基单体会对炭黑体系的分散稳定性产生不同的影响。     

“Grafting-from” polymerization for uniformly bulk modification of pre-existing polymer materials via a supercritical-fluid route

A novel approach to uniformly bulk graft modification of pre-existing polymer materials without ungrafted homopolymers was achieved at relatively low temperature by means of gamma (γ)-rays pre-irradiation-induced “grafting-from” polymerization with supercritical carbon dioxide (scCO₂) both as solvent and as swelling agent. The polymer substrates were first irradiated with γ-rays originated from cobalt-60 resource under nitrogen atmosphere at ambient temperature, and thereby leading to uniform formation of trapped radicals on polymer backbone. Then, the produced polymer-trapped radicals were utilized to initiate graft polymerization of vinyl monomers dissolved in scCO₂ within polymer substrates. A combination of transmission electron microscopy, scanning electron microscopy and elemental analysis shows that side graft chains covalently bonded to polymer substrate backbone in nanometer scale are uniformly dispersed within polymer membranes with a thickness of 5 mm. Altering the experimental conditions can easily control the grafting yield with regard to side graft-chain length. This method can also be applied to various functional polymer chains covalently attached to different polymer substrates, even with high viscosity or limited solubility. The novel graft-polymer materials produced by this method are not formed in the absence of scCO₂ and are impossible to prepare by conventional methodologies.     

影响苯乙烯丙烯腈在聚丁二烯乳胶粒上接枝共聚反应的因素

采用种子乳液聚合技术在聚丁二烯 ( PB)乳胶粒上接枝共聚苯乙烯 ( St)和丙烯腈 ( AN) ,合成了一系列 PB-g-SAN共聚物 ( ABS)。将这些共聚物用丙酮溶解并在超速离心机上将 PB-g-SAN和未接枝在 PB上的游离 SAN分离 ,计算出 SAN在 PB上的接枝率和接枝效率。通过改变共聚单体的组成和加料时间 ,研究了接枝率和接枝效率的变化。结果表明 SAN的接枝率随着 PB含量的增加而降低 ,在共聚单体中增加引发剂 ( CHP)和分子量调节剂 ( TD-DM)的含量 ,SAN在 PB上的接枝率和接枝效率表现出了下降的趋势 ,而共聚单体的配比 St/ AN和加料时间对接枝率和接枝效率的影响不大。     

Poly(dimethylaminoethyl methacrylate) grafted natural rubber from seeded emulsion polymerization

The grafting efficiency of dimethylaminoethylmethacrylate (DMAEMA) on to natural rubber (NR) has been studied. Grafting was by ‘topology-controlled’ emulsion polymerization, whereby polymerization is initiated by a redox couple where one component (tetraethylene pentamine) is hydrophilic and the other (cumene hydroperoxide) is hydrophobic. This should promote grafting at the interface between hydrophobic natural rubber particles and the hydrophilic DMAEMA. The effects of different amounts of monomer were examined, with NMR to obtain the percent branching, transmission electron microscopy to obtain information on morphology, gel fraction measurement and dynamic mechanical analysis to obtain information on mechanical properties. Although there will be significant amounts of ungrafted polyDMAEMA present, there is good evidence for the formation of graft copolymers of NR with core-shell morphology, and significant amounts of grafting, at high concentrations of monomer.     

超临界CO2中的高分子合成研究进展

介绍了超临界二氧化碳的特殊性质，综述了超临界二氧化碳为介质的高分子合成方面的应用进展情况．皿示出超临界二氧化碳是一种对环境无污染且价廉的绿色介质，具有广阔的应用前景。     

Grafting of methyl methylacrylate onto isotactic polypropylene film using supercritical CO2 as a swelling agent

Grafting of methyl methacrylate (MMA) onto isotactic polypropylene (iPP) film was carried out by free radical polymerization using supercritical (SC) carbon dioxide (SC CO₂) as a solvent and swelling agent. The iPP film was first impregnated with the monomer MMA and initiator benzoyl peroxide (BPO) using SC CO₂ at 308.15 K. After releasing CO₂, the MMA molecules in the film were grafted onto the iPP at a higher reaction temperature. Using this method, the grafting level and the morphology can be controlled by the soaking time, pressure and concentrations of MMA and BPO in the fluid phase. The products were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD).