【作者】 熊凯；

【导师】 王炼石；

【作者基本信息】 华南理工大学 ， 材料学， 2011， 博士

【摘要】 聚烯烃弹性体（ES）大分子无碳-碳双键或碳-碳双键含量低而具有优异的耐老化性能。用ES与乙烯基单体（M）的自由基接枝共聚产物对塑料进行共混改性,可制备出耐气候老化黄变性能优异的高抗冲工程塑料。这种高抗冲工程塑料是目前市面上耐候性能较差的ABS的理想升级换代产品,可广泛用作汽车配件、摩托车护罩和其他室外构件,应用前景广阔。本文分别用饱和聚烯烃弹性体二元乙丙橡胶（EPM）和乙烯-α-辛烯共聚物（POE）与甲基丙烯酸甲酯-丙烯腈（MMA-AN）进行悬浮接枝共聚反应。系统研究了EPM/MMA-AN和POE/MMA-AN悬浮接枝共聚体系中AN的用量(f_AN)、弹性体的用量(f_ES)、引发剂BPO用量、溶剂甲苯用量、主分散剂用量、助分散剂用量、水/油比,反应温度和反应时间等聚合反应条件对单体转化率（CR）、平均接枝率（GR）、接枝效率（GE）及相应的接枝共聚产物/SAN树脂共混物的缺口冲击强度的影响,确定了对SAN树脂增韧效率最高的接枝共聚产物的最优合成条件。用最优条件合成的EPM/MMA-AN和POE/MMA-AN两种接枝共聚产物分别与SAN树脂共混制备了共混物AEMS和AOMS。建立了共混物的弹性体含量与共混物的缺口冲击强度、拉伸强度、弯曲强度和熔体流动速率之间的关系曲线。用FTIR、GPC、TEM、SEM、DMA、DSC、TG等现代测试手段和人工模拟气候老化试验研究了接枝共聚反应机理、产物及其共混物的共组成、相容性、相结构、增韧机理、热稳定性和耐老化黄变性能的影响因素,结果表明,两个反应体系都存在弹性体与MMA-AN接枝共聚或与MMA接枝均聚、MMA-AN非接枝共聚和MMA非接枝均聚的基元反应,不存在弹性体与AN接枝均聚或AN非接枝均聚的反应;建立了两个反应体系的单体投料质量比f_AN与接枝共聚产物的共组成比F_AN之间的定量关系,发现接枝共聚产物的F_AN都小于f_AN;当EPM/MMA-AN接枝共聚产物的F_AN为14.8wt%左右,POE/MMA-AN接枝共聚产物的F_AN为12.2wt%左右时,两种接枝共聚物的极性分别与SAN树脂的极性最为匹配,相容性最好,相应的共混物AEMS和AOMS的缺口冲击强度最高。TEM和SEM分析表明,缺口冲击强度达到最高值的AEMS和AOMS,其相结构为近连续相结构,增韧机理为剪切屈服机理。随着f_AN的增加,AEMS和AOMS的热稳定性提高。AEMS的熔体流动速率随着EPM含量的增加而逐渐下降。通过研究PEB/MMA-AN、POE/MMA-AN、EPM/MMA-AN三个悬浮接枝共聚体系和EPDM/St-AN溶液接枝共聚体系的CR、GR和GE与反应时间的关系,发现4个体系都遵循先进行接枝反应,接枝反应基本结束后才进行非接枝共聚反应的规律,表明体系的链增长自由基转移接枝形成接枝共聚物的反应速度大于链增长自由基双基终止形成非接枝共聚物的反应速度。发现用GPC将反应初期形成的非接枝共聚物的不同分子量组分分离进行定量分析,可为推算接枝链的分子量提供依据的原理,应用这一原理推算了4个体系的接枝共聚物的接枝链的分子量,结果表明接枝链的分子量低于体系中单体正常共聚形成的非接枝共聚物的分子量,而明显高于由链增长自由基转移终止形成的非接枝共聚物的分子量。研究了体系中参与反应的弹性体的量随反应时间的延长而发生的变化,发现聚烯烃弹性体与乙烯基单体接枝共聚反应结束后发生两类机理不同的反应,一类是已接枝弹性体与未接枝弹性体发生断链再接形成可溶性多嵌段接枝共聚物,PEB和POE大分子分别带乙基侧基和己基侧基,空间位阻效应较大而发生这一类反应。另一类是已接枝弹性体与未接枝弹性体发生交联反应形成不溶性交联网络结构,EPM大分子带甲基侧基,其空间位阻效应小,EPDM带含碳-碳双键的乙叉降冰片烯侧基,其反应活性较大而发生这类反应。两类反应都具有结合未接枝弹性体越多,产物的增韧效率就越高的特点。通过研究PEB/MMA-AN悬浮接枝共聚产物不同组分对其与SAN树脂共混物ABMS的增韧作用的影响,结果表明,在PEB/MMA-AN接枝共聚产物所含各组分中,起增韧作用的有效组分是接枝共聚物PEB-g-MAN,非接枝共聚物MAN在PEB-g-MAN与SAN基体之间起协同增容作用而提高了增韧效率,未接枝PEB的存在会降低PEB-g-MAN对ABMS的增韧效率。EPDM-g-SAN/SAN树脂、EPDM-g-MAN/SAN树脂和EPM-g-MAN/SAN树脂三种共混物的老化性能研究表明,三种共混物的耐气候老化和耐热氧老化性能都优于ABS;EPDM-g-SAN/SAN树脂和EPDM-g-MAN/SAN树脂两种共混物的人工模拟气候老化机理和热氧老化机理主要都是共混物的大分子发生-CH₂-脱氢、脱氰基、脱苯环和羟基先生成后脱掉的反应。更多还原

【Abstract】 EPM-g-MAN, synthesized by suspension grafting copolymerization of methyl methacrylate and acrylonitrile （MMA-AN） from ethylene-propylene bipolymer （EPM）, was blended with styrene-acrylonitrile copolymer （SAN） to prepare a high impact plastic AEMS. POE-g-MAN, synthesized by suspension grafting copolymerization of methyl methacrylate and acrylonitrile from polyethylene-octene copolymer （POE）, was blended with styrene-acrylonitrile copolymer （SAN） to prepare a high impact plastic AOMS. AEMS and AOMS are characterized by excellent weatherability and yellow discoloration resistivity because of no double bond in molecule chain of polyolefin elastomer （ES）: EPM and POE. AEMS and AOMS are potential engineering plastic,will substitute ABS if it can be in industrial production.The effect of f_AN (f_AN was equal to AN/MMA-AN), f_ES (f_ES was equal to ES/（ES+MMA-AN）, content of initiator BPO, content of solvent toluene, main dispersant PVA,assistant dispersant, water/oil ratio, reactive temperature and reactive time on the monomer conversion ratio （CR）, average grafting ratio （GR） and grafting efficiency （GE） of copolymerization and the notched impact strength of grafting copolymer/SAN resin blends were investigated systematically. EPM-g-MAN and POE-g-MAN synthesize by optimized condition were blended with SAN resin respectively to prepare AEMS and AOMS.Contemporary analysis methods were used to investigate grafting copolymer and blends systematically. The components of the grafted copolymer were separated by different solvent and were qualitative/quantitative analyzed using Fourier transform infrared spectroscopy （FTIR）. The results showed that, the main elementary reactions in EPM/MMA-AN grafting reaction system were graft copolymerization of EPM/MMA-AN, graft polymerization of EPM/MMA, copolymerization of MMA and AN, homopolymerization of MMA, crosslinking reaction of EPM, and there were no grafting polymerization of EPM/AN and homopolymerization of AN. The main elementary reactions in POE/MMA-AN grafting reaction system were graft copolymerization of POE/MMA-AN, graft polymerization of POE/MMA, copolymerization of MMA and AN, homopolymerization of MMA, and there were no grafting polymerization of POE/AN, homopolymerization of AN and crosslinking reaction of POE. DSC analysis indicated that the graft branches affected the crystallization of POE chains and made the melt temperature and the fusion heat be lower. For EPM/MMA-AN system, the quantitative relationship of f_AN on AN unit-to-MMA unit weight ratio in g-MAN chains/non-grafted components had been established by using FTIR quantitative analysis method, and it was found that the average weight fraction of AN unit in g-MAN （FAN-1） was less than f_AN. EPM-g-MAN had a best toughening effect on SAN resin while FAN-1 was 13.9wt%. TEM and SEM analysis showed that the phase structure of AEMS and AOMS were co-continue structure and the toughening machenism was severe shear yielding when the blends reached their highest notched Izod impact strength. DMA analysis showed that the miscibility between grafting copolymer and SAN resin was good. TG/DTG analysis showed that thermal stability of AEMS and AOMS increased with increasing f_AN. The melt flow rate（MFR） of AEMS decreased as EPM increasing. The less EPM content in the blends was, the better rheological and processing properties were.With research on the effect of reaction time on CR, GR, and GE of PEB/MMA-AN suspension system, POE/MMA-AN suspension system, EPM/MMA-AN suspension system and EPDM/St-AN solution system, the grafting copolymerization mechanism was investigated. The grafting polymerization product was characterized by GPC and FTIR analysis, the grafting copolymerization mechanism was investigated and the formula of calculating molecular weight of grafted chain was established. The results showed that, firstly the polymerization was mainly forming non-grafted copolymer with low molecular weight （MANL） of the transferring terminating polymerization of chain propagating free radicals and forming the grafted chains （g-MAN） of the transferring graft polymerization, and then the polymerization was mainly forming non-grafted copolymer with high molecular weight （MANH） of bimolecular terminating polymerization of chain propagating free radicals; molecular weight of MANL was less than that of g-MAN and molecular weight of g-MAN was less than that of MANH. The effects of reaction time on rubber’s grafting ratio of the four system were investigated. The results showed that the reaction mechanism after grafting copolymerization could be divided into two kinds. The one was that there existed chain scission and random regrafting of the backbone of ES-g-M and ungrafted ES which resulted in the production of multi-block polymer of ES and ES-g-M during the grafting copolymerization after transferring grafting polymerization, such as PEB and POE. The other was that the crosslinking reaction between grafted and ungrafted ES which resulted in the production of crosslinked polymer, such as EPDM and EPM. The same point of the two reaction was that the more ungrafted ES joined, the better toughening effect of the product on SAN resin.For PEB/MMA-AN system, toughening effect of different components on SAN resin was studied. The results showed that, grafted PEB （PEB-g-MAN） was the effective component that had toughening effect, non-grafted copolymer （MAN） was synergistic agent between PEB-g-MAN and SAN resin, and ungrafted PEB decreased the toughening effect. The thermal oxidative aging and accelerated weather aging results showed that the aging property of the blends of EPDM-g-SAN/SAN, EPDM-g-MAN/SAN and EPM-g-MAN/SAN was better than ABS. The aging mechanism was mainly the decrease of -CH2, -C≡N and benzene ring and firstly the increase and then the decrease of -OH of the blends during aging process.更多还原