【作者】 刘建平；

【导师】 郑玉斌；

【作者基本信息】 大连理工大学 ， 高分子材料， 2009， 博士

【摘要】 聚氯乙烯(PVC)是五大通用塑料之一,但是其热稳定性差,在加工温度下易发生脱氯化氢形成共轭多烯,导致颜色加深,进而深度交联,失去力学性能,需要添加热稳定剂。PVC的热分解是从不稳定氯原子上引发的一种链式脱氯化氢反应,生成共轭多烯,同时氯化氢对PVC降解有自动催化作用。各种热稳定剂对PVC的作用机理各不相同,主要包括吸收氯化氢,置换不稳定氯,阻断共轭多烯结构形成等。目前的稳定剂主要包括铅盐类、金属皂类和有机锡类等。铅盐类稳定剂毒性大,易造成环境污染等问题,有机锡类成本较高,金属皂稳定剂要么有一定毒性,要么热稳定性不好。随着全球环保要求越来越高,研究新型、高效、无毒性的热稳定剂是非常重要的。本课题的目的就是通过分子设计,合成一系列含马来酸二烷基锡组分高分子化合物,从而期望获得一类综合性能优异的聚合型稳定剂。本课题的研究思路是,基于以往小分子型的热稳定剂有压析、迁移、分散不好等问题,设计一种高分子化合物,其结构特点是:高分子化合物的结构上具有抑制PVC初期热分解的结构单元和抑制PVC中、长期热降解的稳定组份,以及具有与PVC有较好相容性的共聚组份。使得PVC稳定体系在加工时热稳定剂与PVC的相容性好、容易分散。当PVC初期受热分解时,分子链上的初期稳定官能团起作用,抑制其分解。随着受热时间延长,PVC发生中、长期受热分解,此时稳定剂分子链上的中长期稳定官能团起作用,抑制其分解。这样在热稳定剂保证稳定效率的前提下,尽量使稳定剂中价格较贵的金属含量相对降低,并且热稳定作用范围比单一小分子型热稳定剂更为全面。本论文以二丁基氧化锡,二辛基氧化锡,马来酸酐,苯胺,对氯苯胺,对硝基苯胺等为原料,分别合成了马来酸二丁基锡(DBTO),马来酸二辛基锡(DOTO),N-苯基马来酰亚胺(PMI),N-对氯苯基马来酰亚胺(N-p-ClPMI),N-对硝基苯基马来酰亚胺(N-p-NOPMI)等含不饱和键的化合物。再以DBTO,DOTO,PMI,N-p-ClPMI,N-p-NOPMI,苯乙烯,丙烯酸甲酯等为单体,合成了马来酸二丁基锡/苯乙烯二元共聚物{P(DBTM/St)},马来酸二丁基锡/苯乙烯/丙烯酸甲酯三元共聚物{P(DBTM/St/MA)},马来酸二丁基锡/苯乙烯/N-苯基马来酰亚胺三元共聚物{P(DBTM/St/NPMI)},马来酸二丁基锡/苯乙烯/N-对氯苯基马来酰亚胺三元共聚物{P(DBTM/St/NClPMI)},马来酸二丁基锡/苯乙烯/N-对硝基苯基马来酰亚胺三元共聚物{P(DBTM/St/NNOPMI)},马来酸二辛基锡/苯乙烯二元共聚物{P(DOTM/St)},马来酸二辛基锡/苯乙烯/丙烯酸甲酯三元共聚物{P(DOTM/St/MA)},马来酸二辛基锡/苯乙烯/N-苯基马来酰亚胺三元共聚物{P(DOTM/St/NPMI)},马来酸二辛基锡/苯乙烯/N-对氯苯基马来酰亚胺三元共聚物{P(DOTM/St/NClPMI)},马来酸二辛基锡/苯乙烯/N-对硝基苯基马来酰亚胺三元共聚物{P(DOTM/St/NNOPMI)}。通过红外光谱仪(FT-IR)、核磁共振(NMR)、电感耦合等离子体发射光谱仪(ICP)和凝胶色谱(GPC)等检测手段等对聚合物结构进行表征。利用刚果红法研究了上述高分子型热稳定剂对PVC的热稳定性,其中:马来酸二丁基锡系列共聚物热稳定顺序是:P(DBTM/St/MA)＞P(DBTM/St)＞P(DBTM/St/NPMI)＞P(DBTM/St/NClPMI)＞P(DBTM/St/NNOPMI);马来酸二辛基锡系列共聚物热稳定顺序是:P(DOTM/SVMA)＞P(DOTM/St)＞P(DOTM/St/NPMI)＞P(DOTM/St/NClPMI)＞P(DOTM/St/NNOPMI)。利用酸度计法研究了高分子型热稳定剂对PVC的热解脱氯化氢的抑制作用,其中:马来酸二丁基锡系列共聚物抑制效果的顺序是:P(DBTM/St/MA)＞P(DBTM/St)＞P(DBTM/St/NPMI)＞P(DBTM/St/NClPMI)＞P(DBTM/St/NNOPMI);马来酸二辛基锡系列共聚物抑制效果的顺序是:P(DOTM/St/MA)＞P(DOTM/St)＞P(DOTM/St/NPMI)＞P(DOTM/St/NClPMI)＞P(DOTM/St/NNOPMI)。利用烘箱老化法研究了高分子型热稳定剂对PVC的热老化变色的抑制作用:马来酸二丁基锡系列共聚物抑制效果的顺序是:P(DBTM/St/MA)＞P(DBTM/St)＞P(DBTM/St/NPMI)＞P(DBTM/St/NClPMI)＞P(DBTM/St/NNOPMI);马来酸二辛基锡系列共聚物抑制效果的顺序是:P(DOTM/St/MA)＞P(DOTM/St)＞P(DOTM/St/NPMI)＞P(DOTM/St/NClPMI)＞P(DOTM/St/NNOPMI)。从理论上计算了高分子型热稳定剂的溶解度参数,根据吉布斯自由能以及Hildebrand混合焓方程判断了马来酸二丁基锡系列共聚物,马来酸二辛基锡系列共聚物与PVC的相容性,全面探讨了高分子型热稳定剂与PVC相容性对稳定剂热稳定性能的影响,在被研究的系列高分子型热稳定剂的规律是:与PVC相容性好的热稳定剂的热稳定性好。利用AI-7000-LA10型伺服控制拉力实验机、扫描电镜(SEM)对PVC试样进行了力学性能及填料在PVC中分散情况的分析,研究发现:热稳定剂对填料的分散性有一定的影响,填料分散好的试样拉伸强度好。其结果是,添加马来酸二丁基锡系列共聚物的PVC试样的拉伸强度顺序是:P(DBTM/St/MA)＞P(DBTM/St)＞P(DBTM/St/NPMI)＞P(DBTM/St/NClPMI)＞P(DBTM/St/NNOPMI);添加马来酸二辛基锡系列共聚物的PVC试样的拉伸强度顺序是:P(DOTM/St/MA)＞P(DOTM/St)＞P(DOTM/St/NPMI)＞P(DOTM/St/NClPMI)＞P(DOTM/St/NNOPMI)。以热重分析仪(TG/DTG)为研究手段,对含马来酸二烷基锡组分的系列高分子型热稳定剂的PVC体系进行了热分解动力学研究,结果发现加入马来酸二烷基锡共聚物组份的PVC体系的热解活化能较不加入的纯PVC的活化能提高5～15(kJ/mol),说明热稳定剂起到了稳定作用。通过紫外光谱仪研究了PVC稳定体系脱氯化氢形成共轭多烯情况,结果发现热稳定剂对PVC分子链上的共轭多烯的形成有抑制作用,利用红外光谱对高分子型热稳定剂置换PVC上不稳定的氯原子的情况进行了研究,结果发现稳定剂在PVC分子链引入酯键,并进行了其热稳定机理的研究。研究结果表明,在本文合成的系列聚合型稳定剂中,P(DBTM/St/MA)共聚物和P(DOTM/St/MA)共聚物对PVC的热稳定性较好,用其加工得到的PVC材料的力学性能也较好,说明这二种聚合型稳定剂最具有应用前景。更多还原

【Abstract】 As one of the five general plastics,polyvinyl chloride(PVC) was used in many fields,such as water pipes,floor and roof tiles,packing films,and sheets.However,due to its intrinsic thermal instability of PVC,dehydrochlorination happens at the processing temperature.During the thermal degradation of PVC,labile chlorine atoms start the reaction and HCl is released from the PVC,which makes conjugated double bonds formed,ultimately leading to discoloration and severe crosslinking.On the other hand,HCl during thermal degradation acts as auto-catalyst resulting in the loss of mechanical properties of PVC.Hence,the application of heat stabilizers is prerequisite for PVC processing.Heat stabilizers reduce thermal degradation of PVC in two ways:1.HCl enters to reaction by scavenging;2.labile chlorine atoms are substituted and conjugated double bond formation is prevented.As present,lead salt,metal soap and organotin are widely used as heat stabilizers.Many of the most effective heat stabilizers for this polymer contain toxic heavy metals,while alternative safe stabilizer systems are less effective to block degradation of PVC.Organotin still require further improvement in order to achieve a comparable price/performance.Hence,research on highly efficient, non-toxic,low cost heat stabilizer would provide new insights.In this paper,a series of polymers containing dialkyltin maleate units were designed and synthesized,which could improve thermal stability of PVC,and also offer a ’green’, environmentally benign solution.Due to the drawbacks of small molecular heat stabilizers,such as migration and poor dispersion,a series of polymeric stabilizers were designed for excellent compatibility with PVC containing the starting effect groups and the long-term effect groups.These stabilizers could inhibit the thermal decomposition at the early stage,and meanwhile prolong the long-term heat stability of PVC.Besides,the polymeric stabilizers compatible with PVC would be homogeneously dispersed during the processing.It could be desirable to decrease the content of high cost metal in the heat stabilizers as least as effective.Dibutyltin maleate(DBTO),dioctyltin maleate(DOTO),N-phenyl maleimide(NPMI), N-(p-chlorophenyl) maleimide(N-p-ClPMI),N-(p-nitrophenyl) maleimide(N-p-NOPMI) with unsaturated groups were synthesized using dibutyltin oxide,dioctyltin oxide,maleic anhydride, aniline,p-chloroaniline,p-nitroaniline as raw materials,respectively.Then dibutyltin male,ate/styrene bipolymer[P(DBTM/St)],dibutyltin maleate/styrene/methyl acrylate terpolymer[P(DBTM/St/MA)],dibutyltin maleate/styrene/N-phenyl maleimide terpolymer [P(DBTM/St/NPMI)],dibutyltin maleate/styrene/N-(p-chlorophenyl) maleimide terpolymer [P(DBTM/St/NClPMI)],dibutyltin maleate/styrene/N-(p-nitrophenyl) maleimide terpolymer [P(DBTM/St/NNOPMI)],dioctyltin maleate/styrene biopolymer[P(DOTM/St)],dioctyltin maleate/styrene/methyl acrylate terpolymer[P(DOTM/St/MA)],dioctyltin maleate/styrene/ N-phenyl maleimide terpolymer[P(DOTM/St/NPMI)],dioctyltin maleate/styrene/ N-(p-ehlorophenyl) maleimide terpolymer[P(DOTM/St/NC1PMI)],dioctyltin maleate/styrene/N-(p-nitrophenyl) maleimide terpolymer[P(DOTM/St/NNOPMI)]were synthesized using DBTO,DOTO,PMI,N-p-ClPMI,N-p-NOPMI,styrene and methyl acrylate as monomers,respectively.The polymers were characterized by means of Fourier transfer infrared spectroscopy(FT-IR),proton nuclear magnetic resonance spectroscopy(~1H NMR), inductively coupled plasma atomic emission spectroscopy(ICP) and gel permeation chromatography(GPC).The effect of above polymeric stabilizers on the thermal stability of PVC was analyzed by Congo red test.The order of the thermal stability of copolymers containing dibutyltin maleateunits is as follows:P(DBTM/St/MA)＞P(DBTM/St)＞P(DBTM/St/NPMI)＞P(DBTM/St/NClPMI)＞P(DBTM/St/NNOPMI);The order of the thermal stability of copolymers containing dioctyltin maleateunits is as follows:P(DOTM/St/MA)＞P(DOTM/St)＞P(DOTM/St/NPMI)＞P(DOTM/St/NClPMI)＞P(DOTM/St/NNOPMI).The dehydrochlorination of PVC was discussed by means of acidimeter.The order of the inhibition ofcopolymers containing dibutyltin maleate units is as follows:P(DBTM/St/MA)＞P(DBTM/St)＞P(DBTM/St/NPMI)＞P(DBTM/St/NClPMI)＞P(DBTM/St/NNOPMI);The order of the inhibition of copolymers containing dioctyltin maleate units is as follows: P(DOTM/St/MA)＞P(DOTM/St)＞P(DOTM/St/NPMI)＞P(DOTM/St/NClPMI)＞P(DOTM/St/ NNOPMI).The discoloration and thermal aging of PVC was studied in a circulating air oven.The order of the stabilizing effect of copolymers containing dibutyltin maleateunits is as follows:P(DBTM/St/MA)＞P(DBTM/St)＞P(DBTM/St/NPMI)＞P(DBTM/St/NClPMI)＞P(DBTM/St/NNOPMI);The order of the stabilizing effect of copolymers containing dioctyltin maleateunits is as follows:P(DOTM/St/MA)＞P(DOTM/St)＞P(DOTM/St/NPMI)＞P(DOTM/St/NClPMI)＞P(DOTM/St/NNOPMI).Using the theoretical calculation of Gibbs free energy and Hildebrand mixing enthalpy equation,the solubility parameter of the polymeric heat stabilizers was obtained in order to estimate the compatibility of PVC with copolymers containing dibutyltin maleate units and dioctyitin maleate units.The effect of the compatibility on the thermal stability of the PVC stabilizing system was thoroughly explored.It is obtained that thermal stability was increased with excellent compatibility.The mechanical properties of PVC samples were measured with a servocontrolled testing machine.The effect of the filler dispersion in the PVC upon the tensile strength was observed by scan electron microscopy(SEM).It is shown that the tensile strength was increased with favorable dispersion.The order of the tensile strength of the PVC samples with copolymers containing dibutyltin maleateunits is as follows:P(DBTM/St/MA)＞P(DBTM/St)＞P(DBTM/St/NPMI)＞P(DBTM/St/NC1PMI)＞P(DBTM/St/NNOPMI);The order of the tensile strength of the PVC samples with copolymers containing dioctyltin maleate units is: P(DOTM/St/MA)＞P(DOTM/St)＞P(DOTM/St/NPMI)＞P(DOTM/St/NClPMI)＞P(DOTM/St/NNOPMI).A kinetic study was carried out on the thermogravimetric analyzer(TG/DTG).The pyrolysis activation energy of PVC with copolymers containing dialktyltin maleate units is increased by 5-15 kJ/mol compared with pure PVC.That was attributed to stabilization effect of heat stabilizers.Dehydrochlodnation to form conjugated polyene of PVC stable system was studied on UV spectrometer.It is shown that the thermal stabilizer could effectively inhibit the formation of conjugated polyene on the PVC backbone.Through the infrared spectrometer,it is confirmed that the labile chlorine atoms were substituted and the ester groups were introduced into the PVC.Furthermore,a mechanism for the stabilizing action of the synthesized stabilizers was proposed.It is concluded that in the series of the polymeric thermal stabilizers synthesized in this paper,PVC stabilizing systems containing P(DBTM/St/MA) and P(DOTM/St/MA) with the best thermal stability and excellent mechanical properties,might promise candidates for widespread application in the future.更多还原