MONOMER REACTIVITY RATIO AND THERMAL PERFORMANCE OFα-METHYL STYRENE AND GLYCIDYL METHACRYLATE COPOLYMERS

Synthesis and characterization of the copolymers （PAG） of α-methyl styrene （AMS） and glycidyl methacrylate （GMA） are presented. The copolymers of PAG were characterized by gel permeation chromatography （GPC）, Fourier transform infrared spectroscopy （FTIR）, nuclear magnetic resonance （^1H-NMR） and thermogravimetery （TG）. Based on the copolymer compositions determined by ^1H-NMR, the reactivity ratios of AMS and GMA were found to be 0.105 ± 0.012 and 0.883 ± 0.046 respectively by Kelen-Tudos method. TG revealed that thermal stability of the copolymers decreased with increasing the AMS content in the copolymers, which indicated that the degradation was mainly caused by the chain scission of AMS-containing structures. Under heating, the copolymers depolymerize at their weak bonds and form chain radicals, which could further initiate other chemical reactions.

Effect of Methyl Methacrylate– Acrylonitrile -Butadiene–Styrene (MABS) on the Mechanical and Thermal Properties of Poly (Methyl Methacrylate) (PMMA)-Fly Ash Cenospheres (FAC) Filled Composites

With the advent of plastics and the wide range of fillers that are available have made modifications as precise as the tailored resins themselves. To modify the properties of polymer either by using fillers or by preparation of polymer blends gives rise to new materials with tailored properties. More complex, three-component systems, obtained by the addition of polymeric modifier to polymer filled composites may be of interest. Use of Fly ash cenospheres is very attractive because it is inexpensive and its use can reduce the environmental pollution to a significant extent. In the present study, Poly (Methyl Methacrylate) (PMMA)-Fly ash cenospheres composites were prepared using extrusion followed by Injection molding. The effect of matrix modification with Methyl methacrylate– acrylonitrile -butadiene–styrene (MABS) on the performance of PMMA- Fly ash cenospheres compositions was also, studied. It was found that with the addition of Fly ash cenospheres particulate as filler in PMMA showed marginal reduction in Tensile Strength, % Elongation and Impact strength and improvement in Flexural Strength, Heat Deflection Temperature and Vicat Softening Point. Compared with PMMA-cenospheres composites, the notched Impact Strength of the PMMA/MABS/cenospheres composites showed marginal enhancement in values at higher loading of cenospheres. The optimum performances in mechanical and thermal properties were obtained when the ratio of MABS to cenospheres was 1:2.

MEASUREMENTS OF MONOMER REACTIVITY RATIOS FOR COPOLYMERIZATION OF STYRENE AND METHYL METHACRYLATE IN CARBON DIOXIDE AT VAPOR-LIQUID EQUILIBRIUM STATE

The monomer reactivity ratios of free radical copolymerization of styrene and methyl methacrylate in carbon dioxide at vapor-liquid equilibrium state (vlCO(2)) at 65 degrees C and under 7.5-8.5 MPa were measured. The experimental results showed that, in comparison with the data in bulk copolymerization, the monomer reactivity ratio of St in vlCO(2) increased acompanied by a somewhat decrease in that of MMA. Further analysis of the sequence distributions of these copolymers by H-1-NMR spectra indicated that there was a significant bootstrap effect in this system. The local monomer concentrations in the proximity of growing free radicals, rather than the true reactivity of monomers or free radicals, were altered by the presence of vlCO(2), leading to the change in monomer reactivity ratios.

SYNTHESIS OF POLY(METHYL METHACRYLATE)-graft-POLYSTYRENE BY ATOM TRANSFER RADICAL POLYMERIZATION

The radical copolymerization of methyl methacrylate and 2-hydroxyethyl methacrylate was carried out via atomtransfer radical polymerization (ATRP) initiated by ethyl 2-bromoisobutyrate and catalyzed by CuBr/2,2'-bipyridinecomplex. This polymerization proceeds in a living fashion with controlled molecular weight and low polydispersity. Theobtained copolymer was esterified with 2-bromoisobutylryl bromide yielding a macroinitiator, poly(methyl methacrylate-co-2-hydroxyethyl methacrylate-co-2-(2-bromoisobutyryloxy)ethyl methacrylate), and its structure was characterized by ~1H-NMR. This macroinitiator was used for ATRP of styrene to synthesize poly(methyl methacrylate)-graft-polystyrene. Themolecular weight of graft copolymer increased with the monomer conversion, and the polydispersity remained relatively low.The individual grafted polystyrene chains were cleaved from the macroinitiator backbone by hydrolysis and the hydrolyzed product was characterized by ~1H-NMR and GPC.

EFFECTS OF ω-ACRYLOYL POLY (ETHYLENE OXIDE) MACROMONOMER ON EMULSIFIER-FREE EMULSI0N COPOLYMERIZATION OF METHYL METHACRYLATE AND n-BUTYL ACRYLATE

Well-defined nonionic hydrophilic ω-acryloyl poly(ethylene oxide) macro-monomer (PEO-A) has been prepared by living anionic polymerization of ethylene oxidewith diphenyl methyl potassium as the initiator and acryloyl chloride as the reaction termi-nating agent. The polymer was characterized by FTIR and SEC. The emulsifier-free emul-sion polymerization of methyl methacrylate (MMA) and n-butyl acrylate (BA) containingvarious concentrations of PEO-A was studied. In all cases stable emulsion coplymerizationsof MMA and BA were obtained. The stabilizing effect was found to be dependent on themolecular weight and the feed amount of the macromonomer.

The Polymerization of Methyl Methacrylate in the Presence of a New Homogeneous Yttrium Catalyst

Methyl methacrylate(MMA) polymerized in the presence of a new homogeneous catalyst of Y(acac)3-(i-Bu)3Al-BuLi. The effects of MMA/Y, Al/Y, Li/Y molar ratios, polymerization temperature and time are reported. The results show that a small amount of butyl lithium could greatly enhance the activity of the catalyst and the polymerization reaction could be carried out at low temperatures (-25℃-10℃) with a high conversion. 200 kg of poly(methyl methacrylate) (PMMA) with 63% syndiotacticity could be prepared by using 1 mole of yttrium.

Studies on Rheological, Thermal, and Mechanical Properties of Polylactide/Methyl Methacrylate-Butadiene-Styrene Copolymer/Poly(propylene carbonate) Polyurethane Ternary Blends

Polylactide(PLA),methyl methacrylate-butadiene-styrene copolymer(MBS),and poly(propylene carbonate)polyurethane(PPCU)were blended and subjected to blown film process.The rheological,mechanical,morphological,thermal,and crystalline properties of the PLA/MBS/PPCU ternary blends and the mechanical properties of the resulting films were studied.Results of mechanical test showed that PPCU and MBS could synergistically toughen PLA.The impact strength of 50/10/40 PLA/MBS/PPCU blend(74.7 k J/m^2)was about 7.5 times higher than that of the neat PLA(10.8 k J/m^2),and the elongation at break of 50/10/40 PLA/MBS/PPCU blend(276.5%)was higher by about 45 times that of PLA(6.2%).The tear strength of PLA/MBS/PPCU films was 20 k N/m higher than that of PLA,and the elongation at break(MD/TD)of 50/10/40 PLA/MBS/PPCU films was 271.1%/222.3%,whereas that of PLA was only 2.7%/3.0%.POM observations displayed that the density of spherulite nucleation increased and the size of crystalline particles decreased with the addition of MBS.With increasing PPCU content from 5%to 20%,the density of spherulite nucleation increased and the size of crystalline particles decreased continuously,but the nucleation density of spherulites was slightly lowered with increasing PPCU content from 30%to 40%.The PLA/MBS/PPCU films exhibited excellent mechanical properties,which expanded the application range of these biodegradable films.

Preparation and characterization of star ABC triblock copolymer of ethylene oxide,styrene and methyl methacrylate

A universally significant method,which combines the anionic polymerization with photoinduced charge transfer polymerization,for preparation of soluble star ABC triblock copolymer of ethylene oxide,styrene and methyl methacrylate,was described.The poly(ethylene oxide) (PEO) block was formed by initiation of phenoxy an-ions using p-aminophenol protected by Schiff’s base as the parent compound Then the charge transfer system composed of PEO chains with deprotected-amino end groups and benzophenone initiated the polymerization of styrene and methyl metnacrylate sequentially under UV irradiation.The formed star triblock copolymer of styrene,ethylene oxide and methyl methacrylate could be purified by thin-layer chromatography (TLC) and characterized by IR,1H NMR,GPC (gel permeation chromatogrphy) and PGC (pyrolysis gas chromatography).

Ambient Temperature Living Radical Copolymerization of Styrene and Methyl Methacrylate with Sodium Hypophosphite as Reducing Agent

A facile, safe and economical reducing agent, sodium hypophosphite（Na H2PO2·H2O）, has been successfully employed for ambient temperature living radical copolymerization of styrene（St） and methyl methacrylate（MMA）. Such effective reducing agent significantly improved the reactivity of low reactive St monomers during the copolymerization, where the reactivity ratios of St and MMA were determined to be 0.50 and 0.36 by Finemann-Ross method. Thus the copolymerizations proceeded fast and showed typical living/controlled features, as evidenced by pseudo first-order kinetics of polymerization, linear increase in molecular weight versus monomer conversion, and low polydispersity index values. Effects of the concentration of reducing agent and the monomer feed ratio on the copolymerization were investigated in detail. Furthermore, gel permeation chromatography and 1H-NMR analyses as well as chain extension experiments confirmed the high chain-end functionality of the resultant copolymer.

Organostibine mediated controlled/living random copolymerization of styrene and methyl methacrylate

The first example of organostibine mediated controlled/living random copolymerization of styrene(St) and methyl methacrylate(MMA) was achieved by heating a solution of St/MMA/organostibine mediator at 100 °C or St/MMA/organostibine mediator/AIBN with various monomer feed ratios at 60 °C.The addition of AIBN significantly decreased the reaction temperature and enhanced the rate of copolymerization.The structure of poly(St-co-MMA) was verified by 1H NMR.The reactivity ratios at 60 °C were determined by the extended Kelen-Tüds method to be YSt = 0.40 and YMMA = 0.44.The ln([M]0/[M]) increased linearly with increasing reaction time.The number-average molecular weights of poly(St-co-MMA) increased linearly with conversion.Poly(St-co-MMA) with expected number-average molecular weight and low polydispersity index was formed.The living characteristic was further confirmed by chain-extension of poly(St-co-MMA) to form poly(St-co-MMA)-b-PMMA.

钛酸四丁酯催化甲基丙烯酸甲酯与正丁醇酯交换反应动力学研究

由于设备腐蚀和环境污染等问题,甲基丙烯酸丁酯生产工艺逐渐倾向于更为经济环保的酯交换生产工艺。以钛酸四丁酯为催化剂,甲基丙烯酸甲酯与正丁醇通过酯交换法合成甲基丙烯酸丁酯的反应及机理进行了初步研究。首先,根据路易斯酸催化理论,在合理假设和简化的基础上对该反应的机理进行了分析,在此基础上分别建立了基于理想溶液和非理想溶液的动力学模型。通过酯交换反应实验,主要研究了反应温度、反应物初始物质的量之比和催化剂量等因素对反应速率的影响,并根据实验数据回归得到了动力学模型参数和反应的基本热力学数据。结果显示,该酯交换反应为吸热反应,标准摩尔反应焓为14.406 kJ·mol^(-1),正、逆反应活化能分别为70.2和51.1 kJ·mol^(-1)。通过模型计算值与实验数据的比较,证明了推导得到的动力学模型具有较高的可靠性,将为钛酸四丁酯催化甲基丙烯酸甲酯与正丁醇酯交换合成甲基丙烯酸丁酯反应提供一定的理论指导。

MBS对PC/ABS/纤维增强材料界面和力学性能的影响

本研究通过引入甲基丙烯酸甲酯-丁二烯-苯乙烯(MBS)三元共聚物作为增容剂,成功制备了性能增强的聚碳酸酯(PC)/丙烯腈-丁二烯-苯乙烯共聚物(ABS)/玻璃纤维(GF)/MBS与PC/ABS/碳纤维(CF)/MBS共混合金。扫描电子显微镜(SEM)观察液氮脆断断面显示,MBS的加入显著改善了所有合金材料的界面黏附性。力学性能测试结果表明,添加质量分数1%的MBS后,PC/ABS/GF合金的拉伸强度、拉伸模量和缺口冲击强度分别提高了6.52%、53.87%和0.22%;在PC/ABS/CF合金中,添加质量分数3%MBS后,这些性能分别提升10.14%、45.10%和0.66%。然而,由于MBS的低熔点,其加入对合金的热稳定性产生了一定负面影响,导致热性能下降。研究表明,MBS的引入显著增强了PC/ABS基体的界面结合力和力学性能。

ABS改性及其在电子电器产品外观设计中的应用

介绍了乳液法丙烯腈-苯乙烯-丁二烯共聚物(ABS)生产工艺流程。引入马来酸酐和丙烯酸烷基酯类单体可以提高反应转化率,降低残余1,3-丁二烯含量。加入改性回收再利用的ABS/聚碳酸酯(PC)制备的免喷涂斑点ABS/PC复合材料具有较好的抗冲击性能,应用于电子电器产品中,具有较好的防摔性能和外观质感。在相容剂作用下,改性弹性体与ABS混合制备的复合材料可以消除空调表面因摩擦产生的异响。

RAFT法制备羧甲基纤维素接枝丙烯酸酯共聚物

以溶解后改性的羧甲基纤维素(CMC)为大分子引发剂,S-1-十二烷基-S’-(α-α’-二甲基-α”-乙酸)三硫代碳酸酯为可逆加成断裂链转移聚合(RAFT)试剂,通过RAFT法制备了CMC接枝丙烯酸酯的新型接枝共聚物。为了进一步探索共聚物的成膜形态,设计了不同反应时间、不同甲基丙烯酸甲酯(MMA)与丙烯酸丁酯(BA)配比的反应条件,合成了CMC接枝MMA嵌段BA聚合物(Cell-g-PMMA-b-PBA)。结果表明:在反应时间为24 h,MMA与BA体积比为6∶1的条件下,Cell-g-PMMA-b-PBA的成膜性能最好,热稳定性高。

增韧聚氯乙烯电工套管复合材料的制备与性能研究

采用丙烯酸酯橡胶(ACM)、刚性体纳米碳酸钙(nano-CaCO_(3))、弹性体丙烯酸丁酯/甲基丙烯酸甲酯/丁二烯三元共聚物(AMB)作为增韧剂,对聚氯乙烯(PVC)进行复合增韧改性,并对复合材料的冲击性能、拉伸性能、加工流变性、动态热力学性能等进行了表征。结果表明,当PVC/ACM/nano-CaCO_(3)/AMB质量比为100/10/3/9时,复合材料的常温冲击强度为27.64 kJ/m^(2),比纯PVC提升5倍;低温冲击强度为14.91 kJ/m^(2),比纯PVC提升4.1倍。加入AMB能使体系的玻璃化转变温度(Tg)下降,由93.71℃下降到86.36℃。

PC/改性ABS复合材料的制备与性能

在传统的丙烯腈-丁二烯-苯乙烯共聚物(ABS)乳液接枝聚合中加入甲基丙烯酸甲酯(MMA),制得了改性ABS,然后与聚碳酸酯(PC)共混挤出,制得了PC/改性ABS复合材料。研究了MMA用量对PC/改性ABS复合材料的熔体流动速率(MFR)、维卡软化温度、力学性能的影响。结果表明:随着MMA用量的增加,PC/改性ABS复合材料的MFR、拉伸强度、弯曲强度和缺口冲击强度均先升高后降低。当MMA质量分数为20%时,PC/改性ABS复合材料的拉伸强度和弯曲强度均达到最大,分别为48.9 MPa和63.2 MPa;当MMA质量分数为30%时,PC/改性ABS复合材料的缺口冲击强度为41.0 kJ/m^(2);当MMA质量分数不高于30%时,与PC/ABS复合材料相比,PC/改性ABS复合材料的维卡软化温度更高。

熔融共混一步法制备具有优异水氧阻隔性能的苯乙烯-甲基丙烯酸甲酯共聚物量子点扩散板

为了同时增强苯乙烯-甲基丙烯酸甲酯共聚物(SMMA)的光扩散性能和水氧阻隔性能,首次将阻隔性能优异的乙烯-乙烯醇共聚物(EVOH)作为光扩散粒子,通过简单的熔融共混法制备了不同EVOH含量的SMMA/EVOH复合材料。采用扫描电子显微镜、透光率雾度仪、气体渗透仪、水蒸气透过率测试仪等详细研究了复合材料的微观结构、光扩散性能、水氧阻隔性能、力学性能以及量子点荧光强度的变化。研究结果表明,EVOH与SMMA不完全相容,质量分数40%以下的EVOH在SMMA体系中以球形分散相形式存在,可将雾度从纯SMMA的0.3%提高至80%以上,起到光散射粒子的作用,透光率依然保持在60%以上;随着EVOH含量增加,复合材料的拉伸力学性能呈现先增加后降低的趋势,但水氧阻隔性能逐渐提高。将量子点加入阻隔扩散板中,能够有效延长量子点的荧光寿命,具有较强的应用价值。

甲基丙烯酸甲酯-丙烯酸丁酯共聚物的分子动力学模拟

采用分子动力学模拟方法,建立了甲基丙烯酸甲酯(MMA)-丙烯酸丁酯(BA)共聚物体系模型,预测了单体配比对MMA-BA共聚物的玻璃化转变温度(Tg)和力学性能的影响。结果表明,随着MMA和BA物质的量比增大,MMA-BA共聚物的Tg升高,与Fox方程计算的Tg变化趋势一致;MMA-BA共聚物的杨氏模量、剪切模量和体积模量随着MMA和BA物质的量比的增大而增加,且与实验测试的MMA-BA共聚物膜的杨氏模量、剪切模量和体积模量的变化趋势一致。

用甲基橙与溴甲酚绿-甲基红作指示剂标定盐酸溶液的差异分析

实验发现在使用无水碳酸钠标定盐酸溶液时,用甲基橙与溴甲酚绿-甲基红作为指示剂标定的盐酸溶液浓度存在一定差异。本文用以上2种指示剂,标定0.3、0.5、0.8、1.0 mol/L盐酸溶液浓度结果的比对分析,探索其结果差异及对甲基丙烯酸丁酯纯度分析结果的影响。

聚丙烯酸酯共聚物自愈合性能的分子动力学模拟

通过分子动力学模拟方法构建了甲基丙烯酸甲酯(MMA)-丙烯酸丁酯(BA)共聚物微裂纹模型,研究了MMA与BA摩尔比分别为3∶7、4∶6、5∶5和6∶4,温度分别为25℃、50℃和75℃时MMA-BA共聚物的自愈合行为.从MMA-BA共聚物微裂纹模型的密度、均方位移、扩散系数和力学性能等方面评价了MMA-BA共聚物的自愈合性能,并对MMA-BA共聚物膜的自愈合行为进行了实验验证.结果表明,温度越高,MMA-BA共聚物微裂纹模型的愈合速度越快.当MMA与BA摩尔比为5∶5时,MMA-BA共聚物的微裂纹基本消失,自愈合性能最好,修复效率最高,且与实验测试的MMA-BA共聚物膜的自愈合行为变化趋势一致.