聚甲基丙烯酸甲酯/二氧化硅复合材料的热性能

聚甲基丙烯酸甲酯/二氧化硅(PMMA/Si O_2)复合材料可以通过简便的单体浇铸、本体聚合方法制备,二氧化硅用硅烷偶联剂3-(异丁烯酰氧)丙基三甲氧基硅烷(γ-MPS)进行表面修饰,并用红外光谱表征其甲苯抽提后的组成。当加入量为11.76%时,PMMA/Si O_2复合材料的导热率达到0.23 W/(m·K),比基体PMMA提高了27.78%。用PMMA红外光谱的侧甲基弯曲振动峰(δCH3)与羰基(νC=O)的伸缩振动峰比值可以表示PMMA大分子的偶合终止与歧化终止的比例,随着二氧化硅含量的增加,歧化终止比例升高,从而使PMMA/Si O_2复合材料的热稳定性提高,与热重分析结果一致。     

两亲性共聚物P(MMA-co-AMPS)对聚偏氟乙烯超滤膜性能的影响

以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为亲水单体,甲基丙烯酸甲酯(MMA)为疏水单体,偶氮二异丁腈(AIBN)为引发剂,采用自由基共聚合法制得了两亲性共聚物P(AMPS-co-MMA);以两亲性共聚物P(AMPS-co-MMA)与聚偏氟乙烯(PVDF)共混,通过相转变法制备PVDF/P(MMA-co-AMPS)超滤膜。利用傅里叶变换红外光谱、热失重法表征无规共聚物的组成和热稳定性能。并通过扫描电子显微镜,傅里叶变换红外光谱、吸水率测试、表面润湿性测试,探讨了不同单体摩尔比对PVDF/P(MMA-co-AMPS)超滤膜的结构及性能的影响。结果表明,单体AMPS与MMA间发生自由基聚合生成两亲性共聚物P(AMPS-co-MMA)。PVDF/P(MMA-co-AMPS)超滤膜表面多孔,内部有大孔,存在相对致密皮层和多孔的支撑层。当2-丙烯酰胺基-2-甲基丙磺酸和甲基丙烯酸甲酯的摩尔比为2∶1时,PVDF/P(MMA-co-AMPS)超滤膜吸水率和表面润湿性能最好。     

水和甲醇存在下MAMS的消失反应动力学研究

通过实验研究了甲基丙烯酰胺硫酸盐（ＭＡＭＳ）与甲醇、水进行反应的动力学，并对该反应的机理进行了探讨。     

仲丁醇含量对正丁烯直接水合法制仲丁醇的影响

研究了正丁烯直接水合法制仲丁醇工艺中原料水中仲丁醇含量对反应的影响.当原料水中含有少量仲丁醇时(约0.9%时),其对水合反应过程的转化率影响不大;原料水中含有少量仲丁醇时,反应过程的稳定性比较好.当水合反应的原料水中仲丁醇浓度增大时(原料水中仲丁醇浓度为2.0%左右时),反应过程的转化率明显下降.当水合反应的原料水中仲丁醇含量进一步增大时,反应过程的转化率下降明显,但呈非线性变化.     

VAc／MMA半连续乳液共聚合的研究：Ⅰ种子乳液共聚合

以过硫酸铵为引发剂，十二烷基硫酸钠为乳化剂，于７０℃下进行了ＶＡｃ＝ＭＭＡ种子乳液共聚合。试验考察了组分和操作条件对体系稳定性，聚合速度及组成分布等的影响，同时，从理论上给出了加料速率与体系稳定性因子间的关系。     

A RIS treatment of the mean-square dipole moment of PMMA chains in consideration of the pendant ester group orientations

According to the six-state scheme proposed by Vacatello and Flory, the mean-square dipole moments 〈M²〉/x (x: number of monomeric units) of poly(methyl methacrylate) (PMMA) chains and their temperature dependence were calculated by the matrix algebra method of rotational isomeric state theory. To take account of the orientation effect of polar ester groups, the statistical weight matrices, U′ and U″, were recast into an expanded form. A Bernoullian probability λ introduced to measure the preference between the two alternative orientations (χ=0 and χ=π) of the side ester groups was found to give rise to a large effect on the mean-square dipole moment of polymers. When the skeletal bonds of a meso dyad are both in trans, an exceptionally strong dipole-dipole interaction may take place. If the two adjacent ester groups adopt the same orientation, the dipoles must be situated nearly parallel to each other in a close proximity. Such repulsive interactions may be alleviated by taking a staggered conformation, i.e. (χ,χ′)=(0,π) or (π,0). Such neighbor-dependent correlation inherent to the meso dyad is considered by assigning a parameter λ′ to the proper element of the U_m″ matrix. The values of 〈M²〉/x observed at 30 °C were satisfactorily reproduced by adopting λ=0.270 and λ′=0.865. The thermal coefficients were found to be reconciled with the available experimental data by allowing the orientation parameters λ and λ′ to be slightly temperature dependent. The stereochemical characteristics of the chain terminals were examined in order to extend the treatment to include the dipole moment of PMMA oligomers.     

Damage Effect of Space Proton Irradiation with the Low Energy of 50-200 keV on Methyl Silicone Rubber

The damage effects and mechanisms of proton irradiation with 50-200 keV energy to space-grade methyl silicone rubber was performed using a ground-based simulator for space irradiation environment. The changes in surface morphology, mechanicai properties, cross-linking density, glass temperature, infrared attenuated total reflection spectrum, mass spectrum and pyrolysis gas chromatography-mass spectrum indicated that, under lower energy, the proton irradiation would induce cross-linking effect, resulting in an increase in tensile strengths and hardness of the methyl silicon rubber. However, after the irradiation of protons for more than 150 keV, the irradiation induced degradation, which decreased the tensile strengths and hardness, became a dominant effect. A macromolecular network destruction modei for the silicone rubber radiated vvith the protons was proposed.     

甲基丙烯酸全氟辛基乙酯-甲基丙烯酸丁酯乳液共聚动力学

采用十二烷基硫酸钠和OP-10混合乳化剂，将甲基丙烯酸全氟辛基乙酯-甲基丙烯酸丁酯进行乳液共聚，研究了反应温度、引发剂浓度、乳化剂浓度、全氟单体浓度等因素对聚合速率(RP)的影响。结果表明，聚合速率随着引发剂浓度、乳化剂浓度的增加而增加；随着全氟单体浓度的增加而降低，该体系的表现活化自由能为106．27kJ／mol，RP∝[I]^.68，RP∝[S]^0.88，RP∝[FMA8]^0.33     

用Ce~(4 )为引发剂的MMA真丝接枝的研究

本文对由 Ce~(4 )引发的、在真丝上的 MMA(甲基丙烯酸甲酯)接技共聚的反应体系,进行了研究。实验结果表明,接枝反应的速率取决于引发剂及单体的浓度,反应温度和真丝性质的差异。此外,还研究了不同种类稀土离子 Ce~(4 )和硫酸铜浓度对该反应速率的影响。     

Swelling behaviour of amphiphilic poly(methacryloxyethyl dimethylalkane ammonium bromide) gels in alcohol/water solvent systems

Three kinds of amphiphilic PMADAB gels were prepared through radiation-induced polymerization and crosslinking of methacryloxyethyl dimethylalkane ammonium bromide(MADAB) with different alkyl side chains(butyl,octyl and dodecyl).The length of alkyl side chains had significant influence on swelling behavior of the PMADAB gels in alcohol/water solvent.Equilibrium swelling degree(EDS) of PMBDAB(butyl) gel in water was ca.160 and decreased with increasing alcohol content(x),whereas EDS of PMODAB(octyl)and PMDDDAB(dodecyl) gels showed a convex-upward function of x,i.e.,these two gels barely swelled in pure water and swelled with increasing x and then shrank gradually.This phenomenon was explained by the hydrophobic association of long alkyl chains and a cosolvency effect of PMADAB in alcohol and water.The swelling behavior of PMADAB gels in methanol,ethanol and isopropanol were similar,and their EDS are related with the dielectric constant of alcohol solvents.The results suggest that PMADAB gels may be potential absorbents for various kinds of alcohols.