环氧–丙烯酸酯混杂体系光聚合动力学及其力学性能的研究

研究了阳离子和自由基引发剂对混杂体系动力学以及丙烯酸酯种类和含量对混杂体系光固化膜力学性能的影响.结果表明,在阳离子聚合体系中,引发剂6976具有较高的引发活性,双键的转化率随其质量分数的增加而提高,而环氧转化率在其质量分数为3%时存在一个最优值;混杂体系自由基引发剂以651的增感作用最为明显,随着651质量分数的增加,环氧的转化平衡时间减少,当其质量分数为0.5%时,环氧转化平衡时间为8 min,双键转化率达到100%,双键的最大转化速率达到11.5 min-1.动态力学热分析和静态力学性能测试表明,改变丙烯酸酯单体的含量和官能度,可有效改善固化膜的力学性能,当,m(CER-170):m(TPGDA)为2:1～1:4时,混杂体系玻璃化温度为34～44℃,固化膜拉伸模量为25～90 MPa,柔韧性为7,硬度为3H～6H.     

Thermal degradation behavior of PMMA synthesized by emulsifier‐free emulsion polymerization with a Cu2+/HSO3− redox system

In this study, poly(methyl methacrylate) (PMMA) latex was synthesized in an emulsifier‐free emulsion polymerization at 60°C using a Cu²⁺/HSO redox initiator system with different concentrations of Cu²⁺. The experimental results showed that the monomer conversion reached above 90% for all systems. Zeta potential was all negative due to the bonded bisulfite ion and the magnitude was greater than 30 mV, providing the stability of PMMA emulsion. The morphology of the latex observed by scanning electron microscope revealed a uniform particle size, and the average particle size increased from 181.9 to 234.2 nm as the Cu²⁺ ion concentration increased from 2.0 to 6.0 mM in 1M of MMA solution. Thermal degradation behavior of synthesized PMMA was studied by thermogravimetric analysis, in which a two‐stage degradation behavior was observed. These two stages were found to be caused by the degradation of unsaturated end group (PMMA? CR?CH₂) and saturated end group (PMMA? H), respectively. In addition, the higher the concentration of Cu²⁺ ion, the greater the proportion of PMMA? CR?CH₂ in the final product, and in turn rendering more weight loss in the first‐stage degradation. The copper ion not only played a role in the redox initiation, but also acted as a chain transfer agent to terminate growing polymer chains, thus producing PMMA? CR?CH₂. The apparent activation energies of the first stage (E_a1) and second stage (E_a2) were calculated by Ozawa's and Boswell's method. The results showed that E_a1, representing the degradation of PMMA‐CR?CH₂, was lower than E_a2 for the degradation of PMMA‐H. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

引发剂用量对改性C5石油树脂性能的影响

以马来酸酐为改性剂、过氧化二异丙苯为引发剂对C5石油树脂进行改性。考察引发剂用量对C5石油树脂软化点、外观和状态的影响。结果表明,当[m（马来酸酐）/m（C5石油树脂）]为0.09时,m（引发剂）/m（C石油树脂）为0.10时为宜。     

聚丙烯酸/黏土复合高吸水性树脂的合成及性能

以黏土、丙烯酸为原料,Al2O3为交联剂,Na2S2O8-Na2SO3为氧化还原引发剂,用水溶液聚合法合成了聚丙烯酸/黏土复合高吸水性树脂。考察了盐酸浓度、丙烯酸中和度、黏土用量、Al2O3用量和Na2S2O8-Na2SO3用量对复合高吸水性树脂吸水能力的影响;并考察了盐水温度和不同浓度盐溶液对复合高吸水性树脂吸盐水率和吸水倍率的影响。较佳的合成条件:c(盐酸)=6mol/L、丙烯酸中和度60%、黏土的质量分数5.6%(占体系的总质量)、交联剂Al2O3的质量分数0.35%～0.40%(占体系的总质量)、Na2S2O8-Na2SO3的质量分数1.00%(占体系的总质量)。在此条件下合成的复合高吸水性树脂对去离子水和质量分数为0.9%的NaCl溶液的最大吸水倍率和吸盐水率分别为1300,96g/g。     

丙烯酰胺水溶液聚合的几种氧化还原引发体系的研究

对丙烯酰胺水溶液聚合的 4种重要氧化还原引发体系进行了研究。从引发机理出发 ,通过实验探讨了引发剂种类、引发剂浓度对聚丙烯酰胺分子量的影响     

基于广义线性模型的火工品可靠性数据分析

为提高小样本量下火工品可靠性分析的精度,依据火工品感度试验与可靠性分析的特点,提出了一种基于广义线性模型的火工品可靠性分析方法。该方法通过函数变换,将样本似然函数转换为二项分布变量的广义线性表达式,由此,得到感度分布参数的极大似然估计及其相应算法,再根据极大似然估计的渐近正态性,对可靠度函数进行了logit变换,给出了火工品可靠度置信下限。通过某针刺雷管(γ=0.95,R≥0.999)和电雷管(γ=0.95,R≥0.9999)对该方法进行了实验验证,并与大样本试验数据分析结果进行对比,结果表明该方法合理可行,可利用约150个样本对可靠性要求为0.999以上的火工品进行有效评价。     

引发剂对瞬时聚合丙烯酸酯浆料性能的影响

介绍了采用瞬时聚合法合成固体丙烯酸酯浆料的过程,对引发体系及其用量对反应产物的水溶性、水溶液黏度及对涤棉粗纱黏附力等的影响进行了研究,并用红外光谱对产物进行了表征.     

Effect of different initiators on temperature-sensitive monolithic columns and application in online enrichment of β-sitosterol

Three temperature-sensitive monolithic columns were prepared by atom transfer radical polymerization and oxidation–reduction method using the initiator systems of CCl₄/FeCl₂, BPO/DMA, and APS/TEMED, respectively. The three monoliths were characterized by scanning electron microscopy, nitrogen adsorption, and thermogravimetric analysis. The obtained monolithic columns were used as on-line solid phase extraction sorbent coupled with high-performance liquid chromatography for the enrichment of β-sitosterol. By comparing some influencing factors on the adsorption, the optimum temperature-sensitive monolithic column which was initiated by CCl₄/FeCl₂ was selected for enrichment of β-sitosterol from plant oil. The maximum adsorption capacity of the monolith for β-sitosterol was 10.0031 mg/g. The limit of detection and limit of quantitation were 0.039 and 0.13 mg/mL, respectively. The recovery was in the range of 90.21–98.26%. The results showed that the monolith had better selectivity for β-sitosterol and could be used for enrichment of β-sitosterol in food samples. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47683.     

高固体份丙烯酸树脂配方设计的探讨

从配方设计角度着重描述了在高固体份丙烯酸树脂制造过程中的主要影响因素,如聚合物的玻璃化温度,引发剂浓度,体系温度和酸值等等。     

超声波本体聚合在甲基丙烯酸甲酯-Al2O3陶瓷膜注凝成型中的应用研究

通过探讨水浴加热预聚合、微波恒温预聚合、微波预聚合及超声预聚合反应方式对甲基丙烯酸甲酯(MMA)进行预聚合反应,来确定适合作为Al2O3陶瓷膜注凝成型工艺中的预混液制备方式。结果表明:超声的空化作用能够有效地加快预聚合的反应速率,且在预聚合反应过程中,超声波的机械振动作用使MMA反应均匀,且不会发生局部爆聚现象。适合作为MMA预聚合的引发剂为偶氮二异丁腈(AIBN),其最佳用量为0.08%。发现微波的"致热效应"是MMA聚合速率加快的原因。