Thermal decomposition behavior of γ‐irradiated poly(vinyl acetate)/poly(methyl methacrylate) miscible blends

Miscible polymer blends based on various ratios of poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) were prepared in film form by the solution casting technique using benzene as a common solvent. The thermal decomposition behavior of these blends and their individual homopolymers before and after γ‐irradiation at various doses (50–250 kGy) was investigated. The thermogravimetric analysis technique was utilized to determine the temperatures at which the maximum value of the rate of reaction (T_max) occurs and the kinetic parameters of the thermal decomposition. The rate of reaction curves of the individual homopolymers or their blends before or after γ‐ irradiation displayed similar trends in which the T_max corresponding to all polymers was found to exist in the same position but with different values. These findings and the visual observations of the blend solutions and the transparency of the films gave support to the complete miscibility of these blends. Three transitions were observed along the reaction rate versus temperature curves; the first was around 100–200°C with no defined T_max, which may arise from the evaporation of the solvent. The second T_max was in the 340–380°C range, which depended on the polymer blend and the γ‐irradiation condition. A third transition was seen in the rate of reaction curves only for pure PVAc and its blends with PMMA with ratios up to 50%, regardless of γ‐ irradiation. We concluded that γ‐irradiation improved the thermal stability of PVAc/PMMA blends, even though the PMMA polymer was degradable by γ irradiation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1773–1780, 2006     

PE-LLD／EVA／Mg（OH）2／复合阻燃剂高效无卤阻燃体系的研究

采用线形低密度聚乙烯/乙烯-醋酸乙烯共聚物作为复合材料主体,表面处理过的氢氧化镁(Mg(OH)2)为主阻燃剂,以微胶囊化红磷和自制硅类阻燃剂为核心的复合阻燃剂为阻燃增效剂,重点探讨了Mg(OH)2和复合阻燃剂的阻燃效果。结果表明,Mg(OH)2与复合阻燃剂并用具有良好的协同效应,当Mg(OH)2用量40份,复合阻燃剂5～7份时,可获得较高的氧指数,垂直燃烧试验通过FV0级,且材料抗静电能力提高,力学性能、加工性能较好。     

001×7(732)阳离子交换树脂催化醋酸甲酯水解反应过程模拟与优化

在充分搅拌和可忽略粒度影响条件下,测定了间歇搅拌反应釜中001×7(732)阳离子交换树脂催化醋酸甲酯水解反应动力学数据,建立了其拟均相与非均相反应动力学模型,进行了模型筛选和参数估值.结果表明,醋酸甲酯与水均吸附,表面反应为控制步骤的非均相反应动力学模型能较好地拟合实验数据,并满足统计检验.根据优选的反应动力学模型,对醋酸甲酯水解过程进行了模拟计算,考察了反应温度、树脂浓度、水酯摩尔比对水解过程的影响,得到的优化反应条件为:反应温度55℃、树脂浓度260 g·L-1、水酯摩尔比1.5∶1.此时反应90 min接近醋酸甲酯平衡水解率34.8%.     

Structural significance of the alkyl substituent at the C-4 of (+)-trans-verbenyl acetate in sex pheromonal activity of the American cockroach

The significance of the alkyl group at the C-4 of (+)-trans-verbenyl acetate, which is the sex pheromone mimic of the American cockroach, was investigated. Seven alcohols possessing an ethyl, propyl, or dimethyl group at this position of the 6,6-dimethylbicyclo[3.1.1]heptane skeleton were synthesized and evaluated by behavioral assay. All of the alcohols were inactive, while three of four acetates of the 2-alcohols induced sexual behavior in male cockroaches at the 0.02 or 0.5 mg dosage level, either of which is many orders of magnitude higher than the threshold level of the natural sex pheromones (10^–8 mg). Among the acetates, the compounds with a methyl group or an -oriented ethyl group at C-4 showed the highest activity. The results are discussed in terms of spatial requirements of the molecules for interactions with the receptor.Studies on the sex pheromone mimic of the American cockroach, (+)-trans-verbenyl acetate. Part VIII. For Part VII, seeComp. Biochem. Physiol.,70A: 229–234 (1981).     

乙酸甲酯水解工艺设计

在分析目前国内乙酸甲酯水解工艺的基础上,提出采用福州大学催化精馏水解技术代替传统的固定床水解反应器进行水解的新工艺。着重从工程设计方面对其工艺过程进行探讨。     

Design and control of reactive distillation for ethyl and isopropyl acetates production with azeotropic feeds

Reactive distillations for the production of ethyl acetate (EtAc) and isopropyl acetate (IPAc) are classified as the type-II process where the first column consists of a reactive zone and a rectifying section followed by a stripper [Tang et al., 2005. Design of reactive distillations for acetic acid esterification with different alcohols. A.I.Ch.E. Journal 51, 1683-1699]. Instead of using pure alcohols and acetic acid as reactants, this paper studies the effects of reactant purity on the design and control of reactive distillation. This offers significant economical incentives (by reducing raw materials costs), because ethanol forms an azeotrope with water at 90 mol% and isopropanol/water has an azeotrope at 68%. The purities of the acid is set to 95% for acetic acid (industrial grade), 87% for ethanol, and 65% for isopropanol. The results show that the total annual costs (TAC) increase by a factor of 5% for EtAc and 8% for IPAc production using reactive distillation. Next, the operability of the reactive distillations with azeotrope feeds is explored. Three disturbances, feed flow, acid feed purity, and alcohol feed composition, are introduced to assess control performance using dual-temperature control and one-temperature-one-composition control. Simulation results indicate good control performance can be achieved for reactive distillation with azeotropic feeds.     

聚醋酸乙烯酯树脂聚合度的快捷检测方法

通过实验得出不同聚合度、不同质量分数下的黏度数据，并作出平均聚合度-质量分数-黏度三者的关系曲线。在此基础上，提出通过检测聚醋酸乙烯酯树脂的质量分数和黏度，直接查出对应的聚合度的快速检测方法。     

醋酸乙烯-丙烯酸无皂乳液共聚的研究

以醋酸乙烯(VAc)为主单体,丙烯酸(AA)为改性功能单体,以半连续加料方式进行无皂乳液共聚过程,得到了稳定且固含量为30%左右的乳液。探讨了功能单体AA含量、反应温度等对共聚的影响。采用FT-IR、粒径分析等方法对共聚物的组成、乳胶粒子的尺寸及分布进行了分析表征。结果表明:在(65±2)℃下聚合,所得乳液稳定性好、转化率高、反应完全,且随着功能单体AA含量的增加,乳液黏度上升、单体转化率下降、乳胶粒粒径变小且粒径呈单分散性。     

无苯溶剂型三元共聚丙烯酸酯类压敏胶的研制

以丙烯酸丁酯(BA)、醋酸乙烯(VAc)、丙烯酸(AA)为原料,乙酸乙酯为溶剂,过氧化苯甲酰为引发剂对三元共聚丙烯酸酯类压敏胶进行了研究,考察了引发剂的用量与加入方式、单体配比、AA用量、反应温度和反应时间对压敏胶性能的影响;得出了最佳的工艺条件为,引发剂采取分批加入方式、用量为0．45％,AA用量4．3％,V(BA)／V(VAc)为60:9,反应温度84℃,反应时间为8 h;制得了初粘力14(球号)、持粘力>24 h、180°剥离强度达15．33 N·(25mm)-1的具有优良综合性能的压敏胶。     

聚醋酸乙烯酯共聚乳液的改性研究

以醋酸乙烯酯为原料,聚乙烯醇为保护胶体,丙烯酸、丙烯酸丁酯为改性单体,研究了单体配比、引发剂、乳化剂用量和温度对醋酸乙烯酯共聚乳液性能的影响。研究表明,当丙烯酸丁酯与醋酸乙烯酯的质量比为12/30,引发剂的质量分数为0.15%,乳化剂的质量分数为0.3%,在反应温度为75℃时,可制得性能优异的聚醋酸乙烯酯胶粘剂,其T型剥离强度和耐水性能可达105 N/25mm和67 N/25mm。