甲醇对脱醇型RTV-1硅橡胶性能的影响

通过添加无水甲醇模拟脱醇型单组分室温硫化(RTV-1)硅橡胶生产过程中产生的甲醇,研究了甲醇对脱醇型RTV-1硅橡胶性能的影响。结果表明:在配制脱醇型RTV-1硅橡胶时,甲醇的加入对密封胶力学和粘接性能无影响,但会影响部分施工性能。经70℃加速贮存5天后(相当于室温放置6个月),甲醇的存在会导致表干时间延长,力学强度和粘接性能均有一定幅度的下降;当甲醇质量分数为1%时,脱醇型RTV-1硅橡胶不硫化;若控制配制时甲醇的残留质量分数低于0.25%,则在加速贮存后,脱醇型RTV-1硅橡胶的施工性能略有下降,力学性能与粘接性能保持率达到80%以上。     

MP/OMMT对脱醇型RTV阻燃硅橡胶性能的影响

以α,ω-二羟基聚二甲基硅氧烷(107硅橡胶)、甲基三乙氧基硅烷、三聚氰胺磷酸盐(MP)和纳米有机蒙脱土(OMMT)为原料,制备了脱醇型室温硫化(RTV)阻燃硅橡胶。研究了MP/OMMT配比对脱醇型RTV硅橡胶阻燃性能、动态燃烧性能和机械性能、热稳定性的影响,用扫描电镜(SEM)考察了MP、OMMT在RTV硅橡胶中的分散情况。锥形量热仪和极限氧指数测试结果表明,随着OMMT用量的增多和MP用量的减少,硅橡胶的阻燃性能没有显著的变化;热失重分析表明,OMMT的添加使硅橡胶的初始分解温度明显提高,大大提高了硅橡胶燃烧残渣的生成量;机械性能测试表明,OMMT的增多能明显提高硅橡胶的机械性能。与只添加MP的硅橡胶相比,当MP和OMMT各添加20份时,硅橡胶的极限氧指数下降0.6%,初始分解温度提高了95℃,拉伸强度、硬度、撕裂强度分别提高48.6%、4.7%、50.9%;此时的SEM分析表明,OMMT能在硅橡胶中均匀分散,且燃烧残渣表面变得平整、坚硬、致密。即在此配比下硅橡胶能在保持良好阻燃性的同时提高其机械性能。     

单组分脱醇型密封胶的研制

以端羟基聚二甲基硅氧烷(107硅橡胶)为基胶、甲基三甲氧基硅烷和乙烯基三甲氧基硅烷为交联剂、纳米碳酸钙和气相法白炭黑为补强填料、硅烷偶联剂为增粘剂,有机钛为催化剂,制得单组分脱醇型室温硫化(RTV-1)硅橡胶。研究了基胶黏度,填料、交联剂、增粘剂的种类和用量对脱醇型RTV-1硅橡胶性能的影响。较佳配方为:100份黏度50 000 mm2/s的107硅橡胶、5份甲基三甲氧基硅烷与乙烯基三甲氧基硅烷按质量比7∶3复配的交联剂、0.4～0.6份自制氨基硅烷偶联剂。按此配方制得的RTV-1硅橡胶的性能较好。     

Antimicrobial Effects of Wine: Separating the Role of Polyphenols,pH, Ethanol,and Other Wine Components

Abstract: While the antimicrobial effectiveness of wine is well documented, relative contributions of the wine components to its antimicrobial activity is controversial. To separate the role of wine phenolics, ethanol, and pH from other wine constituents, the antimicrobial effects of intact wine were compared to that of phenols-stripped wine, dealcoholized wine, ethanol, and low pH applied separately and in combination, against 2 common foodborne pathogens, Salmonella enterica serovar Enteritidis and Escherichia coli. All samples were biochemically characterized with respect to their total phenolics and resveratrol content, antioxidant capacity, ethanol content, and pH. Antioxidative activity of the samples corresponded to their total phenolics content. Except for respective controls, pH and ethanol content were similar in all samples. The order of antibacterial activity of the samples was: intact wine > phenols-stripped wine > dealcoholized wine > combination of ethanol and low pH > low pH > ethanol. Separate application of ethanol or low pH showed negligible antibacterial activity while their combination showed synergistic effect. Antibacterial activity of the samples could not be related to their total phenolics and resveratrol content, antioxidant capacity, ethanol content, or pH. Our study indicates that antimicrobial activity of complex solutions such as intact wine cannot be exclusively attributed to its phenolic or nonphenolic constituents, nor can the antimicrobial activity of wine be predicted on the basis of its particular components.     

室温快干脱醇型硅橡胶的制备

以烷氧基封端聚二甲基硅氧烷(PDMS)为基础聚合物制得室温快干脱醇型硅橡胶,研究了不同类型的烷氧基封端PDMS、白炭黑种类和用量、交联剂用量、偶联剂和催化剂种类对室温快干脱醇型硅橡胶性能的影响。结果表明,以乙烯基二甲氧基PDMS为基础聚合物制备的脱醇型硅橡胶稳定性最好;白炭黑用量是影响硅橡胶性能的主要因素,其种类对硅橡胶性能影响不大;当交联剂三甲氧基硅烷用量为3份时,硅橡胶的力学性能最好;采用γ-氨丙基三乙氧基硅烷或N-(β-氨乙基)-γ-氨丙基三甲氧基硅烷作偶联剂时,硅橡胶的剪切强度较佳;采用自制有机锡配合液作催化剂,硅橡胶的贮存稳定性较优。     

Control of Native Spoilage Yeast on Dealcoholized Red Wine by Preservatives Alone and in Binary Mixtures

In order to preserve a commercial dealcoholized red wine (DRW), a study with 4 preservatives and binary mixtures of them were performed against 2 native spoilage yeasts: Rhodotorula mucilaginosa and Saccharomyces cerevisiae. Minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) for potassium sorbate, sodium benzoate, sodium metabisulfite and dimethyl dicarbonate (DMDC) were evaluated in DRW stored at 25 °C. MICs of potassium sorbate and sodium metabisulfite were 250 and 60 mg/kg, respectively for both target strains. However for sodium benzoate, differences between yeasts were found; R. mucilaginosa was inhibited at 125 mg/kg, while S. cerevisiae at 250 mg/kg. Regarding MFC, differences between strains were only found for sodium metabisulfite obtaining a MFC of 500 mg/kg for R. mucilaginosa and a MFC of 250 mg/kg for S. cerevisiae. Potassium sorbate and sodium benzoate showed the MFC at 1000 mg/kg and DMDC at 200 mg/kg. Regarding the effect of binary mixtures the Fractional Fungicidal Concentration Index (FFC_i) methodology showed that binary mixtures of 100 mg/kg DMDC/200 mg/kg potassium sorbate (FFC_i = 0.7) and 50 mg/kg DMDC / 400 mg/kg sodium benzoate (FFC_i = 0.65) have both synergistic effect against the 2 target strains. These binary mixtures can control the growth of spoilage yeasts in DRW without metabisulfite addition. The results of this work may be important in preserving the health of DRW consumers by eliminating the use of metabisulfite and reducing the risk of growth of R. mucilagosa, recently recognized as an emerging pathogen.     

双组分脱醇型有机硅密封胶的研制

研制了车灯用双组分脱醇型有机硅密封胶,讨论了交联剂和偶联剂对密封胶性能的影响。结果表明选用四官能的交联剂有助于提高硅橡胶的力学性能。采用不同的偶联剂进行搭配可获得对PC、PVC、ABS、PA、玻璃和铝等多种材质的优异粘接性能。     

脱醇型单组分室温硫化硅橡胶

本文介绍了脱醇型ＲＴＶ硅橡胶的研制及其应用     

脱醇型室温硫化硅橡胶的粘接性能研究

以α,ω-二羟基聚二甲基硅氧烷(107硅橡胶)为基胶,纳米碳酸钙为填料,添加硅烷偶联剂等制得脱醇型单组分室温硫化硅橡胶.研究了纳米碳酸钙、硅烷偶联剂种类和基胶黏度对硅橡胶粘接性能的影响.结果表明,随着纳米碳酸钙平均粒径由60 nm减小到30 nm,硅橡胶的拉伸强度从1.30 MPa上升至1.45 MPa,拉断伸长率从7...