聚六亚甲基碳酸酯聚氨酯脲的体外老化试验

研究了本实验室合成的聚六亚甲基碳酸酯聚氨酯脲(PCUU)的耐水解和耐氧化性能,并与Pellethane(Pe)和Chronoflex(Chro)对照。结果表明,浸热水后PCUU和Chro比Pe有更高的拉伸强度保持率。氧化后PCUU和Chro与Pe相比,有更小的软段氧化程度,更小的Tg值变化,较小的水接触角下降,更高的拉伸强度保持率,更小的特性粘度降低,更小的表面裂纹和破坏程度,由此证明,PCUU和Chro比Pe有更好的耐水解性和耐氧化性。     

干燥方法对白鲢鱼片质量的影响

比较热风干燥、微波干燥、微波真空干燥对鱼片干燥的影响。以硫代巴比妥酸值评价脂肪氧化程度,并进行感官评价。热风干燥鱼片烤肉味最浓,但脂肪氧化也很严重;微波干燥时,功率越高,干燥速度越快,脂肪氧化越轻;微波真空干燥时,真空度越高,干燥速度越快,但脂肪氧化也越重。综合来看,微波干燥是鲢鱼片最佳的干燥方法,干燥时间短,脂肪氧化轻。     

桃仁多肽的酶法制备及其抗氧化活性分析

以桃仁蛋白为原料,对响应面法优化多肽制备条件和酶解多肽各组分的抗氧化活性进行了研究。结果表明:以底物浓度3.5%、pH 10.4、加酶量4 200 U/g、酶解时间4.9 h条件下进行碱性蛋白酶酶解,可获得桃仁蛋白的最高水解度(61.12±0.7)%和多肽得率(67.91±0.5)%。桃仁蛋白及其酶解物的SDS-PAGE凝胶电泳图表明,酶解后的多肽分子质量大部分小于12 000 u。酶解液(PPH)及其超滤分离所得4组分分别采用DPPH自由基清除能力、ABTS自由基清除能力、亚硝酸根离子清除能力和总抗氧化能力4个体外抗氧化活性测试,结果显示不同分子质量组分间的抗氧化活性存在显著性差异(P0.05),分子质量越小,其抗氧活性越强。RP-HPLC分析表明,抗氧化活性最强的P-IV组主要由9种具有一定疏水性的多肽组成。     

Effective preparation and characterization of montmorillonite/poly(ε‐caprolactone)‐based polyurethane nanocomposites

In this study, montmorillonite (MMT)/poly(?‐caprolactone)‐based polyurethane cationomer (MMT/PCL‐PUC) nanocomposites were prepared and their mechanical properties, thermal stability, and biodegradability were investigated. PCL‐PUC has 3 mol % of quaternary ammonium groups in the main chain. The MMT was successfully exfoliated and well dispersed in the PCL‐PUC matrix for up to 7 wt % of MMT. The 3 mol % of quaternary ammonium groups facilitated exfoliation of MMT. The 1 wt % MMT/PCL‐PUC nanocomposites showed enhanced tensile properties relative to the pure PCL‐PU. As the MMT content increased in the MMT/PCL‐PUC nanocomposites, the degree of microphase separation of PCL‐PUC decreased because of the strong interactions between the PCL‐PUC chains and the exfoliated MMT layers. This resulted in an increase in the Young's modulus and a decrease in the elongation at break and maximum stress of the MMT/PCL‐PUC nanocomposites. Biodegradability of the MMT/PCL‐PUC nanocomposites was dramatically increased with increasing content of MMT, likely because of the less phase‐separated morphology of MMT/PCL‐PUC. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

皮革后整理加工废水处理

针对皮革后整理加工废水有机浓度高、可生化性的差特点,经小试后确定采用混凝沉淀-水解酸化-生物接触氧化-流离生化法处理工艺。实践表明,对于难生化处理的有机废水,该工艺设计合理,运行稳定,启动容易,运行费用低,抗冲击的负荷能力强,废水经处理后能达到《污水综合处理排放标准》GB8978-1996一级排放标准。     

清香型大曲淀粉水解酶系解析

对清香型大曲中可能存在的淀粉代谢相关酶类及各自催化作用进行全面分析,并从Brenda数据库中搜索酿酒相关的淀粉水解酶,了解不同来源淀粉水解酶类的酶学特征,并从基因组角度分析酿酒微生物合成的淀粉代谢酶类,对酿酒微生物有更深入的认识,为选育理想的酿酒微生物提供理论依据。     

金属离子配合物的水解作用研究进展

金属离子配合物的水解作用正受到越来越多人的关注。相对于酶和化学试剂的水解作用,金属离子配合物的水解具有条件温和、易于实现和成本低廉的优点。综述了金属离子同环糊精、碳氮杂环、多聚糖和高分子支持物形成的配合物对肽键和磷酸键的水解作用的最新研究进展。     

Degradation of crosslinked poly(ester‐urethanes) elastomers in distilled water: Influence of hard segment

Polyurethane elastomers are frequently used in wet conditions. Crosslinked polyurethanes based on poly(ethylene adipate) diol, 4,4′‐diphenylmethane diisocyanate, 1,6 hexane diisocyanate—with different hard‐segment compositions but with the same molecular weight soft segment—were degraded in distilled water at 37°C, in a specific environment; in the dark without exposure to enzymatic conditions and under the continuous circulation of water. The incubation of polymer samples took place over a period of maximum 30 days. The degradation process was evaluated by the changes in mechanical properties and surface relief observed by optical microscopy. The changes in hydrogen bonding were collected through attenuated total reflectance infrared (ATR‐FTIR) spectroscopy which indicated that aliphatic diisocyanates allow for a better formation of hydrogen bonds. The mechanical properties of the degraded films show that the crosslinked polyurethanes containing aromatic diisocyanate suffer a decrease in tensile strength between 33 and 56% depending on the chain extender and hard segment content. The hydrolytic degradation behavior of crosslinked polyurethanes was found to be dependent on the diisocyanate and chain extender structure, as well as on the hard segment content and chemical crosslinks. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

铝锶比对合成铝酸锶铕发光性能及水解稳定性的影响

合成铝酸锶铕绿色荧光粉时,当改变Al/Sr加料比时,产物的物相组成、发光特性和抗水稳定性均有变化。合成产物主要由两相组成,当Al/Sr比为1.5时,合成产物的主晶相为Sr4Al4O2(Al10O23),同时SrAl2O4相的含量也较高。由于SrAl2O4相易于水解,所以其抗水稳定性差。提高Al/Sr比,抗水稳定性逐渐增强。