氨基二氧化硅固定化纤维素酶及其特性

以氨基化二氧化硅为载体, 戊二醛为交联剂, 采用共价交联法制备固定化纤维素酶, 最佳条件为交联剂浓度4% (体积比), 交联时间60分钟, 给酶量35 U/g载体, 固定化反应时间5小时。所得固定化酶对pH和温度的敏感性降低, 时间稳定性和热稳定性均优于游离酶。热动力学研究表明, 固定酶的失活活化能(Ed)、失活焓(ΔH^*)和失活自由能(ΔG^*)均高于自由酶, 固定化减小酶失活反应速率, 降低酶失活反应趋势。     

一种新型类肝素吸附剂的试制

研究了交联壳聚糖磺化衍生物的制备方法。以壳聚糖为原料，戊二醛为交联剂，并预先采用一定的活化，造粒方法，先制成一种具有一定反应活性的壳聚糖凝胶珠。再以甲酰胺－氯磺酸为磺化剂，在０－７０℃的反应条件下，制得了一种在稀酸，碱以及水中都较稳定的磺化壳聚糖吸附树脂。     

硼交联水基冻胶压裂液的研究发展现状

综述了硼交联水基冻胶压裂液的国内外研究发展现状．着重介绍了国外应用核磁共振（ＮＭＲ）能谱技术研究硼交联机理得出的结论、有机硼配合物交联剂的延迟交联机理和优异性能、硼交联压裂液的粘弹性和测定方法以及破胶剂的最新发展成果—胶囊破胶技术．指出了硼交联水基冻胶压裂液的几个重要研究和发展方向     

超氧阴离子自由基(O_2~-)导致红细胞膜蛋白交联作用的机理探讨

用邻苯三酚在碱性条件下自氧化产生的超氧阴离子自由基(O_2_~-)处理人红细胞膜导致膜蛋白交联形成高分子聚合物(HMP)。用一定量的超氧化物歧化酶(SOD)预处理红细胞膜,HMP明显减少。用巯基抑制剂N-乙基马来酰胺(NEM)预处理红细胞膜,则HMP几乎消失。用特异性标记巯基的荧光探针N-(3-芘)马来酰胺(N-[3-P]NEM)来研究经不同浓度邻苯三酚处理的红细胞膜的荧光强度。结果表明,随着邻苯三酚浓度增高,荧光强度相应降低。上述结果提示,O_2~-可能主要是通过氧化巯基导致膜蛋白交联并形成HMP。     

自乳化水性聚氨酯涂层剂的自交联行为

本文采用聚醚二醇—异氰酸酯预聚体与二乙烯三胺,环氧氯丙烷伸链的方法,制备稳定的自交联自乳化聚氯酯水分散液。运用定量分析法对预聚反应进行了动力学研究,得到甲苯二异氰酸酯与聚醚二醇的预聚反应为假一级反应的结论。运用近代物理及化学测试方法详细研讨了大分子结构与聚氨酯性能的关系。潜在自交联剂的含量对聚氨酯涂层剂的性能如水分散液稳定性、动态粘弹性和力学性能都有较大的影响,并且发现潜在自交联剂含量的最佳值应为:环氧氯丙烷与二乙烯三胺的摩尔比为1:2.此外,本文还详细探讨了聚醚二醇中环氧乙烷的含量与聚氨酯薄膜性能的关系。在合成聚氨酯涂层剂的基础上,还进行了涂层的应用及其性能的测试。     

Nonlinear conductive properties and scaling behavior of conductive particle filled high-density polyethylene composites

The blends prepared by incorporation of carbon black (CB) or graphite powder (GP) into high-density polyethylene (HDPE) matrix have been novel and extensively applied polymeric positive temperature coefficient (PTC) composites. A phenomenological model was proposed on the basis of the GEM equation and the dilution effect of filler volume fraction due to the thermal volume expansion of the polymer matrix. Accordingly, the contribution of the thermal expansion of the matrix to the jump-like PTC transition of the composites was quantitatively estimated and a mechanical explanation was given. It was proved that the contribution of the volume expansion to PTC effect decreased for HDPE/CB composites crosslinked through electron-beam irradiation. Furthermore, the influences of the filler content, temperature and crosslinking on the self-heating behavior as well as the nonlinear conduction characteristics at electrical-thermal equilibrium state were examined. Based on the electric-field and initial resistivity dependence of the self-heating temperature and resistance dependence of the critical field, the mechanisms of the self-heating of the polymeric PTC materials were evaluated. The intrinsic relations between macroscopic electrical properties and microscopic percolation network at electrical-thermal equilibrium state were discussed according to the scaling relationship between the self-heating critical parameter and the conductivity of materials.     

乙烯-乙烯醇共聚纤维的戊二醛交联改性

通过对戊二醛的用量、交联反应时间和交联温度对乙烯－乙烯醇共聚纤维的耐熨性和染色性的影响的研究，认为用戊二醛改性能有效地提高纤维的耐熨温度和降低染色温度，测定了交联改性纤维的力学性能，声速取向，溶胀度，热性能，证实耐熨烫性的提高是表层交联的结果，染色性的改进是内部结构的破坏所造成的。     

田菁胶无粘土冲洗液的交联反应机理

作者近年研制并推广使用了一种新型无粘土钻井液——田菁胶无粘土冲洗液。本文运用红外光谱分析及电子显微镜等现代化测试技术和分析手段,分析探讨了田菁胶的交联反应机理,并导出了田菁胶与高价金属离子的交联反应式。     

交联和羟丙基改性对玉米淀粉糊稳定性的影响

采用Brabender连续黏度测定仪,系统研究了三偏磷酸钠交联、环氧丙烷羟丙基化以及羟丙基、交联复合改性对玉米淀粉糊稳定性的影响.结果表明:玉米淀粉经交联改性后,起糊温度下降,糊的黏度稳定性得到改善,但冻融稳定性变化不明显;羟丙基改性降低了玉米淀粉的起糊温度,改善了淀粉的冻融稳定性,但黏度稳定性变化不大;采用羟丙基和交联复合改性能显著提高淀粉糊的黏度稳定性和冻融稳定性,其中,先交联后羟丙基改性对淀粉糊的稳定性改善更为明显.     

Quasi-solid state dye-sensitized solar cells based on pyridine or imidazole containing copolymer chemically crosslinked gel electrolytes

Quasi-solid state dye-sensitized solar cells based on chemically crosslinking with backbone polymers of poly(vinylpyridine-co-acrylonitrile) (P(VP-co-AN)) or poly(vinylimidazole-co-acrylonitrile) (P(VIM-co- AN)) and diiodide compounds of I(CH2)6I or I(CH2CH2O)nCH2CH2I solidified EC/PC/KI/I2 gel electrolytes have been fabricated. The ionic conductivities and apparent diffusion coefficients of I3? of the electro- lytes and cell performances have been investigated. Providing chemically crosslinking points, pyridine or imidazole from the backbone polymers benefited the open circuit voltage and fill factor of the cells. Consequently, the overall energy conversion efficiencies of the quasi-solid DSSCs improved over 10% even near 20% from that of the liquid electrolyte before solidification. Besides, the employing of crosslinker I(CH2CH2O)nCH2CH2I showed higher electrolytic and cell characters than that of I(CH2)6I.