Study of the effect of BDMA catalyst in the epoxy novolac curing process by isothermal DSC

Epoxy novolac/anhydride cure kinetics has been studied by differential scanning calorimetry under isothermal conditions. The system used in this study was an epoxy novolac resin (DEN431), with nadic methyl anhydride as hardener and benzyldimethylamine as accelerator. Kinetic parameters including the reaction order, activation energy and kinetic rate constants, were investigated. The cure reaction was described with the catalyst concentration, and a normalized kinetic model developed for it. It is shown that the cure reaction is dependent on the cure temperature and catalyst concentration, and that it proceeds through an autocatalytic kinetic mechanism. The curing kinetic constants and the cure activation energies were obtained using the Arrhenius kinetic model. A suggested kinetic model with a diffusion term was successfully used to describe and predict the cure kinetics of epoxy novolac resin compositions as a function of the catalyst content and temperature. Copyright © 2003 Society of Chemical Industry     

曙光油田超稠油井套管损坏的机理和防治

超稠油特殊的油藏特点决定了其生产周期短、注汽频繁、出砂、汽窜、超覆现象严重，以及套管质量等因素的影响，套管损坏较为严重。对曙光油田超稠油井套管损坏的规律和机理进行了研究，并从钻井和完井工艺的完善、套管钢级和射孔工艺的选择、采油生产参数的确定、注汽管柱隔热效果的提高、防治砂工艺等方面，对套管损坏提出了预防措施和对策。并对套管损坏井制定了修复再利用方案。     

Cure reaction for modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide

The glass‐transition temperature as a function of curing conversion for a modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide (BMI) resin was investigated at different temperature regimes and modeled using a modified Di Benedetto equation. Although the relationship between the glass‐transition temperature and conversion of the BMI system conforms to the Di Benedetto equation for α < 0.6 and at lower cure temperatures, at higher cure temperatures the results deviated significantly from the equation; thus, it was an inadequate model for the system. Fourier transform IR analysis showed that the major crosslinking reactions did not occur during cure for the modified BMI at and below 150°C. However, as the cure temperature was increased, the crosslinking reactions responsible for 3‐dimensional network structures became more dominant. At 190°C the C? N? C_stretch vibration of the uncured maleimide ring converted into succinimide rings in the curing process. Simultaneously, a decrease was observed for the absorbance bands of ? C? H_bending (maleimide). The higher cure temperatures induced a significantly faster initial crosslinking rate and also resulted in a shorter period of time after which further crosslinking was retarded, because the increase in the crosslinks also physically slowed further crosslinking activity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 227–235, 2002     

水对植物纤维水泥复合板生产的影响

研究了水对植物纤维水泥复合板性能的影响。选择合适的水分可以提高板材静弯曲强度,减小板材变形。     

快固化淀粉粘合剂的研究

介绍了快固化玉米淀粉粘合剂的制备工艺,对制备参数进行了优化,可使粘合剂的初粘速度和干燥速度显著提高。     

Long-term weathering behavior of UV-curable clearcoats: Depth profiling of photooxidation,UVA, and HALS distributions

The long-term weathering performance of two UV-curable clearcoat systems was studied using in-plane microtomy in combination with infrared spectroscopy, UV spectroscopy, and ESR spectroscopy. Oxygen transport characteristics were also studied using the half-time method. The photooxidation versus depth profile was highly dependant on the presence of hindered amine light stabilizers (HALS) for both coating systems. Ultraviolet light absorbers (UVA) had little effect on the photooxidation profile. A photooxidation gradient was formed in both clearcoats due to a reduction in oxygen solubility when compared to standard thermoset clearcoats. This gradient was only seen in formulations not containing HALS. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

不同促进剂对NR平衡硫化体系的影响

研究了促进剂的种类，促进剂并用及硫化温度等条件对平衡硫化体系（ＥＣ）硫化天然橡胶（ＮＲ）的影响。结果表明，噻唑类促进剂具有较低的硫化返原率，尤其是促进剂ＤＭ，在１３０～１７０℃的硫化温度范围内，硫化２小时的硫化返原率均为０；当促进剂ＮＯＢＳ或ＣＺ与ＤＭ并用时，可缩短正硫化时间；当ＤＭ摩尔分数分别为４０％和５０％左右时，不仅使硫化２小时的硫化返原率为０，而且可使３００％定伸应力保持恒定；以ＮＯＢＳ或ＣＺ为主促进剂时，正硫化时具有较高的拉伸强度和撕裂强度，但硫化２小时时的降低幅度比ＤＭ大。     

Recent studies of self-condensation and co-condensation of melamine-formaldehyde resins; cure at low temperatures

Self-condensation: recent research on the chemical pathways by which alcoholated melamine-formaldehyde (MF) resins react with themselves and on the product structures is summarized. Model compound studies suggest that bridges are less stable than widely thought unless they are in hexahydro-1,3,5-triazine ring structures. In acyclic structures they are probably less stable than bridges. Co-condensation: studies of how the composition of MF resins influences the rates of reaction with poly(ol) co-reactant show that MF resins that contain very low levels of and/or functionality are quite reactive. Reactivities of a variety of poly(ester) and acrylic coreactants were studied. By combining reactive MF resins with reactive co-reactants one can formulate high solids enamels that cure by co-condensation in 30 min at 50 to 65 °C with 0.5 parts per hundred (phr) of p-toluenesulfonic acid (p-TSA) catalyst. Cure at 25 °C appears feasible with higher catalyst levels.     

甲基乙烯基硅橡胶并用体系研究

并用两种乙烯基含量不同的甲基乙烯基硅橡胶，添加适量含氢硅油，同时采用过氧化物和铂催化加成这两种硫化方式。可以得到高撕裂乙烯基硅橡胶。结果表明，当乙烯基质量分数为0．09％和0．13％的生胶并用比为50／50时，其撕裂强度比单独使用两种生胶时分别提高了46．9％和21．7％；两种硫化体系并用时，性能有了显著提高，超过了单独使用一种硫化方式的性能。     

环氧丙烯酸树脂的合成研究

研究合成了一种环氧丙烯酸树脂,该树脂既具有环氧树脂优良的黏结性能、收缩率低等特点,又克服了其抗冲击性差的缺点,还可以室温固化,应用广泛.