A study on the curing kinetics of epoxycyclohexyl polyhedral oligomeric silsesquioxanes and hydrogenated carboxylated nitrile rubber by dynamic differential scanning calorimetry

A new organic–inorganic hybrid material was prepared through reactive blending of hydrogenated carboxylated nitrile rubber (HXNBR) with epoxycyclohexyl polyhedral oligomeric silsesquioxanes (epoxycyclohexyl POSS). The structure of the composite was characterized by Fourier transform infrared spectroscopy (FTIR) and solid‐state ¹³C Nuclear Magnetic Resonance spectra (solid‐state ¹³C‐NMR). The differential scanning calorimetry (DSC) at different heating rates was conducted to investigate the curing kinetics. A single overall curing process by an nth‐order function (1 ? α)ⁿ was considered, and multiple‐heating‐rate models (Kissinger, Flynn–Wall–Ozawa, and Crane methods) and the single‐heating‐rate model were employed. The apparent activation energy (E_a) obtained showed dependence on the POSS content and the heating rate (β). The overall reaction order n was practically constant and close to 1. The isoconversion Flynn–Wall–Ozawa method was also performed and fit well in the study. With the single‐heating‐rate model, the average E_a for the compound with a certain POSS content, 66.90–104.13 kJ/mol was greater than that obtained with Kissinger and Flynn–Wall–Ozawa methods. Furthermore, the calculated reaction rate (dα/dt) versus temperature curves fit with the experimental data. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Homogeneous catalytic hydrogenation of hydroxyl‐terminated liquid nitrile rubber

It was difficult to obtain high degree of hydrogenation of hydroxyl‐terminated liquid nitrile rubber (HTBN) by using homogeneous noble metal catalyst because the hydroxyl (? OH) in HTBN was likely to cause catalyst poisoning. In this study, with hexamethyl disilylamine protecting ? OH, a good yields of hydrogenated HTBN was synthesized through the use of homogeneous metal catalyst. The effects of catalyst concentration, reaction time, hydrogen pressure, and temperature on the hydrogenation of HTBN were investigated and obtained the following optimum process parameter values: catalyst mass fraction of 0.8%, reaction time of 8 h, pressure of 1.6 MPa, and temperature of 100°C. Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy were used to characterize the hydrogenation product of the protected HTBN, indicating that under certain conditions a high degree of hydrogenation of HTBN can be achieved. Only the carbon–carbon double bonds (C?C), not the ? CN bonds, are subject to hydrogenation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

丁腈橡胶的烯烃复分解及其产物的非均相加氢

采用烯烃复分解方式制备低相对分子质量的丁腈橡胶并对其进行非均相加氢,考察了烯烃复分解催化剂加入量、反应温度及反应时间对丁腈橡胶相对分子质量及其分布的影响。结果表明,在10 m L三氯甲烷中溶解1 g丁腈橡胶、催化剂用量0.001 g、反应温度30℃及反应时间3 h的条件下,所制备丁腈橡胶的数均分子量为(1.5~5.5)×104,重均分子量为(3.0~12.0)×104。采用非均相催化剂对低相对分子质量丁腈橡胶进行加氢的氢化度可达99%以上。     

Novel method for preparation of carboxylated nitrile rubber–natural rubber blends using bis(diisopropyl)thiophosphoryl polysulfides

Bis(diisopropyl)thiophosphoryl trisulfide (DIPTRI) and bis(diisopropyl)thiophosphoryl tetrasulfide (DIPTET) are successfully used as a novel coupling agent and accelerator, respectively, to covulcanize an elastomer blend comprising polar carboxylated nitrile rubber (XNBR) and nonpolar natural rubber (NR). These compounds are capable of forming a chemical link between these dissimilar rubbers to produce a technologically compatible blend as judged by a swelling experiment. The blend vulcanizates thus produced exhibit enhanced physical properties that can further be improved by adopting the two‐stage vulcanization technique and also by judicious selection of the NR:XNBR ratio. The blend morphology assessed by scanning electron microcroscopy micrographs accounts for significant improvement in the physical properties of the blend vulcanizates, particularly in two‐stage vulcanization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1725–1736, 2001     

HDPE／NBR共混物流变性能研究

通过熔融共混法制备了HDPE／NBR共混物,用毛细管流变仪研究了其流变特性,此共混物属于假塑性流体,表观粘度随剪切速率和温度的升高而降低,随NBR和增容剂含量的降低而降低。     

Active Site Mapping of Human Cathepsin F with Dipeptide Nitrile Inhibitors

Cleavage of the invariant chain is the key event in the trafficking pathway of major histocompatibility complex class II. Cathepsin S is the major processing enzyme of the invariant chain, but cathepsin F acts in macrophages as its functional synergist which is as potent as cathepsin S in invariant chain cleavage. Dedicated low‐molecular‐weight inhibitors for cathepsin F have not yet been developed. An active site mapping with 52 dipeptide nitriles, reacting as covalent–reversible inhibitors, was performed to draw structure–activity relationships for the non‐primed binding region of human cathepsin F. In a stepwise process, new compounds with optimized fragment combinations were designed and synthesized. These dipeptide nitriles were evaluated on human cysteine cathepsins F, B, L, K and S. Compounds 10 (N‐(4‐phenylbenzoyl)‐leucylglycine nitrile) and 12 (N‐(4‐phenylbenzoyl)leucylmethionine nitrile) were found to be potent inhibitors of human cathepsin F, with K_i values <10 nM . With all dipeptide nitriles from our study, a 3D activity landscape was generated to visualize structure–activity relationships for this series of cathepsin F inhibitors.     

Novel poly(aryl ether nitrile ketone) foams and the influence of copolymer structure on the foaming result

Novel poly(aryl ether nitrile ketone) foams were prepared through the batch foaming method with supercritical CO₂ as the blowing agent. Both temperature‐induced and pressure‐induced foaming methods were conducted to examine the influence of nitrile groups on the foaming result. The results indicated that nitrile groups influenced the foaming result by affecting both the viscoelasticity and CO₂ absorption of the polymers. In addition, the CO₂ solubility of the polymers increased with increasing CN content presumably because of the Lewis acid–base nature of the interaction between the CO₂ molecules and the nitrile groups. The cell growth process was assessed by analyzing the influence of foaming temperature and foaming time on the cell morphology. Nanocellular foams with a minimum size of 30–50 nm were achieved by the temperature‐induced foaming method. Moreover, highly expanded foams with a maximum expansion ratio of 23.6 were obtained by the pressure‐induced foaming method. © 2018 Society of Chemical Industry     

高级脂肪腈合成工艺技术进展

介绍了目前高级脂肪腈合成工艺技术路线,简述了国内脂肪酸氨化脱水制腈工艺技术研究及开发进展情况,并对发展国内脂肪腈/脂肪胺生产提出了建议。     

3-丁烯腈在盐酸催化剂溶液中的水解动力学研究

以盐酸为催化剂,通过水解3-丁烯腈合成3-丁烯酸,考察了3-丁烯腈初始浓度、反应温度、盐酸浓度对水解反应过程的影响;在此基础上,研究了3-丁烯腈水解动力学,拟合出了反应速率常数和反应活化能。结果表明,该反应为1级串连反应,同时盐酸浓度对水解反应速率常数有很大的影响:当盐酸的浓度低于5.0 mol/L时速率常数的关系为k1k2;且随着盐酸浓度的增大,腈水解反应活化能逐渐减小。     

烯基聚醚含能黏合剂的合成与固化

以三羟甲基丙烷为引发剂、三氟化硼·乙醚络合物为催化剂、3-硝酸酯甲基-3-甲基氧杂环丁烷(NIMMO)为单体,制备了三官能度的聚NIMMO(T-PNIMMO),随后在其端基共聚烯丙基缩水甘油醚(AGE),合成了烯基聚醚含能黏合剂(AGE-T-PNIMMO)。采用FTIR和NMR对产物进行了表征,并以四甲基对苯二腈氧化物(TTNO)为固化剂固化合成的烯基聚醚含能黏合剂制备出弹性体,考察了弹性体的力学和热性能。结果表明:该黏合剂具有低黏度(20℃黏度为8.93 Pa·s)、较低的玻璃化转变温度(-57.4℃)及可室温固化的特点;R(固化剂TTNO的腈氧基团与AGE-T-PNIMMO双键的物质的量之比,下同)=1.0时,得到的弹性体拉伸强度最高可达0.80 MPa,分解峰峰温为202℃。