Non-invasive headspace measurement for characterizing oxygen-scavenging in polymers

A non-invasive headspace analysis method to measure rate and amount of oxygen uptake in oxygen-scavenging polymers is presented. Oxygen uptake data for metal-catalyzed poly(1,4-butadiene) at 30 °C are provided to illustrate the method. These data were obtained by measuring oxygen headspace concentration above the scavenging polymer with an OxySense^® 200T non-invasive oxygen sensor, and, for comparison, oxygen uptake was measured with an analytical balance. Excellent agreement was observed between these two independent experiments.     

EBR胶乳凝胶的控制及其对ABS树脂冲击性能的影响

主要讨论了摩尔质量调节剂，延长后期反应时间，提高后期反应温度，过硫酸钾用量等对乙烯－丁二烯橡胶（EBR）胶乳凝胶的影响；同时讨论了低凝胶条件和高凝胶条件下凝胶对ABS树脂性能的影响。结果表明：低凝胶条件,ABS树脂的冲击性能随凝胶质量分数的增加而增加；高凝胶条件下，则随凝胶质量分的增加而降低，得到了EBR胶乳生产中凝胶的主要控制方法，并通过控制EBR胶乳凝胶来实现对ABS树脂冲击性能的控制。     

液体聚丁二烯的环氧化

分析了影响环氧化聚丁二烯合成条件的诸多因素、原料以及产物的结构，为该产物的实际应用创造条件。     

丁二烯在Ni（naph）2—n—C4H9Li—BF3.OEt2催化体系中的引发聚合

本文报道Ni(naph)_2-n-C_4H_9Li-BF_3·OEt_2催化体系对丁二烯的聚合活性.发现.只有Ni(naph)_2与n-C_4H_9Li二元陈化方式有较好的聚合活性.聚合物的特性粘度[η]和5％苯乙烯的动力粘度(η_(c.p)均低.顺式-1,4结构含量约为94％.几乎不生成凝胶。     

Ni(naph)_2-i-Bu_3Al_2Cl_3催化丁二烯聚合的研究

Ｎｉ（ｎａｐｈ）_２－ｉ－Ｂｕ_３Ａｌ_２Ｃｌ_３催化丁二烯聚合的研究徐玲，李绍军，陈滇宝，仲崇淇，唐学明（高材系）０前言目前，我国镍系顺丁橡胶工业化生产采用以加氢汽油为溶剂，Ｎｉ－－Ａｌ陈化，稀Ｂ单加的聚合工艺［１］，但由于ＢＦ３·ＯＥｔ２在加氢汽油中...     

Motional coherency in chain dynamics of polybutadiene studied by molecular dynamics simulations

Molecular dynamics simulations of 1,4-polybutadiene in bulk amorphous state were performed. Results were compared with the recent neutron spin-echo measurements. To investigate motional coherency the relaxation rates for the collective and self-motions, the collective and self-relaxation rates, were evaluated for the short and long time regimes of the normalized intermediate scattering functions. The scattering vector dependence of the collective relaxation rates estimated for both fast and slow processes indicated a minimum at scattering vector q = 1.5 Å⁻¹, corresponding to the position of a peak in the static structure factor. The self-relaxation rates increased monotonously with q. A phenomenon known as de Gennes narrowing was reproduced well in the simulation and found to be originated from the inter-molecular correlation. The collective relaxation rate evaluated for fast process appeared to modulate around a peak of q = 2.9 Å⁻¹, corresponding to the intra-molecular correlation.     

TSS1126型脱水振动筛的设计与分析

针对原１万ｔ／ａ橡胶后处理装置中脱水振动筛存在的问题，在５万ｔ／ａ橡胶后处理装置中设计了ＴＳＳ１１２６型激振电机式振动筛，并对其进行了运动学参数的计算和自同步动力学分析，较好的解决了生产中的振动问题。     

Studies on Advanced RDX/TATB Based Low Vulnerable Sheet Explosives with HTPB Binder

Hydroxyl‐terminated polybutadiene (HTPB) based sheet explosives incorporating insensitive 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) as a part replacement of cyclotrimethylene trinitramine (RDX) have been prepared during this work. The effect of incorporation of TATB on physical, thermal, and sensitivity behavior as well as initiation by small and high caliber shaped charges has been determined. Composition containing 85% dioctyl phthalate (DOP) coated RDX and 15% HTPB binder was taken as control. The incorporation of 10–20% TATB at the cost of RDX led to a remarkable increase in density (1.43→1.49 g cm⁻³) and tensile strength (10→15 kg cm⁻²) compared to the control composition RDX/HTPB(85/15). RDX/TATB/HTPB based compositions were found less vulnerable to shock stimuli. Shock sensitivity was found to be of the order of 20.0–29.2 GPa as against 18.0 GPa for control composition whereas their energetics in terms of velocity of detonation (VOD) were altered marginally. Differential scanning calorimeter (DSC) and thermogravimetry (TG) studies brought out that compositions undergo major decomposition in the temperature region of 170–240 °C.     

Synthesis of well-defined star-branched polymers by stepwise iterative methodology using living anionic polymerization

This article reviews the synthesis of regular and asymmetric star-branched polymers with well-defined structures by methodologies using living anionic polymerization, especially focusing on the synthetic approaches accessible for precisely controlled architectures of star-branched polymers concerning molecular weight, molecular weight distribution, arm number, and composition. The reason for selecting living anionic polymerization from many living/controlled polymerization systems so far developed is that this living polymerization system is still the best to meet the strict requirements for the precise structures of star-branched polymers. Furthermore, we herein mainly introduce a novel and quite versatile stepwise iterative methodology recently developed by our group for the successive synthesis of many-armed and multi-compositional asymmetric star-branched polymers. The methodology basically involves only two sets of the reaction conditions for the entire iterative synthetic sequence. The reaction sequence can be, in principle, limitlessly iterated to introduce a definite number of the same or different polymer segments at each stage of the iteration. As a result, a wide variety of many-armed and multi-compositional asymmetric star-branched polymers can be synthesized.     

NMR relaxation reveals modifications in rubber phase dynamics during long-term degradation of high-impact polystyrene (HIPS)

The microstructure of rubber-modified polystyrene after thermal ageing at 90 °C and multiple extrusion was analyzed by time-domain nuclear magnetic resonance (TD-NMR) in a non-destructive manner. The transverse magnetization decay behaviour observed in TD-NMR was related to the total rubber fraction and its cross-linking density. The data reveal different mechanisms of long-term rubber degradation in high-impact polystyrene (HIPS) during thermo-oxidation and multiple processing: Multiple processing causes a slight increase in the cross-linking density of the rubber phase, without appreciably altering the total amount of rubber fraction. Thermo-oxidation is accompanied by a significant overall decrease of the rubber fraction, an increase of the cross-linking density, and a pronounced increase of the non-crosslinked fraction (chain ends and fragmented segments). The NMR results correlate well with spectroscopic observations and moderately with macroscopic mechanical properties.