我国NiBR催化聚合技术发展的分析

总结燕化公司合成橡胶了ＮｉＢＲ催化聚合技术的发展过程，分析了技术进步的原因，提出了改进我国ＮｉＢＲ催化聚合技术的意见。     

Crosslinking of elastomers upon ageing: a kinetic approach based on crystallinity changes followed by DSC

It was observed that crosslinking reactions resulting both from peroxide decomposition or photoageing at wavelengths longer than 300 nm involve a drastic decrease of the crystallinity of some dienic elastomers, such as polybutadienes (rich in cis 1,4 and 1,2 microstructures) and polycyclo‐octene. By comparing precisely the rate of decomposition of dicumyl peroxide and that of the crystallinity decrease, it was possible to show that the kinetics of crystallinity loss observed upon ageing can be identified with that of the crosslinking of elastomers. The results indicate that the crosslinking process can be followed directly by DSC measurement of the crystallization/melting cycle. © 2003 Society of Chemical Industry     

The effect of initiator‐to‐monomer ratio on the properties of the polybutadiene‐ol synthesized by free radical solution polymerization of 1,3‐butadiene

Polybutadiene‐ol was synthesized by solution radical polymerization of 1,3‐butadiene in the presence of hydrogen peroxide as initiator and 2‐propanol as solvent. The ratio of initiator to monomer molar concentration, [I₀]/[M₀], was varied while temperature, reaction time and the type and amount of solvent were kept constant. The effects on the M_n; M_w; M_v; PDI, OH‐number and functionality of the synthesized polyols were studied. By taking several samples during a polymerization batch and analyzing them, the time of reaction was chosen as 100 min, after which the PDI changed dramatically. M_n decreased exponentially with increasing [I₀]/[M₀] according to the relationship M_n = 565.55 ([I₀]/[M₀])^?0.7553. The decrease observed in M_w gradually levelled off with increasing [I₀]/[M₀] and molecular weight distribution broadened at larger values of [I₀]/[M₀]. The OH‐number increases with [I₀]/[M₀]. In addition to the number‐average molecular weight, functionality is dependent on the number of hydroxyl‐terminated chain radicals in the reaction medium. Copyright © 2003 Society of Chemical Industry     

Functionality distribution and crosslink density of hydroxyl-terminated polybutadiene

A novel approach is proposed for estimating the average molecular weight between crosslinks (M?_c) from the functionality distribution of hydroxyl-terminated polybutadiene ( HTPB ). The functionality distribution of four free-radically polymerised HTPB prepolymers of varying hydroxyl content and molecular weight was determined by a combination of preparative and analytical gel permeation chromatography. The gumstock properties of the samples cured with stoichiometric amounts of toluene diisocyanate were not correlatable with the relative amounts of difunctional chain extender and multifunctional crosslinker present, unlike the case of HTPB with similar hydroxyl content and molecular weight. However, the mechanical properties and sol content could be correlated with the average molecular weight between crosslink sites, M?_c, of the cured polymer. The M?_c values derived by our method compare well with those of classical methods, and the observed differences are attributed to segmental entanglement. These M?_c values give consistently good correlation with all the gumstock properties, confirming the validity of our approach and the soundness of the techniques developed for the determination of the functionality distribution of HTPB .     

二哌啶乙烷的合成及其在合成聚丁二烯中的应用

合成了二哌啶乙烷（ＤＰＥ），并进行了分析与鉴定。采用ＤＰＥ做丁二烯阴离子聚合的调节剂，考察了ＤＰＥ／ｎ－ＢｕＬｉ（正丁基锂）和ＤＰＥ／α－ＭＮＬｉ（α－甲基萘锂）比值对形成１，２－聚丁二烯（１，２－ＰＢ）微观结构调节规律，得到了１，２－结构近１００％的聚丁二烯。采用高分子设计方法，通过引入ＤＰＥ合成了１，４－１，２两嵌段和１，２－１，４－１，２三嵌段聚丁二烯，ＤＳＣ－ＤＴＡ示差扫描量热计测示表明：聚丁二烯的１，２－结构含量影响其玻璃化转变温度（Ｔｇ），一定嵌段比的聚丁二烯可以产生微观相分离     

Failure pressure estimations on a solid propellant rocket motor with a circular perforated grain

This paper presents analytical as well as finite element estimations of the failure pressure of a typical rocket motor, which is modelled as a body of a HTPB-based propellant material enclosed by a thin-walled flexible casing of 15CDV6 steel. The estimations are based on non-linear analyses, using stress–strain curves generated from the uniaxial tension specimens of the propellant as well as casing materials. Solid propellant being viscoelastic in nature, stress–strain curves generated at different strain rates have been used in the analysis. It is noted that the failure pressure of the rocket motor slightly increases in the presence of propellants. As the grain web thickness decreases, due to propellant burning the failure pressure slightly reduces and approaches the value of the maximum pressure in the hydroburst test of the motor case at the end of the propellant burning.     

端羟基聚丁二烯包覆多壁碳纳米管的制备及其对顺丁橡胶的补强研究

研究端羟基聚丁二烯包覆多壁碳纳米管(MWNTs)的制备及其对顺丁橡胶(BR)的补强效果。结果表明:将MWNTs与HTPB研磨,可使聚合物包覆在MWNTs表面,显著提高MWNTs在甲苯等溶剂中的溶解性;对MWNTs进行羧酸化处理可进一步改善HTPB对MWNTs的包覆效果,提高MWNTs在BR中的分散性,增强MWNTs与BR的界面粘合力,使其在BR基体中表现出更好的补强效果。     

Anti-corrosive,weatherproof and self-healing polyurethane developed from hydrogenated hydroxyl-terminated polybutadiene toward surface-protective applications

Self-healing polyurethane (PU) faces aging deterioration due to active dynamic bonds, which remain a challenging predicament for practical use. In this work, a novel strategy is developed to address this predicament by leveraging the hydrophobicity and gas barrier of hydrogenated hydroxyl-terminated polybutadiene (HHPB). The dynamic oxime-carbamate bonds derived from 2, 4-pentanedione dioxime (PDO) enable the elastomer to exhibit surface self-repairability upon applied mild heat and achieve ~99.5% mechanical self-healing efficiency. The mechanical properties remained nearly intact after 30-d exposure to thermal oxidation, xenon lamp, acids, bases, and salts. Gas permeability, positron annihilation lifetime spectroscopy (PALS), and contact angle measurements reveal the pivotal role of gas barrier, free volume, and hydrophobicity in blocking undesirable molecules and ions which effectively protects the elastomer from deterioration. HHPB-PU also exhibits excellent adhesion to steel substrate. The shear strength achieves (3.02 ± 0.42) MPa after heating at 80 °C for 4 h, and (3.06 ± 0.2) MPa after heating at 130 °C for 0.5 h. Regarding its outstanding anti-corrosive and weatherproof performances, this self-healable elastomer is a promising candidate in surface-protective applications.     

Surface oxidation of styrene butadiene copolymers: Study by laser ablation and secondary ion mass spectrometry

The capabilities of ion bombardment and laser ablation coupled to mass spectrometry as independent techniques to investigate the surface thermooxidative stability of polystyrene, polybutadiene polymers, and styrene butadiene rubber (SBR) copolymers were investigated. Surface chemical modifications were detected according to the polymeric structure. The degradation products detected by static secondary ion mass spectrometry appeared at m/z 29, 43, and 55. Their compositions were related to the general formulae C_nH_mO⁺ with n = 1–3 and m = 1–3 for polybutadiene and styrene butadiene copolymers, whereas polystyrene was not affected by the aging treatment. The C_nH_mO⁺ ions result from butadiene unit degradation. The laser ablation ionization Fourier transform ion cyclotron resonance mass‐spectrometry results confirmed the detection of C_nH_mO⁺ ions. Finally, it may be considered that the surface thermooxidative process of SBR copolymers begins with butadiene unit degradation. The development of butadiene unit oxidation showed a dynamic oxidation phase, which coincided with a loss of unsaturation. The influence of the polymer conformation (blocked, branched, and random) on the surface oxidation for 30% styrene SBR compounds was also studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1910–1917, 2003