负离子聚合法合成α-羟基-ω-羧基聚丁二烯及其表征

以叔丁基二甲基硅氧基丙基锂为引发剂、环己烷为溶剂进行负离子聚合,合成高1,4-结构含量的α-羟基-ω-羧基聚丁二烯(HO-PB-COOH),并用傅里叶变换红外光谱、核磁共振和凝胶渗透色谱对其主链结构、分子量分布和平均官能度进行了表征。结果表明,HO-PB-COOH的1,4-结构摩尔分数高达约90.00%,多分散指数不大于1.10,平均官能度接近2.00。     

端羟基聚丁二烯官能度分布的测定

本工作采用高压液相色谱法测定端羟基聚丁二烯(HTPB)的官能度分布.将3,5-二硝基苯甲酰氯(DNBC)在一定条件下,进行衍生化反应.衍生化后的 HTPB 经高压液相色谱仪的紫外(UV)和方差(RI)双检测器进行检测。所得色谱图经数据处理,并分区统计组合,得到 HTPB的羟基官能团随分子量的分布,同时得到相应的数均分子量、重均分子量、分子量分散指数、数均官能度、重均官能度及官能度分散指数.     

线型及星形端羟基聚丁二烯的合成与表征

以叔丁基二甲基硅氧基丙基锂为引发剂,丁二烯为单体,环己烷为溶剂,甲基三氯硅烷为偶联剂,采用活性负离子聚合法合成了线型端羟基聚丁二烯(L-HTPB)和星形端羟基聚丁二烯(S-HTPB),并用凝胶渗透色谱和核磁共振氢谱对其结构进行了表征。结果表明,采用该方法合成的2种聚丁二烯,其1,4-结构摩尔分数均接近90.00%,L-HTPB的平均官能度接近2.00,S-HTPB的平均官能度接近3.00,与分子设计值基本相符。     

不同聚合方法端羟基聚丁二烯复配物的制备及其固化物的力学性能

采用端羟基聚丁二烯(HTPB)与负离子法HTPB(A-HTPB)复配的方法制备了不同平均官能度(f)及其分布的HTPB,研究了f对固化物胶片和铝粉填充固化胶片力学性能的影响。结果表明,对于A-HTPB/HTPB固化胶片,随着A-HTPB用量的增加,当A-HTPB用量不大于25份,即f值不小于2.28时,其拉伸强度基本不变,但扯断伸长率逐渐增加;当A-HTPB用量大于25份,即f值小于2.28时,其拉伸强度虽然有所降低,但扯断伸长率增加幅度较大。对于铝粉填充A-HTPB/HTPB固化胶片,当A-HTPB用量为40份,即f值为2.22时,拉伸强度下降和扯断伸长率上升的幅度均较大,与A-HTPB/HTPB固化胶片的力学性能相近,说明f值是影响A-HTPB/HTPB固化胶片力学性能的重要因素。     

高1,4-结构含量双端羟基聚丁二烯的合成与表征

以含硅氧烷的有机锂引发丁二烯负离子聚合,在30℃反应20h后通过环氧乙烷羟基化及酸解脱除保护基合成了双端羟基聚丁二烯(DHTPB),并采用凝胶渗透色谱、傅里叶变换红外光谱、核磁共振、羟值滴定对其进行了表征。结果表明,在不加入四氢呋喃时DHTPB的1,4-结构摩尔分数可达92.1%,得到的DHTPB相对分子质量大小可控、分子量分布不超过1.12、官能度接近2.00。     

四羟基聚丁二烯的合成及其改性端羟基聚丁二烯液体橡胶的力学性能

采用自制的烷基锂引发剂,以环己烷为溶剂、四氢呋喃为结构调节剂、四氯硅烷为偶联剂合成了具有四羟基的端羟基聚丁二烯(HTPB)液体橡胶,通过凝胶渗透色谱仪、核磁共振仪等对其进行了表征.结果表明,四羟基HTPB的多分散指数小于1.1,平均官能度接近4,微观结构可调.用该四羟基HTPB改性现有商品HTPB可提高其拉伸强度,但扯...     

端羟基液体聚丁二烯橡胶微观结构及其力学性能

通过FT—IR,HNMR,CNMR,GPC等方法,对相同牌号HTPB样品A和B的主链微观结构、羟基类型、环氧基团、官能度分布和固化物力学性能进行了对比,2个样品的主链微观结构、羟基类型、环氧基团含量基本一致,而官能度分布存在较大差异,由结果可得,HTPB官能度分布对其力学性能影响较大,二官能度为84．2％的样品A具有较好的力学性能,二官能度为676％的样品B具有相对较差的力学性能。     

端羟基聚丁二烯官能度及分布的测定

用凝胶渗透色谱法（GPC）测定端羟基聚丁二烯（HTPB）官能度分布。将HTPB用3,5-二硝基苯甲酰氯在一定条件下进行衍生化反应,衍生化后的HTPB经GPC的示差／紫外（RI／UV）双检测器进行检测,所得的色谱图经数据处理,得到HTPB的官能度及其分布。     

阴离子端羟基聚丁二烯的表征及其固化物的力学性能

简述了以硅烷保护羟基的烷基锂为引发剂,环己烷为溶剂合成丁羟胶的聚合方法;通过IR、^1H—NMR和GPC等方法研究了阴离子端羟基聚丁二烯主链结构、分子质量分布、官能度及其分布;对其固化物力学性能进行了评价。研究结果表明,阴离子端羟基聚丁二烯的1,4-结构含量高达约90％、分子质量分布指数≤1．05、官能度接近2,其固化物具有优异的力学性能。     

腈氧化物固化端羟基聚丁二烯

首先,以1,2,4,5-四甲基苯为原料,经溴甲基化、氧化、缩合、脱氢氧化4步反应,得到了四甲基对苯二腈氧化物(TTNO),各步产物的结构用FTIR、1HNMR和13CNMR进行了表征。然后,将TTNO用于端羟基聚丁二烯(HTPB)的室温固化,按照固化剂腈氧基团与HTPB中双键的物质的量之比(R值)分别为0.03、0.04、0.05、0.06和0.07制备了哑铃形聚合物弹性体。最后,通过FTIR、拉伸强度测试、DSC、TG和接触角测试对聚合物弹性体的结构和性能进行了考察。结果显示:随着R值的增加,聚合物弹性体的拉伸强度从0.135 MPa增至0.416MPa,玻璃化转变温度(Tg)从-73.08℃增至-66.70℃,接触角从98.80°减小到73.54°。在室温下,四甲基对苯二腈氧化物能实现HTPB的固化,固化后的聚合物弹性体有望用于复合固体推进剂。     

Characterization of hydroxyl-terminated polybutadiene

A comparison between the molecular structure of conventional and low molecular weight hydroxyl terminated polybutadienes (HTPBs) is presented. The conventional HTPB samples were R45M, R45HT (Atochem). Liquiflex P and H (Petroflex, Brazil), and the low molecular weight ones were R20LM (Atochem) and two laboratory synthesized materials. The structural differences found were attributed to dissimilarities in fabrication processes for each type of HTPB. Some mechanistic pathways for the polymerization are suggested.     

Characterization of hydroxyl-terminated polybutadiene

Commercial samples of hydroxyl terminated polybutadienes (HTPB) were analysed by ¹H and ¹³C NMR spectroscopy, in regard to hydroxylated end groups. The results were discussed and compared with those reported so far.     

Characterization of hydroxyl-terminated polybutadiene

¹H and ¹³C NMR spectra were used to study the structure of hydroxyl-terminated polybutadiene (HTPB) obtained by using hydrogen peroxide as initiator and an alcohol as solvent. This alcohol was introduced into the polymer chain, forming a hydroxylated end group. The subject has aroused some argument in the literature and is considered further in our discussion of reaction mechanisms. Received: 29 November 1996/Revised: 4 December 1996/Accepted: 9 December 1996     

The molecular characteristics of hydroxyl-terminated polybutadiene

Three samples of a commercial hydroxyl-terminated polybutadiene, Arco R45M. were characterised with respect to number-average and weight-average molar mass, intrinsic viscosity, number-average hydroxyl functionality and effective functionality for gelation. Two of the samples were fractionated on the basis of solubility in toluene/methanol mixtures, and the fractions were characterised with respect to number-average molar mass, intrinsic viscosity and number-average hydroxyl functionality. For both sets of fractions, the average functionality was practically independent of average molar mass. It is concluded that the functionality distribution is almost identical at all points in the molar mass range of Arco R45M.     

合成环氧化端羟基聚丁二烯的反应动力学

采用过氧乙酸原位法合成不同环氧值的环氧化端羟基聚丁二烯(EHTPB),从合成EHTPB的基本反应式出发,推导了反应动力学方程,讨论了碳碳双键浓度与反应温度和时间的关系.结果表明,用过氧乙酸对端羟基聚丁二烯进行环氧化改性合成EHTPB的反应为二级反应,其反应速率常数为1.868×10-6dm3/(mol·s),活化能为39.39 kJ/mol,而碳碳双键和过氧化氢的反应则为一级反应.     

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 .     

环氧化端羟基聚丁二烯/甲苯二异氰酸酯型聚氨酯的合成

用环氧化端羟基聚丁二烯(EHTPB)与甲苯二异氰酸酯(TDI)合成了聚氨酯,考察了反应时间、TDI用量、环氧值以及扩链剂1,4-丁二醇(BDO)用量对聚氨酯拉伸性能的影响,通过差示扫描量热法(DSC)分析确定了反应温度,并研究了反应的表现活化能(Ea)和反应级数(n).结果表明,在反应温度为70℃、时间为7 d、-NCO/-OH(摩尔比)为1.4、环氧值为0.001 8 mol/g左右时,聚氨酯的拉伸性能较好;适当加入扩链剂BDO可以同时提高聚氨酯的拉伸强度和扯断伸长率,BDO与EHTPB中-OH的最佳摩尔比为1.0;EHTPB与TDI反应的Ea为59.44 kJ/mol,n为1.02,70℃下的反应速率常数为1.2×10-2s-1     

端羟基聚丁二烯增韧环氧树脂的性能和微观形貌

以不同数均分子量（珚Mn）的端羟基聚丁二烯（HTPB）为增韧剂,4,4-二氨基二苯甲烷为固化剂,考察了HTPB的珚Mn及用量对环氧树脂的冲击强度、拉伸性能、热稳定性及微观形貌的影响。结果表明,在胺类固化体系中,当HTPB的珚Mn为2 300--3 500且质量分数为1%~3%时,其对环氧树脂具有较佳的增韧效果,且不会对热稳定性产生太大的影响;随着HTPB用量的增加,改性环氧树脂中大尺寸橡胶粒子增多,且HTPB的珚Mn越大,改性环氧树脂中橡胶粒径越大,断裂面由光滑的脆性断裂特性变为粗糙、存在大量应力纹及应力发白区域的韧性断裂特性,再到平滑断裂和大尺度的橡胶颗粒两相分布的低韧性特性。     

端羟基聚丁二烯液体橡胶老化性能研究

研究了不同防老剂种类及用量，不同环境温度条件下，端羟基聚丁二烯（ＨＴＰＢ）液体橡胶粘度变化规律。结果表明，加入防老剂，尤其是２２４６可以显著改善ＨＴＰＢ的老化性能，且防老剂２２４６最佳用量为０．２％￣０．５％，室温下，ＨＴＰＢ不加防老剂的贮存期长达１年。     

端羟基聚丁二烯改性氰酸酯体系固化反应动力学

采用示差扫描量热法(DSC)研究了端羟基聚丁二烯(HTPB)改性双酚A型氰酸酯树脂(BADCy)体系的固化反应动力学,根据Arrhenius方程对固化过程动力学参数进行了求解,建立了固化反应动力学模型。结果表明,随着HTPB含量的增大,动态DSC固化反应放热峰向低温方向移动,说明HTPB可以催化固化反应并降低体系的反应温度。纯BADCy和BADCy/15%HTPB体系等温固化符合自催化反应模型。纯BADCy体系以及BADCy/15%HTPB体系的表观反应活化能分别为59.67 kJ/mol、56.91 kJ/mol。