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     

负离子聚合法合成端羟基聚丁二烯与自由基法端羟基聚丁二烯的性能对比

以硅烷保护羟基的烷基锂为引发剂,采用负离子聚合法合成了端羟基聚丁二烯(HTPB),通过核磁共振氢谱、傅里叶变换红外光谱、凝胶渗透色谱和差示扫描量热法表征了HTPB的微观结构、分子量分布、官能度及玻璃化转变温度(Tg),研究了HTPB胶片的拉伸性能,并与自由基法HTPB进行了对比。结果表明,负离子法HTPB的1,4-结构摩尔分数约为90%,比自由基法HTPB高约12%,分子量分布小于1.1,低于自由基法HTPB,平均官能度比自由基法HTPB更接近理想值2,Tg为-88.3℃,较自由基法HTPB低9.7℃;负离子法HTPB胶片的拉伸强度与自由基法HTPB胶片相近,但扯断伸长率比自由基法HTPB胶片提高约74%。     

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.     

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。     

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     

端羟基聚丁二烯基聚氨酯的溶胀试验研究

以HTPB(端羟基聚丁二烯)基PU(聚氨酯)作为RDX(黑索金)/AP(高氯酸铵)含能材料包覆用黏合剂,在废弃复合推进剂的回收过程中,比较了7种溶剂对HTPB基PU溶胀效果的影响;采用红外光谱(FT-IR)法对RDX、AP在三氯甲烷中浸泡前后的结构进行了表征,并采用分子动力学模拟计算了溶剂与HTPB基PU的结合能、溶剂在其中的扩散系数。研究结果表明:三氯甲烷对HTPB基PU的溶胀率相对最高(700%),7种溶剂对HTPB基PU的溶胀率依次为三氯甲烷甲苯苯二氯甲烷环己烷乙酸乙酯丙酮;温度对溶胀率没有明显的影响,仅仅缩短了溶胀平衡所需的时间;浸泡前后RDX和AP的特征峰没有发生变化,说明两者与三氯甲烷未发生反应;分子动力学模拟计算而得的结合能、扩散系数判定的溶胀效果排序与溶胀率大小排序基本吻合。     

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。     

环氧丁羟增韧环氧树脂应用研究

采用环氧化端羟基聚丁二烯(EHTPB,简称环氧丁羟)作为环氧树脂固化体系的增韧剂,研究了不同EHTPB质量分数对固化体系力学性能、热性能和电性能的影响。结果表明:随EHTPB质量分数的增加,EHTPB增韧环氧树脂灌封胶的冲击强度呈现先增加后减小的趋势;EHTPB质量分数为10%时增韧环氧树脂灌封胶的冲击强度较佳,增韧性能较好。     

阴离子法合成端羟基聚丁二烯研究进展

介绍了阴离子法端羟基聚丁二烯(HTPB)的特点和应用,以及国外阴离子法生产HTPB的工业化情况。详细叙述了阴离子法HTPB的国内外研究进展情况,重点介绍了羟基保护的阴离子法合成HTPB的方法。     

用过氧乙酸原位法合成环氧化端羟基聚丁二烯

用过氧乙酸原位法制备了不同环氧值的环氧化端羟基聚丁二烯,研究了反应温度,反应时间,过氧化氢与端羟基聚丁二烯(HTPB)、冰乙酸与HTPB及磺酸催化剂与HTPB质量比等对产物环氧值、羟值及开环率的影响,并用红外光谱对其结构进行了表征.结果表明,用过氧乙酸原位法可有效控制产物的开环率.最佳环氧化反应条件为反应温度50℃、反应时间7 h、过氧化氢与HTPB质量比2.50、冰乙酸与HTPB质量比0.90、磺酸催化剂与HTPB质量比0.15.     

Synthesis and characterization of terminally functionalized and epoxidized hydroxyl-terminated polybutadiene

Pyridyl N-oxide derivatives of hydroxyl terminated polybutadiene-pyridine (HTPB-PY) were synthesized via functionalization on terminal carbon atoms of HTPB backbone by 2-chloropyridine and epoxidation of C=C bonds and N atoms using in situ generated dimethyl dioxirane (DMD). ¹HNMR, ¹³CNMR, ¹⁴NNMR, and FT–IR spectroscopy techniques used in order to investigate the structural elucidation of products. In this synthesis method, HTPB terminal hydroxyl groups have preserved unchanged without applying any conditional controllers.     

端羟基聚丁二烯改性喷涂聚脲弹性体的制备及性能

以端羟基聚丁二烯(HTPB)和端羟基聚醚(DL-2000)与二苯甲烷二异氰酸酯反应合成A组分;以端氨基聚醚、交联剂聚醚胺和扩链剂3,3'-二氯-4,4'-二胺基二苯甲烷(MOCA)在有机铋或有机锡二月桂酸二丁基锡催化剂的作用下制备B组分;然后A、B 2组分等体积喷涂制备HTPB改性聚脲弹性体.研究了有机铋和有机锡2种催...     

端羟基聚丁二烯改性醇酸树脂的合成与性能研究

利用梓油和桐油以及带端羟基的聚丁二烯(下文简称丁羟)合成了具有快干特征的醇酸树脂。利用该树脂配制的涂料不仅干性好,且涂层光泽高、鲜映性好,保色保光性优异,可用于农业机械、工程机械等涂装。     

环氧丁羟环氧值测定方法的研究

研究了在盐酸-四氢呋喃介质中,以酚酞-乙醇作指示剂,氢氧化钠溶液返滴法测定环氧丁羟(EHTPB)的环氧值的方法,考察了反应时间、反应温度、反应介质、指示剂对结果的影响.最终确定了在常温下,EHTPB样品在盐酸-四氢呋喃[V(盐酸):V(四氢呋喃)=1:40]介质中搅拌溶解后静置30 min,以10 g/L酚酞-乙醇作指...     

韦氏法测定端羟基聚丁二烯碘值的探究

采用韦氏法研究了端羟基聚丁二烯(HTPB)样品的碘值测定,对其实验条件,如称样量、反应时间、液封等进行了探究。结果表明,在HTPB样品碘值的测定过程中,要用碘化钾溶液密封反应瓶口,最优称样量为0.3 g,反应时间为100 min。该法具有较高的精密度,且存放30 d后样品的检测结果重现性的相对标准偏差为1.32%。