端羟基聚丁二烯官能度对推进剂力学性能的影响研究

通过凝胶渗透色谱（GPC）测定端羟基聚丁二烯（HTPB）样品的平均相对分子质量,化学滴定测定样品羟值,根据相对分子质量和羟值计算得到产品的平均官能度。通过假设交联密度和交联点间相对分子质量分别与推进剂抗拉强度和延伸率成正比,建立简单的官能度数学模型,阐述了平均官能度对推进剂力学性能的影响,同时官能度变化可很好地解释HTPB推进剂固化“活性”的差异。     

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.     

GPC法测定HTPB的官能度分布

端羟基聚丁二烯(HTPB)是一种重要的预聚物。据报道,HTPB的分子量(Mi)、分子量分布、官能度(f)和官能度分布对其物理和加工性能均有很大的影响。因此,对HTPB官能度分布的研究,具有十分重要的意义。 HTPB在聚合过程中,由于无法控制链的转移而产生了不同的官能度。预聚物的官能度被定义为预聚物的数均分子量(Mn)     

用GPC法测定环氧乙烷/四氢呋喃共聚醚分子量和官能度分布

采用交联聚苯乙烯凝胶柱和示差折光检测器测定环氧乙烷/四氢呋喃共聚醚分子量和分子量分布。在数均分子量2000～4000,与 VPO 测定结果相比较,偏差小于±8％。用3,5-二硝基苯甲酰氯对样品进行衍生化反应,处理后的衍生物用 GPC 分离并用双检测器检测,进行了官能度分布测定。样品的数均官能度多数为1.7.～2.0,官能度分布的分区表征表明,官能度在1.5～2.5的组分占90％以上。     

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%。     

改性HDI产品中游离HDI含量及各官能度分布的测定方法

介绍了用凝胶渗透色谱法(GPC)测定改性六亚甲基二异氰酸酯(HDI)样品官能度分布的方法,完成了样品衍生条件的探索研究,以及改性HDI不同官能度组分的定性定量测试。该测试方法可将改性HDI中游离的HDI和官能度为3、4、5及以上的组分进行较好的分离,并定量给出各组分峰面积相对百分含量。测定结果重现性较好,偏差均在1.0%以下。     

三臂星形端羟基聚丁二烯的阴离子合成及其表征

以叔丁基二甲基硅氧基丙基锂为引发剂,环己烷为溶剂进行阴离子聚合合成三臂星形端羟基聚丁二烯。采用凝胶渗透色谱(GPC)和1H-NMR方法表征了聚合物相对分子质量及其分布、支化度、平均官能度和主链微观结构。研究结果表明,三臂星形端羟基聚丁二烯的相对分子质量分布指数≤1.1,平均官能度和支化度均接近3。     

端胺基聚丁二烯的合成与表征

采用阴离子聚合法合成了端羟基聚丁二烯,通过端基转化法将羟基转化成胺基,从而合成了端胺基聚丁二烯,通过红外光谱（IR）、核磁共振（1H-NMR）、凝胶渗透色谱（GPC）等对其进行了表征。结果表明,所合成的端胺基聚丁二烯相对分子质量分布较窄（≤1.10）,平均官能度接近2,且微观结构可调;通过羟基值与胺基值的测定表明,端基转化率大于98%。     

蓖麻油基聚酯多元醇的制备及表征

以可再生资源蓖麻油、苯酐和小分子醇为原料,钛酸正丁酯为催化剂,经酯化、缩聚合成蓖麻油基聚酯多元醇,考察了反应时间对聚酯多元醇酸值的影响以及不同官能度的小分子醇对醇解蓖麻油结构和羟值的影响。采用红外光谱仪（FT—IR）、凝胶色谱（GPC）、热失重仪（TGA）对醇解蓖麻油、蓖麻油基聚酯多元醇的相对分子质量、热稳定性进行了表征。结果表明,随着小分子醇官能度的增加,醇解体系中单酯和二酯含量明显减少,转化率也相应减小;甘油醇解蓖麻油和蓖麻油基聚酯多元醇较普通聚醚多元醇635具有更高的热稳定性。     

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。     

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 .     

Functionality distribution of hydroxyl-terminated polybutadienes using gel permeation chromatography. I. The method and calibration procedure

A method for simultaneously determining the molecular weight averages, molecular weight distribution, hydroxyl equivalent weight, functionality averages, and functionality distribution of hydroxyl-terminated polybutadienes using GPC has been developed. The method is based on the preparation of a UV absorbing derivative of the hydroxyl group and GPC analysis using dual differential refractive index and UV detectors. In order to determine the hydroxyl equivalent weight, quantitative derivatization of the hydroxyl group is required. If the equivalent weight can be determined by an independent method, the derivatization reaction can be less than quantitative if sufficient UV absorptivity can be obtained. The procedure used for calibrating the GPC columns and UV detector are presented. Equations for calculating number- and weight-average functionalities from GPC data were also developed. The number-average functionality is independent of the functionality distribution, but the weight-average functionality is dependent upon the distribution of functionality. The ratio of the weight-average to number-average functionality is indicative of how the functionality is skewed as a function of molecular weight.     

单官能度端伯,仲羟基聚丁二烯的研制

本文较详细地研究以ｎ－ＢｕＬｉ为引发剂，丁二烯为单体，抽余油为溶剂，四氢呋喃为１，２－结构调节剂，环氧乙烷和环氧丙烷为羟基化试剂，单官能度端伯、仲羟基聚丁二烯的合成。实验表明，丁羟胶的分子量为２０００～８０００可调；１，２－结构含量可控制在２５％以下，也可随意提高至４０％以上；分子量分布＜１．１，平均官能度接近１。此外，对所得样品采用ＶＰＯ、ＧＰＣ、ＩＲ、Ｈ’－ＮＭＲ等仪器和化学方法进行表征。     

Functionality distribution of hydroxyl-terminated polybutadienes using gel permeation chromatography. II. Measurements for commercial polymers

The functionality averages, functionality distribution, hydroxyl equivalent weight, molecular weight averages, and molecular weight distribution of three commercial hydroxyl terminated polybutadienes have been determined using a dual-detector GPC method used to analyze the polymers before and after derivatization with phenyl isocyanate. The values of these parameters are compared with existing literature data. The determined number-average functionalities were in reasonable agreement with previously published values. However, the distribution of functionality as a function of molecular weight differs from distribution data obtained by column fractionation techniques. Our distribution data appears to be generally consistent with the distribution expected from the polymerization mechanisms. The differences in the variation of hydroxyl content with molecular weight obtained from the dual-detector GPC method and the column fractionation procedures should be resolved since a combination of these procedures could provide additional information regarding the actual amounts of mono-, di-, and polyfunctional polymer and their molecular weight distributions. The dual-detector GPC method should be applicable for the determination of the distribution of a variety of functional groups provided a selective derivatization reaction is available or a second detector which can directly and accurately determine the concentration of the functional group is available.     

不同增溶剂体系合成端羟基聚丁二烯液体橡胶的性能及应用

研究了分别由工业乙醇／水和工业丙醇／水作增溶剂的聚合体系制备的端羟基聚丁二烯液体橡胶（ＨＴＰＢ）的相对分子质量及其分布、粘度、羟值及官能度等物理性能,结果表明２种体系的差别较大。应用结果表明,工业乙醇／水体系的ＨＴＰＢ的工艺及力学性能优于后者。对工业乙醇／水体系ＨＴＰＢ在固体推进剂、水轮机及电子灌封等领域的应用进行了简述。     

Molecular Weight Distribution of Low Molecular Weight Polyols Derived from Fatty Acid Methyl Esters

A series of commercial polyether polyols with well-defined molecular weights (MW) was used along with propylene glycol and dipropylene glycol as gel permeation chromatography (GPC) calibration standards to determine the MW and oligomeric composition of the synthesized low MW fatty acid methyl ester (FAME) polyols, having an MW of lower than 600 Da. This GPC analysis was compared to the one calibrated against the commercially-available polystyrene (PS) standards and to the number-average molecular weight (M _n) obtained via vapor pressure osmometry (VPO) technique. The MW of FAME polyols obtained with GPC calibrated against polyether polyols were closer to the M _n values obtained via VPO than the MW obtained via GPC calibrated against PS standards. Using the reliable GPC calibration, the MW distribution and the hydroxyl functionality of FAME polyols were determined with greater confidence.     

Molecular characterization of hydroxyl-terminated polybutadienes

A comparative study has been made on the functionality distribution of two hydroxyl terminated polybutadiene products which are used largely as prepolymers for sealants, adhesives, and solid propellants. They are known to possess nearly the same molecular characteristics. To this end, each product was fractionated into 17 fractions with different molecular weights by the preparative GPC technique. Sample fractions thus obtained were subjected to “polarity-controlled adsorption” thin-layer chromatography (TLC) to determine the functionality distribution. From these experimental results it was concluded that a decisive difference between these products consists in the functionality distribution, within a molecular weight range higher than 7000.     

高拉伸强度高伸长率丁羟弹性体的研究进展

综述了影响丁羟弹性体力学性能的几种关键因素,包括固化参数、固化剂类型、扩链剂类型等,对比了几种提高丁羟弹性体力学性能的方法及其研究进展。提出了通过合成具有不同官能度的窄分子质量分布的丁羟液体橡胶,并进行复配研究,将是制备高拉仲强度、高伸长率丁羟弹性体的研究方向。