可作为标样的端羟基聚丁二烯的合成与表征

采用阴离子聚合法合成出了一系列分子量分布窄、主链微观结构可调、官能度接近理想值2的端羟基聚丁二烯样品。通过HNMR、FT-IR、VPO、GPC等方法对其进行了表征,结果表明,样品分子量分布指数1.05,主链1,2微观结构含量可在10.02%～94.80%之间调节。展望了端羟基聚丁二烯作为GPC的标准样品,在示差/紫外(RI/UV)双检测器凝胶渗透色谱(GPC)测定端羟基聚丁二烯聚合物分子量分布及官能度分布中应用的重要意义。     

羟基封端聚月桂烯的制备及测试

以过氧化氢为引发剂、正丁醇为溶剂,月桂烯在100℃左右进行聚合,制得了羟基封端的低分子量聚月桂烯。此聚合物的分子量,分子量分布以及官能度皆与引发剂的浓度有关,其分子量及官能度分别为2000～5000和1.3～2.6。将所得聚合物的热重分析和差热扫描量热分析结果均和商品羟基封端聚丁二烯(Arco RH45-HT)的测定结果进行了比较。以红外光谱和核磁共振谱研究聚合物的微结构,提出了依据核磁共振谱计算微结构的新算式。分析结果说明聚合时链的增长主要是以1·4加成进行。     

溶聚丁苯橡胶玻璃化转变温度的主要影响因素研究

采用活性阴离子聚合方法和分子结构设计技术制备出具有不同分子结构参数的溶聚丁苯橡胶(SSBR)。研究了SSBR的结合苯乙烯含量、1,2-聚丁二烯含量、分子量、分子量分布(聚合物分散性指数PDI)以及嵌段结构等对SSBR生胶玻璃化转变温度的影响。结果表明,结合苯乙烯含量、1,2-聚丁二烯含量和嵌段结构是溶聚丁苯橡胶玻璃化转变温度的主要影响因素,对阻尼性能有着显著影响。     

端羟基聚丁二烯改性聚醚酯弹性体的合成与表征EI北大核心CSCD

以对苯二甲酸二甲酯(DMT)、1,4丁二醇(BD)、聚四氢呋喃醚(PTMG)和端羟基聚丁二烯(HTPB)为原料,采用熔融缩聚方法一步合成了一系列端羟基聚丁二烯改性的聚醚酯弹性体(PBT-co-PTMG/HTPB)。通过红外、核磁和凝胶色谱等分析方法对其分子结构和分子量进行了表征;测定了聚合物的热性能和物理力学性能。结果发现,随着PBT-co-PTMG/HTPB共聚物中端羟基聚丁二烯含量的增加,数均分子量逐渐增大,最高突破8万;玻璃化转变温度由-25℃降低到-65℃,耐低温性能得到明显改善;共聚物力学性能测试结果表明,当HTPB的质量分数在10%以下时,其强度和断裂伸长率随着HTPB含量的增加而变大,但是质量分数超过10%以后,材料的强度和断裂伸长率随其含量的增加而变小。     

羧基官能化聚丁二烯:点击化学合成及对环氧树脂的固化机理

采用"巯基-乙烯"点击化学的方法合成了羧基官能化聚丁二烯,以此为固化剂成功得到了环氧热固性树脂。通过核磁共振氢谱(1 H NMR)、傅里叶红外光谱(FTIR)对羧基官能化聚丁二烯进行了化学结构表征;此外,用傅里叶红外光谱(FTIR)追踪了固化反应过程并探讨了羧基官能化聚丁二烯固化环氧树脂的机理;采用差示扫描量热法(DSC)表征聚丁二烯和羧基官能化聚丁二烯的热性能。结果表明,成功合成的羧基官能化聚丁二烯较聚丁二烯有较高的玻璃化转变温度,其固化环氧树脂是通过羧基官能化聚丁二烯分子链上含有的多个羧基与环氧基开环加成生成酯基和羟基。在本实验固化条件下,固化剂与环氧树脂的质量比为3∶7便可使环氧树脂完全固化。     

端羟基聚丁二烯改性聚醚酯弹性体的合成与表征

以对苯二甲酸二甲酯(DMT)、1,4丁二醇(BD)、聚四氢呋喃醚(PTMG)和端羟基聚丁二烯(HTPB)为原料,采用熔融缩聚方法一步合成了一系列端羟基聚丁二烯改性的聚醚酯弹性体(PBT-co-PTMG/HTPB)。通过红外、核磁和凝胶色谱等分析方法对其分子结构和分子量进行了表征;测定了聚合物的热性能和物理力学性能。结果发现,随着PBT-co-PTMG/HTPB共聚物中端羟基聚丁二烯含量的增加,数均分子量逐渐增大,最高突破8万;玻璃化转变温度由-25℃降低到-65℃,耐低温性能得到明显改善;共聚物力学性能测试结果表明,当HTPB的质量分数在10%以下时,其强度和断裂伸长率随着HTPB含量的增加而变大,但是质量分数超过10%以后,材料的强度和断裂伸长率随其含量的增加而变小。     

基于梳状结构的复杂交联聚己内酯的合成及形状记忆行为

以正丁基锂为引发剂,通过活性阴离子聚合得到窄分布的聚丁二烯,然后通过环氧化和羟基化反应得到多羟基聚丁二烯.并以多羟基聚丁二烯作为大分子引发剂,通过开环聚合方法合成了梳状聚己内酯(gPCL),通过核磁共振波谱和凝胶渗透色谱测定结构信息,证明得到了分子量分布窄(PDI<1.18)的具有接枝结构的梳状聚己内酯.通过合成的梳状...     

用γ—丁内酯制备丁羟胶的研究

本文详细研究了(?)丁内酯与活性聚丁二烯锂的反应机理和产物:探讨了高活性种浓度下影响聚丁二烯微观结构的因素;用萘-锂络合物作为引发剂,在抽余油中合成了高乙烯基含量,多官能度的丁羟胶。     

保护性基团法合成液体丁羟预聚物的研究

本文首先考察了自制保护性基团引发剂的基本性质;继而在抽余油中引发了丁二烯的活性阴离子聚合;经环氧乙烷终止、缩醛水解两步反应,得到了1,2-结构含量为30％,分子量分散系数在1.2左右,官能度大于1.88的液体丁羟预聚物。     

端羟基聚丙烯酸丁酯的合成与表征

以α-溴代异丁酸乙酯为引发剂,采用原子转移自由基聚合(ATRP)合成了分子量为500的聚丙烯酸丁酯。以N-甲基单乙醇胺作为亲核试剂,对带有活性溴端基的聚丙烯酸丁酯进行亲核取代反应,得到了一端带有羟基的聚丙烯酸丁酯。利用红外光谱仪、核磁共振谱仪、凝胶渗透色谱仪等对产物的结构进行表征。结果表明,成功合成了端羟基聚丙烯酸丁酯,且聚合物分子量可控,分子量分布窄(PDI=1.09)。     

超支化聚醚/丁羟聚氨酯互穿网络的制备及力学性能

本文采用阳离子开环聚合的方法,合成了端羟基超支化聚醚,并对其端基进行改性,调节超支化聚醚与丁羟聚氨酯的相容性。采用FT-IR,1H-NMR对改性前后超支化聚醚进行结构表征。HTPB型聚氨酯在改性超支化聚醚的存在下原位聚合形成超支化聚醚/丁羟聚氨酯互穿聚合物网络,力学性能测试结果表明,加入超支化聚醚可以明显提高HTPB型聚氨酯胶片的力学性能。其中加入30%第4代改性超支化聚醚时,其最大拉伸强度提高了3.86倍,达到2.65 MPa。最大延伸率提高了3.7倍,达到1868%。     

Effect of Humic Substances on Plutonium and Americium Speciation in Soils and Soil Solutions

The molecular-weight distribution of humic substances (HSs) of the organic and mineral soils and corresponding soil solutions was studied by gel chromatography, and their distribution over fractions of humus acids was evaluated by the Ponomareva-Plotnikova chemical fractionation technique. Distribution of ^239,240Pu and ²⁴¹Am over HS fractions of different dispersity was studied. In these fractions, HSs are associated with different mineral components and have different solubility and mobility. Plutonium and americium are more strongly associated with humic substances of organic soils as compared to those of mineral soils. Therefore, in passing from mineral to organic soils, the migration ability of radionuclides decreases. These effects are caused by qualitative difference in the HS chemical composition of the HSs of organic and mineral soils. As compared to plutonium, americium enters the composition of poorly soluble organomineral complexes to a smaller extent, forming to a greater extent mobile anionic complexes in the soil solutions. This difference can be responsible for enhanced americium mobility and its easier availability to plants.     

不同端基改性超支化聚酯/丁羟聚氨酯互穿聚合物网络力学性能研究

采用硬脂酸和乙酸酐对端羟基超支化聚酯的端基进行改性,并将其与端羟基聚丁二烯型聚氨酯(丁羟聚氨酯)形成互穿聚合网络。结果表明,硬脂酸改性超支化聚酯/丁羟聚氨酯互穿聚合物网络的最大强度和最大延伸率均比空白胶片提高了3倍以上,而乙酸酐改性的超支化聚酯与丁羟聚氨酯形成的互穿聚合物网络存在明显的相分离。     

不同1,2-结构含量聚丁二烯的自由基接枝反应

以正丁基锂为引发剂,四氢呋喃为结构调节剂,通过丁二烯的活性负离子聚合制备出不同1,2-结构含量的低相对分子质量且分布窄的模型聚丁二烯(PB)。以过氧化苯甲酰(BPO)为引发剂,2,2,6,6-四甲基哌啶-1-氧基自由基(TEMPO)为自由基捕捉剂,进行模型PB的自由基接枝反应。采用核磁共振氢谱对模型PB接枝产物的微观结构、TEMPO及BPO残基的含量进行了分析表征。实验结果表明,PB的自由基接枝反应以夺氢反应为主,同时1,2-结构含量对PB自由基接枝反应有着重要的影响。随1,2-结构含量增加,自由基接枝反中夺氢反应比例增大,当1,2-结构含量达到53.6%时,其自由基接枝反应全部为夺氢反应而无加成反应存在。     

Functionalization of hydroxyl terminated polybutadiene with biologically active fluorescent molecule

A biologically active molecule, 2-chloro-4,6-bis(dimethylamino)-1,3,5-triazine (CBDT), has been covalently attached at the terminal carbon atoms of the hydroxyl terminated polybutadiene (HTPB) backbone. The modification of HTPB backbone by CBDT molecule does not affect the unique physico-chemical properties such as fluidity, hydroxyl value and microstructure of the parent HTPB. The formation of hydrogen bonding between the terminal hydroxyl groups and the nitrogen atoms of triazine moiety is the driving force for the terminal attachment chemistry. The functionalized HTPB (HTPB-CBDT) shows a strong fluorescence emission at 385 nm.     

聚丁二烯型丙烯酸羟基酯的紫外光固化行为

通过改变紫外光的光强,光致引发剂的种类和浓度,以及活性稀释剂三羟基甲丙烷三丙烯酸的浓度,研究了１００％和局部丙烯酸酯化的液体环聚丁二烯型丙烯酸羟基酯的有关光固化,热固化和光热联立固化行为,研究了酯化度不同的大分子丙烯酸羟基酯固化体系,在不同紫外光强下的热焓及双键转人率,并讨论了有关光致引发体系的诱导期和反应机制。     

二丁基镁对镍催化体系合成高顺式聚丁二烯的影响

采用二丁基镁(M gBu2)部分或全部代替三异丁基铝(A l(i-Bu)3)作为镍催化体系的烷基化试剂,构成N i(naph)2-M gBu2-BF3OE t2体系和N i(naph)2-A l(i-Bu)3-M gBu2-BF3OE t2体系合成高顺式聚丁二烯橡胶。研究了体系在不同陈化方式和温度下的聚合反应动力学,并对聚合产物进行了测试表征。动力学研究结果表明,M gBu2的加入能增大N i-A l-B体系的聚合反应活性,且N i-M g-B体系的聚合反应活性明显高于N i-A l-B体系和N i-A l-M g-B体系;聚合产物测试结果表明,聚丁二烯的顺1,4-结构稍有下降,其相对分子质量、分子量分布以及门尼黏度等基本保持不变。     

Role of the rubber particle and polybutadiene cis content on the toughness of high impact polystyrene

High impact polystyrene (HIPS) is a classical reactor polymer blend produced by in situ polymerization of styrene in solution with polybutadiene rubber. The importance of the particle size and rubber crosslink density on the particle cavitation capability and the controlling of toughening mechanisms in the styrenic matrix is well established in current literature. In the present work, the role of the rubber particle on the HIPS toughness has been investigated for two commercial grades with low and high cis polybutadiene. Transmission electron microscopy (TEM) was employed for observation of particle size distribution and digital imaging applied for quantitative analysis of the micrographs. Measurements of apparent volume fraction and average particle size were determined in TEM images for both grades, while the gel content and swelling index were employed to evaluate the effect of the polybutadiene cis isomer on the rubber crosslink density. Grade morphology and crosslink effects on mechanical properties were assessed by slow three-point bending and uniaxial tensile testing. The results illustrate that polybutadiene cis content in HIPS grades has strong influence on the mechanical properties, particularly affecting yielding and energy to failure. Accordingly, it was observed that HIPS grades with equivalent average particle size and apparent volume fractions present a much higher energy to failure and a lower yield stress with high cis content polybutadiene when compared to their lower cis polybutadiene counterparts.     

Precipitation Behaviour of Photographic Gelatin with Alcohol

Precipitation behaviour of gelatin with alcohol has been examinai by precipitation curves and SDS electrophoresis. The precipitability of normal gelatin is almost the same although the molecular-weight distribution is not. The precipitability of deionized gelatin is low and sensitive to pH and other conditions. This may be the reason for the apparent variety in the precipitability of gelatin samples. SDS electrophoretic patterns of normal gelatin clearly show that the average molecular-weight of each precipitate is higher than the corresponding supernatant. However, this is not the case for deionized gelatin.     

环氧化端羟基聚丁二烯改性环氧树脂隔热涂层的研究(英文)

本研究采用自制环氧值为0.19的环氧化端羟基聚丁二烯(EHTPB)改性以双酚A型环氧树脂为基体的隔热涂层材料,以提高涂层材料断裂伸长率为主要目标,研究了EHTPB与环氧树脂的质量配比,甲苯二异氰酸酯含量以及低分子量聚酰胺固化剂含量对改性体系拉伸断裂伸长率及断裂强度的影响规律,改性结果表明,隔热涂层的断裂伸长率从未改性时的0.25%提高到改性后的30.84%,超过了实际应用的需求(≥5%).同时热重分析的结果表明改性后涂层能更好地适应高温下的性能要求。