An experimental and theoretical study of the PVT equation of state of butadiene and isoprene elastomers to 200°C and 200 MPa

We have performed and analyzed extensive pressure-volume-temperature (PVT) measurements on uncrosslinked polybutadiene and polyisoprene elastomers from ambient temperature to about 200°C and 200 MPa. In the polybutadiene series, 1,2 content varied from 8 to 87%, the remainder being similar amounts of cis-1,4 and trans-1,4. In the polyisoprene series the 3,4 content varied from 8 to 64%, the trans-1,4 content was 12–16%, and the remainder was cis-1,4, with < 4% 1,2 content. We report parameters describing the experimental data in terms of the empirical Tait equation, the cell model, the Simha-Som-cynsky equation, the Sanchez-Lacombe, and the Flory-Orwoll-Vrij models. In general the parameters show systematic changes with the microstructure content. The agreement between theory and experiment is excellent for the Tait equation, and also for the Simha-Somcynsky model and the cell model. The maximum deviation between theory and experiment was less than 0.004 cm³/g for the Simha-Somcynsky theory, and less than 0.005 cm³/g for the cell model. Average absolute deviations are three to four times less. For the Sanchez-Lacombe and the Flory-Orwoll-Vrij models, the maximum deviations are 5–8 times as large, and very systematic. Parameter derived from the Simha-Somcynsky theory are discussed with respect to the microstructure, and with respect to the glass transition of these two series of materials. © 1993 John Wiley & Sons, Inc.     

Cure characterization of rubber modified epoxy novolacs

A new type of toughened epoxy polymer based on epoxy cresol novolac resin (ECN) and carboxy terminated polybutadiene (CTPB) liquid functional rubber has been studied. ECN has been synthesized in the laboratory and CTPB used was also of indigenised origin. Rubber modified epoxies were characterized with the help of differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM) techniques.     

聚丁二烯聚氨酯(脲)

综述了聚丁二烯聚氨酯（脲）的结构与性能，影响性能的因素和改性方法，并简要介绍了其应用。     

Molecular mobility in rubbery composites: Effect of filler particle size

We have measured proton NMR T₂ relaxation spectra in Arco R45M OH-terminated poly-butadienes (PBs) cured with isophorone diisocyanate and filled with 65 wt % SiO₂ particles of each of six different average sizes. Identifying the short T₂ component with the gel, we find that the gel fraction is displaced from nominal NCO/OH stoichiometry, probably as a result of water adsorbed on filler particle surfaces. Near effective stoichiometry and in the presence of filler, molecular and segmental mobilities decrease, most strongly in specimens with the smallest filler particles. Comparison with parallel Monte Carlo simulations of the PB matrix geometry indicates that segmental mobility and sol migration decrease uniformly in a wide vicinity of the filler particles. Thus the rigidification of the matrix measured via NMR has a range of approximately 1-3 μm from nearby filler particle surfaces, representing the rms diffusion distance of the light components of the sol during the T₂ relaxation. © 1993 John Wiley & Sons, Inc.     

液体聚丁二烯原位涂层研究——Ⅰ.LPB在碳钢表面的成膜层及其缓蚀性能

采用乳化或接枝共聚合引进—COOH,—OH亲水基团后的液体聚丁二烯,溶于模拟碳钢酸洗液中,在过氧化物与碳钢腐蚀产物所组成的氧化还原引发体系的作用下,于“金/溶”界面聚合成膜。失重试验结果表明膜层的缓蚀性能取决于乳液体系的成份,浓度和温度等。文中探讨了这一聚合作用的机理。     

丁苯接枝的高乙烯基聚丁二烯橡胶合成及其与丁苯橡胶的相容性研究

以n-BuLi为引发剂,THF为结构调节剂合成一定分子量和苯乙烯结构单元含量的丁苯大分子(SB).在SB的加氢汽油溶液中用Mo-Al(正辛醇取代的MoCl5和Al(OPhCH3)(i-Bu)2)催化丁二烯配位聚合制备丁苯接枝的高乙烯基聚丁二烯橡胶(SB-grafted HVPBR).接枝结构是通过聚丁二烯活性链与SB分...     

聚丁二烯丙烯酸酯液态光学透明胶的合成及其UV固化膜的性能

针对丙烯酸酯大单体在合成过程中常带有颜色,以及由其制备的液态光学透明胶的UV固化膜易黄变的问题,本文报道了一条新的大单体合成路线:首先以端羟基聚丁二烯(HTPB)、萘钾、丙烯酰氯(AC)为原料,通过一锅法合成了一种无色透明的聚丁二烯丙烯酸酯大单体(PBAM);然后将PBAM与丙烯酸酯活性稀释单体、光引发剂混合,制备了液态光学透明胶;最后通过UV固化制备了一系列无色透明的薄膜。利用GPC、1H-NMR、FTIR等手段对PBAM进行了表征;进一步研究了液态光学透明胶UV固化膜的光学性能、耐黄变性能、耐低温性能等。结果表明:基于新路线合成的PBAM呈现无色透明,液态光学透明胶的UV固化膜展现出优良的光学性能和耐黄变性能,固化膜透光率高达98%;经紫外线加速老化264h后,色差(ΔE)≤1.5;此外,该固化膜还具有优良的耐低温性能,玻璃化转变温度为-30℃。     

Evaluation of the 3-hydroxy pyridine antioxidant effect on the thermal-oxidative degradation of HTPB

The effect of the mixture of two antioxidants has been evaluated on the thermal-oxidant degradation of the hydroxyl-terminated polybutadiene (HTPB) because of its importance in the coatings and adhesives industries. 2,2-Methylene bis(4-methyl-6-tertiarybutylphenol) or A.O.2246 and 3-hydroxy pyridine have been considered as antioxidants in this study as a common HTPB antioxidant and an active antioxidant, respectively. The thermal-oxidant degradation behavior of the HTPB has been investigated in the presence of a mixture of two antioxidants by TGA and DTG tests, and, subsequently, the results of these tests have been interpreted by two model-free methods, e.g., Kissinger–Akahira–Sunose and Friedman methods. The results revealed that the mixture of two antioxidants affected the activation energy of the thermal-oxidant degradation reaction of the HTPB. The calculated activation energy value obtained from the Kissinger–Akahira–Sunose method was about 199 ± 1 kJ⋅mol⁻¹. In addition, the E_a value at various conversion rates has also been calculated by using the Friedman method. This method showed that the highest E_a value in the thermal-oxidant degradation reaction belonged to the initiation step of the reaction (about 299 kJ⋅mol⁻¹). Moreover, the lowest activation energy value was correlated to the second step of the degradation reaction at a conversion rate of 0.6 (about 184 kJ⋅mol⁻¹).     

Influence of polar modifiers on microstructure of polybutadiene obtained by anionic polymerization. Part 3: Lewis acid alkoxide (μ) and Lewis base amine,amine-ether,and ether mixed-type (σ+μ) polar modifiers

The influence of mixtures of sodium mentholate (SMT) as a Lewis acid polar modifier and different Lewis base polar modifiers (amines, amine-ethers, ethers) on the microstructure of polybutadiene obtained by anionic polymerization was studied and compared to the influence of the same polar modifiers used separately. Detailed characterization of the polybutadienes in terms of the content and distribution of butadiene isomeric repeating units was performed by ¹³C NMR and supported by FT-IR-ATR and ¹H NMR data analysis. The results obtained indicated that the use of a mixture of Lewis acid and Lewis base in most cases enhanced formation of 1,2 butadiene structures in comparison to the Lewis bases used separately. However, application of a mixture of SMT and DTP resulted in lower vinyl content than when DTP was applied alone. It is worthwhile to note that the combination of a Lewis acid (SMT) and one of Lewis bases tested (DMEAEE) enabled obtaining very high vinyl polybutadiene (88% ¹H NMR, 96% ¹³C NMR).     

Improving the Mechanical Properties of Glycidyl Azide Polymeric Matrix Used in Composite Solid Rocket Propellant by Adding Advanced Cross‐Linker

Glycidyl azide polymer (GAP) based binders have poor mechanical characteristics in comparison with hydroxyl terminated polybutadiene (HTPB) binders. In this study, advanced cross‐linker was used to improve the mechanical properties of GAP binder. GAP was prepared and characterized in comparison with HTPB prepolymer. Density, characteristics groups, nitrogen content, humidity, viscosity, and milligram equivalent of (OH) per binders were determined. A cross‐linker consists of trimethylol propane (TMP) and curing catalyst, dibutyltin dilaurate (DBTDL), was used as an additive to GAP polymeric matrix to enhance its functionality. Polymeric matrices based on GAP and HTPB were prepared with different curing ratio (NCO/OH) ranging from 0.7 to 1.5. Different weight percentages of cross‐linker were added to study its effect on the mechanical properties of GAP matrix. Five samples based on HTPB polymer and twenty samples based on GAP polymer were prepared. A LLOYD testing machine was used to determine the stress‐strain curves of all the studied samples. It was concluded that the cross‐linker used has significant influence on the characteristics of GAP polymeric matrix. Also the addition of 5 wt % of cross‐linker to GAP matrix at curing ratio = 1 produced optimum mechanical characteristics very close to that of HTPB matrix used in composite solid rocket propellants (CSRP). The optimum GAP polymeric matrix is candidate to replace the traditional HTPB binder in advanced CSRP.