环氧化端羟基聚丁二烯改性氰酸酯树脂体系研究

采用环氧化端羟基聚丁二烯(EHTPB)对双酚A型二氰酸酯树脂(BADCy)进行增韧改性。运用差示扫描量热法分析改性体系的反应性,发现EHTPB对BADCy的固化反应有一定的催化作用。采用傅立叶变换红外光谱仪、扫描电子显微镜和广角X射线衍射仪等表征共混物的结构特征,研究增韧改性机理,并对固化产物进行热重分析和力学性能测试。结果表明,EHTPB能在不显著降低体系热稳定性的同时改善体系的韧性,使得改性树脂具有较好的综合性能。     

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。     

EHTPB-TDI和HTPB-TDI固化反应的比较与分子模拟研究

对环氧化端羟基聚丁二烯(EHTPB)、端羟基聚丁二烯(HTPB)或EHTPB/HTPB(摩尔比1/1)与固化剂甲苯二异氰酸酯(TDI)的固化反应效果进行了比较。采用Materials Studio Modeling软件,对EHTPB固化反应机理及活化能进行了理论计算。结果表明,EHTPB-TDI体系的反应比HTPB-TDI快,具有较短的固化时间,其适用期比HTPB-TDI体系要短;EHTPB-TDI的反应活化能为364.9 k J/mol,较HTPB-TDI的活化能要小,也说明EHTPB反应活性高于HTPB。     

端羟基聚丁二烯液体橡胶的环氧化研究

采用过氧甲酸原地法对端羟基聚丁二烯液体橡胶(HTPB)进行环氧化,通过过氧化氢消耗率、环氧值及开环几率详细讨论了反应温度、反应时间、原料配比等因素对环氧化反应影响的规律。并对环氧化产物(E HTPB)的固化性能进行了研究,实验表明EHTPB用于环氧树脂改性时有较好的共混相容性,能显著提高环氧树脂固化物的柔韧性和耐热性。     

端羟基聚丁二烯橡胶增韧环氧树脂的研究

研究了端羟基聚丁二烯(HTPB)液态橡胶对环氧树脂的增韧作用。实验证明,HTPB对环氧树脂有较好的增韧效果,特别是具有良好的抗低温开裂性能。从相分离和动态力学分析的角度对其进行了讨论,还对HTPB与端羟—端羧聚丁二烯(HCTPB)的增韧作用进行了比较。     

双酚A在HTPB和HCTPB增韧的环氧树脂中的作用

本文研究了双酚A在端羟基聚丁二烯(HTPB)增韧及端羟基端羧基聚丁二烯(羟羧橡胶HCTPB)增韧的环氧树脂中的作用。对其增韧效果进行了实验测定,并用动态力学分析和扫描电镜对双酚A的作用机理进行了初步探讨。     

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。     

HTPB液体橡胶/纳米SiO2协同增韧环氧树脂的研究

为了解决单一材料改性环氧树脂(EP)综合性能不足的问题，采用端羟基聚丁二烯(HTPB)和纳米二氧化硅(SiO₂)对EP进行协同改性。结果表明：HTPB的端羟基和纳米SiO₂表面的硅羟基可以与树脂基体的环氧基团反应，形成良好的界面结合。HTPB可以显著提升EP的韧性，但增强作用有限，且耐热性较差。纳米SiO₂能够起增强、增韧作用，同时也具有很好的热稳定性，但增韧效果不如HTPB。采用两者共同改性EP，具有很好的协同增强增韧效果。当HTPB添加量为3份、纳米SiO₂添加量为1份时，复合材料的拉伸强度、弯曲强度和冲击强度相比于未改性EP，分别提升52.3%、54.0%和106.5%。添加HTPB和纳米SiO₂后，复合材料相比纯EP具有更低的介电常数。     

硝酸酯基端羟基聚丁二烯合成、结构表征及性能评价

通过正交实验采用稀硝酸硝化环氧基端羟基聚丁二烯(EHTPB)对硝酸酯基端羟基聚丁二烯(NHTPB)进行了合成,采用FT–IR对NHTPB样品进行了结构表征,采用DSC、TGA–DTA研究了样品热稳定性,并对样品进行了撞击感度测试。测试结果表明,样品结构中存在硝酸酯基,撞击感度低,安全性能好,热稳定性良好;用户使用结果表明,样品与硝酸酯含能增塑剂相容性好,NHTPB黏合剂配方比端羟基聚丁二烯(HTPB)黏合剂配方燃速提高了2 mm/s,可满足配方使用要求。     

HTPB–异氰酸酯体系固化影响因素的研究进展

综述了端羟基聚丁二烯(HTPB)–异氰酸酯体系固化过程中常见的几种主要因素,如固化剂、催化剂、扩链剂等对固化反应的影响。认为聚丁二烯结构单元的疏水性和较低的玻璃化温度,使HTPB基聚氨酯与通常的聚醚或聚酯系聚氨酯相比,产品在低温下呈现更好的耐水解性和更高的弹性。     

Simultaneously enhanced impact strength and dielectric properties of an epoxy resin modified with EHTPB liquid rubber

To simultaneously improve the impact strength and dielectric properties of cured epoxy (EP), herein we explore liquid rubber toughened EP based on a nonpolar epoxidized hydroxyl-terminated polybutadiene (EHTPB), where the rubber is covalently bonded to the EP. Fourier transform infrared and nuclear magnetic resonance proved the chemical reaction between EHTPB and EP, which makes the immiscible EHTPB-EP blend change to compatible one. The results indicate that both the impact strength and dielectric properties can be visibly enhanced with the addition of EHTPB and the maximum values are obtained at 10 phr of EHTPB loading. The improved mechanical toughness can be ascribed to the extensive shear yielding induced by the uniformly dispersed EHTPB domains and the enhanced interfacial compatibility between the two components. Moreover, the enhanced electrical resistivity and dielectric breakdown strength as well as the reduced dielectric constant and loss for the EHTPB-EP can be attributed to the combination of the excellent insulating properties of HTPB and dielectrically favorable interfaces. Therefore, the EHTPB-EP with a concurrent improvement in impact strength and dielectric properties can be used as promising insulating materials for high-frequency microelectronics and high-voltage electrical equipment.     

Modification of epoxy resin by isocyanate‐terminated polybutadiene

Hydroxy‐terminated polybutadiene was functionalized with isocyanate groups and employed in preparation of a block copolymer of polybutadiene and bisphenol A diglycidyl ether (DGEBA)‐based epoxy resin. The block copolymer was characterized by Fourier transform infrared (FTIR) spectroscopy and size‐exclusion chromatography (SEC). Cured blends of epoxy resin and hydroxy‐terminated polybutadiene (HTPB) or a corresponding block copolymer were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMTA), and scanning electron microscopy (SEM). All modified epoxy resin networks presented improved impact resistance with the addition of the rubber component at a proportion up to 10 wt % when compared to the neat cured resin. The modification with HTPB resulted in milky cured materials with phase‐separated morphology. Epoxy resin blends with the block copolymer resulted in cured transparent and flexible materials with outstanding impact resistance and lower glass transition temperatures. No phase separation was discernible in blends with the block copolymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 838–849, 2002     

High-toughness,environment-friendly solid epoxy resins: Preparation,mechanical performance,curing behavior,and thermal properties

The development of a facile and efficient approach to prepare high-toughness epoxy resin is vital but has remained an enormous challenge. Herein, we have developed a high-performance environment-friendly solid epoxy resin modified with epoxidized hydroxyl-terminated polybutadiene (EHTPB) via one-step melt blending. The characterization, mechanical performance, curing behavior, and thermal properties of EHTPB-modified epoxy resin were investigated. EHTPB-modified epoxy resin exhibited excellent toughness with a 100% increase in elongation at break of tensile than that of neat epoxy resin. The transfer stress and dissipated energy in the rubber phase were predominant mechanisms of toughening. The toughening effect of EHTPB on solid epoxy resin was better than that of some of the previously reported liquid epoxy resins. Meanwhile, at 10 wt % of EHTPB loading, the EHTPB-modified epoxy resin displayed high strength and 22 and 101% improvement of flexural strength and impact strength, respectively. Moreover, at 10 wt % of EHTPB loading, the activation energy of EHTPB-modified epoxy resin for curing reaction decreased from 73.89 to 65.12 kJ·mol⁻¹, which is beneficial for the curing reaction. Furthermore, EHTPB-modified epoxy resin had a good thermal stability and the initial degradation temperature increased from 249 to 313 °C at 10 wt % of EHTPB loading. This work provides a simple-preparation and highly efficient and large-scale approach for the production of high-toughness environment-friendly solid epoxy resins. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48596.     

Chemical toughening of epoxies. II. Mechanical,thermal, and microscopic studies of epoxies toughened with hydroxyl-terminated poly(butadiene-co-acrylonitrile)

Diglycidyl ether–bisphenol-A-based epoxies toughened with various levels (0–12%) of chemically reacted liquid rubber, hydroxyl-terminated poly(butadiene-co-acrylonitrile) (HTBN) were studied for some of the mechanical and thermal properties. Although the ultimate tensile strength showed a continuous decrease with increasing rubber content, the toughness as measured by the area under the stress-vs.-strain curve and flexural strength reach a maximum around an optimum rubber concentration of 3% before decreasing. Tensile modulus was found to increase for concentrations below 6%. The glass transition temperature T_g as measured by DTA showed no variation for the toughened formulations. The TGA showed no variations in the pattern of decomposition. The weight losses for the toughened epoxies at elevated temperatures compare well with that of the neat epoxy. Scanning electron microscopy revealed the presence of a dual phase morphology with the spherical rubber particles precipitating out in the cured resin with diameter varying between 0.33 and 6.3 μm. In contrast, a physically blended rubber–epoxy showed much less effect towards toughening with the precipitated rubber particles of much bigger diameter (0.6–21.3 μm).     

Synthesis and characterization of siliconized epoxy-1,3-bis(maleimido)benzene intercrosslinked matrix materials

Intercrosslinked network of siliconized epoxy-1,3-bis(maleimido)benzene matrix systems have been developed. The siliconization of epoxy resin was carried out by using various percentages of (5-15%) hydroxyl-terminated polydimethylsiloxane (HTPDMS) with γ-aminopropyltriethoxysilane (γ-APS) as crosslinking agent and dibutyltindilaurate as catalyst. The siliconized epoxy systems were further modified with various percentages of (5-15%) 1,3-bis(maleimido)benzene (BMI) and cured by using diaminodiphenylmethane (DDM). The neat resin castings prepared were characterized for their mechanical properties. Mechanical studies indicate that the introduction of siloxane into epoxy resin improves the toughness of epoxy resin with reduction in the values of stress-strain properties whereas, incorporation of bismaleimide into epoxy resin improves stress-strain properties with lowering of toughness. However, the introduction of both siloxane and bismaleimide into epoxy resin influences the mechanical properties according to their percentage content. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and measurement of heat distortion temperature were also carried out to assess the thermal behavior of the matrix samples. DSC thermogram of the BMI modified epoxy systems show unimodel reaction exotherms. The glass transition temperature (T_g), thermal degradation temperature and heat distortion temperature of the cured BMI modified epoxy and siliconized epoxy systems increase with increasing BMI content and this may be due to the homopolymerization of BMI rather than Michael addition reaction. The morphology of the BMI modified epoxy and siliconized epoxy systems were also studied by scanning electron microscopy.     

HTPB引入方式对不饱和树脂改性效果的影响

以高顺式端羟基液体顺丁橡胶（HTPB）为改性剂,分别采用共混-共固化法、共缩聚法制备了共混改性型不饱和聚酯[UPR+HTPB(blend)]、无规共缩聚改性型不饱和聚酯（UPR-HTPB）和嵌段共缩聚改性型不饱和聚酯（UPR-MAH-HTPB）,系统地考察了三种改性不饱和聚酯固化样品的机械物理性能。结果表明,三种改性不饱和树脂的断裂伸长率、拉伸强度和冲击强度均优于未改性的不饱和树脂,固化收缩率大幅降低,且共缩聚改性树脂（UPR-HTPB和UPR-MAH-HTPB）的增韧效果和降收缩效果明显优于共混改性树脂。此外,UPRMAH-HTPB的拉伸模量也优于未改性的不饱和树脂,硬度和热变形温度则基本保持不变。冲击断面的形貌、交联密度和DMA分析表明,UPR+HTPB(blend)固化体系中存在着HTPB聚团的现象,而共缩聚改性树脂,尤其是嵌段型的UPR-MAH-HTPB,因HTPB嵌入到UPR的主链中,使HTPB微相分离,并更多地参与交联,在增韧的同时保持了树脂良好的刚性和强度。     

Epoxy resins toughened with in situ azide–alkyne polymerized polysulfones

To simultaneously improve the fracture toughness and heat resistance of a cured toughened epoxy resin along with a reduction in its viscosity during the mixing process, two novel polysulfone‐type polymers are synthesized via azide–alkyne polymerization for use as toughening agents. The epoxy resin toughened with these polymers by in situ azide–alkyne polymerization during the cure process, which shows excellent processibility and based on the significantly lower viscosity (61 and 62 cP) during epoxy mixing process than that of commonly commercial polyethersulfone (PES, 127,612 cP). The novel polysulfone‐type polymer toughened epoxy resin showed the advantage in excellent fracture toughness than the PES toughened epoxy. In addition, the glass transition temperature of the novel polysulfone‐type polymer toughened epoxy resin is similar to that of the neat one (～230 °C) and does not decrease, which implies excellent heat resistance of the toughened epoxy. These phenomena can be attributed to the formation of semi‐interpenetrating polymer networks comprising the epoxy network and the linear polysulfone‐type polymers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45790.     

Synthesis and architecture study of a reactive polybutadiene polyamine as a toughening agent for epoxy resin

In this study, a novel reactive toughener for the epoxy resin was developed and compared with traditional hydroxyl‐terminated polybutadiene (HTPB). For this purpose, the highly reactive aliphatic amine‐terminated polybutadiene (ATPB) was synthesized at ambient conditions by nucleophilic substitution amination. The characterizations of the product were provided by Fourier transform infrared and ¹H NMR spectroscopy. According to the mechanical test results, incorporation of ATPB into epoxy networks can significantly toughen the epoxy matrix. The addition of 10 phr ATPB increased the critical stress intensity factor (K_IC) and critical strain energy release rate (G_IC) of the epoxy from 0.85 to 2.16 MPa m^1/2 and from 0.38 to 3.02 kJ m^?2, respectively. Furthermore, unlike HTPB, the presence of the ATPB did not deteriorate the tensile strength of the matrix. The toughening and failure mechanisms were discussed based on the epoxy network morphological characteristics. The reduction in cross‐linking density and glass transition temperature of the epoxy system upon modification with liquid rubbers was confirmed by dynamic mechanical analysis. This article opens up the possibility of utilizing reactive flexible diamines with polybutadiene backbone as effective toughening agents for thermoset polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44061.