端氨基树枝状大分子/环氧树脂体系固化动力学的FTIR研究

用傅立叶变换红外光谱(FTIR)法研究了双酚A二缩水甘油醚环氧树脂(GEBA)用低代端氨基聚(酯-胺)树枝状大分子G1.0(NH2)3、G1.5(NH2)8和聚(胺-酰胺)树枝状大分子PAMAM1.0(NH2)4作为固化剂的等温固化动力学,得到了不同温度下转化率与固化时间及反应速率与固化时间的关系.与小分子固化剂相比,端氨基树枝状大分子作固化剂时环氧基转化率在反应开始时增长得更快,较高代树枝状大分子在高温下固化环氧树脂时尤其如此.在相同温度和时间下,PAMAM1.0(NH2)4/DGEBA、G1.0(NH2)3/DGEBA、G1.5(NH2)8/DGEBA体系的转化率依次增大.进一步估算了3个体系在一定转化率下的固化反应表观活化能.在相同转化率时,用G1.5(NH2)8、PAMAM1.0(NH2)4、G1.0(NH2)3作固化剂的体系表观活化能依次减小.     

水性环氧树脂固化反应的研究

通过测定凝胶时间,利用红外光谱仪、差示扫描量热仪等对水性环氧树脂的固化反应进行了研究,并根据K issinger和Ozawa方法分别求得水性环氧树脂体系固化反应的表观活化能。结果表明,凝胶时间随着环氧与胺氢物质的量比的增大而增加,且环氧与胺氢物质的量比为1∶1时较好。环氧基特征吸收峰的强度随着固化反应时间的延长明显变弱,且固化4 h后,环氧的特征峰几乎全部消失。水性环氧体系固化的初始温度、峰值温度和终止温度随着升温速率的增加,均向高温方向移动,用Kissinger和Ozawa法求得水性环氧树脂固化的表观活化能分别为27.35 kJ/mol、32.77 kJ/mol,表明体系的表观活化能很低,固化反应很容易进行。     

烯丙基双酚A型环氧树脂-环硫树脂固化反应的研究

以DADGEBA(烯丙基双酚A型环氧树脂)和DADGEBAES(烯丙基双酚A型环氧树脂-环硫树脂)分别作为基体树脂,以T33(酚醛胺类化合物)作为固化剂,制备相应的胶粘剂。采用在线FT-IR(红外光谱)法、DSC(差示扫描量热)法和Arrhenius方程对两种体系固化过程的特征吸收峰、放热焓和表观活化能等进行了表征和分析,并采用计算机软件模拟法计算出两种树脂单聚体的福井函数。研究结果表明:DADGEBAES/T33体系中的环硫基比DADGEBA/T33体系中的环氧基更易反应,前者的固化反应放热焓和表观活化能均小于后者;DADGEBAES中环硫基的福井函数分布多于DADGEBA中环氧基的福井函数分布,说明前者的反应活性更高。     

氨基-环氧基新型有机硅固化体系

以六甲基二硅氧烷、四甲氧基硅烷为原料合成了MQ树脂,然后与带环氧基的硅氧烷反应,合成了环氧基改性硅树脂;用γ-氨丙基三乙氧基硅烷合成氨基笼形倍半硅氧烷(氨基POSS)。并用红外光谱仪和X射线衍射仪表征了二者。将氨基POSS作为环氧基改性硅树脂的固化剂,利用多氨基和环氧基的开环加成反应组成一种新型有机硅固化体系。考察了环氧基改性硅树脂与氨基POSS的质量比对固化体系表干时间及固化物硬度的影响、固化物的耐热性。结果表明,环氧基改性硅树脂与氨基POSS的质量比为100∶1～150∶1时,表干时间较快,固化物表面光滑平整、硬度较好;环氧基改性硅树脂与氨基POSS的最佳质量比为100∶1;此固化体系室温下的操作时间较长,放置4周后黏度上升不超过15%;差热分析结果显示,固化物在40～300℃时的质量损失率为5%左右,分解温度在450℃左右,在681.28℃时的残留率仍有53%。     

非离子型自乳化水性环氧固化剂的合成与性能

常用的环氧-多胺加成物类阳离子水性环氧固化剂因使用挥发性有机酸成盐而给涂膜性能及环境保护带来不利的影响.开发非离子型水性环氧固化剂是其发展趋势之一.目前,文献报道的非离子型水性环氧固化剂的制备工艺一般比较复杂.今采用聚醚多元醇二缩水甘油醚(DGEPG)、三乙烯四胺(TETA)及液体环氧树脂(EPON828)为原料,采用二步扩链法合成一种新的非离子型自乳化水性环氧固化剂.首先通过滴加DGEPG到TETA的丙二醇甲醚(PM)溶液中进行扩链反应,在固化剂分子中引入亲水性的柔性聚醚链段.考察了物料摩尔比(TETA/DGEPG)、反应温度、反应时间对DGEPG环氧转化率的影响.然后滴加EPON828到TETA-DGEPG加成物的PM溶液中进一步扩链反应,在固化剂分子中引入环氧树脂分子链段,以提高固化剂与环氧树脂的相容性.考察了反应温度、反应时间对EPON828环氧转化率的影响.最后减压蒸馏除去大部分的PM溶剂后,在50～60℃温度范围内,滴加蒸馏水到TETA-DGEPG-EPON828加成物中,将其稀释到固含量为50%～55%左右,最终制备出一种新的非离子型自乳化水性环氧固化剂,其制备工艺比较简单.实验结果表明所合成出的新的非离子型水性环氧固化剂具有良好的乳化液体环氧树脂的功能,与液体环氧树脂所形成的双组分室温固化涂膜性能优良,具有良好的柔韧性和耐冲击性,同时改善了普通环氧树脂固化后性能较脆的缺陷.     

含联萘结构环氧树脂的合成、固化动力学及其性能

合成了两种含联萘结构的环氧树脂2,2'-二(9-环氧基壬酰氧基)-1,1'-联萘(R1)和2,2'-二(3-环氧基丙酰氧基)-1,1'-联萘(R2)。通过1HNMR和EA对目标产物结构进行了表征。以4,4'-二氨基二苯基甲烷(DDM)为固化剂,通过Ozawa法计算出R1/DDM和R2/DDM固化体系的反应活化能(E_a)分别为56.29和56.88 k J/mol,随着固化反应转化率(α)的增加,R1/DDM的E_a不断增大,而R2/DDM的E_a略微减小。考察了不同长度碳链对固化物的热稳定性、玻璃化转变温度(T_g)、力学性能和吸水率的影响。结果表明:短碳链的R2/DDM较长碳链的R1/DDM,固化物的初始分解温度由220.3℃下降到210.5℃,800℃下残炭率由3.45%上升至6.77%,T_g由135℃上升到141℃,断裂伸长率由6.7%下降至4.3%,吸水率由0.35%降至0.28%。     

环氧大豆油和CO_2合成环状碳酸酯及NIPU的研究

以环氧大豆油(ESBO)和二氧化碳为原料合成五元环状碳酸酯,然后与胺反应制备非异氰酸酯聚氨酯(NIPU)。通过环氧值测定、红外光谱分析考察了反应时间对合成环碳酸酯的影响,并研究了环氧大豆油的不同转化率、胺固化基团摩尔比对环碳酸酯经胺固化合成的NIPU综合力学性能的影响。结果表明,随着反应时间的延长,环氧大豆油的转化率逐步提高,反应40 h后,环氧大豆油的环氧基转化率达到99.8%;并且随着ESBO转化率的提高,合成的NIPU的力学性能越来越好;胺用量的增加有利于环碳酸酯转化成氨基甲酸酯,当环碳酸酯与胺的基团摩尔比为1∶1.0时,合成的NIPU综合力学性能最佳。     

EP/SAN共混物反应诱导黏弹相分离研究

利用差示扫描量热仪(DSC)和光学显微镜(OM)研究了苯乙烯-丙烯腈共聚物(SAN)用量以及反应温度对环氧树脂(EP)/SAN共混物反应诱导相分离的影响。同时,详细介绍了一种计算浊点转化率的方法。结果发现:不同SAN用量的EP/SAN体系最终形成了不同的相结构,而适量SAN的添加可使体系发生黏弹相分离,且反应温度越高,体系固化前相分离的程度越高。通过计算浊点转化率,可确定该EP/SAN体系为上临界会溶温度(UCST)体系。此外,体系反应诱导相分离时间与温度的依赖关系遵循Arrhenius方程,由该方程得到的体系分相活化能(Ea,ps)与SAN用量无关。     

拉挤成型用树脂配方体系的研究

通过对拉挤成型用树脂配方体系的研究,为拉挤用树脂配方的设计与改进提供思路与方向,从而满足拉挤生产中的不同需求。通过FTIR和GC-MS研究了树脂配方的成分,该配方主要由环氧/酸酐体系加上叔胺类促进剂以及添加剂组成;通过树脂凝胶试验仪和DSC研究了该树脂配方体系的固化反应行为,发现其在140℃时具有最短的凝胶时间(121.0 s)和固化时间(184.5 s),同时在升温速率为5℃/min时的最佳固化反应温度为136℃;对该树脂配方体系和环氧/酸酐体系固化物的力学性能、热变形温度进行了对比研究,发现该树脂配方体系在韧性较好的同时其热变形温度没有受到影响,进一步通过SEM研究发现拉挤用树脂配方体系为韧性断裂而环氧/酸酐树脂体系为脆性断裂。     

环氧—酚醛体系固化过程及固化工艺

树脂固化不完全与开裂是浸渍制品的两个主要质量问题。 本文在探讨树脂固化机理的基础上,用红外光谱追踪不同温度、不同时间环氧基的吸收峰变化,得到了环氧基的转化率随温度、时间变化的曲线。以环氧基的转化率作为固化度,以此建立了红外光谱测环氧树脂固化程度的方法。由此,得到了树脂完全固化所需的温度和时间。对等当量配比与固化剂不足之配比在固化速度与固化程度上进行了对比。 我们又在分析开裂原因的基础上,用热分析配合红外光谱找出环氧—酚醛体系固化过程的反应温度区及反应速度最快的温度点。提出了能防止产生破坏性内应力的升温程序和固化工艺。     

Epoxy layered-silicate nanocomposites

Polymer layered-silicate nanocomposites have attracted a lot of attention because of impressive enhancements of polymeric properties. In this research, both commercially available and synthesized organolayered silicates, which are compatible with the epoxy resins, were used to make epoxy nanocomposites. The epoxy resin used in this research includes Epon 862/curing agent W (the aerospace epoxy resin), the Epon 828/Epi-Cure curing agent 8290-Y-60 (used as the primer layer for corrosion prevention in aircraft coating), and Epon 828/Jeffamine D400. The morphology of the nanocomposites was characterized using wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The morphology development for the aerospace epoxy-organoclay nanocomposite was monitored through in situ SAXS and analyzed. The solvent absorption of the exfoliated aerospace epoxy-organoclay nanocomposite in acetone was examined, and the diffusion coefficients of solvent in the nanocomposites were reduced. The organoclay/Epon 828/Y-60 and organoclay/Epon 828/D400 nanocomposite were used to make coatings on an Al surface. The anticorrosion properties of the nanocomposite coating were evaluated and discussed.     

Curing behavior of dicyandiamide/epoxy resin system using different accelerators

Various amounts of dicyandiamide (Dicy), two grades of epoxy resins, i.e. Epiran 06 and Epikote 828, and three different accelerators including benzyl dimethyl amine (BDMA), 3-(4-chlorophenyl)-1,1-dimethyl urea (Monuron) and 2-methyl imidazole (Im) were used in curing of Dicy/epoxy resin system. Both of the used epoxy resins were based on diglycidyl ether of bisphenol A (DGEBA). The effects of type and concentration of accelerators on curing behavior were studied by differential scanning calorimetry (DSC) method in dynamic or non-isothermal mode. The optimum concentration of Dicy for curing of epoxy resins was obtained based on the glass transition temperature of the cured epoxy/Dicy formulations. The maximum glass transition temperature of 139 °C was obtained at the stoichiometric ratio of Dicy to epoxy of 0.65. The results showed that BDMA has a broader curing peak in DSC and starts the cure reaction earlier than the others. However, Monuron has a narrow curing reaction peak with good cure latency. The tensile properties of Dicy-cured Epiran 06 and Epikote 828 epoxy resins reinforced with chopped strand mat showed that these two epoxy resins have similar mechanical properties. For composites based on the Epiran 06 and Epikote 828 reinforced with 40 wt % glass chopped strand mat, tensile strength and modulus were 156 and 153.4 MPa and 11.6 and 12.4 GPa, respectively.     

Properties of Epon 828 resin cured by cyclic phosphine oxide tetra acid

A new phosphorylated epoxy polymer was obtained using Epon 828 resin cured with a phosphorus-containing curing agent, 10-phenylphenoxaphosphine-2,3,7,8-tetracarboxylic acid-10-oxide (PDAC). In addition, compositions of Epon 828 with common curing agents, for example, 4,4′-diaminodiphenylmethane (DDM) and 4,4′-diaminodiphenylsulfone (DDS), were used for making a comparison of its curing reactivity, heat, and flame retardation with that of PDAC. The reactivites of the three curing agents toward Epon 828, as measured by differential scanning calorimetry (DSC), was in the following order: DDM > PDAC > DDS. Through thermal gravimetric analysis evaluation (TGA), the thermal and flame resistance of epoxy polymers were confirmed in this study as capable of being improved through introduction of the cyclic phosphine oxide group into the carboxyl curing agent structure. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1877–1885, 1998     

TPP/PMMA复合物促进环氧树脂/酸酐体系的固化动力学研究

以三苯基膦(TPP)和甲基丙烯酸甲酯(MMA)为原料合成了TPP/PMMA复合物,用DSC研究了TPP/PMMA催化双酚A二缩水甘油醚(EP828)/甲基四氢苯酐(MTHPA)体系固化反应动力学。非等温固化动力学研究结果表明,转化率在20%～60%范围内,用Ozawa法能较好地描述环氧树脂/酸酐体系的固化反应过程。     

Mechanical and thermal properties of epoxy resins with reversible crosslinks

The tensile properties: Young's modulus, ultimate tensile strength, ultimate elongation, the glass transition temperature, and the dynamic mechanical properties (dynamic shear modulus (G'), loss tangent (Tan δ)), of three epoxy resins (Epon 828, Epon 836, Epon HPT 1071) cured with the disulfide-containing crosslinking agent—4.4-dithiodianilme (DTDA) have been characterized. The results show that DTDA is a satisfactory crosslinking agent for the epoxide resins that have been studied as compared to the well-known curing agent methylene dianiline (MDA). There are no significant differences between the properties of Epon 828 cured with DTDA at stoichiometric ratio (2:1) and Epon 828 cured with DTDA at small amine excess ratio (1.75:1). The glass transition temperature of the cured tetrafunctional epoxy resin Epon HPT 1971 (235°C) is significantly higher than that of difunctional epoxy resins such as Epon 828 (T_g–175°C), but the product is too brittle to be used without plasticizer.     

Study on Curing Kinetics and Thermal Degradation Kinetics of Hyperbranched Poly(Trimellitic Anhydride Ethylene Glycol) Epoxy (HTME)/Diglycidyl Ether of Bisphenol-A Epoxy Hybrid Resin

Hyperbranched poly(trimellitic anhydride ethylene glycol) epoxy (HTME) not only has relatively low viscosity and high molecular weight but also is a functional additive of enhancement and toughness and is used in the thermosetting resin field widely. The curing kinetics and thermal degradation kinetics of HTME/diglycidyl ether of bisphenol-A epoxy hybrid resin were studied in detail using differential scanning calorimetry and thermogravimetric analysis technique, respectively, by the Coats-Redfern model. The effect of molecular weight or generation and content of HTME on activation energy, reaction order, curing time, and curing reaction were discussed and analyzed, and the results indicated that HTME could accelerate curing reaction and reduce activation energy and reaction order of the curing reaction.     

聚酰胺酸对环氧树脂胶膜固化反应的影响及其机理

以液体环氧树脂与固体环氧树脂混配,4,4′-二氨基二苯砜(DDS)为固化剂,加入聚酰胺酸(PAA)对固液混配环氧树脂进行改性,采用刮膜法制备环氧树脂胶膜.通过DSC分析、平板拉丝法和傅里叶转换红外光谱法,研究了环氧树脂固液比、PAA用量等对环氧树脂胶膜成膜性、同化温度和同化速率的影响,并探索了PAA对环氧树脂/DDS体系固化反应的作用机理.结果表明,PAA可提高环氧树脂胶膜韧性,可降低固化温度,加快固化速度.对于环氧树脂(固/液质量比为50/50)/DDS/PAA体系,当PAA质量分数5%时,同化起始温度由未加PAA时的175.9℃下降到138.8℃,140℃时的固化凝胶时间由162 min下降到46 min,体系由高温固化变为近中温固化.     

聚碳酸酯改性环氧树脂的固化动力学与热性能研究

用动态DSC法研究了聚碳酸酯(PC)改性环氧树脂(EP)体系的固化行为,采用Flynn-Wall-Ozawa法分析了EP/PC体系固化活化能与转化率的关系,利用Kissinger和Crane方程研究了EP/PC体系固化动力学参数,并用TG和DSC研究了复合体系的热性能。结果表明:PC的加入没有改变EP的固化机理,反应级数基本不变,但是降低了EP固化物的热分解温度和玻璃化转变温度。     

液晶环氧/二元胺/CYD-128体系固化行为的研究

采用含芳香酯类液晶基元的环氧化物 (PHBHQ)增韧环氧CYD - 12 8,依据DTA、二元胺的结构、熔点、FTIR分析确定了混胺的比例及固化工艺。通过CYD - 12 8/混胺体系筛选出了较佳的配方 ,即当n (DDE)∶n (DDS)∶n (DDM) =1∶2 5∶5时 ,综合性能较佳     

受阻胺类固化剂固化环氧树脂的固化过程研究

通过差示扫描量热法(DSC)研究了几种不同基团取代脂肪族二元胺中的一个氢原子所形成的三官能度脂肪胺类固化剂固化环氧树脂的过程。分别使用Kissinger模型和Flynn-Wall-Ozawa模型对三种固化剂固化环氧树脂的动力学参数进行了计算。结果表明,三种固化剂固化环氧树脂的反应活性大小比较为:N-乙基乙二胺≈N-甲基乙二胺>N-苯基乙二胺。这不仅与得到的固化度-时间曲线结果相符,并且可以从结构的角度以电子效应,共轭效应和位阻效应理论给予合理解释。N-苯基乙二胺中,由于苯环的刚性较大,空间位阻效应尤为明显,活化能(E a)在固化度(α)=0.5时为61.99 kJ/mol,而在α=0.9时达到97.63 kJ/mol,随着固化度的增加反应活性迅速下降,因此该类固化剂固化过程中更需要控制工艺。