脲醛树脂固化剂体系的研究

固化剂体系对脲醛树脂的固化有显著影响,根据固化剂的作用机理,对单组分、双组分和复合固化剂体系进行了系统研究,旨在找出不同固化剂体系在不同条件下的变化趋势。     

Low temperature acid catalyzed curing of melamine resin systems

Summary Melamine resins having a high concentration of secondary amino groups (-NH-CH₂OR groups) are able to cure at low temperature under strongly acidic conditions. It is shown by spectroscopic methods that the characteristic curing reaction of this type of resin proceeds via an imino group intermediate.Analogous reactions are proposed for the self-curing of the melamine resin and the co-condensation with hydroxyl containing polymers.     

Analysis of the curing behavior of cyanate ester resin systems

The role of metal catalysts on the curing characteristics of bisphenol A-based cyanate ester resin systems was investigated using Fourier transform infrared spectroscopy, differential scanning calorimetry, and rheological measurements. Bisphenol A dicyanate was cured with the octoates and naphthenates of zinc and manganese and with cobalt acetylacetonate at concentrations ranging from 0 to 750 ppm metal. Nonylphenol at concentrations between 0 and 8 phr was used as the cocatalyst. The results show that at metal catalyst concentrations less than 100 ppm and nonylphenol concentrations less than 4 phr, a maximum glass transition temperature of 250 to 260°C is obtained, irrespective of the type of catalyst used. For samples cured without nonylphenol, the maximum T_g was 298 to 302°C. At high catalyst concentrations, the T_g decreases with increasing catalyst concentration for the zinc catalysts, whereas no concentration effect was observed for samples cured with either manganese or cobalt. Nonylphenol was effective as a cocatalyst in achieving high conversions; however, the T_g at full conversion was found to decrease with increasing nonylphenol levels.     

低甲醛释放脲醛树脂的固化剂体系及其固化特性

脲醛树脂的固化是将线型可溶性树脂转化成不溶不熔体型结构并获得胶接强度的过程。固化剂是脲醛树脂胶接固化的关键组成,其种类与用量都会密切影响固化树脂的性能。氯化铵是脲醛树脂胶粘剂的传统固化剂,然而随着F/U的降低、合成工艺的调整、改性剂的加入等操作,使脲醛树脂的固化历程、固化前的化学结构、固化特性等发生改变,氯化铵已难以再满足脲醛树脂的胶接固化要求,人们研究提出了多种固化剂体系。为此,综述了脲醛树脂胶粘剂的不同固化体系及其固化特性。     

脲醛树脂的复合固化剂体系及其固化特性研究

以NH4Cl为固化剂胶接的木制品在回收燃烧过程中会产生剧毒物质二噁英.本文结合固化剂存在下中密度纤维板的内结合强度、游离甲醛释放量、耐水解性等指标的评价,对某种新型复合固化剂存在下脲醛树脂的固化特性进行了探究,结果表明:与NH4Cl固化剂相比,新型复合固化剂存在下,脲醛树脂的游离甲醛释放量更低,化学结构更稳定,耐水解性...     

端羧基超支化聚酯改性环氧树脂固化体系研究

利用丁二酸酐对端羟基超支化聚酯(AHBP)的端基进行改性,得到新的端羧基超支化聚酯(CHBP),并将其用于环氧树脂体系的增韧。研究了CHBP用量、羧基含量对环氧树脂/甲基四氢苯酐(EP/MeTHPA)固化体系的力学性能和热性能的影响。结果表明,改性后分子末端全部带羧基的CHBP的增韧作用最好,冲击强度可达18.5kJ/m2。CHBP质量分数为15%时,固化物的冲击强度可达18.2 kJ/m2,拉伸强度64.86 MPa,玻璃化温度(Tg)从100℃提高到106℃左右,可满足增韧环氧树脂的同时不降低其耐热性的要求。     

风电叶片用环氧树脂固化体系的研究

分别以BH-1、2,4,6-三(二甲氨基甲基)苯酚(DMP-30)和2-乙基-4-甲基咪唑(2,4-EMI)作为促进剂,研究了三种不同促进剂对环氧树脂(EP)/酸酐固化体系力学性能和耐热性能的影响;并以此作为复合材料的基体树脂,以玻璃纤维作为增强材料,制备风电叶片用EP基玻璃纤维增强复合材料。结果表明:三种基体树脂及其玻璃纤维增强复合材料均具有优异的力学性能,能够用于风电叶片的制备;其中以BH-1为促进剂的EP/酸酐体系具有最好的韧性和综合力学性能,其最大拉伸强度超过80MPa,断裂伸长率为3.80%。     

Effect of wood on the curing behavior of commercial phenolic resin systems

Differential scanning calorimetry (DSC) was used to study the effect of wood on the curing behavior of two types of commercial oriented‐strand‐board phenolic resins. DSC analysis showed that the curing behavior of the core resin differed significantly from that of the face resin in terms of the peak shape, peak temperature, and activation energy. The addition of wood to the resins moved the two separated peaks in the DSC curves of the core resin adjacent to each other. It also accelerated the addition reactions in the curing processes of both the core and face resins. The two peaks in the DSC curves were the result of the high pH values of the resins. These two peaks became either jointed together or overlapped when the pH value of the resin was reduced. Wood also reduced the activation energies for both the core and face resins by decreasing the pH values of the curing systems. Moreover, the effects of wood on the curing behavior of the resins among the five species studied were similar. The lowest activation energy for a phenolic resin probably appeared at pH 10–11 under alkaline conditions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 185–192, 2005     

Effect of microencapsulated curing agents on the curing behavior for diglycidyl ether of bisphenol A epoxy resin systems

Microcapsules containing a curing agent, 2‐phenyl imidazole (2PZ), for a diglycidyl ether of bisphenol A (DGEBA) epoxy resin were prepared by a solid‐in‐oil‐in‐water emulsion solvent evaporation technique with poly(methyl methacrylate) (PMMA) as a polymeric wall. The mean particle size of the microcapsules and the concentration of 2PZ were about 10 μm and nearly 10 wt %, respectively. The onset cure temperature and peak temperature of the DGEBA/2PZ–PMMA microcapsule system appeared to increase by nearly 30 and 10°C, respectively, versus those of the DGEBA/2PZ system because of the increased reaction energy of curing. The former could take more than 3 months at room temperature, whereas the latter was cured after only a week. The values of the reaction order (a curing kinetic parameter) for DGEBA/2PZ and DGEBA/2PZ–PMMA microcapsules were quite close, and this showed that the curing reactions of the two samples proceeded conformably. The curing mechanism was investigated, and a two‐step initiation mechanism was considered: the first was assigned to adduct formation, whereas the second was due to alkoxide‐initiated polymerization. The glass‐transition temperature of DGEBA/2PZ was 165.2°C, nearly 20°C higher than the glass‐transition temperatures of DGEBA/2PZ–PMMA microcapsules and DGEBA/2PZ/PMMA microspheres, as determined by differential scanning calorimetry measurements. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

高耐热透明阻燃环氧树脂固化体系研究

在以双酚A/四溴双酚A混合环氧树脂(EP)与甲基六氢邻苯二甲酸酐(MeHHPA)构成的胶料基础上,通过加入氯桥酸酐,制备出了具有良好耐热性和阻燃性的透明EP固化物。结果表明:与未加入氯桥酸酐体系相比,当w(氯桥酸酐)=20%(相对于固化剂质量而言)时,EP固化物的总燃烧时间由21 s降至2 s,而氧指数由31%增至37%,玻璃化转变温度(Tg)从123℃提高到148℃,负荷热变形温度(HDT)从108℃增加到129℃。     

不饱和聚酯树脂的常温固化

(续接上期)5不饱和聚酯树脂固化网络结构分析5·1不饱和聚酯树脂交联网络结构不饱和聚酯中的双键与交联剂中的双键聚合形成不溶不熔的交联网络,网络中含有2种聚合物分子链结构。网络主体由不饱和聚酯分子链的无规线团组成,苯乙烯共聚分子链穿插其中,将不饱和聚酯分子链连接和固     

不饱和聚酯树脂的常温固化

综述了不饱和聚酯树脂的固化特征、固化反应,固化机理和交联固化反应活性。介绍了4种固化反应过程、引发剂和固化反应链增长过程,同时介绍了其交联固化反应活性及影响因素。     

新型可见光固化树脂

针对一些过氧化物固化不能满足特殊的施工环境,以及紫外光固化存在对人体有害、应用范围窄、厚膜固化性不好等缺点,开发了1种利用可见光光源进行固化的变性乙烯基酯树脂(VLC树脂),通过测定其黏度、比重、酸价、力学性能、Tg、热变形温度、积层板在一定浓度的酸、碱、水、有机溶剂等介质里面的强度保持率,分别对树脂液态特性、树脂浇铸体及积层板的力学性能以及积层板的耐腐蚀性能进行了表征,通过与一般的过氧化物固化的乙烯基酯树脂的浇铸体及积层板性能比较,可以看出:可见光固化与常见的过氧化物固化相比,性能相当甚至更佳,并且可见光固化速度极快,苯乙烯挥发极少,作业简单,无须加促进剂和固化剂,无须繁琐的搅拌和脱泡过程,提高生产效率的同时,大幅度降低施工成本。     

钝化2-乙基-4-甲基咪唑/环氧树脂低温固化体系研究

测定了三种α-甲基丙烯酸钝化2-乙基-4-甲基咪唑固化环氧树脂(EP)体系的凝胶时间及固化反应放热曲线,制定了EP固化体系的固化工艺条件,并对这三种EP固化体系的室温(20℃)储存特性及其浇铸体的综合性能进行了比较。结果表明:这三种EP固化体系均可在80℃时快速固化,浇铸体的固化工艺条件为80℃/4 h;当m(E-51)∶m(Eg-031)∶m(固化剂)=25∶25∶2时,EP固化体系预浸料具有最长的储存期(15 d),是综合性能优良的低成本复合材料制造用基体树脂,其弯曲强度、弯曲模量、冲击强度和热变形温度分别为109.3 MPa、3.0 GPa、7.76 kJ/m2和125℃。     

多巯基树脂固化聚氨酯丙烯酸树脂的研究

采用凝胶时间测试和实时红外光谱(RT-IR)研究了不同固化剂、稀释剂及促进剂用量对聚氨酯丙烯酸树脂(PUA)/稀释剂二缩三丙二醇二丙烯酸酯(TPGDA)/自制多巯基树脂固化剂(T-41)/促进剂1,8-二氮杂环[5,4,0]-十一烯(DBU)体系固化速度的影响及固化过程中转化率与反应时间的对应关系。结果表明,该体系中,TPG-DA用量存在一最佳值,使体系凝胶时间最短。凝胶时间随烯烃双键/巯基比例的增加而缩短,随促进剂用量的增加而缩短。通过改变各组分配比,体系的固化时间可控制在数分钟到数十分钟之间,实现PUA的快速固化。     

UV固化水性环氧树脂的合成研究

对紫外光固化水性环氧树脂的合成工艺进行了研究,讨论了反应温度、反应时间、催化剂种类和用量,阻聚剂、羧基含量及固含量、中和剂等对水性环氧丙烯酸酯的合成和性能的影响。结果表明,合成环氧丙烯酸酯的最佳反应温度110℃,环氧丙烯酸酯与马来酸酐的最佳反应反应温度为80℃。反应时间均为5 h,三乙胺作催化剂,用量为反应物总质量的0.5%,对羟基苯甲醚作阻聚剂。实验表明,提出的紫外光固化水性环氧树脂的合成工艺可行,合成树脂具有水性特征,性能指标可以满足应用要求。     

Isothermal curing by dynamic mechanical analysis of three epoxy resin systems: Gelation and vitrification

Times to gelation (t_gel) and times to vitrification (t_vit) during isothermal curing for the epoxy systems diglycidyl ether of bisphenol A (DGEBA)/1,3‐bisaminomethylcyclohexane (1,3‐BAC), tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM)/4‐4′‐diaminodiphenylsulfone (DDS), and TGDDM/epoxy novolac (EPN)/DDS were measured at different curing temperatures. This article reports on a method to determine t_gel and t_vit by dynamic mechanical analysis (DMA). Gelation was determined at the onset of the storage modulus or by the peak of the loss factor. Vitrification was defined as the curve of the storage modulus as the curve reached a constant level (endset) in DMA tests. The experimental values obtained for t_gel and t_vit were compared with values obtained by other experimental methods and with theoretical values (t_gel's) or indirect determinations (t_vit's). From kinetic analysis by differential scanning calorimetry, conversions corresponding to gelation were obtained for the three systems; this yielded a constant value for each system that was higher than theoretical value. Values of the apparent activation energies of the DGEBA/1,3‐BAC, TGDDM/DDS, and TGDDM/EPN/DDS epoxy systems were obtained from plots of t_gel's against reciprocal temperatures. They were 53.2, 58.2, and 46.5 kJ/mol, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 78–85, 2002     

改性胺类环氧固化剂的研制

介绍了由苯基苯酚生产中的副产物杂酚为原料,制备酚醛改性胺类环氧固化剂的合成工艺,产品分析,实际应用情况等。