Epoxy Resins Outlook

<正> Epoxy resin is an important kind of thermosettingresin.Owing to its excellentphysical and mechanical properties,electricinsulation,chemical corrosionresistance,heat resistance and bondingproperty,it is extensively used in variousindustrial sectors such as chemicals,coatings,machinery,electronics,householdelectric appliances and aviation/aerospace.With the upgrading of resin productiontechnologies,China's epoxy resin sector developedrapidly up until 2008.Due to impactsfrom the global financial crisis,     

An Improved Method to Determine Epoxy Index of Epoxy Resins

In this communication, the effects of testing conditions, i.e., reaction time and temperature, on the accuracy for determining epoxy index of chloroepoxy propane were investigated, in order to reduce errors generated by using the current Chinese Standard GB1677-81 for determining epoxy indexes of epoxy resins. Experimental results showed that, for chloroepoxy propane reacting with hydrochloric acid-acetone for 4 h at 45°C, its epoxy index was very close to the theoretical value. The relative error of this improved method was ca. 0.40%, much lower than that determined by the method defined in GB1677-81, which results in the maximum error of 6.77%.     

Engineering Plastics from Lignin. 22. Cure of Lignin Based Epoxy Resins

The kinetic cure parameters-activation energy, pre-Arrhenius factor, and reaction order-for three lignin copolymer epoxides were determined by multiple heating rate dynamic DSC experiments in accordance with the procedure of Ozawa and Doyle. The three epoxides differed in degree of polyether chain extension (and thereby in lignin content) and in molecular weight. Exothermic cure reactions were observed over a temperature range of between 100 and 240°C. Activation energy, pre-Arrhenius constant, and reaction order ranged between 53 and 66 kJ/mol, 10,000 and 440,000, and 1.21 and 1.28, respectively. Lignin content and molecular weight differences had surprisingly little effect on cure performance. This suggests that there are no steric or mobility obstacles to cure. Whereas the activation energy of the cure reaction is similar to that of commercial epoxy resins (i.e., approximately 60 kJ/mol), the reaction order of the n-th order reaction ranges from 1.21 to 1.28 instead of the expected value of 2. This may be explained by a similar rate of the activation and ring-opening step of the cure reaction.     

Differential Scanning Calorimetry Cure Studies of Tetra-N-glycidyldiaminodiphenylmethane Epoxy Resins. Part 1 - Reaction with 4,4′-Diaminodiphenylsulphone

Rates and extents of cure are determined using differential scanning calorimetry in the isothermal mode over the temperature range 170–220°C, and from d.s.c. scans at various heating rates. The isothermal data are consistent with an autocatalytic mechanism at conversions up to about 20–30%. Data from d.s.c. scans fit a simple kinetic model which indicates that the apparent activation energy (E) for cure increases with increasing conversion, consistent with an increasing degree of diffusion control. At low levels of conversion the isothermal and dynamic data both provide estimates for E of about 70 kJ mol^?1. The heat of cure is about 105 kJ mol^?1 epoxide, and is constant over a wide range of amine concentration. This indicates that any parallel or competing processes which occur must have the same heat of reaction.     

Synthesis and Characterization of Tetra-Functional Epoxy Resins from Rosin

Tetra functional epoxy resins were prepared by the reaction of diethanolamine with Diels–Alder adducts of rosin ketone. These adducts were reacted with epichlorohydrine in the presence of NaOH as a catalyst to produce epoxy resins. The resins obtained were characterized by IR and ¹H NMR spectroscopy. The curing behaviours of these resins with their poly (amide-imide) derivatives were investigated by viscosity measurements. The curing activation energy was calculated from the gel time and critical viscosity measurements. The curing exotherms of the epoxy resins produced with poly (amide-imide) hardeners were investigated. The curing and gel times of the resins produced show slight differences between the synthesized resins. The chemical resistances and mechanical properties of the cured films were evaluated. The produced coats show high stability for salt spray at a duration time of 563 h.     

环氧化硅油改性邻甲酚醛环氧树脂的研究

采用侧基环氧化硅油(ES)及其改性物(PSA)改性邻甲酚醛环氧树脂(ECN),制备出一系列可用于电子封装等具有高韧性高耐热性的环氧基料。通过对固化物的冲击强度、拉伸强度、断裂伸长率和玻璃化转变温度(Tg)以及断裂面形态的测定,探讨了改性方法、有机硅组成与含量等对改性材料性能的影响。结果表明,用有机硅改性ECN后,其韧性和耐热性均有不同程度的提高,且环氧值高的ES和PSA的改性效果较好。其中环氧树脂经10份(质量份数,下同)ES-16或10份PSA-16改性后,韧性和耐热性均提高,符合电子封装等材料的改性要求,后者的耐热效果更为显著,Tg达183.46℃,比未改性环氧树脂提高了近20℃。     

分子模拟方法在环氧树脂研究中的应用

分子模拟方法是一种新型的科学研究的方法,而环氧树脂材料是一类重要的高分子材料。近年来,分子模拟方法被应用于环氧树脂及其固化剂的分子设计中并且引起了极大的关注。笔者根据相关文献从研究的主要问题和方法对分子模拟法在环氧树脂中的应用作一综述。     

Surface Pretreatment of Zinc and its Adhesion to Epoxy Resins

An epoxy resin based on the diglycidyl ether of bis-phenol A cured with piperidine and containing 7 or 15% rubber toughening agent has been bonded to zinc and the adhesion measured by calculating the critical strain energy release rate, Gc, from single edge notched (SEN) and tapered double cantilever beam (TDCB) specimens. The zinc has been pretreated to give surfaces ranging from relatively flat to “microfibrous” ones covered with dendrites of the metal. The microfibrous surfaces give highest values of Gc with both modified and unmodified resins. The fracture surfaces have been studied with SEM, XPS and EPMA and the failure mode related to the joint toughness.     

环氧树脂用---天然长链取代酚醋胺固化剂

作为环氧树脂的固化剂,天然长链承代酚醛胺兼有脂肪胺和聚胺的特点,它与环氧树脂制砀的涂料具有低温快速固化,适用期长,良好的耐水性、柔性和附着性,以及低ＶＯＣ与低成本等优点。     

环氧树脂的弹性体增韧改性

综述了国内外有关环氧树脂的聚合物弹性体增韧改性的最新研究进展,并分析了其增韧机理     

环氧树脂无卤阻燃化的研究

阐述了近年来国内外对无卤阻燃环氧树脂的研究情况,分别就填料型阻燃和结构型阻燃技术进行了介绍,并且简述了这两种阻燃方法对环氧树脂固化体系性能的影响。     

Synthesis and Characterizations of Melamine-Based Epoxy Resins

A new, easy and cost-effective synthetic procedure for the preparation of thermosetting melamine-based epoxy resins is reported. By this innovative synthetic method, different kinds of resins can be obtained just by mixing the reagents in the presence of a catalyst without solvent and with mild curing conditions. Two types of resins were synthesized using melamine and a glycidyl derivative (resins I) or by adding a silane derivative (resin II). The resins were characterized by means of chemical-physical and thermal techniques. Experimental results show that all the prepared resins have a good thermal stability, but differ for their mechanical properties: resin I exhibits remarkable stiffness with a storage modulus value up to 830 MPa at room temperature, while lower storage moduli were found for resin II, indicating that the presence of silane groups could enhance the flexibility of these materials. The resins show a pot life higher than 30 min, which makes these resins good candidates for practical applications. The functionalization with silane terminations can be exploited in the formulation of hybrid organic-inorganic composite materials.     

Fracture Behaviour of Thermoplastic Modified Epoxy Resins

This work has shown that the addition of polyetherimide (PEI) can significantly increase the toughness of highly cross-linked epoxy resins, whilst retaining a high T_g and modulus. These combined properties indicate the potential of PEI modified epoxy resins for use as matrices for advanced composite materials. In terms of G_IC, addition of 20wt% PEI raised the toughness by a factor of eight. Evidence from SEM fracture surfaces suggests that the toughening mechanism operating in bulk PEI modified epoxy resin is ductile drawing of the PEI. Carbon fibre composites based on 30wt% PEI modified epoxy resin matrices show considerable improvement in toughness at low and high strain rates when compared with CFRP possessing unmodified or 20wt% modified PEI content epoxy resins.     

端环氧基硅油改性环氧树脂性能研究

采用端环氧基硅油及其预反应物来改性双酚A型环氧树脂。采用热分析、扫描电镜和力学性能等测试方法系统探讨了改性方法、有机硅含量对环氧树脂性能的影响。采用端环氧基硅油直接物理共混改性的EP,其耐热性几乎不变,但力学性能下降较大。采用5份端环氧基硅油预反应物改性的EP,其玻璃化转变温度由未改性的163.23 ℃提高到165.90 ℃,拉伸强度几乎保持不变,断裂伸长率由7.6 %提高到16.7 %,冲击强度由20.23 kJ/m2提高到27.19 kJ/m2。拉伸断面的SEM照片表明,环氧树脂固化物显示出明显的增韧效果。     

自乳化水性环氧树脂的研究进展

水性环氧树脂涂料已成为绿色涂料中的研究热点.介绍了水性环氧树脂的自乳化改性法,主要综述了目前水性环氧树脂以接枝法、羧基反应法及胺基反应法改性的研究进展.     

环氧树脂增韧改性研究进展

回顾了环氧树脂韧改性的一些常用方法,详细介绍了以橡胶弹性体,热塑性树脂及则性粒子增韧环氧树脂的一些重要研究情况。并且对环氧树脂增韧性性的进行了比较系统的总结,例举了一些已被人们承认的增韧机理。 还介绍了环氧树脂改性的最新方法,液晶聚合物改性,大分子固化剂增韧的一些研究情况。     

Bio-based Epoxy Resins from Epoxidized Plant Oils and Their Shape Memory Behaviors

In this study, bio‐based epoxy materials containing functionalized plant oil, such as epoxidized soybean oil (ESO) and epoxidized linseed oil (ELO), were processed with 4‐methylhexahydrophthalic anhydride (MHPA) as a curing agent. In the presence of tetraethylammonium bromide, the curing reaction of epoxidized plant oil and MHPA proceeded at 130 °C to give transparent plant oil‐based epoxy materials. The resulting bio‐based epoxy materials exhibited relatively soft and flexible characters, due to the aliphatic chains of plant oil. The thermal and mechanical properties of the ESO/MHPA polymers depended on the feed molar ratio of anhydride to oxirane. The mechanical properties such as tensile strength and Young's modulus of the ELO/MHPA polymer increased, compared with those of the ESO/MHPA polymer. The glass transition temperature of the ELO/MHPA polymer was higher than that of the ESO/MHPA polymer, because of the high oxirane number of ELO. Furthermore, the ELO/MHPA polymer showed excellent shape memory property.     

松香合成环氧树脂及其固化剂的研究进展

综述了松香制备特种环氧树脂及固化剂的研究进展,分析了以松香为原料合成缩水甘油酯、缩水甘油醚型环氧树脂、松香基固化剂的反应机理及产品性能,分析了以松香为原料制备环氧树脂及固化剂的优势,展望了此领域的发展趋势和前景。     

微波技术在环氧树脂及其复合材料中的应用

论述了近年来微波固化技术在环氧树脂及其复合材料固化中的应用,重点比较了微波固化与传统热固化后环氧树脂及其复合材料的力学性能、热性能和粘结强度的变化,并对环氧树脂复合材料微波固化的研究进行了展望。     

Flame Retardant Unsaturated Poly(Ester Amide) Resins Based on Epoxy Resins

ABSTRACT

Novel flame retardant unsaturated poly(ester amide) resins (FR-UPEAs) were prepared by the reaction of brominated epoxy resins (BER) with unsaturated aliphatic bisamic acids using a base catalyst. These FR-UPEAs were characterized by elemental analysis and number average molecular weight determination by non-aqueous conductometric titrations. The curing of these FR-UPEAs was carried out by using benzoyl peroxide (BPO) as a catalyst and was monitored on a differential scanning calorimeter (DSC). Based on DSC data, the glass fiber reinforced composites (i.e., laminates) of these FR-UPEAs have been fabricated and their chemical, mechanical, and electrical properties have been evaluated. The composites were analyzed for their self-extinguishing time. The unreinforced cured samples of FR-UPEAs resins were analyzed thermogravimetrically.