不同POSS对磷⁃硅协同阻燃环氧树脂性能的影响

将两种多面体低聚倍半硅氧烷(POSS)分别与9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)基有机磷阻燃剂(D-bp)复配,制备了磷-硅协同阻燃环氧树脂,并对其阻燃、热、力学和动态力学性能等进行分析.结果表明,在磷含量仅为0.25％(质量分数,下同)时,磷-硅协同阻燃环氧树脂就能达到UL 94 V-0级...     

Epoxy resins from fatty esters derived from cyclohexane and epoxycyclohexane

The magnitude of the physical properties of resins obtained by the phthalic anhydride cure of non-terminal epoxy monomers, prepared from fatty derivatives, was shown to be dependent on the distribution of the epoxy groups in the monomer. The monomers were prepared by epoxidizing a series of unsaturated esters, selected to test the effect of the addition of a single symmetrically disposed epoxide group. Oleoyl and linoleoyl esters of tetrahydrophthalyl alcohol, as well as dioleyl and dilinoleyl tetrahydrophthalate, were epoxidized and cured with phthalic anhydride (Group A). For comparison, epoxy monomers were prepared from oleoyl and linoleoyl esters of hexahydrophthalyl alcohol, as well as dioleyl and dilinoleyl hexahydrophthalate (Group B). When these epoxides were cured with phthalic anhydride, it was found that the resins derived from Group A had heat distortion temperatures which were approximately 55–65C higher than those from Group B. Presented in part at the AOCS meeting in New Orleans, La., 1962, It is V in the series “Epoxy REsins from Fats”. A laboratory of the E. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.     

Curing of epoxy resins with 1-[di(2-chloroethoxyphosphinyl) methyl]-2,4-and -2,6-diaminobenzene

Fire-resistant compositions were prepared using 1-[di(2-chloroethoxyphosphinyl)methyl]-2,4- and -2,6-diaminobenzene (DCEPD) as a curing agent for typical epoxy resins such as EPON 828 (Shell), XD 7342 (Dow), and MY 720 (Ciba Geigy). In addition, compositions of these three epoxy resins with common curing agents such as m-phenylenediamine (MPD) or 4,4′-diaminodiphenyl-sulfone (DDS) were studied to compare their reactions with those of DCEPD. The reactivity of the three curing agents toward the epoxy resins, measured by differential scanning calorimetry (DSC), was of the order MPD > DCEPD > DDS. The relatively lower reactivity of DCEPD toward epoxy resins was attributed to electronic effects. It was shown that the heat of polymerization (ΔH_pol) increases with increasing epoxy functionality of the resin. The polymers obtained were characterized by DSC, thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and Fourier-transform infrared (FT-IR). The polymers of DCEPD showed a relatively lower polymer decomposition temperature (PDT) and a higher char yield than the polymers of the common curing agents. Furthermore, it was shown that the thermal characteristics of the compositions were dependent upon the ratio of the reactants. The fire resistance of the polymers was evaluated by determining their limiting oxygen index (LOI) value. The DCEPD polymers, especially those with polyfunctional epoxy resins, showed a significantly higher fire resistance as compared with those polymers of common curing agents.     

Oleoresinous varnishes from epoxy resins and drying oils

Summary Epoxy resins derived from epichlorohydrin and Bisphenol-A have been converted into air-drying varnishes by cooking with vegetable oils. Compared to varnishes derived from ordinary varnish resins, the epoxy resin-oil varnishes have faster bodying rate, higher viscosity, lighter color, and lower acid number. Although the epoxy resin-oil varnishes dry slowly and yield soft films like many other soft oil varnishes, they have remarkably good exterior durability in clear films upon wood, and in pigmented films have good chalk resistance. The varnishes are quite different from epoxy esters derived from epoxy resins and fatty acids. These latter products dry rapidly and yield hard, flexible films possessing good abrasion and chemical resistance. In cooking the varnishes at the high temperatures (580°F.) employed, epoxy groups are destroyed and the total hydroxyl content remains essentially unchanged. At lower temperatures (480°F.) the alcoholysis of oils by the hydroxyl groups in the epoxy resin proceeds readily while the epoxy groups remain essentially intact. Such alcoholyzed products may be used for further cooking with acids of various types. Phthalic anhydride, for example, was used to convert the product to an alkyd having good drying properties. Presented at the Minneapolis meeting of the American Oil Chemists' Society, October 11–13, 1954.     

Synthesis of acid anhydride-modified flexible epoxy resins and enhancement of impact resistance in the epoxy composites

Epoxy resins are key materials used in various applications, including coatings, adhesives, and composites. Tougheners, such as nanoparticles, soft polymers, elastomeric polyurethanes, and core/shell particles, have been widely applied to compensate for the brittleness of the epoxy matrix and to enhance the impact resistance. Modifying epoxy resin by reacting it with a flexible component is one of the representative methods to overcome the weakness of cured epoxy polymers upon impact. For introducing flexible parts, we synthesized three types of epoxy-modified resins by reacting acid anhydride with glycidol, followed by reaction with bisphenol [F, S, or J] glycidyl ether to produce flexible modified epoxy resins. Mechanical tests, such as flexural strength and impact resistance tests, were performed by adding various amounts of the synthesized resin to the epoxy composites. The results of these tests suggest that the modified resins were effective in improving the toughness of the epoxy matrix.     

Preparation of epoxy resin/acrylic composite latexes by miniemulsion polymerization method

Epoxy resin/acrylic composite latexes were prepared by miniemulsion polymerization. Epoxy resins have a functional epoxy group in them and excellent characteristics, such as heat resistance and good adhesion. Acrylic latexes have weather and water resistance. Combining the epoxy resin and the acrylic latex was an attempt to actualize these advantages. The miniemulsion polymerization method was effective in obtaining the composite latex. A less than 500‐nm droplet size for the monomer preemulsion was necessary to obtain the latex in a stable manner. Dimethylaminoethylmethacrylate and methacrylic acid as the reactive functional monomer with an epoxy group were introduced to the latexes. The effect of the polymerization method of these functional groups on the properties of latexes and their films was investigated. The latex prepared by the two‐stage polymerization method had good polymerization stability, storage stability, and solvent resistance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 128–133, 2001     

Synthesis and film properties of epoxy esters modified with amino resins from glycolysis products of postconsumer PET bottles

Glycolysis of waste polyethylene terephthalate (PET) flakes obtained from grinding postconsumer bottles was carried out at 225–250°C and molar ratios of PET/ethylene glycol were taken as 1/1, 1/1.5, 1/5, and 1/10. Reaction product was extracted by hot water for three times and water‐soluble crystallizable fraction and water‐insoluble fraction were obtained. These fractions were characterized by acid and hydroxyl value determinations, differential scanning calorimeter analysis, and ¹H‐NMR analysis. Glycolysis product was used for synthesis of PET‐based epoxy resin. This epoxy resin was used to prepare epoxy ester resins having 40% and 50% oil content. Epoxy ester resin having 40% oil content was modified with urea‐formaldehyde and melamine‐formaldehyde resins for synthesis of epoxy ester–amino resin. Physical and chemical film properties of epoxy ester and modified epoxy ester resins were investigated. All the epoxy ester and modified epoxy ester films were having excellent adhesion, water, and salt water resistance properties. Modification of PET‐based epoxy ester resins with amino resin has significantly improved hardness, impact resistance, and alkaline and acid resistance of resin films. As a result, PET oligomers obtained from glycolysis of postconsumer PET bottles are suitable for manufacturing of amino‐resin‐modified epoxy ester resins that have improved physical and chemical surface coating properties. POLYM. ENG. SCI., 55:2519–2525, 2015. © 2015 Society of Plastics Engineers     

Effect of Processing Conditions on Mechanical Properties of Pretreated Gelatin Samples

Abstract

The flexural strength of epoxy resins cured at different temperatures and times was investigated and compared to the heat capacities obtained during thermal analysis. Theoretical and experimental results indicated that the change in heat capacity at the glass transition temperature of epoxy resins decreases with increasing cure time and temperature. Further, for the given epoxy resin composition, it was determined that those samples with higher ΔC_p values have higher flexural strength than those with lower ΔC_p values.

Epoxy resins show a strong co-relation between flexural strength and measured heat capacities. Since the measurement of heat capacity by the Differential Scanning Calorimetry technique is simple and reproducible, it presents a means of evaluating the flexural properties of epoxy resins which will result from any known set of cure conditions.     

Studies on the cure kinetics and networks properties of neat and polydimethylsioxane modified tetrafunctional epoxy resins

The cure kinetics of tetrafunctional epoxy resins with three different backbone structures and their modification by polydimethylsioxane (PDMS) were studied by means of differential scanning calorimetry with dynamic approach. The development of epoxy networks was characterized by dynamic viscoelastic measurements. Results showed that all the epoxy resins obeyed the autocatalytic reaction mechanism with a reaction order of about 3. Epoxy resin with softer aliphatic backbone demonstrated a higher cure reactivity and stronger tendency towards autocatalysis, as well as lower crosslinking density. The PDMS‐modified epoxy resins showed higher early cure reactivity and a lower crosslinking density due to the plasticization and restriction effect of the dispersed PDMS phase, respectively. Based on cure kinetics and dynamic viscoelastic results, the α_m was found to be an effective precursor for describing the developing of epoxy networks during the course of cure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermal and dielectric properties of epoxy resins

Epoxy resins were prepared using various molar ratios of epichlorohydrin and bisphenol-A and then cured with four different hardeners: diaminodiphenyl methane (DADPM), dithioterephthalic acid (DTTPH), dimethylamino propylamine (DMAPA) and diethylene triamine (DT). The thermal behaviour of these epoxy resins was studied. From the energy of activation data it was observed that DADPM gives the highest thermal stability of all these curing agents. Dielectric constant measurements of uncured resins were made at 30°C and at a frequency of 2.5 × 10³ Hz. The higher activation energies of the resins are related to the polarity of the hydroxyl moiety in the epoxy resins.     

双邻苯二甲腈改性环氧及其玻纤复合材料制备

采用双邻苯二甲腈树脂(BAPh)对环氧树脂E-44(EP)进行改性,同时制备了BAPh/EP/玻纤复合材料。采用示差扫描量热仪,热重分析,力学性能测试及氧指数仪研究了改性树脂的热性能、力学性能及阻燃性能,并对BAPh/EP/玻纤复合材料的力学性能进行了表征。结果表明,当BAPh质量分数达到50%时,改性树脂固化物在空气中的起始分解温度达到377.6℃,比纯环氧提高74.3℃,氧指数达到34.5%,复合材料的弯曲性能指标达到最大,添加双邻苯二甲腈后环氧树脂的耐热性、力学性能和阻燃性能得到了明显改善。     

环氧-亚胺树脂研究进展

环氧树脂有优异的粘接性能和好的机械性能而被广泛应用，但耐热性较差、脆性大限制了其高性能领域的应用；聚酰亚胺是一类耐热性好、机械性能等优异的工程塑料。用聚酰亚胺改性环氧树脂将2者的优势结合起来，从而成为改善环氧树脂性能的一个有潜力的途径。本文介绍了几种合成环氧-亚胺树脂的方法以及树脂的性能，并对其应用前景进行了展望。     

有机硅改性环氧树脂的合成与性能

热熔法制备了系列聚甲基苯基硅氧烷(PMPS)改性环氧树脂,通过环氧值、红外光谱(IR)和凝胶色谱(GPC)分析表明,有机硅接枝到了环氧树脂上,且环氧基保持不变。探讨了改性方法、有机硅含量对改性树脂固化体系的微观形态、韧性及耐热性的影响。实验表明,当m(E-20)∶m(DC-3074)=7∶3时,化学改性树脂固化体系的韧性和耐热性能明显提高,玻璃化转变温度(Tg)为88.33℃,质量损失50%时的热分解温度(Td)为487.80℃,分别比物理改性环氧树脂提高了52.63℃和36.75℃,同时此改性树脂固化物还具有优良的涂膜性能。     

Rheology of Precipitated Silica in Epoxies

Epoxy resins are used in the RP/C industry when high-quality resins are needed. Adhesives, castings, and maintenance coatings are three areas where epoxies are used. Their superior chemical resistance allows them to be used as coatings, and their low shrinkage makes them ideal for use in castings [1]. There is a need for viscosity control in some of these epoxy applications.     

环氧树脂材料在变电站的应用

综述了环氧树脂材料在变电站电力系统中的应用情况。利用环氧树脂浇注变压器可以提高变压器绝缘性能和力学性能。将环氧树脂与固化剂反应形成环氧聚合物,覆盖在电力设备相关硬件表面,可以避免电力设备自身振动所引起的噪声,减少噪音污染。不同结构和性能的环氧树脂具有良好的力学性能,所制涂料具有优良的金属附着力,防腐性能优异。环氧树脂应用于电力行业领域,具有良好的性能,避免了环境污染。     

Epoxidharze

Epoxy Resins The significance of epoxy resins in view of new commercial developments is explained. Developments and advances in the application of basic types of epoxy resins based on Bisphenol A are described and the present status in the field of flame resistant epoxy resins, epoxidized novolacs, reactive diluents, and flexible cycloaliphatic diepoxy compounds is shown.     

Simultaneously increasing cryogenic strength, ductility and impact resistance of epoxy resins modified by n-butyl glycidyl ether

Epoxy resins are increasingly used in cryogenic engineering areas due to rapid developments of spacecraft and superconducting cable technologies as well as large cryogenic engineering projects (e.g., International Thermonuclear Experimental Reactor). Cryogenic mechanical properties are important parameters for epoxy resins to be employed in such areas. In this paper, a traditional reactive aliphatic diluent, namely n-butyl glycidyl ether (BGE, JX-013) with a low viscosity, was used to modify diethyl toluene diamine (DETD)-cured diglycidyl ether of bisphenol-F (DGEBF) epoxy system for enhancing cryogenic mechanical properties at liquid nitrogen temperature (77 K). The results showed that the cryogenic strength, ductility and impact resistance (impact strength) have been simultaneously enhanced by the addition of BGE with appropriate contents. Moreover, the comparison of the mechanical properties between 77 K and room temperature (RT) indicated that at the same composition, the tensile strength and Young's modulus at 77 K were higher than those at RT but the failure strain and impact resistance showed the opposite results. Finally, differential scanning calorimetry (DSC) exhibited that the glass transition temperatures (T_g) of the epoxy resins decreased with increasing the BGE content.     

Synthesis of solid epoxy resins base on BPC II and bisphenol A using conventional heating equipment and microwave

New solid state epoxy resins based on diglycidyl ether of 1,1‐dichloro‐2,2 bis (4‐hydroxyphenyl), ethylene (BPC) and BPA epoxy resins in the reaction with BPC and BPA were developed. Solid epoxy resins were synthesised by the use of two different heating methods: conventional and microwave reactor. The use of microwave radiation as novel heating medium as an alternative to the conventional methods, which provide a quicker and more effective synthesis. The solid epoxies have high melting points higher than 100°C and the polycondensation degree remains between n = 4–12. Epoxy value stays low and occurs around 0,02–0,1. BPA epoxy resins and diglycidylether of BPC II were compared in terms of reaction speed. It can be seen that the reaction of BPC diglycidylether occurs approximately 20% quicker given the same reaction conditions of temperature, and balance of catalyst. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3850–3854, 2006     

Synthesis of curing agent for epoxy resin based on halogenophosphazene

Epoxy resins are, due to their excellent properties (such as chemical resistance, dimensional stability, and heat resistence), widely used in practice. The basic principle of curing epoxy resins with a hardener containing multiple amino groups is the crosslinking reaction between active hydrogen atoms in the hardener and the oxirane groups in the epoxy resin. This study deals with the synthesis and characterization of hexachloro‐cyclo‐triphosphazene derivative and its subsequent use for curing epoxy resins. The new hardener was prepared from hexachloro‐cyclo‐triphosphazene by nucleophilic substitution with isophorone diamine and its curing capability was compared with original isophorone diamine. The prepared derivative hexaisophorone diamino‐cyclo‐triphosphazene (HICTP) provided advantages over conventional curing system, as it improved mechanical properties as well as the flame resistance. Testing of the cured epoxy resin during burning was carried out using dual cone calorimeter, which enables more extensive monitoring of parameters in comparison with testing using oxygen index that has been used in many publications. The epoxy resin cured with the prepared phosphorus containing HICTP exhibits lower values for total heat release, amount of smoke released and oxygen consumed, which may cause a slower flame spread. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42917.     

Preparation and Characterization of Cured Epoxy Resin with Hexachloro-Cyclo-Triphosphazene

Epoxy resins can exhibit some excellent properties. The basic principle of curing epoxy resins with a curing agent containing multiple amino groups is the crosslinking reaction between active hydrogen atoms from the curing agent and the oxirane groups in the epoxy resin structure. This study deals with the synthesis of derivative of hexachloro-cyclo-triphosphazene (HCCTP) using curing of epoxy resins. The study of our interest is nucleophilic substitution of HCCTP using N-[3-(trimethoxysilyl)propyl]ethylene diamine. The prepared derivative offers two potential advantages over conventional curing systems, namely improving properties during burning.