Monoallylester derivatives having allyl group and hydroxyl group were synthesized by the reaction of a monoallylester with epoxy compounds, the use of which could be thought to improve the adhesive property of diallyl phthalate resins (DAP). Lap shear strength of a cured resin was improved by the modification of diallyl phthalate resin with synthesized monoallylester derivatives. By this modification, the electrical property was maintained though its heat resistance and anti-water property were decreased. While, by adding a monoallylester derivative that contained two ally! groups, the lap shear strength increased by 140% in maximum, moreover the decrease of other properties of the cured resin was very small. Hence, the modification with a monoallylester derivative that contained a single allyl group led to the large decrease of the properties except adhesiveness of the cured resin, because those derivatives acted as a plasticizer. Water absorption was increased with increasing the concentration of hydroxyl group in the modification system.

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This article deals with the further discussion of the steric effect of long-chain alkyl groups on the network formation in the free-radical crosslinking copolymerizations of alkyl methacrylates including hexyl methacrylate (HMA), lauryl methacrylate (LMA), and stearyl methacrylate (SMA) with trimethylolpropane trimethacrylate (TMPTMA), especially focused on the control of intermolecular crosslinking leading to gelation. The MWD curves were broadened toward higher molecular weight side with conversion for HMA/TMPTMA copolymerization as a reflection of the occurrence of intermolecular crosslinking induced by a lessened steric hindrance of shortened alkyl groups. On the other hand, the opposite results were observed when LMA was replaced by SMA having a longer alkyl group. Then, the solvent effect on the gelation in LMA/TMPTMA copolymerization was discussed because the steric effect of long-chain alkyl groups on the intermolecular crosslinking leading to gelation would be influenced by the change of the conformation or the interpenetration of polymer chains in various solutions caused by the difference in their solvent powers. The delay of gelation from theory became smaller in dioxane than in benzene, whereas it was reversed in cyclohexane/benzene (9/1 v/v), suggesting that the steric effect of long-chain alkyl groups on gelation was reduced or enhanced in a tight-coiled or rather extended conformation, respectively. The interpenetration of polymer chains was enhanced in dioxane as reflected on the MWD curves broadened toward higher molecular weight side with conversion.

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The interpenetrating polymer networks (IPNs) formed diglycidyl ether of bisphenol-A (DGEBA) and poly (ethylene glycol) diacrylate (PEGDA) were prepared by simultaneous polymerization techniques. 2-ethyl-4-methylimidazole was used as curing agent for DGEBA, and AIBN or BPO was used as free radical initiators for PEGDA. The curing products were analyzed by the dynamic mechanical measurements, tensile testing, fracture toughness testing and bonding testing. As the results, the product induced by AIBN initiators system, which have phase-separated IPN structure. In the case of BPO initiation systems, the resultant products have the sequential-IPN structure. The mechanical properties, tensile strength and fracture toughness were improved in comparison with 2E4MZ-cured epoxy resin. The tensile shear strength drastically increased at the acrylate content of 30wt% in the both radical initiation systems.

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The UV cured epoxy resins modified with a reactive elastomer such as amino-terminated butadiene-acrylonitrile copolymer (ATBN) and dimethoxymethylsilyl-polypropylenoxide (DMSi-PPO) were prepared. Relationship between the fracture toughness and phase structure of cured films was studied. Using ATBN, which has active hydrogen at the end of molecular chain, it was clear that ATBN system was not cured under UV irradiation, This was because of capturing H⁺ from photo cationic initiator by nitrogen atoms at the terminal of ATBN. On the other hand, using the DMSi-PPO, which does not have any active hydrogen at end of molecular chain, the system showed a phase separation structure in which DMSi-PPO particles were dispersed throughout the epoxy matrix.
By the addition of 3-glycidyloxypropyltrimethoxysilane (GPTMS) as a compatibilizer onto the DMSi-PPO / bisphenol A type epoxy resin (DGEBA) system, an almost-transparent cured film was obtained and its fracture energy increased with increasing the amount of GPTMS.

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Magnetic fields are applied in two different ways to improve the electrical conductivity of epoxy and unsaturated polyester composites containing grinding chips as a conductive filler. In one method, a magnet is slid along the surface of the casting mold, and in the other, a series of magnets are aligned along the surface. The incorporation of cutting oil (light oil) entrained with grinding chips is found to improve the electrical conductivity of the epoxy composite, attributed to reduction of the viscosity of curing mixtures, and protection of the surface of the grinding chips against oxidation by air. Not only light oil but also hydrocarbons of low viscosity are found to improve the conductivity of the epoxy composite.

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Epoxy resin is widely utilized as high performance adhesives, because of the good bonding strength, excellent thermal and chemical stabilities. However, the brittleness of this resin is limitting the applied fields of the resin as the adhesives. Even now, a development of novel toughened epoxy adhesives is required in the many industrial field, for example, the machine, electric and electronic industry, etc. This article reviewed the recent high functional epoxy adhesives toughened with some elastmeric materials and by the introduction of mesogenic groups. In all toughened adhesives, novel useful characters, such as pre-fastening effect, rubber elastic property, or high plastic deformability, is appeared in addition to their high bonding properties.

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