Cyclic monoterpene bisphenols as starting materials include a commercial terpene bisphenol (YP-90^TM, Yasuhara Chemical Corp., a mixture of 1, 3-menthane bisphenol and 2, 8-menthane bisphenol (60 : 40 wt ratio)), 1, 3-menthane bisphenol, 2, 8-menthane bisphenol and terpene bis-2', 6'-dimethylphenol. Four kinds of novel epoxy resins were prepared in two step reactions, because the cyclic monoterpene bisphenols were hardly soluble in aq.NaOH solution : the reaction of the bisphenols and epichlorohydrin using a phase transfer catalyst, tetrabutylammonium bromide, at 80°C in the absence of alkali, followed by epoxidation with aq.NaOH solution at a lower temperature (<10°C). The differential thermal analysis indicates that the curing reactivities of the epoxy resins based on the cyclic monoterpene bisphenols (DGETB) were lower than that of bisphenol A diglycidyl ether (DGEBA) when using 3, 3'- dimethyl-5, 5'-diethyl-4, 4'-diaminodiphenylmethane (Curehard MED^TM, Ihara Chemical Corp.) as a curing agent. Physical properties for the Curehard MED-cured DGETB resins were examined. Tg's of the cured DGETB resins were higher than that of the cured DGEBA resin. Water absorption of the cured DGETB resin based on YP-90 was lower than that of the cured DGEBA resin. Physical properties for the DGETB resins cured with methyl hexahydrophthalic anhydride (MeHHPA) were also examined. In the MeHHPA curing system, Tg's for the cured DGETB resins were also higher than that for the cured DGEBA resin.

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Several different structures have been proposed for dicyanodiamide (N ''-cyanoguanidine : CG), but no absolutely conclusive evidence has been given for any one of them. The structure of NC-NH-C (=NH) NH₂ hitherto have been preferred and widely used. We investigated the structure of CG by means of X-ray crystal analysis, spectrophotometry in the ultraviolet region, and ¹H- and ¹³C-NMR spectrometry. The crystal is monoclinic, space group C2/c, a=14.986 (2), b=4.499 (3), c= 13.112 (3) Å, β=115.35 (1) °, V =799.0 (3) ų, μ=0.47cm^-1, Z = 8. Among 5 C-N bonds in CG, C (1) -N (1) corresponding to the cyano group is the shortest (1.157Å) and have a strong triple bond nature. The C (1) -N (2) adjacent to the cyano group is 1.315Å (the next shortest). The other 3 C-N bonds (C (2) -N (2), C (2) -N (3), and C (2) -N (4)) are 1.329-1.341Å and conjugated. Four atoms of C (2), N (2), N (3), and N (4) for composing the guanidine moiety are located on the same plane, and also two atoms of the cyano group (C (1) and N (1)) are located approximately on the same plane. The structure of NC-N=C (NH₂) ₂ for CG is proposed from data in X-ray crystal analysis, ultraviolet spectra, and.¹H-and¹³C-NMR spectra.

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Properties of the cured bismaleimide (BMI) / o, o'-dially1 bisphenol A (CA) resin system were investigated from the viewpoints of bismaleimide skeleton structure and BMI /CA molar ratio.
The properties of cured BMI / CA resin ; glass transition temperature (Tg), specific gravity, flexural strength, flexural modulus and thermal degradation temperature increased as BMI/CA molar ratio increased. And water absorption did too. These results are mainly due to crosslinking density or maleimide content varying with BMI/CA ratio.
Crosslinking density also varies with bismaleimide skeleton structure. Therefore the properties of cured BMI/CA resin Properties ; glass transition temperature (Tg), flexural strength and modulus, water absorption etc. vary with it.
Generally, BMI with shorter skeleton length and symmetrical structure tended to have higher crosslinking density. The skeleton structure of BMI had little effect on thermal degradation temperature. But BMI/CA molar ratio did a significant effect on it.

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A new artificial marble bathtub called “Crystal bathtub” was developed by applying an in-mold coating (IMC) process to compression molding. Unevenness of flow behavior of materials, molding pressure, and cured state was apt to an imperfect product, because of its largeness and deeply pressed shape. A tight adhesion between the base material and the coating was succeeded by use of BMC with a retarder and by optimization in injection time of the coating. Moreover, for the success in molding, it also was a key point to preserve the moldability of the coating. Thus, surface waviness of BMC was eliminated and IMC molded parts obtained had superior characteristics of fine smoothness and gloss, compared with a conventional marble like BMC.

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This review describes the modification of thermosetting plastics by N-phenylmaleimide-styrene copolymers. Thermosetting plastics include epoxy and bismaleimide resins. N-Phenylmaleimide-styrene copolymer (PMS) was prepared by radical polymerization of N-phenylmaleimide and styrene and has a high transition temperature of over 200°C. PMS was dissolved in the epoxy and bismaleimide resins without solvents by heating and an effective modifier for both modification systems. Toughening can be achieved by cocontinuous phase structure of the modified resins in both epoxy and bismaleimide resin systems, where fracture toughness K_IC increased considerably with a medium loss of flexural strength. The decrease in flexural strength can be restored by using terpolymers (PMSH) containing p-hydroxyphenyl unit as a reactive group. When using PMS/PMSH hybrid modifiers, the modified epoxy resins had balanced properties.

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