The bulk and solution polymerization of 1, 6-diacrylate-2, 4-hexadiyne (DAHD) and 1, 6-dimethacrylate-2, 4-hexadiyne (DMHD) was studied. A model reaction experiment showed that the diacetylene groups gave rise to initiating radicals. The propagation before gelation occurred by the reaction of the double bonds. The products obtained before gelation were soluble oligomers. The diacetylene groups didn't react with propagating radicals until gelation took place. The polymerization of these compounds seemed to be accompanied by degrading chain transfer of the propargyl metylene groups and radical capture by the diacetylene groups.
The properties of the cured products of DAHD and DMHD were investigated. These cured products have excellent isotropical properties, such as modulus, ultrasonic velocity, Vickers hardness, thermal conductivity and thermal expansion. The properties in DMHD were generally inferior to those in DAHD because of bulkiness of methyl groups. The moduli (curing condition : 100°C, 7h) were 13. 2 GPa for DAHD and 9. 2 GPa DMHD, respectively. The post curing led to improvement of the properties. Especially, the maximum value of the moduli reached 20. 2 GPa by post curing at 650 MPa, 200°C for 1h.

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Fiber reinforced thermosetting resin composites have played an important role as engineering materials. Whereas properties of the composites are determined by raw materials, lay-up design and manufacturing process, contribution of the raw materials is presented in this article, especially focusing on the reinforcement fibers. With carbon fiber reinforced composites (CFRP), longitudinal tensile properties of CFRP are splendid because of very high elastic modulus and very high strength of carbon fibers, but properties for transverse direction, inter-layer and compression are not so good because matrix resin dominates them. One of drawbacks which have been required to be improved in CFRP as aircraft materials is poor impact resistance; research from the point of increasing resin toughness is under way. Cost of the composites relates to processability at fabrication and reproducibility of the products, witch depend primarily on the resin. Development of novel thermosetting resin of easy-to-process and easy-to-provide stable products is requested as well as of higher performances.

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For comments on the quinone methide theory that quinone methides act as reactive intermediates in the heat-hardening reactions of a resole, it may be unavoidable to understand the properties and the reactions of quinone methides. On account of this reason the present paper describes the following items concerned with quinone methides : chemical stability, synthetic methods, structures of cycloaddition products, structures of quinone methide dimers and some topics related to quinone methides.

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Recent instrumental analyses were possible to make it clear that resoles consist of polymethylolphenols and that compounds obtained by heating the compounds which are modeled after methylolphenols agree with the results assumed from solid-state ¹³C-NMR of heat-hardened resole. The reaction mechanisms to form the various products from methylolphenols are assumed as follows ; (i) methylene bond may be formed via quinone methide, (ii) elimination of a methylol from a methylolphenol may belong to the retro-ene reaction or to a fragmentation of β-hydroxyolefin, (iii) formyl group may be formed via quinone methide.

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Thanks to the many previous investigations on the components of ammonia-resoles, it becomes clear now that ammonia-resoles consist of primary, secondary and tertiary hydroxybenzylamine together with N- (hydroxybenzyl) -benzo [e] -3, 4-dihydro-2H-1, 3-oxazine. At the heat-hardening stage, secondary and tertiary hydroxybenzylamine afford one quinone methide and the one lower hydroxybenzylamine, primary hydroxybenzylamine decomposes into one quinone methide and ammonia, and N- (hydroxybenzyl) -benzo [e] -3, 4-dihydro-2H-1, 3-oxazine affords N, N-di (hydroxybenzyl) methyleneammonium cation in the presence of Brönsted acid such as phenol and the cation changes to tertiary hydroxybenzylamine.

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