θ Temperatures for o-cresol resin in o-dichlorobenzene and for acetylated o-cresol resin in 2-ethoxyethanol were determined as 119. 2°C and 92. 0°C, respectively, from the experiments of phase equilibrium using Shultz-Flory equation.
The values of the exponent a in Mark-Houwink-Sakurada viscosity equation for acetylated o-cresol resin in the θ solvent was obtained to be 0. 50. From the result, it becomes obvious that the molecules of acetylated o-cresol resin behave as an unperturbed chain in the θ solvent since there is no branching and no intramolecular hydrogen bonding by acetylation of phenolic OH groups. In the good solvent (THF) however, the value of a becomes larger (a = 0. 65) by the effect of the excluded volume. Before acetylation, the molecules becomes compact both in the good solvent and in the θ solvent by the effect of intramolecular hydrogen bonding.

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A new phenolic resin having aromatic diamine in the main chain was prepared by the thermal polymerization of p-phenylenediamine and 2, 6-bis (hydroxylmethyl) -p-cresol. The resin contains both amino linkages and dimethylene ether linkages, because the condensation proceeds between methylol groups as well as between an amino group and a methylol group. A branching structure on the nitrogen atoms was also confirmed, thus, the resin becomes easily crosslinked and insoluble in THF. Mark-Houwink-Sakurada viscosity equation for the resin was determined in a THF solution. The small values of the exponent a in MHS equation indicate that the conformation of the resins are considerably compact in THF.

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Polymer networks (MC-V) containing small amounts of thermotropic liquid crystalline poly (p-oxybenzoate-co-ethylene terephtalate) (LCP) have been prepared by causing a bisphenol-A-type epoxy resin to cure in a LCP/epoxy micro-dispersed state. Also, additional polymer networks, namely the heat treated specimens (MC-H), have been prepared by heating MC-V under the melting temperature of LCP.
Physical proterties of MC-V were studied by comparing with those of neat epoxy resin. Modulus at glassy state (E'g), glass transition temperature (Tg) and elongation at break (ΔL) of MC-V were larger than those of neat epoxy resin. These features of MC-V resembled those of what is called “molecular composite”. E'g and ΔL of MC-H increased futher compared with those of MC-V. That is, the reinforcing efficiency of LCP could be increased further by heat treatment of MC-V. From the changes in mechanical dispersion, birefringence and infrared spectra, it can be deduced that the dispersed state of LCP is improved and the interaction between LCP and epoxy resin matrix is strengthened accompanying the heat treatment of MC-V.

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The relation between the structure and viscoelastic properties of epoxy resins prepared from o-cresol novolacs having different molecular weight distribution was studied. Five kinds of o-cresol novolac were prepared by fractional precipitation of a commerical o-cresol novolac. The fractionated novolacs and commericial novolac were glycidyletherified by epichlorohydrin. These epoxy resins were cured with fournuclei o-cresol novolac as a hardener. Characteristic properties of the cured resins, such as glass transition temperature (Tg), average molecular weight between crosslinking points (Mc), and front facter (φ), were obtained.
The conclusions were as follows : (1) The higher the average molecular weight of a starting novolac, (i) the higher was the Tg, (ii) the larger was the E' in a rubbery region, (iii) the smaller was the Mc, and (iv) the larger was the φ, in the cured epoxy resin. (2) The viscoelastic parameters had a better correlation with the number average molecular weight of a starting novolac than with the weight average molecular weight. (3) The coefficient of linear expansion of a cured epoxy resin was not much influenced by the average molecular weight of a starting novolac.

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Cathodic Electrodeposition (CED) coating resin has one or more basic groups (ex. amine, ammonium salt, sulfonium salt, phosphonium salt, and Mannich salt group). It is dispersed in water after neutralized by acid. Therefore CED is water dispersible paint which deposits to the cathode under the application of direct current.
Epi-bis type epoxy CED coating with urethane curing system has been in use for automotive primer since later 1970's, and having a high corrosion inhibition, it has rapidly progressed in a short period, and today established a firm position in almost all the automotive production-line.
Recently, market needs higher corrosion inhibition (ex. edge corrosion inhibition), film quality (ex. appearance, weatherability), and cost down (ex. lower weight loss on heating, lower temperature curing). Along these needs, investigations on substance, curing reaction, and film making process have been progressed.
This paper discusses principally the basic design concept of CED resin and the recent technical trend, with citing literatures and patents.

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A Serious problem of the composite structure is its low fracture toughness and low compression strength after impact. This problem is notified through the application of composites to aircraft. Tough thermoplastic resins, therefore, are now introduced as the matrix of composites, and epoxy composites are toughened. A current state-of-the-art and a background of such trends are overviewed. Recent knowledge of fracture toughness testing is also mentioned.

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In 1935 G. Walter published an article on “The Condensation of Urea and Formaldehyde” at the Faraday Society Symposium on “Phenomena of Polymerisation and Condensation.” There he postulated new chemical formulae for the two crystalline condensation products, i. e. Meth A and Meth B. But these have been rejected by almost all resin chemists, besides, his other works seem to have little been cited in the literatures. To clarify the state of affairs the present author introduced and discussed Walter's articles on “Constitution of Synthetic Resins.” : Part I, II (1931) and IX (1934) with the article of the “Symposium.”

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