Glass fiber reinforced plastics (GFRP) are extensively used in many kinds of industrial fields. Matrices commonly used for GFRP are unsaturated polyester, epoxy, and phenolic resins. Especially expected are phenolic resins because of their good heat and flame resistance, and high mechanical properties. The objective of this study is to develop a new type of high-performance phenolic GFRP which needs no catalysts and releases no volatiles in the curing process.
Bisphenol-A type novolac based benzoxazine (BisAN-a), as a new type phenolic resin precursor, was prepared from bisphenol-A type novolac, formaline and aniline. Matrix used was a molten mixture from BisAN-a and bisoxazoline. Bisoxazoline is a well known compound for improving the interfacial bond strength between the matrix and fibers. GFRP laminate was prepared by hand lay-up method using E-glass woven fabric (cloth) of 10 plies, the fiber surface of which had been treated with an acrylic silane. As a result, GFRP from BisAN-a and bisoxazoline showed higher heat resistance, tensile strength, flexural strength, and especially impact strength than GFRP from a conventional bisphenol-A type novolac (BisAN) and bisoxazoline. The reason for getting such high performances with the former laminate was considered as follows : the interfacial bond strength of the former was slightly weaker than that of the latter, and so much stress concentration would not build up in the matrix due to relaxation caused by interfacial partial delamination.

View full abstract

Poly (ether ketone ketone) s were prepared and used to improve the brittleness of the cyanate ester resin The poly (ether ketone ketone) s include poly (phthaloyl diphenyl ether) (PPDE), poly (phthaloyl diphenyl ether-co-isophthaloyl diphenyl ether) (PPIDE) and poly (phthaloyl diphenyl ether-co-terephthaloyl diphenyl ether) (PPTDE). PPDE was more effective as a modifiers for improving the brittleness of the cyanate ester resin than were PPIDE (50 mol% isophthaloyl unit) and PPTDE (50 mol% terephthaloyl unit). When using 15 wt% of PPDE (MW 28,300), the modified resin had a particulate structure and the fracture toughness (K_IC) increased 30% at a slight loss of flexural strength and no deterioration of flexural modulus and glass transition temperature, compared with those of the unmodified cured cyanate ester resin. The thermal stability of the modified resin was also comparable to that of the unmodified resin. Water absorptivity of the cured resin was not deteriorated by the modification with PPDE.

View full abstract

The effects of resinous reaction products of N"-cyanoguanidine (CG), and free bases of N, N- (diaminomethylene) urea (DU), or N, N'-methylenebis [N'- (diamino methylene) urea] (Bis-DU) with formaldehyde (F) on the fish and microorganisms were assessed. The harmful effects of resinous products of DU-F, CG-F, and Bis-DU-F to Oryzias Latipes Orange-red Variety, decreased in this order, because the values of Tlm for 48h and (72h) of these resins are 13-15 (11-13), 26-28 (21-23), and 43-45 (39-41) mg · dm^-3, respectively. Though the inhibitory effects of these products on biodegradation of aniline by the activated sludges and on the growth of several bacteria were observed, they as well as the harmful effects to the fish are practically negligible and do not prevent the use of these resinous products as flocculants. Because harmful or inhibitory effects appeared in the concentration of 5.0 × 10 ^-3 mol · dm^-3 and above, and the minimum flocculation concentration of CG-F, DU-F, and Bis-DU-F resins are 2.7× 10^-5, 1.1 ×10^-5, and 9.0×10^-6 mol ·dm^-3, respectively, and these resins are used for flocculation in the concentration of 10^-5 ·10^-4mol ·dm^-3.

View full abstract

Because phenolic resins are far superior to many thermoplastics in heat resistance, electrical insulation and fire resistance, they are applied to auto-parts, electrical appliances and mechanical parts, etc. But their wastes can not be remelted for recycling and voluminous ones are dumped at landfill sites. We have two purposes on this study : one is to mix the wastes with virgin compounds to make recycled plastics; another is to reuse them as a filler for thermoplastics. The results obtained are as follows : (1) The suppression of generating dust particles could be attained by adding alcohol at mixing crushed materials with virgin compounds. (2) Injection moulding was tried using the recycled plastics which contained 30 wt% crushed materials. This gave us satisfactory results in appearance, mechanical property, and moldability. (3) Reuse of the wastes as a filler for thermoplastics was also tried. The heat distortion temperature of the resultant resins was improved by 3 %, compared with that of polystyrene moulding materials, though their tensile strength and flexural stress decreased with increasing content of the wastes. (4) It was confirmed that this recycling technology could be put to practical use and would contribute toward reduction of environmental burdens.

View full abstract

The entitled reactions were investigated by molecular orbital calculations. Methyl isocyanate and ethylene oxide were adopted as model reactants. The product, 2-oxazolidone, may be produced through a dual S_N2 reaction, where a catalyst base (e.g. Cl^-) will attack the ethylene-oxide carbon nucleophilically. An isocyanurate is generated by the stepwise association of three isocyanate molecules, where one of them has been linked with the base from the initial stage. The 6-membered-ring isocyanurate is isomerized stepwise and converted into the corresponding isocyanate and 2-oxazolidone. A tetrahedral-type complex from the isocyanurate and base-catalyzed ethylene oxide is the key intermediate for the isomerization.

View full abstract

An amphiphilic molecule that contains a tripeptide part forms an aggregate not only in water but also in nonpolar organic solvents. Fourie transform infrared (FT-IR) spectroscopy reveals that the aggregate in the organic solvents is a lyotropic liquid-crystal, because the alkyl chains within the aggregate in organic solvents are more disorderly than those within an aqueous aggregate which is the well-known lyotropic aggregate called the bilayer membrane. Although the aggregates contain a parallel β-sheet structure irrespective of the media, hydrogen bonding is more tightly formed in the nonpolar organic solvents. Therefore, the H-bonding prevents the alkyl chains from forming stable arrangements.

View full abstract