Akira Fukami

Positive Photoreactive Polyimides. II. Preparation and Characterization of Polyimide Precursors Containing α-(2-Nitrophenyl)ethyl Ester Side Chains

Abstract The monomers were derived from pyromellitic dianhydride and α-(2-nitrophenyl)ethanol, which was prepared by selective reduction of 2-nitroacetophenone. Polyimide precursors were synthesized by an interfacial polycondensation technique. Their thermal properties in nitrogen were studied by dynamic thermogravimetry. The photore-arrangement of 2-nitrobenzyl ester having a methyl group at the α-position compared to that of the unsubstituted ester was investigated by infrared spectrophotometry. The polymers obtained in this study gave a high proportion of photorearrangement to show high sensitivity. The exposed areas dissolved in 2% aqueous KOH, forming high resolution patterns because they did not swell during the developing process.

Simultaneous interpenetrating polymer networks of epoxy resin/bismaleimide-allylester copolymer. I. Dynamic mechanical properties

Abstract Simultaneous interpenetrating polymer networks (SINs) were prepared from nadic methyl anhydride-cured epoxy resin and bismaleimide (BMI) coreacted with triallyltrimellitate (TAT), triallylisocyanurate (TAIC), and diallylisophthalate (DAP), under the same gelling conditions for both the epoxide resin and BMI-allylester comonomer. Dynamic mechanical properties of the SINs were measured over the temperature range from room temperature to about 300°C. The rubbery modulus and glass transition temperature (Tg) due to the cured epoxy resin considerably increased with loading of BMI-allylester copolymer. The value of Tg exhibited an asymptotic behavior at high loading, the value increasing in the order of BMI-TAT, -TAIC, and -DAP. The relative modulus in the rubber state shows that phase inversion occurs in the SINs at the concentration of 30–40 wt% BMI-allylester. The increase in Tg with loading can be explained in terms of the contributions of both an increase in crosslink density and an interaction be...

Dependence of solvent crazing in bisphenol–A polycarbonate on molecular weight of organic liquids

Abstract Solvent crazing has been investigated for bisphenol-A poly-carbonate exposed to the liquids of n-alcohols, di-n-alkylphthalates, and adipic acid polyesters. The critical strain at which crazes appeared was determined with a Bergen elliptical strain device. In the case of the n-alcohol and di-n-alkylphthalate liquids with a small number of carbons in the alkyl chain, crazes spread rapidly to areas of lower strain with time and ceased within 30 min at room temperature. Such a lower limiting value of critical strain can be predicted by using polar-nonpolar solubility parameter plotting representations employing the molar volume term. On the other hand, craze initiation was more delayed for two higher molecular weight liquids, di-n-octylphthalate and adipic acid polyester. Sorption studies were also conducted on polycarbonate immersed in both liquids. The values of the activation energy and diffusion coefficient estimated from the experimental data on craze initiation were found to be nearly comparab...

Mechanical Behavior of Interpenatrating Polymer Networks from Epoxy Resin and Bismaleimide-Allylester Copolymer

ABSTRACT Interpenetrating polymer networks (IPNs) were prepared with an equal weight of anhydride-cured epoxy resin and bismaleimide (BMI) coreacted with three kinds of allylesters, under different gelling conditions for both the epoxy resin and comonomer. Dynamic mechanical and tensile properties were examined for these IPNs. The rubbery modulus increased largely with increasing a gel-time ratio of the epoxy resin to the comonomer, suggesting that the BMI—allylester copolymer networks become more continuous. On the other hand, the glass transition temperature (Tg) and the tensile strength exhibited maxima when the two gellations were most nearly simultaneous. These can be explained in terms of the greatest extent of molecular mixing. Such behaviors were irrespective of the kinds of the allylesters.