Study on modified phenolic resin. III. Modification with p‐hydroxyphenylmaleimide/acrylic ester copolymer

Abstract

SYNOPSISThe improvement of toughness and heat resistance of phenolic resin was examined by blend of novolac and copolymers prepared from p -hydroxyphenylmaleimide ( HPMI ) and acrylic ester. Copolymers of HPMI and acrylic esters, such as methyl acrylate, ethylacrylate, n -butylacrylate, or 2-ethylhexyl acrylate, were synthesized. Average molecular weights, glass transition temperatures ( T,) and thermal decomposition temperatures were measured.The miscibility of the copolymers with novolac was evaluated. It was found that these copolymers had higher average molecular weight and higher thermal decomposition temperature than those of novolac; they also had good miscibility with novolac. Molding compounds were prepared by hot roll-kneading of mixtures, which involved novolac, the copolymer, hexamethylenetetramine ( hexamine) , and glass fiber. Test pieces of the modified phenolic resins were prepared by transfer molding from the molding compounds. It was found that phenolic resin, modified with HPMI/ethylacrylate copolymer or HPMI/nbutylacrylate copolymer, which consisted of numerous units of acrylic ester, showed both good toughness and good heat resistance. I NTRO DU CTlO NPhenolic resin is used widely as an industrial material because of its good heat resistance, electrical insulation, dimensional stability, and chemical resistance. Recently, improvement in properties, especially toughness and heat resistance, have been required particularly for the industrial field. However, the improvement of mechanical properties, especially toughness, is usually incompatible with the improvement of heat resistance.Many approaches have been tried attempting to improve the heat resistance of phenolic resin. Fukuda et al.' have improved the heat resistance of the phenolic resins by means of the after-cure or an increase in hardening agent content. It was reported2 that high temperature phenolic resins were produced by the addition of a modifier that has good heat re-* To whom correspondence should be addressed. In the previous article5 it was found that the modification of phenolic resin with HPMI/styrene copolymer improved both flexural strength and heat resistance, but didn't much improve the toughness. It is expected that phenolic resin modified with HPMI /acrylic ester copolymer has higher toughness than the phenolic resin modified with HPMIlstyrene copolymer, because HPMI/acrylic ester copolymer is more flexible than HPMIlstyrene copolymer. Therefore, we studied the heat resistance and mechanical properties, especially toughness, of phenolic resin modified with copolymer prepared from HPMI and acrylic ester.In this study, copolymers of HPMI and acrylic ester, such as methylacrylate (MA), ethylacrylate (EA) , n-butylacrylate ( n-BuA) , or Z-ethylhexylacrylate (EHA), were synthesized and identified by 'H-NMR. Average molecular weight, Tg, and thermal decomposition temperature of the copolymers were measured by gel permeation chromatography (GPC ) , differential scanning calorimetry (DSC) , and thermogravimetry (TG) , respecti...

Synthesis and Properties of Organosoluble Poly(phenylenemethylene)s from Substituted Benzenes or Naphthalenes

“…(Table I. run [4][5][6]. For the 1,2,4-trimethylbenzene (3), the polymerization proceeded, but the number-average molecular weights of the obtained polymer was lower than that of polymer 2.…”

Developing a Renewable Hybrid Resin System. Part I: Characterization of Co-Polymers of Isocyanate with Different Molecular Weights of Phenolic Resins

“…For many decades, researchers have shown interest in improving the toughness of phenolic resins. In those studies (Matsumoto et al 1991(Matsumoto et al , 1992(Matsumoto et al , 1993, different kinds of polymers were blended with phenolic resins to accomplish this goal. Among these polymers, isocyanate resin, known as methylene diphenyl diisocyanate (MDI), which is also an important binder used in the woodworking industry, has the highest potential to react with PF resin.…”

New class of reactive novolac: synthesis of bisphenol A-based novolac with methylol groups

“…The phenolic resin with a low-molecular weight (4) (1.0 g) and HMTA (0.1 g) were added in a 50 ml vial. The mixture was heated at 140 1C for a few minutes to give the organo-insoluble resin (6).…”

“…These resins have interesting properties that make them suitable for industrial use, such as thermostability and mechanical strength. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] During the curing of novolacs, hexamethylenetetramine (HMTA) is frequently used as the curing agent; 1 however, the resultant curing products usually tend to contain amine derivatives and the unreacted curing agent as impurities, which often lead to coloration and degradation of the products.…”