Dynamic Viscoelasticity of High Modulus Fiber Reinforced Composite Resins and Molecular Motion and Dynamic Viscoelasticity of Molecular Composite Resins

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Macro level composite specimens of treated carbon fiber (CF) and Kevlar fiber (KF) cloths sandwiched by PMMA resin, and micro level molecular composites composed of PMMA resin as matrix reinforced with polyaramides as rigid core molecules have been developed to produce denture base polymers with improved dental material properties.The epoxy treated CF cloth (called ECF short, 0.1mm thickness 1 sheet) reinforced resin was improved in bending strength by 25% and tensile strength by 50% from ACRON. The chlorosulfonated latex resorcine treated KF cloth (calledCLRKF short, 0.1mm thickness 1 sheet) reinforced resin was improved in bending strength by 25%, in tensile strength by 80% and izod impact strength by 70% from ACRON.The interaction between surface treated fiber cloths and the matrix resin in the fiber reinforced composites was investigated using a Dynamic Mechanical Thermal Analyzer (DMTA).The dynamic storage modulus (E') value and tan delta of alpha peak of these specimens were meas … More ured in the region from glass state to viscous flow state (50-250 ^。C) by DMTA. E' value of the composite specimen of the non-treated CF Cloth (1 sheet) was increased by 50% from ACRON at 150 ^。C. E' value of the composite specimen of the non-treated KF cloth (1 sheet) was increased by 40% from ACRON at 150 ^。C. These findings indicate a significant effect of the polar groups on the molecular interaction between the surface cloths and matrix in the cloth sandwiched composite specimens. The E' value of composite specimen of chemically treated CF cloth was lower than the E' value of composite specimen of non-treated CF Cloth. The fiber surface of the chemically treated CF cloth. Was assumed to be damaged by the chemical reaction. ECFA was increased in E' value by 120% from ACRON at 200^。C and showed the lowest (1.31) value in tan delta in the composite specimens.The bending, tensile and izod impact strength and E' value of the composite specimens of the ECF cloth increased with the number of ECF pile sheets (0.1mm thickness), while the temperature of the alpha peak of composite specimens decreased with the number of the ECF pile sheets. This may be due to the increase of the amount of low molecular weight and non-polymerized epoxy treated agent with the number of ECF.Rigid core composites made of derivatives of poly-p-phenylene terephthalamide (PPTA). Poly-m-phenylene isophthalamide (MPIA) and poly-p-phenylene-3.4'-oxydiphenylene terephthalamide (PPOT) molecules themselves were also examined.N-octylated polyaramides were soluble in methylmethacrylate nonomer. Themechanical properties of the nolecular composite resins (called Oct-PPTA-PMMA, Oct-MPIA-PMMA and Oct-PPOT-PMMA short) compounding 3wt% of N-octylated-PPTA (Oct-PPTA), N-octylated-MPIA (Oct-MPIA) and N-octylated-PPOT (Oct-PPOT) to PMMA. Were in the order of Oct-PPTA-PMMA>Oct-PPOT-PMMA >Oct-MPIA-PMMA *PMMA.The characters of the molecular composites were examined, using nuclearmagnetic resonance (NMR) spectroscopy, thermogravimetric (TG) analysis and DMTA.The molecular motion of carbonyl and methyl group of N-octylated polyaramides were in the order of Oct-PPTA <Oct-PPOT<Oct-MPIA by T_1 (inversion recovery method) NMR spectra in CDCI_3. T_1 values of carbonyl and methyl group of the core molecules which have superior straight property of main chain are rather small. Initial temperature of weight loss of the composite were in the order of Oct-PPTA-PMMA (266 ^。C) >Oct-PPOT-PMMA (263 ^。C) >Oct-PPTA-MPIA (246 ^。C) >PMMA (237 ^。C) by TG analysis.E' values of Oct-PPTA-PMMA and Oct-PPOT-PMMA were improved by 35% and E'value of Oct-MPIA-PMMA was improved by 15% from PMMA at 200 ^。C.There was a good correlation among the T_1 values, stating temperature of weight loss, E' values and dental material properties of Oct-PPTA-PMMA, Oct-MPIA-PMMA, Oct-PPOT-PMMA and PMMA.In conclusion, PMMA resins composed of the polyaramide molecule of straight main chain have suit able dental material properties. Less