Peel adhesive strengths of multi-layered laminates composed of two polypropylene (PP) sheets and ... more Peel adhesive strengths of multi-layered laminates composed of two polypropylene (PP) sheets and an inserted polyethylene (PE) layer (the middle layer) between the PP layers were evaluated. PE-glycidyl methacrylate (GMA) copolymers and a maleic-anhydride grafted PP (MAPP) were compared to the PE homopolymer and the PP homopolymer. The peel adhesive strength of PE-GMA/MAPP laminates was much higher than that of PE homopolymer/PP homopolymer laminates. Meanwhile, the blends composed of the PE-GMA and three types of PE homopolymer (PE-GMA+LDPE, PE-GMA+MDPE, PE-GMA+HDPE) were formulated as the PE middle layer of the multi-layered laminates. The PE blends had the same amount of glycidyl groups, and the deformation capacity was different in each. Namely, the PE blend of LDPE had higher elongation to break than the PE blend of HDPE. The peel adhesive strength of the multi-layered laminates with the middle layer of the LDPE blend was highest among the three types of laminates with the middl...
Abstract The effect of small amounts of curing catalysts on the nanostructures and mechanical pro... more Abstract The effect of small amounts of curing catalysts on the nanostructures and mechanical properties of epoxy/acrylic block copolymer blends were investigated. Poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly (methyl methacrylate) (PMMA-b-PnBA-b-PMMA) triblock copolymer (acrylic BCP) was blended with diglycidyl ether of bisphenol-A epoxy thermosets. The blends were cured using phenol novolac (PN) with curing catalysts at less than 1 wt%. Three different curing catalysts, triphenylphosphine (TPP), 2,4,6-tris(dimethyl amino methyl)phenol (DMP), and 1,2-dimethylimidazole (DMIz), were compared. A polyol-type linkage structure was formed in the cured epoxy matrix using TPP, whereas both polyether-type linkage structure and polyol-type linkage structure were formed when DMP and DMIz were used. As a result, different nanostructures were formed in response to the different linkage structures in the epoxy matrix originated from the same blend composition of epoxy/acrylic BCP/PN. The TPP catalyst gave a spherical nanostructure, while the DMP and DMIz catalysts gave branched cylindrical nanostructures in the epoxy/acrylic BCP/PN blends. The compatibility of the PMMA-block chains of the acrylic BCPs to the cured epoxy matrix was a key factor that determined the nanostructures. The fracture toughness of the cured blends was dependent on both the nanostructures in the blends and the ductility (extent of cross-linking density) of the epoxy matrix.
The phase structures obtained from blends consisting of an epoxy resin, an aromatic amine and a P... more The phase structures obtained from blends consisting of an epoxy resin, an aromatic amine and a PMMA-b-PnBA-b-PMMA triblock copolymer (BCP) were studied, in terms of the effect of the process used to blend the BCP into the epoxy/amine mixture. The thermal dissolution of the BCP in the amine was found to promote the in situ generation of carboxylic acids in the PMMA segments of the BCP. This enhanced the compatibility of the BCP with the cured epoxy/aromatic amine resin, allowing the self-assembly of the BCP to form nanophase structures in the polymeric matrix. This work also determined that modification of the heating conditions was an effective means of controlling the quantity of carboxyl groups generated (that is, the acid value). Such variations led to the formation of different types of micelle structures, such as curved lamellae, coexisting of worm-like micelles and vesicles and spheres, from epoxy/amine/BCP blends having the same composition. The blends of epoxy/amine/acrylic block copolymer (BCP) provided nanophase structures by optimizing the dissolution process of BCP. The thermal dissolution of the BCP in the amine promoted the in situ formation of carboxylic acids. Tuning the amount of carboxylic acids changed the phase structure, such variations led to the formation of different types of micelle structures, such as curved lamellae, coexisting of worm-like micelles and vesicles, and spherical micelles from epoxy/amine/BCP blends having the same composition.
The objective of the present study was to determine whether the ductility and toughenability of a... more The objective of the present study was to determine whether the ductility and toughenability of a highly cross-linked epoxy resin, which has a high glass transition temperature, T g, can be enhanced by the incorporation of a ductile thermoplastic resin. Diglycidyl ether of bisphenol-A (DGEBA) cured by diamino diphenyl sulphone (DDS) was used as the base resin. Polyethersulphone (PES) was
Wood-based epoxy resin was synthesized from resorcinol-liquefied wood. First, wood components wer... more Wood-based epoxy resin was synthesized from resorcinol-liquefied wood. First, wood components were depolymerized and liquefied by reaction with resorcinol. The resorcinol-liquefied wood with plenty of hydroxyl groups could be considered as a precursor for synthesizing wood-based epoxy resin. Namely, the phenolic-OH groups of the liquefied wood reacted with epichlorohydrine under alkali condition. By the glycidyl etherification, epoxy functionality was introduced to the liquefied wood. The wood-based epoxy resin was cured with 4, 4’- diamino diphenyl sulphone (DDS) and the thermal and mechanical properties were evaluated. The flexural modulus and strength of the cured wood-based epoxy resin were comparable to those of the petroleum-based bisphenol-A type epoxy resin (diglycidyl ether of bisphenol-A: DGEBA). The mechanical and adhesive properties of the wood-based epoxy resins suited well for matrix resins of fiber reinforced composites. Therefore, biomass composites consist of ramie ...
Peel adhesive strengths of multi-layered laminates composed of two polypropylene (PP) sheets and ... more Peel adhesive strengths of multi-layered laminates composed of two polypropylene (PP) sheets and an inserted polyethylene (PE) layer (the middle layer) between the PP layers were evaluated. PE-glycidyl methacrylate (GMA) copolymers and a maleic-anhydride grafted PP (MAPP) were compared to the PE homopolymer and the PP homopolymer. The peel adhesive strength of PE-GMA/MAPP laminates was much higher than that of PE homopolymer/PP homopolymer laminates. Meanwhile, the blends composed of the PE-GMA and three types of PE homopolymer (PE-GMA+LDPE, PE-GMA+MDPE, PE-GMA+HDPE) were formulated as the PE middle layer of the multi-layered laminates. The PE blends had the same amount of glycidyl groups, and the deformation capacity was different in each. Namely, the PE blend of LDPE had higher elongation to break than the PE blend of HDPE. The peel adhesive strength of the multi-layered laminates with the middle layer of the LDPE blend was highest among the three types of laminates with the middl...
Abstract The effect of small amounts of curing catalysts on the nanostructures and mechanical pro... more Abstract The effect of small amounts of curing catalysts on the nanostructures and mechanical properties of epoxy/acrylic block copolymer blends were investigated. Poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly (methyl methacrylate) (PMMA-b-PnBA-b-PMMA) triblock copolymer (acrylic BCP) was blended with diglycidyl ether of bisphenol-A epoxy thermosets. The blends were cured using phenol novolac (PN) with curing catalysts at less than 1 wt%. Three different curing catalysts, triphenylphosphine (TPP), 2,4,6-tris(dimethyl amino methyl)phenol (DMP), and 1,2-dimethylimidazole (DMIz), were compared. A polyol-type linkage structure was formed in the cured epoxy matrix using TPP, whereas both polyether-type linkage structure and polyol-type linkage structure were formed when DMP and DMIz were used. As a result, different nanostructures were formed in response to the different linkage structures in the epoxy matrix originated from the same blend composition of epoxy/acrylic BCP/PN. The TPP catalyst gave a spherical nanostructure, while the DMP and DMIz catalysts gave branched cylindrical nanostructures in the epoxy/acrylic BCP/PN blends. The compatibility of the PMMA-block chains of the acrylic BCPs to the cured epoxy matrix was a key factor that determined the nanostructures. The fracture toughness of the cured blends was dependent on both the nanostructures in the blends and the ductility (extent of cross-linking density) of the epoxy matrix.
The phase structures obtained from blends consisting of an epoxy resin, an aromatic amine and a P... more The phase structures obtained from blends consisting of an epoxy resin, an aromatic amine and a PMMA-b-PnBA-b-PMMA triblock copolymer (BCP) were studied, in terms of the effect of the process used to blend the BCP into the epoxy/amine mixture. The thermal dissolution of the BCP in the amine was found to promote the in situ generation of carboxylic acids in the PMMA segments of the BCP. This enhanced the compatibility of the BCP with the cured epoxy/aromatic amine resin, allowing the self-assembly of the BCP to form nanophase structures in the polymeric matrix. This work also determined that modification of the heating conditions was an effective means of controlling the quantity of carboxyl groups generated (that is, the acid value). Such variations led to the formation of different types of micelle structures, such as curved lamellae, coexisting of worm-like micelles and vesicles and spheres, from epoxy/amine/BCP blends having the same composition. The blends of epoxy/amine/acrylic block copolymer (BCP) provided nanophase structures by optimizing the dissolution process of BCP. The thermal dissolution of the BCP in the amine promoted the in situ formation of carboxylic acids. Tuning the amount of carboxylic acids changed the phase structure, such variations led to the formation of different types of micelle structures, such as curved lamellae, coexisting of worm-like micelles and vesicles, and spherical micelles from epoxy/amine/BCP blends having the same composition.
The objective of the present study was to determine whether the ductility and toughenability of a... more The objective of the present study was to determine whether the ductility and toughenability of a highly cross-linked epoxy resin, which has a high glass transition temperature, T g, can be enhanced by the incorporation of a ductile thermoplastic resin. Diglycidyl ether of bisphenol-A (DGEBA) cured by diamino diphenyl sulphone (DDS) was used as the base resin. Polyethersulphone (PES) was
Wood-based epoxy resin was synthesized from resorcinol-liquefied wood. First, wood components wer... more Wood-based epoxy resin was synthesized from resorcinol-liquefied wood. First, wood components were depolymerized and liquefied by reaction with resorcinol. The resorcinol-liquefied wood with plenty of hydroxyl groups could be considered as a precursor for synthesizing wood-based epoxy resin. Namely, the phenolic-OH groups of the liquefied wood reacted with epichlorohydrine under alkali condition. By the glycidyl etherification, epoxy functionality was introduced to the liquefied wood. The wood-based epoxy resin was cured with 4, 4’- diamino diphenyl sulphone (DDS) and the thermal and mechanical properties were evaluated. The flexural modulus and strength of the cured wood-based epoxy resin were comparable to those of the petroleum-based bisphenol-A type epoxy resin (diglycidyl ether of bisphenol-A: DGEBA). The mechanical and adhesive properties of the wood-based epoxy resins suited well for matrix resins of fiber reinforced composites. Therefore, biomass composites consist of ramie ...
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Papers by Hajime Kishi