Mechanlcal properties of epoxy resin were investigated by adding core-shell elastic particles (CSEP). The results indicated that optimized core-shell ratio was 60/40 and the loading volume of CSEP was 10 phr (per hund...Mechanlcal properties of epoxy resin were investigated by adding core-shell elastic particles (CSEP). The results indicated that optimized core-shell ratio was 60/40 and the loading volume of CSEP was 10 phr (per hundred parts of epoxy resin by weight). The impact strength of modified systems increased apparently with the decrease of core sizes. However, the shearing strength changed gently with the particle sizes. CSEP with lightly crosslinked rubbery core showed more effectiveness on toughness than others. With solution blending, CSEP could be dispersed in epoxy matrix well, and the morphologies of dispersed rubber domains were controlled perfectly by CSEP whose structure was predesigned. A cavitation-shearing band toughness mechanism was observed from the SEM micrographs of fracture surface. It also was found that the deforming temperature (DT) of modified epoxy did not decline apparently.展开更多
Polybutylacrylate (PBA)/poly(methyl methacrylate) (PMMA) core-shell elastic particles (CSEP), whose rubbery core diameter ranged from 0.08 μm to 1.38μm, were synthesized by using conventional emulsion polymerization...Polybutylacrylate (PBA)/poly(methyl methacrylate) (PMMA) core-shell elastic particles (CSEP), whose rubbery core diameter ranged from 0.08 μm to 1.38μm, were synthesized by using conventional emulsion polymerization, multi-step emulsion polymerization, and soapless polymerization. Allyl methacylate (ALMA) and ethylene glycol dimethacrylate (EGDMA) were selected as crosslinking reagents for core polymerization. Methacrylic acid (MAA) was used as functional co-monomer with methyl methacrylate as shell component. The content of vinyl groups in PBA rubbery core increased with the amount of crosslinking reagents. The core-shell ratio affected great on the morphology of the complex particles. Furthermore, the amounts of carboxyl on the surface of core-shell particles, copolymerized with acrylic acid, were determined by potentiometric titration. Results showed that methylacrylic acid was distributed mostly on the surface of particles.展开更多
A model was deveIoped to investigate impregnation behavior of thermoplastic resin into filament bundle based on Darcy's law. Consolidation processes of unidirectional laminate were performed to evaluate the validi...A model was deveIoped to investigate impregnation behavior of thermoplastic resin into filament bundle based on Darcy's law. Consolidation processes of unidirectional laminate were performed to evaluate the validity of the model. Friction spun core yarns were used in the experiments with polypropylene fiber sheath and glass filament core. The processing conditions, such as temperature and pressure, and filament parameters were taken into consideration. A good agreement was found between theoretical prediction and experiment data.展开更多
This paper presents the erosion results of the AISI H13 steel impinged by resin-bonded silica sand, using a testing rig that closely simulates the real blowing conditions during industrial core-making. Steel specimens...This paper presents the erosion results of the AISI H13 steel impinged by resin-bonded silica sand, using a testing rig that closely simulates the real blowing conditions during industrial core-making. Steel specimens were heat treated to obtain hardness of 294, 445 and 595 HV200 (29, 45 and 55 HRC). Erosion tests were carried out at impingement angles from 20° to 90° and air drag pressures of 1.38, 2.07 and 2.76 bar (20, 30 and 40 psi). The main results are summarized as follows:(i) The harder material, the lower erosion;(ii) the maximum erosion rate is at 30°;(iii) Little difference in erosion rate at impact angle of 60° and 90° for a constant pressure tested regardless of the hardness level;(iv) As the pressure increases, so does the erosion rate, being more sensitive for low impact angles. Finally, a differential form of the general erosion equation is applied on a practical core-making case to evaluate the erosion rate of the H13 steel at 30° and 90° impingement angles.展开更多
Sub-micron sized phenolic epoxy resin waterborne particles were prepared by phase inversion emulsification. Micro-phase separation occurred during the curing process at high temperature. The as-prepared samples posses...Sub-micron sized phenolic epoxy resin waterborne particles were prepared by phase inversion emulsification. Micro-phase separation occurred during the curing process at high temperature. The as-prepared samples possessed one glass transition temperature （Tg） and two exothermal processes during DSC heating scannings. After being thermally treated above the exothermal peak temperature, they possessed two glass transition temperatures with the disappearance of exothermal peaks, whilst a core/shell structure was formed. This was likely related with the outward diffusion of reactive oligomers to the outer layer of particles.展开更多
文摘Mechanlcal properties of epoxy resin were investigated by adding core-shell elastic particles (CSEP). The results indicated that optimized core-shell ratio was 60/40 and the loading volume of CSEP was 10 phr (per hundred parts of epoxy resin by weight). The impact strength of modified systems increased apparently with the decrease of core sizes. However, the shearing strength changed gently with the particle sizes. CSEP with lightly crosslinked rubbery core showed more effectiveness on toughness than others. With solution blending, CSEP could be dispersed in epoxy matrix well, and the morphologies of dispersed rubber domains were controlled perfectly by CSEP whose structure was predesigned. A cavitation-shearing band toughness mechanism was observed from the SEM micrographs of fracture surface. It also was found that the deforming temperature (DT) of modified epoxy did not decline apparently.
文摘Polybutylacrylate (PBA)/poly(methyl methacrylate) (PMMA) core-shell elastic particles (CSEP), whose rubbery core diameter ranged from 0.08 μm to 1.38μm, were synthesized by using conventional emulsion polymerization, multi-step emulsion polymerization, and soapless polymerization. Allyl methacylate (ALMA) and ethylene glycol dimethacrylate (EGDMA) were selected as crosslinking reagents for core polymerization. Methacrylic acid (MAA) was used as functional co-monomer with methyl methacrylate as shell component. The content of vinyl groups in PBA rubbery core increased with the amount of crosslinking reagents. The core-shell ratio affected great on the morphology of the complex particles. Furthermore, the amounts of carboxyl on the surface of core-shell particles, copolymerized with acrylic acid, were determined by potentiometric titration. Results showed that methylacrylic acid was distributed mostly on the surface of particles.
基金Funded by the Research Fund for the Doctoral Program of High Education
文摘A model was deveIoped to investigate impregnation behavior of thermoplastic resin into filament bundle based on Darcy's law. Consolidation processes of unidirectional laminate were performed to evaluate the validity of the model. Friction spun core yarns were used in the experiments with polypropylene fiber sheath and glass filament core. The processing conditions, such as temperature and pressure, and filament parameters were taken into consideration. A good agreement was found between theoretical prediction and experiment data.
基金financially supported by NEMAK S.A. and Industria Meccanica Bassi Luigi&Co
文摘This paper presents the erosion results of the AISI H13 steel impinged by resin-bonded silica sand, using a testing rig that closely simulates the real blowing conditions during industrial core-making. Steel specimens were heat treated to obtain hardness of 294, 445 and 595 HV200 (29, 45 and 55 HRC). Erosion tests were carried out at impingement angles from 20° to 90° and air drag pressures of 1.38, 2.07 and 2.76 bar (20, 30 and 40 psi). The main results are summarized as follows:(i) The harder material, the lower erosion;(ii) the maximum erosion rate is at 30°;(iii) Little difference in erosion rate at impact angle of 60° and 90° for a constant pressure tested regardless of the hardness level;(iv) As the pressure increases, so does the erosion rate, being more sensitive for low impact angles. Finally, a differential form of the general erosion equation is applied on a practical core-making case to evaluate the erosion rate of the H13 steel at 30° and 90° impingement angles.
基金This work was financially supported by the National Natural Science Foundation of China(No.20104008).
文摘Sub-micron sized phenolic epoxy resin waterborne particles were prepared by phase inversion emulsification. Micro-phase separation occurred during the curing process at high temperature. The as-prepared samples possessed one glass transition temperature （Tg） and two exothermal processes during DSC heating scannings. After being thermally treated above the exothermal peak temperature, they possessed two glass transition temperatures with the disappearance of exothermal peaks, whilst a core/shell structure was formed. This was likely related with the outward diffusion of reactive oligomers to the outer layer of particles.
