Acrylate modified polyurethane resin was first synthesized, and interpenetrated with unsaturated polyester resin to form IPNs and gradient IPNs which cured at room temperature. The polymerization process was traced by...Acrylate modified polyurethane resin was first synthesized, and interpenetrated with unsaturated polyester resin to form IPNs and gradient IPNs which cured at room temperature. The polymerization process was traced by an IR spectroscopy technique and the simultaneous interpenetrating techniques were determined. The morphology of these IPNs were estimated by TMA and TEM methods. The results indicated that large amount of interpenetrating and entanglement make T g linked up effectively, and domains between two phases can be in nanometre ranges, which changed with composition ratios. The mechanical properties results showed that IPNs varied from elastomeric to plastic materials. It was noteworthy that, with the introduction of modified groups and the formation of graft construction in IPNs, the miscibility in the systems was improved a lot. These further led to the improved mechanical properties of IPNs with elastomer reinforced and plasticizer toughened as well. The reinforced miscibility between the networks can apparently change mechanical property especially for the gradient ones when the materials are elongated.展开更多
P（BA-GMA）（PBG）, having various molecular weights, was synthesized by in situ polymerization of butyl acrylate（BA） and glycidyl methacrylate（GMA）, and further used as a modifier to improve the comprehensive pro...P（BA-GMA）（PBG）, having various molecular weights, was synthesized by in situ polymerization of butyl acrylate（BA） and glycidyl methacrylate（GMA）, and further used as a modifier to improve the comprehensive properties of the epoxy curing system. The copolymers were characterized by gel permeation chromatography（GPC）. The effects of various molecular weights of copolymers on the mechanical properties, thermal performance, and phase behavior of the curing system were carefully evaluated. The experimental results of differential scanning calorimetry（DSC） and dynamic mechanical analysis（DMA） showed that glass transition temperature decreased and the tan δ peak shifted to a lower temperature with decreasing molecular weight of copolymer. Mechanical properties analysis of curing films showed that the impact strength and fracture toughness increased significantly upon the addition of PBG, indicating good toughness of the modified epoxy resins. From scanning electron microscopy（SEM） studies of the fracture surfaces of ER/PBG systems, the fracture behavior of epoxy matrix was changed from brittleness to toughness.展开更多
This research explored replacing acrylic core-shell impact modifier （AIM） by silica fume to toughen PVC. 100%, 75%, 50% and 25% of AIM （8 phr） were substituted by silica fume in PVC respectively, and then processe...This research explored replacing acrylic core-shell impact modifier （AIM） by silica fume to toughen PVC. 100%, 75%, 50% and 25% of AIM （8 phr） were substituted by silica fume in PVC respectively, and then processed by dry blending and twin-screw extrusion. Severe silica fume agglomeration was observed by scanning electron microscope （SEM） in the PVC matrix when 8 phr pure silica fume was used and processed by screw speed of 20 rpm. Its tensile strength was thereby reduced by 38% comparing to unmodified PVC. The silica fume was successfully dispersed while the screw speed was slowed down to 10 rpm to give a stronger screw torque and a longer melt residential time in the extruder. The tensile strength was ’recovered’ to a level comparable to unmodified PVC. Impact test were performed on all formulations extruded at 10 rpm screw speed and synergetic toughening effect was found with 50% substitution and it had the impact strength that was comparable to 8 phr pure AIM toughened PVC.展开更多
Acrylic fibres are highly crystalline and non-polar polymers,which makes their dyeing a very difficult step that poses real technical challenges.In order to overcome this concern,it is intended in this paper to modify...Acrylic fibres are highly crystalline and non-polar polymers,which makes their dyeing a very difficult step that poses real technical challenges.In order to overcome this concern,it is intended in this paper to modify acrylic fibers by different methods namely cationisation using the Crosscolor DRT then amidoximation using hydroxylamine hydrochloride and ammonium acetate.The resulted samples were dyed then with the bio-colorant extracted from grape marc.The effect of the pretreatment on fibers fine structure using X-ray diffraction and the scanning electron microscope(SEM)images and its correlation with the colour strength of the dyed fabrics was investigated.The dyeing parameters,such as dye bath pH and temperature on the performances of this dyeing process were studied.Good dyeing qualities and new shades varying from brown to grey and dark green have been obtained following process optimization,mordanting and modification of acrylic fibers by the technique of cationisation.展开更多
文摘Acrylate modified polyurethane resin was first synthesized, and interpenetrated with unsaturated polyester resin to form IPNs and gradient IPNs which cured at room temperature. The polymerization process was traced by an IR spectroscopy technique and the simultaneous interpenetrating techniques were determined. The morphology of these IPNs were estimated by TMA and TEM methods. The results indicated that large amount of interpenetrating and entanglement make T g linked up effectively, and domains between two phases can be in nanometre ranges, which changed with composition ratios. The mechanical properties results showed that IPNs varied from elastomeric to plastic materials. It was noteworthy that, with the introduction of modified groups and the formation of graft construction in IPNs, the miscibility in the systems was improved a lot. These further led to the improved mechanical properties of IPNs with elastomer reinforced and plasticizer toughened as well. The reinforced miscibility between the networks can apparently change mechanical property especially for the gradient ones when the materials are elongated.
基金Funded by the National Natural Science Foundation of China(51373129)the Fundamental Research Funds for the Central University(WUT:2013-IV-011)
文摘P（BA-GMA）（PBG）, having various molecular weights, was synthesized by in situ polymerization of butyl acrylate（BA） and glycidyl methacrylate（GMA）, and further used as a modifier to improve the comprehensive properties of the epoxy curing system. The copolymers were characterized by gel permeation chromatography（GPC）. The effects of various molecular weights of copolymers on the mechanical properties, thermal performance, and phase behavior of the curing system were carefully evaluated. The experimental results of differential scanning calorimetry（DSC） and dynamic mechanical analysis（DMA） showed that glass transition temperature decreased and the tan δ peak shifted to a lower temperature with decreasing molecular weight of copolymer. Mechanical properties analysis of curing films showed that the impact strength and fracture toughness increased significantly upon the addition of PBG, indicating good toughness of the modified epoxy resins. From scanning electron microscopy（SEM） studies of the fracture surfaces of ER/PBG systems, the fracture behavior of epoxy matrix was changed from brittleness to toughness.
文摘This research explored replacing acrylic core-shell impact modifier （AIM） by silica fume to toughen PVC. 100%, 75%, 50% and 25% of AIM （8 phr） were substituted by silica fume in PVC respectively, and then processed by dry blending and twin-screw extrusion. Severe silica fume agglomeration was observed by scanning electron microscope （SEM） in the PVC matrix when 8 phr pure silica fume was used and processed by screw speed of 20 rpm. Its tensile strength was thereby reduced by 38% comparing to unmodified PVC. The silica fume was successfully dispersed while the screw speed was slowed down to 10 rpm to give a stronger screw torque and a longer melt residential time in the extruder. The tensile strength was ’recovered’ to a level comparable to unmodified PVC. Impact test were performed on all formulations extruded at 10 rpm screw speed and synergetic toughening effect was found with 50% substitution and it had the impact strength that was comparable to 8 phr pure AIM toughened PVC.
文摘Acrylic fibres are highly crystalline and non-polar polymers,which makes their dyeing a very difficult step that poses real technical challenges.In order to overcome this concern,it is intended in this paper to modify acrylic fibers by different methods namely cationisation using the Crosscolor DRT then amidoximation using hydroxylamine hydrochloride and ammonium acetate.The resulted samples were dyed then with the bio-colorant extracted from grape marc.The effect of the pretreatment on fibers fine structure using X-ray diffraction and the scanning electron microscope(SEM)images and its correlation with the colour strength of the dyed fabrics was investigated.The dyeing parameters,such as dye bath pH and temperature on the performances of this dyeing process were studied.Good dyeing qualities and new shades varying from brown to grey and dark green have been obtained following process optimization,mordanting and modification of acrylic fibers by the technique of cationisation.
