Based on the X- ray scattering intensity theory, the correction factors of the degree ofcrystallinity formulae of the multicomponent polymers have been clearly defined. The formulae ofthe degree of crystallinity of th...Based on the X- ray scattering intensity theory, the correction factors of the degree ofcrystallinity formulae of the multicomponent polymers have been clearly defined. The formulae ofthe degree of crystallinity of the multicomponent polymers were derived in terms of WAXDtheory and improved graphic multipeak resolution methods. The results calculated aresatisfactory in comparison with the density measurement.展开更多
Based on the X-ray scattering intensity theory and using the atomic scattering factorapproximate expression,the correction factors for three main crystalline peaks and an amorphouspeak of Nylon-1010 were calculated an...Based on the X-ray scattering intensity theory and using the atomic scattering factorapproximate expression,the correction factors for three main crystalline peaks and an amorphouspeak of Nylon-1010 were calculated and the formula of degree of crystallinity of Nylon-1010 wasderived by graphic multipeak resolution method. The results calculated are compatible with the density measurement and calorimetry.展开更多
Based on the X-ray scattering intensity theory and using the approximate expression for the atomic scattering factor, the correction factors for three crystalline peaks and an amorphous peak of Nylon 1212 were calcula...Based on the X-ray scattering intensity theory and using the approximate expression for the atomic scattering factor, the correction factors for three crystalline peaks and an amorphous peak of Nylon 1212 were calculated and the formula of degree of crystallinity of Nylon 1212 was derived by a graphic multipeak resolution method. The degree of crystallinity calculated from the WAXD method is compatible with those obtained by density and calorimetry methods.展开更多
The present work concerns the crystallization of PET accelerated by addition of thermotropic liquid crystalline polymers (TLCP)based on two aromatic copolyesters: PHB/PET (60:40 ) and PHB/HDA/2,6-DNA /IPA ( 50:25 : 12...The present work concerns the crystallization of PET accelerated by addition of thermotropic liquid crystalline polymers (TLCP)based on two aromatic copolyesters: PHB/PET (60:40 ) and PHB/HDA/2,6-DNA /IPA ( 50:25 : 12.5 : 12.5 ). The investigation has been made by measurements of the cold-crystallization and melt-crystallization temperatures by DSC and of the changes of density and depolarizing light intensity during the isothermal process. In addition, the morphology of selectively etched surface of compressing pellets proved the presence of crystalline fibrillar structure, it can be supposed to have grown up from the micelle nucleus based on bundle of rigid TLCP chains.展开更多
Dual endotherms during differenUal scanning calorimetric (DSC) measurement occur when dried PET pellets are pretreated with solld state polyeondensation (SSP) at 215-230℃ for appropriate holding, times. The two endot...Dual endotherms during differenUal scanning calorimetric (DSC) measurement occur when dried PET pellets are pretreated with solld state polyeondensation (SSP) at 215-230℃ for appropriate holding, times. The two endothermic fusion peaks arise from melting and recrystallization, taking place during scanning in the calorimeter,of imperfect crystals initial present in sample. The lower temperature peak appears higher than the SSP reaction temperature for 5-20℃ accordingly and linear relaflonship with SSP reaction temperature, logarithmic linear relationship vs. SSP reaction time, while the position of higher temperature peak nearly does not change. The higher the SSP reaction temperature, the larger the total area of the endotherms, namely, the higher crystallinity. For 4 reaction temperatures the crystallinity show logarithmic linear relationship vs, SSP reaction time.展开更多
Polyethylene terephthalate(PET) resin was hydrolyzed to terephthalate acid(TPA) and ethylene glycol(EG) under microwave irradiation.The effects of crystallinity on the depolymerization of PET was investigated.PET resi...Polyethylene terephthalate(PET) resin was hydrolyzed to terephthalate acid(TPA) and ethylene glycol(EG) under microwave irradiation.The effects of crystallinity on the depolymerization of PET was investigated.PET resin was isothermal crystallized at temperature of 140,170,200 and 230 ℃ for 5 hours,the crystallinity of the resin was 25.7%,29.5%,33.9% and 40.6%,respectively,then the resin with different crystallinity was hydrolyzed under microwave irriadition. Under the same conditions of hydrolytic depolymerization, the degree of PET depolymerization decreased from 72.8% to 69.34% with the increase of crystallinity of PET resin,the rate of depolymerization varied little with the increasing of crystallinity of PET,this indicated that the crystallinity of PET has little effect on the hydrolytic depolymerization.The crystallinity of PET was increased during the temperature elevating process of the hydrolytic depolymerization.Investigation by DSC proved that the crystallinity of PET resin increased notability during the same temperature elevating process as the hydrolyzed depolymerization.According to the theory that depolymerization was firstly proceed in the amorphous phase,the crystallinity should increase during the reaction.However,the crystallinity of PET residue was decreased during all the reaction process,this indicates that the hydrolysis did not preferentially occur in the amorphous phase.展开更多
基金This work is supported by the National Natural Science Foundation of China and the National Basic Research Project- Macromolecular Condensed State
文摘Based on the X- ray scattering intensity theory, the correction factors of the degree ofcrystallinity formulae of the multicomponent polymers have been clearly defined. The formulae ofthe degree of crystallinity of the multicomponent polymers were derived in terms of WAXDtheory and improved graphic multipeak resolution methods. The results calculated aresatisfactory in comparison with the density measurement.
基金This project was supported by the National Natural Science Foundation of China and the National Basic Research Project Macromolecular Condensed State.
文摘Based on the X-ray scattering intensity theory and using the atomic scattering factorapproximate expression,the correction factors for three main crystalline peaks and an amorphouspeak of Nylon-1010 were calculated and the formula of degree of crystallinity of Nylon-1010 wasderived by graphic multipeak resolution method. The results calculated are compatible with the density measurement and calorimetry.
基金This work was supported by the National Natural Science Foundation of China (No. 270274049 and No. 220374051) andJilin Provincial Commission of Science and Technology (No. 20020629).
文摘Based on the X-ray scattering intensity theory and using the approximate expression for the atomic scattering factor, the correction factors for three crystalline peaks and an amorphous peak of Nylon 1212 were calculated and the formula of degree of crystallinity of Nylon 1212 was derived by a graphic multipeak resolution method. The degree of crystallinity calculated from the WAXD method is compatible with those obtained by density and calorimetry methods.
文摘The present work concerns the crystallization of PET accelerated by addition of thermotropic liquid crystalline polymers (TLCP)based on two aromatic copolyesters: PHB/PET (60:40 ) and PHB/HDA/2,6-DNA /IPA ( 50:25 : 12.5 : 12.5 ). The investigation has been made by measurements of the cold-crystallization and melt-crystallization temperatures by DSC and of the changes of density and depolarizing light intensity during the isothermal process. In addition, the morphology of selectively etched surface of compressing pellets proved the presence of crystalline fibrillar structure, it can be supposed to have grown up from the micelle nucleus based on bundle of rigid TLCP chains.
文摘Dual endotherms during differenUal scanning calorimetric (DSC) measurement occur when dried PET pellets are pretreated with solld state polyeondensation (SSP) at 215-230℃ for appropriate holding, times. The two endothermic fusion peaks arise from melting and recrystallization, taking place during scanning in the calorimeter,of imperfect crystals initial present in sample. The lower temperature peak appears higher than the SSP reaction temperature for 5-20℃ accordingly and linear relaflonship with SSP reaction temperature, logarithmic linear relationship vs. SSP reaction time, while the position of higher temperature peak nearly does not change. The higher the SSP reaction temperature, the larger the total area of the endotherms, namely, the higher crystallinity. For 4 reaction temperatures the crystallinity show logarithmic linear relationship vs, SSP reaction time.
文摘Polyethylene terephthalate(PET) resin was hydrolyzed to terephthalate acid(TPA) and ethylene glycol(EG) under microwave irradiation.The effects of crystallinity on the depolymerization of PET was investigated.PET resin was isothermal crystallized at temperature of 140,170,200 and 230 ℃ for 5 hours,the crystallinity of the resin was 25.7%,29.5%,33.9% and 40.6%,respectively,then the resin with different crystallinity was hydrolyzed under microwave irriadition. Under the same conditions of hydrolytic depolymerization, the degree of PET depolymerization decreased from 72.8% to 69.34% with the increase of crystallinity of PET resin,the rate of depolymerization varied little with the increasing of crystallinity of PET,this indicated that the crystallinity of PET has little effect on the hydrolytic depolymerization.The crystallinity of PET was increased during the temperature elevating process of the hydrolytic depolymerization.Investigation by DSC proved that the crystallinity of PET resin increased notability during the same temperature elevating process as the hydrolyzed depolymerization.According to the theory that depolymerization was firstly proceed in the amorphous phase,the crystallinity should increase during the reaction.However,the crystallinity of PET residue was decreased during all the reaction process,this indicates that the hydrolysis did not preferentially occur in the amorphous phase.
