In the two-parameter corresponding states principle(CSP), the critical compressibility factors of the fluid under study(called 'a' fluid) and the reference fluid(called 'o' fluid) must be identical. Th...In the two-parameter corresponding states principle(CSP), the critical compressibility factors of the fluid under study(called 'a' fluid) and the reference fluid(called 'o' fluid) must be identical. This is not generally observed in nature. To overcome this limitation, a perfect shape factor CSP is proposed in which the compressibility factors of 'a' and 'o' fluids are corresponded perfectly by introducing a new pressure shape factor 8. Using methane as the 'o' fluid, the shape factors of many fluids are calculated from PVT properties at saturation state and the second virial coefficients. Models are also formulated for the shape factors with the assumption of is a function of temperature and volume while 6 and 5 are temperature dependent only. The models described the shape factors satisfactorily in whole region including vapor, liquid and their co-existing phases. The perfect shape factor CSP could be applied for both polar and non-polar fluids.展开更多
Linear and star-shaped polylactides（PLA） with similar molecular weights of each arm are synthesized via ringopening polymerization of LA with 3-butyn-1-ol and pentaerythritol as initiators,respectively.By solution b...Linear and star-shaped polylactides（PLA） with similar molecular weights of each arm are synthesized via ringopening polymerization of LA with 3-butyn-1-ol and pentaerythritol as initiators,respectively.By solution blending of equivalent mass of poly（L-lactic acid）s（PLLAs） and poly（D-lactic acid）s（PDLAs）,perfect PLA stereocomplexes（sc PLAs） are prepared and confirmed by WAXD and FTIR analysis.Effect of chain architectures on stereocomplex crystallization is investigated by studying the non-isothermal and isothermal crystallization of linear and star-shaped polylactide stereocomplexes.In dynamic DSC and POM test,star-shaped PLLA（4s PLLA）/PDLA and PLLA/star-shaped PDLA（4s PDLA） stereocomplexes reach rapid crystallization and higher crystallinity due to larger spherulite density of star-shaped chain and excellent chain mobility of linear chain.In isothermal crystallization test,much faster crystallization and less crystallization half-time is obtained with the increase of star-shaped chain.Meanwhile,4s PLLA/PDLA and PLLA/4s PDLA are found to have the highest crystallinity,suggesting limitation of too much star-shaped chain for 4s PLLA/4s PDLA and restriction of linear chain in nucleation capacity for PLLA/PDLA.The results reveal that star-shaped chain has an important influence on the crystallization of sc PLAs.展开更多
基金Supported by the National Natural Science Foundation of China (No.29876033), the Doctoral Foundation of Ministry of Education of China (No. 98033508) and the Zhejiang Natural Science Foundation (No. 298030).
文摘In the two-parameter corresponding states principle(CSP), the critical compressibility factors of the fluid under study(called 'a' fluid) and the reference fluid(called 'o' fluid) must be identical. This is not generally observed in nature. To overcome this limitation, a perfect shape factor CSP is proposed in which the compressibility factors of 'a' and 'o' fluids are corresponded perfectly by introducing a new pressure shape factor 8. Using methane as the 'o' fluid, the shape factors of many fluids are calculated from PVT properties at saturation state and the second virial coefficients. Models are also formulated for the shape factors with the assumption of is a function of temperature and volume while 6 and 5 are temperature dependent only. The models described the shape factors satisfactorily in whole region including vapor, liquid and their co-existing phases. The perfect shape factor CSP could be applied for both polar and non-polar fluids.
基金financially supported by the National High-Tech R&D Program of China(No.2013AA032202)the National Natural Science Foundation of China(No.51203118)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Open Funds for Characterization of Tongji University
文摘Linear and star-shaped polylactides（PLA） with similar molecular weights of each arm are synthesized via ringopening polymerization of LA with 3-butyn-1-ol and pentaerythritol as initiators,respectively.By solution blending of equivalent mass of poly（L-lactic acid）s（PLLAs） and poly（D-lactic acid）s（PDLAs）,perfect PLA stereocomplexes（sc PLAs） are prepared and confirmed by WAXD and FTIR analysis.Effect of chain architectures on stereocomplex crystallization is investigated by studying the non-isothermal and isothermal crystallization of linear and star-shaped polylactide stereocomplexes.In dynamic DSC and POM test,star-shaped PLLA（4s PLLA）/PDLA and PLLA/star-shaped PDLA（4s PDLA） stereocomplexes reach rapid crystallization and higher crystallinity due to larger spherulite density of star-shaped chain and excellent chain mobility of linear chain.In isothermal crystallization test,much faster crystallization and less crystallization half-time is obtained with the increase of star-shaped chain.Meanwhile,4s PLLA/PDLA and PLLA/4s PDLA are found to have the highest crystallinity,suggesting limitation of too much star-shaped chain for 4s PLLA/4s PDLA and restriction of linear chain in nucleation capacity for PLLA/PDLA.The results reveal that star-shaped chain has an important influence on the crystallization of sc PLAs.
