Studies on the cohesional entenglement network of polymers in glass state by equilibrium swelling

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	Studies on the cohesional entenglement network of polymers in glass state by equilibrium swelling
	Yu Yansheng; Qian Renyuan
刊名	ACTA POLYMERICA SINICA
	2006-07-01
期号	4 页码:615-619
关键词	Polymer/solvent System Ps/dioxane-water Equilibrium Swelling Cohesionalentanglement Network
ISSN号	1000-3304
英文摘要	Equilibrium swelling in a non-solvent is a simple experimental method to reveal the cohesional. entanglement network structure present in an amorphous polymer in its glassy state. In the present work results of visual observation of the swelling behavior of two PS granules in a series of dioxane/water mixed solvents are presented. On decreasing the water content in the mixed solvent a change of physical state of the PS granules from glassy state (water in dioxane 40 Vol%) to swollen glassy state (water in dioxane 35 Vol% similar to 30 Vol% to swollen rubbery state (water in dioxane 25 Vol % similar to 20 Vol %) and to fluid state ( water in dioxane 10 Vol % 5 Vol%) was observed. It corresponds to the change from glassy state to rubbery state and to fluid state on raising temperature of the granules. Base on these observations a mixed solvent of dioxane/water (water 6.8 wt %) was chosen for equilibrium swelling and phase separation equilibrium measurements for a monodisperse PS sample of M. = 1.68 x 10(5) at 30 degrees C. In this mixed solvent PS granule can only swell but not dissolved. For the phase separation equilibrium the PS granule in the mixed solvent was first brought to 130 degrees C (in a sealed tube) to become a homogeneous single phase solution, then phase separation occurred on cooling and phase separation equilibrium at 30 degrees C was reached in 30 days to give a volume fraction of the polymer in the concentrated phase phi(n)(p) = 0.304. The dilute phase is practically the pure solvent. Monodisperse PS granules quenched from being heated to 120 degrees C for 30 min to erase thermal history of the sample (rho(p) = 1.0451 g/mL) reached a swelling equilibrium in the mixed solvent in 80 days to give phi(n)(p) = 0. 308. This quenched PS granules after being subjected to a sub-T-g annealing at 80 degrees C for 100 days (rho(p) = 1.0470 g/mL) reached swelling equilibrium in the mixed solvent in 70 days to give phi(n)(p) = 0.312. From the curve of increasing volume of the swollen phase V-s (t), in mL/g PS, during the equilibrium swelling process it could be inferred that during sub-T-g annealing the cohesional network structure in the PS glass became more uniform, being closer to the equilibrium state at the annealing temperature, the van der Waals crosslinking density was increased, with tighter inter-chain cohesion resulting in higher density of the glass. If we take the polymer-solvent interaction parameter chi = 0.63 obtained from phase separation equilibrium measurement, we obtained the molar mass between crosslinking points of the network, M-c = 11.6 x 10(4) for the quenched sample,and M-c = 6.9 x 104 for the annealed sample from Flory theory of network swelling. The experimental results clearly indicate that swelling process and swelling equilibrium measurements in a very poor solvent can offer a rather sensitive way to obtain some idea about the structure details of the cohesional network in polymer glassy state.
语种	英语
出版者	SCIENCE CHINA PRESS
WOS记录号	WOS:000240320400012
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/59649]
专题	中国科学院化学研究所
通讯作者	Yu Yansheng
作者单位	Chinese Acad Sci, Inst Chem, Ctr Mol Sci, State Key Lab Polymer Chem Phys, Beijing 100080, Peoples R China
推荐引用方式 GB/T 7714	Yu Yansheng,Qian Renyuan. Studies on the cohesional entenglement network of polymers in glass state by equilibrium swelling[J]. ACTA POLYMERICA SINICA,2006(4):615-619.
APA	Yu Yansheng,&Qian Renyuan.(2006).Studies on the cohesional entenglement network of polymers in glass state by equilibrium swelling.ACTA POLYMERICA SINICA(4),615-619.
MLA	Yu Yansheng,et al."Studies on the cohesional entenglement network of polymers in glass state by equilibrium swelling".ACTA POLYMERICA SINICA .4(2006):615-619.