Solvent-Induced Stresses during Sorption in Glassy Polycarbonate: Experimental Analysis and Model Simulation for a Novel Bending Cantilever Apparatus
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- 作者：Maria-Chiara Ferrari ; Enrico Piccinini ; Marco Giacinti Baschetti ; Ferruccio Doghieri ; Giulio C. Sarti
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2008
- 出版时间：February 20, 2008
- 年：2008
- 卷：47
- 期：4
- 页码：1071 - 1080
- 全文大小：170K
- 年卷期：v.47,no.4(February 20, 2008)
- ISSN：1520-5045
文摘
A new experimental apparatus has been set up to analyze the polymer dilation as well as the stress profileinduced by vapor sorption in constrained films. The device couples the bending cantilever technique with anew digital micrometer, which allows one to measure both deflection and polymer swelling at the same time.The apparatus has been applied to study the effects of acetonitrile mass uptake in polycarbonate at 40 
C,obtaining the time evolution of swelling and of cantilever deflection during integral sorption tests, in theactivity range from 0 up to 0.35. A simulation model is also proposed, which couples Fick's law for diffusionto the study of strain and stress distributions in the cantilever; the mechanical problem has been formulatedfollowing the classical laminate theory. The relevant values of the material properties entering the model,such as solubility, diffusivity, and penetrant induced dilation, have all been determined through separateindependent measurements, and the results obtained are in good agreement with the corresponding valuesreported in the literature. The simulation model is able to predict with good precision both the kinetics ofdeflection during sorption and its final equilibrium value, as well as the overall swelling kinetics, with noneed of any adjustable parameters. The model also allows one to calculate the time evolution of the stressprofile in the polymer film during sorption/desorption steps.
C,obtaining the time evolution of swelling and of cantilever deflection during integral sorption tests, in theactivity range from 0 up to 0.35. A simulation model is also proposed, which couples Fick's law for diffusionto the study of strain and stress distributions in the cantilever; the mechanical problem has been formulatedfollowing the classical laminate theory. The relevant values of the material properties entering the model,such as solubility, diffusivity, and penetrant induced dilation, have all been determined through separateindependent measurements, and the results obtained are in good agreement with the corresponding valuesreported in the literature. The simulation model is able to predict with good precision both the kinetics ofdeflection during sorption and its final equilibrium value, as well as the overall swelling kinetics, with noneed of any adjustable parameters. The model also allows one to calculate the time evolution of the stressprofile in the polymer film during sorption/desorption steps.