Related Experiment Video
Updated: Aug 11, 2026

Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films
Published on: January 26, 2016
Predicting migration of trace amounts of styrene in poly(styrene) below the glass transition temperature
1Center for the Study of Polymer Solvent Systems, Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802, USA.
Abstract:
The use of general purpose polystyrene (GPPS) as food packaging material is widespread. Therefore, the rate of migration of the styrene in GPPS is of interest in order to predict the potential exposure of consumers to styrene. Studies have shown a relatively weak dependence of the diffusion coefficient on the residual styrene content, and a strong dependence on temperature. We have compared the predictions of the free-volume theory with experimentally measured diffusivity data. The predictions and the measured values are observed to be consistent with each other. These results illustrate the capability of the free-volume theory of transport to predict the diffusivity of trace amounts of impurity in a glassy polymer.
Related Concept Videos
Thermal Sigmatropic Reactions: Overview
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in 1,5-hexadiene, referred to as...
Polymer Classification: Architecture
Polymer Classification: Crystallinity
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Polymer Classification: Stereospecificity
Molecular Weight of Step-Growth Polymers
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
Types of Step-Growth Polymers: Polyesters
Polyesters are commonly prepared from terephthalic acid and ethylene glycol; the crude product is known as poly(ethylene terephthalate) or PET. However, polyesters are synthesized industrially by transesterification of dimethyl terephthalate with ethylene glycol at 150 °C. The two reactants and the polymer...

