Masters Theses

Date of Award

12-1990

Degree Type

Thesis

Degree Name

Master of Science

Major

Polymer Engineering

Major Professor

Paul J. Phillips

Committee Members

Roberto Benson, J. E. Spruiell

Abstract

A technique has been developed using differential scanning calorimetry (DSC) to study the annealing behavior of semicrystalline polyolefins. Using software available on the DSC, an annealed endotherm can be subtracted from an unannealed endotherm to generate a subtraction curve. The position of the loss peak on the subtraction curve, Td, yields an estimation of the annealing temperature, and the temperature at which the gain peak occurs, Tp, follows a logarithmic annealing time dependence from which the kinetics of annealing can be followed. The annealing behavior of crosslinked low density polyethylene (XLPE), ethylene propylene copolymer (EPR) and terpolymer (EPDM) as well as crosslinked EPR and crosslinked EPDM, materials typically used in the composition of nuclear control cable insulation, were studied using this subtraction technique. Several actual insulation formulations were studied as well. The results indicated that the annealing process is ubiquitous and can generally be described by an equation of the form:

Tp = A + BLog(t) where A is a parameter dependent upon the annealing temperature and B is a parameter dependent only upon the material for annealing temperatures between approximately 45 to 70 °C. Once the annealing parameter B is known for a material, the thermal history (i.e. time and temperature of annealing) can be estimated using this general annealing equation. Estimations of the thermal history of several aged cable samples were determined using this technique.

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