Accession Number : ADA306856

Title :   Thermal Degradation of Polyesters: Part 1. Aliphatic Polymers.

Descriptive Note : Technical rept. 1 Jan 67-1 Apr 68,

Corporate Author : AIR FORCE MATERIALS LAB WRIGHT-PATTERSON AFB OH

Personal Author(s) : Goldfarb, Ivan J. ; McGuchan, Robert

PDF Url : ADA306856

Report Date : SEP 1968

Pagination or Media Count : 51

Abstract : A study has been made of the pyrolysis of eight aliphatic polyesters prepared from various diacids and diols. The polymers start to degrade at about 275 deg C by random scission of the ester linkage and are comparable to poly(ethylene terephthalate) with respect to thermal stability. Providing a beta-hydrogen atom is available in the diol portion of the ester, which was the case for the polymers studied, the classical cyclic mechanism observed for the decomposition of simple esters is applicable. Differences in degradation behavior are best explained in terms of secondary reactions which are dependent upon the nature of the end-groups formed by scission and on the chain length of the acid and diol used to prepare the polymer. Thus, olefinic end-groups break down to aldehydes, dienes, cyclic ethers, and enols while acid end-groups give carbon dioxide, cyclic ketones (C5-C7 diacids), and cyclic anhydrides (C4, C5 diacids). Water is produced by anhydride formation and dehydration of hydroxyl end-groups.

Descriptors :   *ALIPHATIC COMPOUNDS, *THERMAL DEGRADATION, *PYROLYSIS, *POLYESTER FIBERS, WATER, POLYMERS, SECONDARY, ANHYDRIDES, THERMAL STABILITY, ATOMS, CYCLES, HYDROGEN, CHAINS, ETHERS, CARBON DIOXIDE, ESTERS, LINKAGES, DECOMPOSITION, HYDROXYL RADICALS, ALDEHYDES, ACIDS, DIENES, DEHYDRATION, KETONES.

Subject Categories : Polymer Chemistry
      Organic Chemistry
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE