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Polymer Rejuvenation And Enhancement

IP.com Disclosure Number: IPCOM000062775D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Anschel, M: AUTHOR

Abstract

Polymers upon aging become hard, brittle and less elastic. As the polymer becomes stiffer its dampening ability decreases and so do its creep and stress relaxation rates. This aging phenonemon occurs in a broad temperature range below the glass transition temperature (Tg) as illustrated in the drawing. Physical aging may be conceived as the gradual vitrification of a plastic approaching Tg affecting those properties having temperature and large volume change dependance. The mechanism of physical aging occurs on the basis of Tg rising with time, so that the aging range of a specific plastic includes the temperature range of a specific interest. A material heated above Tg attains thermodynamic equilibrium and its original properties can be thus restored. The technique works as follows.

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Polymer Rejuvenation And Enhancement

Polymers upon aging become hard, brittle and less elastic. As the polymer becomes stiffer its dampening ability decreases and so do its creep and stress relaxation rates. This aging phenonemon occurs in a broad temperature range below the glass transition temperature (Tg) as illustrated in the drawing. Physical aging may be conceived as the gradual vitrification of a plastic approaching Tg affecting those properties having temperature and large volume change dependance. The mechanism of physical aging occurs on the basis of Tg rising with time, so that the aging range of a specific plastic includes the temperature range of a specific interest. A material heated above Tg attains thermodynamic equilibrium and its original properties can be thus restored. The technique works as follows.

Physically aged plastics can be rejuvenated by the lowering of Tg. The Tg can be reduced by the addition of chemically inert organic liquids which function by reducing dipole-dipole and van der Waal's forces between polymer chains. The lasting effect of Tg lowering organic liquids varies, thus plasticizers can be considered more permanent than the generally known organic solvents.

The process of reclaiming polymers is accomplished by significantly lowering the Tg of polymers, e.g., 85% monochlorobenzene with 15% n-methyl-2- pyrrolidone. Reflowing and redistributing polymeric coatings in a uniform manner so uneven stress distributions are drastical...