Premium
The rate of plasticizer uptake by suspension PVC
Author(s) -
Davidson John A.
Publication year - 1982
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1982.070270904
Subject(s) - plasticizer , suspension (topology) , materials science , chemical engineering , composite material , polymer chemistry , mathematics , homotopy , pure mathematics , engineering
A microscopic technique employing image analysis was developed to measure the rate of swell of suspension PVC particles in both excess and finite amounts of plasticizer at temperatures below the crystalline melting point. The rates of plasticizer uptake derived from these swell measurements were found to be dependent upon the concentration of plasticizer and the rate of heating. A high value for the activation energy for plasticizer uptake was observed (60–100 kcal/mol) in agreement with earlier work. Each resin was also characterized by a total capacity for plasticizer (TC) which was found to be dependent on the resin type, the plasticizer type, and the maximum temperature achieved. An expression was derived for the rate of plasticizer uptake in a Brabender powder mix experiment. In this case the dry time is controlled by a single rate up to the maximum capacity for plasticizer of the resin ( G max ). Values of G max and TC were found to correlate on a one‐to‐one basis when measured at the same temperature. In all the cases investigated the rate of plasticizer uptake in the Brabender was found to correspond to a rate derived from image analysis swell at a plasticizer level of 0.25 cc/g. This behavior was in apparent contradiction to the concentration dependence generally observed and was demonstrated to be due to the large thermal gradients which exist in the Brabender powder mix head during the experiment. This work illustrates that Brabender powder mix times may have no relationship to dry times in a high speed mixer where heating is both even and higher temperatures are achieved.