A new approach to quantitatively assessing the effects of polymer additives

A novel approach involving stability parameter mapping and stability vector analysis is developed for assessing the effect of an additive on polymer performance. The potential usefulness of the method is illustrated by applying it to (i) DSC oxidative induction time (OIt) data for medium-density polyethylene (MDPE) formulations made using two levels of carbon black and base-stabilized with Irgafos 168™ (tris-(2,4-di-tert-butylphenyl)-phosphite) and Irganox 1010™ pentaerythrityl-tetrakis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), and (ii) chemiluminescence OIt data for low-density polyethylene (LDPE) containing 0.2% (w/w) of Chimassorb 944™ and 0.5% (w/w) or 1.0% (w/w) of dicumyl peroxide cross-linking agent and base-stabilized with 0.2% (w/w) of various commercial antioxidants. The proposed method is validated using data from a previous study on MDPE and is applied to a preliminary investigation of LDPE destabilization by dicumyl peroxide. The results suggest that a styrenated phenolic stabilizer blended with zinc dibutyldithiocarbamate and zinc stearate is an effective system for stabilizing LDPE in the presence of dicumyl peroxide.