Mathematical Correlation of Polydispersity using Gel Permeation Chromatography and Rubber Process Analyzer for Raw Rubbers

Abstract

In this study, an attempt has been made to correlate the polydispersity value measured through gel permeation chromatography (GPC) and that obtained through rubber process analyzer (RPA 2000). The tanδ at higher and lower frequencies is measured using RPA 2000. The inverse of tanδ difference at higher and lower frequencies obtained through RPA 2000 is correlated with the polydispersity data measured from GPC for different grades of raw rubbers like ethylene propylene diene rubber (EPDM) and butyl rubber (IIR). Polydispersity as predicted by RPA 2000 shows excellent correlation with that measured through GPC. The coefficient of correlation is found to be 0.98 for EPDM and 0.99 for IIR. The predicted polydispersity value obtained through RPA 2000 is within ±8% from that measured through GPC.