GPC ANALYSIS OF POLYMER NETWORK FORMATION .2. BIFUNCTIONAL PPG PREPOLYMER CROSSLINKER SYSTEM/

Size distribution of polymer clusters in pre-gel state has been measur ed by means of gel permeation chromatography (GPC) for crosslinking sy stem between bifunctional prepolymer and trifunctional crosslinker. Ex perimental chromatograms have been obtained at various degree of conve rsion, and compared with theoretical chromatograms predicted by the Fl ory-Stockmayer model. Experimental size distribution at low conversion is well described by the theory. On the other hand, experimental chro matograms at higher conversions show a long tail in lower elution volu me region which is unexpected by the theory. This result suggests that clusters with relatively linear structure which is not predicted by t he theory are formed. The formation of the clusters with fairly linear structure is estimated to originate from unequality in reactivity of sites in crosslinker which is due to steric hindrance by the reacted s ites.