Electron spin resonance study and reactive extrusion of polyacrylamide and polydiallyldimethylammonium chloride

In this article we report results from an experimental investigation on reactive extrusion of water‐soluble polymers. A polymer system containing homopolymers of diallyldimethylammonium chloride (PolyDADMAC) and acrylamide (PAM) was chosen for this study. Reactive extrusion was performed in a counter‐rotating, tangential twin screw extruder using glycerol as a plasticizer and 2,5‐dimethyl‐2,5‐di‐(t‐butylperoxy) hexene‐3 (Lupersol 130) as an initiator. The effects of three processing parameters (polyDADMAC/PAM weight ratio, extrusion temperature, and residence time) on grafting efficiency and degree of grafting of polyDADMAC on PAM were examined. We found the grafting efficiency of polyDADMAC onto PAM decreased with increasing extrusion temperature, polyDADMAC/PAM weight ratio, and residence time. The degree of grafting of polyDADMAC increased with increasing polyDADMAC/PAM weight ratio, but decreased with increasing extrusion temperature and residence time. The insoluble gel fraction in the extruded copolymer increased with increasing extrusion temperature and residence time, but decreased with increasing polyDADMAC/PAM weight ratio. The chemistry and free radical mechanism of PAM‐peroxide and polyDADMAC‐peroxide systems were studied for three different peroxides using an electron spin resonance technique. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1154–1164, 2000