Electron spin resonance study and reactive extrusion of polyacrylamide andpolydiallyldimethylammonium chloride

In this article we report results from an experimental investigation on rea ctive extrusion of water-soluble polymers. A polymer system containing homo polymers of diallyldimethylammonium chloride (PolyDADMAC) and acrylamide (P AM) was chosen for this study. Reactive extrusion was performed in a counte rrotating, tangential twin screw extruder using glycerol as a plasticizer a nd 2,5-dimethyl-2,5-di-(t-butylperoxy) hexene-3 (Lupersol 130) as an initia tor. The effects of three processing parameters (polyDADMAC/PAM weight rati o, extrusion temperature, and residence time) on grafting efficiency and de gree of grafting of polyDADMAC on PAM were examined. Ne found the grafting efficiency of polyDADMAC onto PAM decreased with increasing extrusion tempe rature, polyDADMAC/PAM weight ratio, and residence time. The degree of graf ting of polyDADMAC increased with increasing polyDADMAC/PAM weight ratio, b ut 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 pol yDADMAC/PAM weight ratio. The chemistry and free radical mechanism of PAM-p eroxide and polyDADMAC-peroxide systems were studied for three different pe roxides using an electron spin resonance technique. (C) 2000 John Wiley & S ons, Inc.