Abstract
This present study represents an attempt to assess degraded polyacetal resin as a curing agent for novolac resins.
First, degraded polyacetal was obtained by extrusion of virgin DELRIN®. Secondly, it was investigated for its reactivity with novolacs by torque rheometry analysis, by differential scanning calorimetry (DSC) and by a solubility test. Once the ability of degraded polyacetal to cure novolac resin was confirmed, the thermal decomposition behaviour of degraded polyacetal and hexamethylene tetramine (HMTA) were compared by thermogravimetric analysis (TGA). The results show that degraded polyacetal decomposes at higher temperatures and at lower rates than HMTA.
As expected from the TGA results, the extent of prior degradation of polyacetal affects its curing capability. The best curing performance (in terms of curing rate, degree of cure and impact strength) was obtained with the most degraded polyacetal product.
Finally, in order to establish the optimum conditions for the use of degraded polyacetal as a curing agent for novolac resins, the effects of polyacetal content and processing temperature were investigated.