EFFECT OF PROCESSING PARAMETERS ON CURE KINETICS IN FILLED POLYURETHANES

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Authors
  1. Pearce, R.
  2. Sammut, P.
  3. Cole, K.
Corporate Authors
Defence Research Establishment Valcartier, Valcartier QUE (CAN);Industrial Materials Inst, Boucherville QUE (CAN)
Abstract
The present report summarizes the results obtained in the second part of a project aimed at monitoring the cure process in polyurethanes prepared by the reaction between hydroxy-terminated polybutadiene and diisocyanates. Ammonium chloride was used as an inert filler in order to simulate the presence of a solid explosive. The standard formulation was based on toluene diisocyanate (TDI) at an NCO/OH ratio of 1.1/1, with 80 wt% solids, cured at 60C. The technique of simultaneous rheology/dielectrometry was used to examine the effect of processing parameters on the cure kinetics. When TDI was replaced with isophorone diisocyanate (IPDI) and dibutyltin dilaurate (DBTDL) as catalyst, it was found that the cure kinetics varied greatly with level of catalyst. It was found that as the stoichiometric ratio NCO/OH was increased from 1.0/1 to 1.3/1, the cure process slowed, as revealed by rheology and dielectrometry. It was observed that as cure temperature was varied between 40 and 80C, there was an important increase in the rate of cure. An activation energy of 12.7 kcal/mol was estimated for the process. The effect of solid content was found to be negligible when it was varied between 70 and 80 wt%.
Keywords
Cure kinetics;Hydroxy terminated polybutadiene (HTPB);Microdieletrometry
Report Number
DREV-CR-894;NRC-IMI96RT-617FA-68723-C — Contract Report
Date of publication
01 May 1996
Number of Pages
76
DSTKIM No
97-04492
CANDIS No
506394
Format(s):
Hardcopy;Document Image stored on Optical Disk

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