Chemical stress relaxation of filled and unfilled polyurethane elastomers

The thermo-oxidative and hydrolytic stability of two commercially available polyurethane gum stocks, namely Genthane~S and Adiprene CM which were respectively polyester and polyether-based, were studied by means of chemical stress relaxation.Dicumyl peroxide was the curative used and samples were either unfilled or carbon black filled (SAF, Super Abrasion Furnace, or MT, Medium Thermal).Sol fraction measurements showed that the carbon black fillers reduced the amount of curative available for cross linking. Unfilled Genthane-S vulcanisates degrade non-oxidativelyPig* Pagi 5.5Stress relaxomefcer -humid air experiments 5.6Transducer bridge -humid air experiments 5.7 Water supply system for humidity cabinet 5.8Upper frame -internal straining mechanism 5*9 Lower frame -external straining mechanism 5.10 Power supply -dry air relaxometers 5.11 Transducer bridge -dry air relaxometers 5.12 Saturable reactor Genthane-S, second order plots, continuous relaxation in dry air 6.1 MT ~ black, 25 phr 6.2 MT -black, 40 phr 6.3 SAP -black, 25 phr 6.4 SAP' -black, 40 phr Genthane-S, first order plots, continuous relaxation in dry air 6.5 MT-black, 25 phr 6.6 MT -black, 40 phr 6.7 SAP -black, 25 pbr * 6.8 SAP -black, 40 phr 6.9 Genthane-S, Arrhenius plots, ~ second order rate constants 6.10 Genthane-S -plot of In A v£ E Genthane-S -continuous, intermittent and A data 6.11 MT -black, 25 phr 6.12 MT -black, 40 phr 6.13 SAP -black, 25 phr 6.14 SAP1 -black, 40 phr 6.15 Plot of A ye f(t)/f(o) , Genthane-S (MT -black, 25 phr) Fl£.Page -15 -6.16 Relaxation of filled Adiprene -CM -189 schematic representation Adiprene CM, continuous relaxation in dry air 6.17 MT ~ black, 25 phr 193 6. l8 MT ~ black, 40 phr i9"' 6.19 SAF' -black, 25 phr 199 6.20 SAF -black, 40 phr 196 6.21 Arrhenius plots -I nk vs l/T 19 6.2c Arrhenius plots -Ink vs l/T 198 Adiprene CM -continuous, intermittent and A data 6.23 MT -black, 25 phr 202 6.24 MT ~ black, 40 phr 203 6.25 SAF -black, 25 phr 204 6.26 SAF -black, 40 phr Adiprene -CM, plots of f v_s f .6.2? MT -black, 25 phr 206 6.28 MT -black, 40 phr 207 6.29 SAF -black, 25 phr 208 6.30 SAF ~ black, 40 phr " 209 Genthane--S, continuous relaxation in humid air 6.31 Unfilled vulcanisates 313 6.30 MT -black, 25 phr 214 6.33 MT -black, 40 phr 219 6.34 SAP' -black, 2p phr 18 6.35SAP1 -black, 40 phr 21,/ 6.36 Arrhenius plots -Ink vs l/T 218 Adiprene CM, continuous relaxation in humid air 6.37 unfilled vulcanisates 6.38 Arrhenius plot -Ink vs 1/T 824 vr.vjn vjt