Synthesis and Mechanical Properties of Diimide-Hydrogenated Natural Rubber Vulcanizates

Hydrogenated natural rubber (HNR), providing an ethylene-propylene alternating copolymer, was prepared by the chemical modification of natural rubber latex (NRL) using diimide generated from hydrazine (N(2)H(4)) and hydrogen peroxide (H(2)O(2)), with copper sulfate (CuSO(4)) as catalyst. (1)H-NMR analysis indicated that 48% hydrogenation was performed with a mole ratio of N(2)H(4)/double bonds = 4 and H(2)O(2)/N(2)H(4) = 1.5 at 50 degrees C for 7 h. The obtained HNR was subjected to a sulfur cure by using a conventional milling process. The cure characteristics, mechanical properties before and after heat aging, and abrasion and ozone resistances of HNR vulcanizate were examined and compared with those of natural rubber (NR), ethylene propylene diene terpolymer (EPDM) and 50 : 50 NR/EPDM vulcanizates. The results indicated that the cure rate of 48% HNR showed no significant change when compare to both NR and 50 : 50 NR/EPDM blends, and offered a better processing advantage over EPDM. The mechanical properties and abrasion resistance of a 48% HNR vulcanizate were comparable to those of a NR vulcanizate. Additionally, its heat and ozone resistances were better than those of NR vulcanizate, due to a reduction in the amount of double bonds in the backbone chain. Thus, hydrogenation of NR can lead to a type of rubber that has improved heat and ozone resistances while still maintaining its good mechanical properties. Consequently, it improves the properties of NR for a wide range of applications. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 4066-4075, 2009