000			01641nam a2200157Ia 4500
008			220216s9999 xx 000 0 und d
100			_aYunyongwattanakorn Jintana
245		0	_aPhysical property changes in commercial natural rubbers during long term storage
260			_bRubber Chemistry and Technology _c2006
300			_a72-81
520			_aThe physical properties during long term storage of selected commercial Standard Thai Rubbers (STR), i.e. STR XL, STR 5L and STR CV60 as high-graded natural rubber (NR), were investigated. Sections of commercial NR were subjected to examination after storage-hardening. STR 5L showed clearly an increase in Mooney viscosity (V R), Mooney relaxation (MR 30), gel content and initial plasticity (P 0), higher than that of STR XL. This result suggests that STR 5L exhibits the highest inconsistency in physical properties. The increasing viscosity and gel content of STR 5L and STR XL samples suggest the occurrence of a crosslink structure during storage. STR CV60, known as a viscosity-stabilized NR sample, also showed an increase in V R, gel content, P 0 and high PRI value during long storage. These findings indicate that storage-hardening occurred in the rubber samples even after carefully controlled production procedures. As for the different sections of samples, there was no clear relation with gel content with respect to storage time, indicating that depth or positions of specimens in a certain rubber bale did not affect the storage-hardening phenomenon.
650			_aPhysical properties
650			_aStandard Tahi rubber
700			_aSakdapipanich Jitladda T
942			_cJS
999			_c64955 _d64955