The Fifth Conference “ Nuclear Science and Its Application”, 14-17 October 2008
G A M M A IR R A D IA T IO N S T IM U L A T E D C H A N G E O F R E S I S T IV I T Y A N D C R Y S T A L L IN IT Y O F R E C Y C L E D P O L Y E T H Y L E N E B A S E D T H E R M O P L A S T IC C O M P O S IT E S
U. GAFUROV. L . KABISOVA, N. MUKHTAROVA, Z. FAZILOVA, E. VLASOVA Institute of Nuclear Physics, Uzbekistan Academy o f Sciences, Tashkent, Uzbekistan
The dose dependence o f resistivity o f thermoplastic composites on y-irradiated recycled high density polyethylene - HDPE bases has been investigated. The composite samples were y-irradiated at different dose o f the irradiation (y - source Co60 with energy o f 1.25 MeV).
The following thermoplastic composites were investigated: 1 - HDPER :EPDM
2 -HDPER :EPDM:GTR, EPDM(ethylene-propylene diamine) 3 - HDPER :EPD M :G TR/plast-2(l/l)
Significant differences were found between various polymer composite y-irradiation dose dependences. The volume resistivity isn’t change for composite sample w ithout rubber - HDPER :EPDM (1) with low value the resistivity, while for other investigated polym er composites the increase takes place with y-irradiated dose rising above -1 0 0 kGy.
The resistivity behavior was explained by radiation stimulated cross-links formation and oxidation processes. It is confirmed by the measurements o f the IR (FTIR) spectra o f irradiated samples.
General changes o f the X-Ray diffraction pattern for different vulcanizers even after a relatively high irradiation doses were insignificant.
Change o f crystallinity degree (CD) o f sample 1 with dose rise has nonlinear character up to 6000 k G y , it is rather insignificant (in the interval o f 34,5+38 %) and an error o f definition CD - A(CK) ~ ±1%. The characteristic change o f CD for vulcanized composites on high density polyethylene and recycled high density polyethylene bases is similar. A lthough effect o f initial crystallinity degree o f vulcanizer on high density polyethylene is higher.
Conducted tests o f electrical properties ofT D V ’s have shown that the recycled polyethylene and TD V ’s o n its basis have high radiation resistance and good insulating properties (pv > 1014 O hm • cm).
In methodical standards for radiation resistance definition o f the recom m ended quantity of Kc (the limiting relative change o f the diagnostic parameter for electrical performances ) is -1 5 %. From the dose dependence one can find the quantity o f Dr -as the dose at which quantity o f the diagnostic variable parameters amount to Kc.
It is necessary to note that for TDV HDPER+EPDM (1) an index o f radiation resistance D r > 1000 kGy.
The work was supported by EC (STCU Project N° U3009).
