000			01797nam a2200277Ia 4500
008			220216s9999 xx 000 0 und d
100			_aHassan J
245		0	_aTransition of complex permittivity losses in Hevea rubber latex from conductivity losses to dipolar losses at 2.6 GHz
260			_bJournal of Rubber Research _c2003
300			_a65-72
520			_aDielectric properties of Hevea rubber latex with moisture content 38;-98;were measured using the open-ended coaxial line sensor coupled to the Automated Network Analyser. Measurements were made at frequencies 0.2 GHz-20 GHz and at selected temperatures -30oC to 50oC. Complex permitivity losses or dielectric loss factor showed a very interesting phenomena at 0.2 GHz to 2.6 GHz where a transition occured from conductivity losses to dipolar losses. Below 2.6 GHz, the losses were due to the conducting phases in the Hevea latex arising from proteins, fatty acid soaps, phospholipids and various types of ohmic species. Higher losses were achieved from latex concentrate due to the addition of ammonia as preservative. Above 2.6 GHz the losses were governed by orientation of the water molecules. The transition was clearly observed in the plots of dielectric losses versus temperature at 0.2, 0.6, 1.0, 1.4, 1.8, 2.2 and 2.6 GHz for latex concentrate, fresh latex, diluted fresh latex and deionised water at moisture contents 38;, 56;, 89;and 100;, respectively.
650			_aConductivity
650			_aDielectric
650			_aDipolar
650			_aHevea brasiliensis
650			_aLatex
650			_aLoss
650			_aMoisture content
650			_aPermittivity
650			_aProperties
650			_aTemperature
650			_aTransition
700			_aKhalid K
700			_aYusoff W M D Wan
942			_cJS
999			_c71489 _d71489