Determination of tensile strength of paraffin waxes

Abstract

The tens i le s t rength of paraff in wax is cons idered to be one of the impor tan t p rope r ty indices that a r e used to c h a r a c t e r i z e the s e r v i c e p r o p e r t i e s of this m a t e r i a l . Methods used to d e t e r m i n e the tens i le s t rength of waxes a r e based on the use of Pe rk ins and T in ius -Olsen t e s t e r s [1]. Essent ia l ly , these methods cons is t of de te rmina t ions of the fo rce requi red to b r e a k a spec imen in tension with constant ly inc reas ing load, this spec imen having a na r row pa r t with known c r o s s sect ion [2, 3]. These methods have been used in inves t iga t ing the mechanica l p rope r t i e s of waxes f r o m var ious sources , the influence of wax composi t ion on the s t rength, and the influence of modifying addi t ives on the mechan ica l s t reng th of waxes [4, 6]. In the U.S.A., a t e s t me th od for de te rmin ing the tens i le s t rength of wax has been s t andarda rd ized [7] and is being applied in ra t ing the quality of waxes used p r i m a r i l y in packing [8]. The shor tcoming of such methods is that, while they do define the b reak ing s t rength, they do not give any definition of the b reak ing p r o c e s s . The na ture of this p r o c e s s is e x t r e m e l y important , s ince the behav io r of wax dur ing extension can give ce r ta in informat ion on its p las t ic p rope r t i e s . In o r d e r to e l iminate the shor t comings just d i scussed , we have developed an ins t rument and a method for de te rmin ing the tens i le s t rength of paraf f in wax with automat ic r ecord ing of the load curve and s imul taneous m e a s u r e m e n t of the elongation of the t es t spec imen up to comple te b reak .