Ultradrawing of thermoplastics by solid state coextrusion illustrated with high density polyethylene

Abstract

Ultra‐thin films of high density polyethylene of high orientation have been produced by the recently developed technique of solid state coextrusion. The films were prepared under moderate conditions, without lubricant in continuous lengths by extruding through conical dies of extrusion draw ratio up to 36. This is a draw ratio higher than achievable by conventional solid state extrusion at comparable processing conditions through slit dies. The ultra‐thin films of high orientation were transparent and exhibited dead bend. The physical and mechanical properties were evaluated and compared with the properties of the same high density polyethylene extruded through a slit die. The increase in the melt point, crystallinity, tensile modulus, and birefringence indicates that the method is very efficient for the production of ultra‐thin and highly oriented films. An experimental technique is also presented for preparing billets of controlled and uniform initial morphology and free of voids.

Push–pull extrusion: A new approach for the solid‐state deformation illustrated with high density polyethylene

“…= e x p ( B d (10) where B is p cot&, , u is the coefficient of friction, and LY is the die angle. Thus, if X equals 3, B equals 0.3066, and hence p is 0.05.…”

Extrusion of self-reinforced thermoplastic composites illustrated by high density polyethylene

“…Billets of HDPE were prepared free of voids in a specially-designed apparatus described elsewhere [2]. Briefly, pellets of polymer were packed in a press having a cylindrical bore of 0.95 cm.…”

“…It involves using preformed, split or tubular billets of HDPE [1,2]. It involves using preformed, split or tubular billets of HDPE [1,2].…”

Nanocomposites of Au/Disentangled UHMWPE: A Combined Optical and Structural Study

“…The effect of uniaxial orientation has on the physical properties and characteristics of polyethylene has been under investigation for the past 40 years [ 16 , 17 , 18 ]. Highly anisotropic stretched dis-UHMWPE samples can be solid-state-produced via compression molding, rolling, and tensile stretching [ 19 , 20 , 21 ]. Uniaxial orientation was found to significantly increase the tensile modulus and strength [ 22 , 23 , 24 ], and more recently, the thermal conductivity of UHMWPE samples, achieving metal-like thermal conductivities in the stretched direction [ 25 , 26 ].…”