Photodegradation of UHMWPE Filled with Iron Ore Fine

Frederick Louis Dias De Morais,Glaura Goulart Silva,Felipe Da Silva Medeiros,Marcelo Silveira Rabello,Alexandre Rangel De Sousa

doi:10.1590/1980-5373-mr-2016-0320

Abstract

Ultra high molecular weight polyethylene (UHMWPE) is one of the most important engineering materials owing to outstanding properties like impact strength and abrasion resistance. However, the relatively low Young´s modulus restricts some application and the use of fillers may be a suitable way to overcome this. The fillers can influence the photo stabilization of the compound, as it occurs to other polymers. Neat UHMWPE and its composites with 1 and 10% of iron ore fine were exposed to ultraviolet radiation for up to 33 days and then tested for mechanical properties. The stress-strain behaviour changed with degradation, with an evident necking and strain hardening region that was not observed before exposure, due to a reduction in entanglements density. From the tensile results, the filler may have a protection action against UV, particularly when a loading of 10% was present. Complementary analyses were performed, including X-ray diffraction, DSC and SEM.

Highlights

Ultra high molecular weight polyethylene (UHMWPE) is rather similar to high-density polyethylene (HDPE) based on the chemical structure and molecular architecture[1,2]
Because of the very high molar mass that results on special properties like high impact strength and abrasion resistance, UHMWPE is classified as an engineering polymer[4], whereas HDPE is considered a commodity[5]
Not many studies were conducted on this issue, it was shown that the degradation behaviour of UHMWPE is similar to HDPE, except for mobility differences of free radicals due the difference in molecular sizes of these two polymers[11,12]

Summary

Introduction

Ultra high molecular weight polyethylene (UHMWPE) is rather similar to high-density polyethylene (HDPE) based on the chemical structure and molecular architecture[1,2]. UHMWPE is applied, among others, as internal human body prosthesis, which prompted several studies on the gamma radiation and electron beam effects on its properties[6,7,8]. These radiations are used for sterilization and to promote crosslinking, improving the wear strength[9,10,4]. To the best of our knowledge, this is the first study using a residue from the mining industry as filler to improve UV stability of UHMWPE

Experimental

Iron ore fine characterization

Mechanical properties

Impact Tests Results

Filler Distribution in the UHMWPE Polymer Matrix

Conclusion