Correlation of a Temperate UV-Weathering Cycle to Outdoor Exposure for the Determination of the Environmental Instability of Polyethylene Films Using HT-GPC Analysis.

Gavin Hill,Faith Ly,Richard Lloyd,Florence Huynh,Celine Moreira,Ana Trufasila,Christopher J Wallis,Hasan Sawal

doi:10.3390/polym13040591

Abstract

Accelerated UV-weathering cycles are predominately used for evaluating the durability of plastic materials, particularly polyethylene (PE) films. The point of failure for this testing is usually the loss of a physical property, such as the loss of tensile strength over time. For plastics designed to be instable under environmental conditions, the accelerated weathering cycles are yet to be defined and their correlation to outdoor exposure has yet to be made. This study demonstrates the utility of a newly defined temperate accelerated UV-weathering cycle, recently codified in the British Standard PAS 9017:2020. In addition, the effectiveness of the laboratory weathering cycle has been correlated to real-world outdoor exposure through simultaneous testing of the same samples at a specialist outdoor exposure site in Florida. The utility of the testing methodology and the performance of the polyethylene samples was demonstrated through the use of High Temperature Gel Permeation Chromatography (HT-GPC) analysis. The data led to a detailed insight into the physico-chemical changes occurring in the PE films upon exposure to environmental stimuli. By comparison, and surprisingly, the techniques employed appear to provide an insight into the processes in which secondary micro-particles of PE are formed from macro-polyethylene samples. The temperate accelerated UV-weathering cycle over 14 days demonstrated an approximate correlation to 90 days of outdoor exposure in Florida for the PE film studied.

Highlights

The stability of plastic materials is a key determining factor for many plastic products whose application is based upon outdoor use
The Service Life Prediction of these polymeric materials has gained scientific enquiry since the large-scale adoption of polymers as commercial materials [1]. It is well-noted that the determination of the Service Life Prediction of a polymer is dependent on the point of failure chosen, as determined by the testing methodology employed [1,2]
Samples were cut to 30 cm × 15 cm and held in high density polyethylene (HDPE) net to prevent sample cross contamination and loss due to wind during the aging process

Summary

Introduction

The stability of plastic materials is a key determining factor for many plastic products whose application is based upon outdoor use. Examples of this include, piping, automobile parts and even packaging, to name just a few. The Service Life Prediction of these polymeric materials has gained scientific enquiry since the large-scale adoption of polymers as commercial materials [1] It is well-noted that the determination of the Service Life Prediction of a polymer is dependent on the point of failure chosen, as determined by the testing methodology employed [1,2]. It became critical to correlate accelerated laboratory weathering techniques to outdoor exposure [3,4]

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