Standard testing methods for mechanical properties and degradation of low density polyethylene (LDPE) films used as greenhouse covering materials: a critical evaluation

LDPE films are currently the most widespread greenhouse covering material in the countries of the Mediterranean region. Taking into account the size of this market, the effect of the material performance on the greenhouse production as well as the related environmental impact problems arising from its disposal, the standardization of the testing of these materials should have already been achieved. However, there are no standard methods available in the European Union for testing LDPE greenhouse films. Furthermore, for predicting the useful lifetime of such films both the critical effect of the various climatic conditions and the effect of the harsh greenhouse micro-environment on their properties should be taken into account. In this paper the various methods for testing the mechanical properties of greenhouse polyethylene films will be presented and discussed critically. Also, the factors affecting ageing of LDPE used as greenhouse covering are presented, including methods for inducing ageing and testing methods in order to probe ageing. (C) 1998 Elsevier Science Ltd. All rights reserved.