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 i n the countries of the Mediterranean region. Taking into account the size o f this market, the effect of the material performance on the greenhouse pro duction as well as the related environmental impact problems arising from i ts disposal, the standardization of the testing of these materials should h ave 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 th e 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 po lyethylene films will be presented and discussed critically. Also, the fact ors affecting ageing of LDPE used as greenhouse covering are presented, inc luding methods for inducing ageing and testing methods in order to probe ag eing. (C) 1998 Elsevier Science Ltd. All rights reserved.