Morphological analysis of photodegradable polyethylene films for agricultural use

摘要

The application of photodegradable polyethylene is increasingly important for agricultural uses due to its ability to degrade after suggested shelf life and to counter measure pollution issue caused by conventional polyethylene films. The photodegradable polyethylene (PE) mixtures were formulated with added polypropylene (PP) and photodegradant (RM master batch) and tested in oil palm seedlings cultivation. PP is known to have photodegradable ability and RM master batch is proven to induce photo degradation of polyethylene. Thus, the mixture of these three components according to different ratios was processed into agricultural plastic films. There are four formulations that are tested in this study, namely Tl (80% PE:20% PP:5% RM master batch), T2 (70% PE:30% PP:5% RM master batch), T3 (80% PE:20% PP:3% RM master batch) and T4 (70% PE:30% PP:3% RM master batch). All formulations except control sample were added with photodegradant to impart degradation reaction and compatibiliser was also affixed to allow coalesce between polyethylene and polypropylene. Carbon black was added 0.5% into the formulation as for poly bags application, dark environment of soil is crucial for root development and growth. Penetration of sun light into the planting soil could commence development of shoot instead of root growth. All four formulations showed observable morphological changes on microscopic images on the surfaces after being used in oil palm nursery. From the study, it is shown that T1 and T3, with 20% of additional polypropylene had demonstrated clear surface disintegration when viewed microscopically. The addition of 3% and 5% of photodegradant into the formulations did not show any expressive difference thus suggesting that 3% of photodegradant is the optimum amount to induce photo degradation.