Scott-Gilead

The Scott-Gilead systems, the scientific principles of which are dealt with in other parts of this book, satisfy the requirements for degradability and have found wide application in agriculture [20]. 

Mechanical strength is a function of the film thickness. Over the years down-gauging of the films has become possible by the introduction of improved raw materials and more sophisticated production methods. As the price of the films is based on their weight per unit area it becomes obvious that adequate mechanical strength becomes the governing property. Photodegradable films must not impair mechanical properties as compared to normal films. The Scott-Gilead methods have been shown to maintain the full mechanical... 

Years of research have confirmed the essential need for the removal of agricultural films at such a time as fits the requirements of the cultivation. Moreover, the Scott-Gilead system, using additives which are soluble in the polymer but insoluble in water in very small quantities and thus control the life times of the films, is undoubtedly the safest and the most elegant solution. 

Research was undertaken to consolidate this technology by adapting the Scott-Gilead system to polymers that require higher processing temperatures. The iron/nickel ratio the Scott-Gilead system was varied in order to optimize the induction periods of very thin films (7-12 pm). 

Fig. 3 Single ( 221) and double ( 131) cropping of fast-growing vegetables with Scott-Gilead formulations over the winter period in Tainan, Taiwan [26].

The products of oxo-biodegradation from polyethylene agricultural mulch films, based on Scott/Gilead technology, have been shown to be harmless and... 

Kawai F, Shibata M, Yokoyama S, Maeda S, Tada K and Hayashi S (1999) Biodegradability of Scott-Gilead photodegradable polyethylene and polyethylene wax by microorganisms . Degradability, Renewability and Recycling, 5th International Scientific Workshop on biodegradable Plastics and Polymers, Macromolecular Symposia, eds, Albertsson A-C, Chiellini E, Feijen J, Scott G and Vert M, Wiley-VCH, pp. 73-84. 

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