tailieunhanh - Photodegradable films based on polyethylene-cassava starch blend using benzophenone/antra-quinone or fe(ii) compound as photosensitive agents

This paper is dealing with formulation of photodegradable films based on polyethylenecassava starch blend using benzophenone/antraquinone or Fe(II) compound as photosensitive compound. Benzophenone, antraquinone and Fe(II) compound were synthesized in the laboratory and characterized by IR and NMR spectra. The films were obtained by extrusion-blowing method and showed good mechanical properties. They were exposed outdoor and indoor for photodegradability testing. It showed that after four months outdoor their tensile at break decreased 85% and elongation at break about 90%. It is interesting to note that the films keeping 4 months inside the room showed little decrease in mechanical properties. The films are suitable to be used as mulch films and for other purposes. | Journal of Chemistry Vol. 45 3 P. 392 - 396 2007 PHOTODEGRADABLE FILMS BASED ON POLYETHYLENECASSAVA STARCH BLEND USING BENZOPHENONE ANTRA-QUINONE OR Fe II COMPOUND AS PHOTOSENSITIVE AGENTS Received 9 Oct. 2006 PHAM NGQC LAN NGUyEN CHAU GIANG AND NGUyEN HQNG THUy Polymer Center Hanoi University of Technology SUMMARy This paper is dealing with formulation of photode gradable films based on polyethylenecassava starch blend using benzophenone antraquinone or Fe II compound as photosensitive compound. Benzophenone antraquinone and Fe II compound were synthesized in the laboratory and characterized by IR and NMR spectra. The films were obtained by extrusion-blowing method and showed good mechanical properties. They were exposed outdoor and indoor for photodegradability testing. It showed that after four months outdoor their tensile at break decreased 85 and elongation at break about 90 . It is interesting to note that the films keeping 4 months inside the room showed little decrease in mechanical properties. The films are suitable to be used as mulch films and for other purposes. Keyword Cassava starch photodegradable film photosensitizer. I - INTRODUCTION Most polymers are in their pure state insensitive to sunlight 290 nm . However the absorption spectra of commercial polymers are rather complicated and exhibit weak absorptions in the near-ultraviolet region. This is partly due to the existence of crystalline parts that scatter light in the UV-wave length region. Another factor that influences the light absorption is the thermal history of the polymers. Heat treatment melting and extrusion of polymers in the presence of air makes the susceptibility of polymers to sunlight increase through the formation of chromophores such as carbonyl groups hydroperoxides and unsaturated bonds. Metallic impurities such as iron and titanium incorporated into polymers during processing also act as chromophores. Some chromophoric impurities are absorbed from the atmosphere during the .