Polyethylene starch composites

Four main types of polymer are currently accepted as being environmentally degradable. They are the photolytic polymers, peroxidisable polymers, photo-biodegradable polymers and hydro-biodegradable polymers. Commercial products may be composite materials in which hydrolysable and peroxidisable polymers are combined (e.g. starch-polyethylene composites containing prooxidants). The application, advantages and limitations of each group will be briefly discussed. 

Keywords starch, polyethylene, composition, physical and mechanic properties. 

Raghavan and Emekalam [9] examined the microstruc-tural aspects of a starch/polyethylene/poly(lactic acid)/ver-nonia oil composite. Polymer composite films containing different percentages of additives were melt processed and acid hydrolyzed. Scanning electron microscopy (SEM) of the... 

Considerable attention has been generated in the commercial sector on blends and composites consisting of synthetic polymers and natural degradable materials. These include starch-polyethylene and starch-ethylene-acrylic acid copolymers. Other natural polymers have also been considered.Until the main concern is addressed that the polyalkene is actually degraded, instead of the specimen having physically disintegrated, this remains a questionable approach. 

Yoo, Y., Kim, Y. and Cho, W. (1995) Biodegradable polyethylene composition chemically bonded with starch and a process for preparing thereof United States Patent 5,461,094. 

The second section deals with the degradability of commodity plastics and specialty potymers. Emphasis is on the biodegradation of polyethylene, its blends with starch, and constraints in the decay of such composites. Additionally, the biodegradability of different functional groups (polyethers, carbotylic adds, esters, and dioxanones) is mcamined with respect to composition and miaostructure. 

T. Muthukumar, A. Aravinthana, R. Dineshiam, R. Venkatesan, M, Doble. Biodegradation of Starch Blended High Density Polyethylene using Marine Bacteria Associated with Biofilm Formation and its Isolation Characterization , Microb. Biochem. TechnoL, 6, 116-122 (2014) M. Takev, P. Velev, V. Samichkov. Physicomechanical Properties of Biodegradable Composites, Based on Polyjnopylene and Paper From old Newspapers , J. Chem. TechnoL and... 

Senna, M. M., Hossam, E M., El-naggar, A. W. M., Compatibilization of low-density polyethylene/plasticized starch blends by reactive compounds and electron beam irradiation. Polymer Composites 2008,29(10), 1137-1144. 

Formulations based on thermoplastic starch, EAA and polyethylene (PE) in different ratio, are suitable for film production. In Table 2.1 a few examples of such compositions (some of them containing also polyvinyl alcohol, PVOH) with their related tensile strength properties are reported. As can be seen, the film obtained with a gelatinized starch level of about 50% shows good tensile properties. 

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