The production of a new partially biodegradable starch plastic by reactive extrusion

Abstract

The grafting of polystyrene onto dissolved starch in a twin screw extruder has been studied. This copolymerization was initiated using the thermal initiators benmy1 peroxide and K&O,. As end product a mixture containing polystyrene-grafted starch, homopolymer of polystyrene and starch was obtained. Parameters like screw rotation rate, fully filled length of the extruder, wall temperature and throughput have been varied in order to obtain information about their influence on conversion, graft percentages and molecular weight of the materials formed. To increase the amount of graft points, maleic acid anhydride (MAH) was added resulting in an increased graftmg of polystyrene onto starch. Graft percentages of 60% could be achieved. The total conversion of styrene could be controlled by adjusting extruder parameters like barrel temperature, fully filled length and initiator type. Conversions of 95% were found. Molecular weights of the polystyrene formed could be controlled by adding a chain transfer agent (dodecylmercaptan) to the styrene phase. In this way the molecular welght (MJ of the styrenic part could be varied from 20,000 to 140,000. The experiments with the chain transfer agent showed that the grafkg of polystyrene onto starch is a process occurring at the interface between the dissolved starch and the styrene phase.

Thermal Transitions and Extrusion of Glycerol‐Plasticized Whey Protein Mixtures

“…Calender rolls are widely used in the production of poly(vinyl chloride) sheet and film (Robertson 1993). Studies on extrusion of certain biopolymers such as starch, soy protein, and caseinate (Mungara and others 1998; De Graaf and Janssen 2000; Fossen 2000; Li and Lee 2000; Nabeshima and Grossman 2001) suggest the possibility of extruding whey proteins to form films.…”

Nano clay reinforced biodegradable plastics of PCL starch blends

“…Therefore, possibilities to blend with lower-priced starch are being studied. [3][4][5][6] Past studies have shown that the amount of starch blended with plastics is relatively small and the dynamic properties are not sufficient. It is necessary to modify ordinay starch, which has inferior mechanical characteristics compared with the general-purpose plastics, such as poly(ethylene) and poly(propylene).…”

Induction of Biodegradability in the Plastic Waste Through Graft Copolymerization

“…Few additives having hydrophilic groups, make plastic hydrophilic and susceptible for photo and chemical degradation. Modification of plastic through copolymerization and through anchoring monosaccharide into it or blending with nutrients and biodegradable fillers makes it degradable [11][12][13][14] . These micronutrients help the growth of specific microorganisms and this incorporation of polar functional groups can serve as point for microbial attack [15] .…”