Chemicals recycling starches

There have been more efforts to use blends such as Nova Chemicals Arcel (an ethylene styrene interpolymer in bead form) to create a more durable foam than EPS. EPP can be moulded into complex shapes, with the steam bonding of the beads (291). These packaging foams compete with polyolefin film products such as Jiffy foam (bubblewrap) and macrobubbles made by heat sealing 150 mm lengths of tubular LDPE film. As it is difficult or costly to recycle such foam products, in some countries there is a move towards biodegradable starch foams and moulded paperboard. 

It is clear that there are many possibilities for avoiding the use of classical acid and base catalysts in a wide variety of chemical reactions. Their application will result in the development of more sustainable processes with a substantial reduction in the inorganic waste produced by the chemical industry. Particularly noteworthy in this context is the use of chemically modified expanded com starches, containing pendant S03H or NH2 groups, as solid acid or base catalysts, respectively [152]. In addition to being recyclable these catalysts are biodegradable and derived from renewable raw materials (see Chapter 8). 

Renewable raw materials can contribute to the sustainability of chemical products in two ways (i) by developing greener, biomass-derived products which replace existing oil-based products, e.g. a biodegradable plastic, and (ii) greener processes for the manufacture of existing chemicals from biomass instead of from fossil feedstocks. These conversion processes should, of course, be catalytic in order to maximize atom efficiencies and minimize waste (E factors) but they could be chemo- or biocatalytic, e.g. fermentation [3-5]. Even the chemocatalysts themselves can be derived from biomass, e.g. expanded com starches modified with surface S03H or amine moieties can be used as recyclable solid acid or base catalysts, respectively [6]. 

Some 20 to 25 years ago there was a popular belief that plastics should be made degradable and a series of additives were developed to achieve this end. These substances included photodegradable chemicals, chemicals slowly attacked by light and heat, starches which are subjected to microbial attack, e.g. edible substances, and water hydrolysable substances. More recently it has become preferable to reuse, recycle or incinerate plastic so that energy can be either conserved or recovered. 

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