Thermoforming property development

DuPont s Biomax is used in a number of specialty packaging applications, injection-moulded parts, coatings for paper, thermoformed cups and trays, and films because of its superior barrier properties. DuPont has targeted fast-food disposable packaging, as well as yard-waste bags, diaper backing, agricultural film, flowerpots, and bottles, for particular development. 

PS is one of the most versatile packaging resins. The amorphous grade, crystal PS, is used to make bottles for pills, tablets, and capsules. High impact PS (HIPS) is commonly used as thermoformed containers for dairy products. PS foam has good shock absorbing and heat insulation characteristics. Applications in food packaging include egg cartons and meat trays. Varieties of styrene-based copolymers have also been developed to exhibit special combinations of properties. Typical PS properties are shown in Table 4.10. 

Multilayer materials specially developed for longer best before dates and better barrier properties can be processed by means of thermoforming in one... 

Blow molded parts demonstrate that, from technical and cost standpoints, BM offers a promising alternative to other processes, particularly injection molding (IM) and thermoforming. The technical evolution of BM, plus accompanying improvements and new developments in plastics, has led to new BM parts. With the coextrusion technology now established and the hardware in place, the variety of achievable properties can readily be extended by the correct combination of different materials (see Chapter 3). The potential for BM products includes much more than the simple bottles that have been made for many decades. Now the expertise and economics of the method are such that many ideas once deemed futuristic are much closer to realization (2, 96, 186-212). 

The mechanical properties of polylactic acid are similar to those of polystyrene (Table 4). Problems still unsolved are the too low glass transition temperature, the limited stability to hydrolysis and the slow crystallization rate. Main applications at development stage are in the sectors of bottles, thermoformed containers for food, films and fibers. 

Polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) represents a typical blend that from its commercial introduction in the 1960s has become a major material in the automotive industry, as well as applications in business machine and electronic sectors. The blends provide the balance of properties required for these applications at an economic cost. These include low temperature ductility/impact and processability including injection moulding, extrusion and thermoforming. The commercial growth has been maintained by developments in heat stability, thermal ageing in hot wet environments and halogen free flame retardency [8]. 

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