Packaging materials polymers

There are a number of studies that look at the absorption of flavor compounds into different polymer packaging materials (Arora et al., 1991 Ayhan et al., 2001 Charara et al., 1992 Fukamachi et al., 1996 Hernandez-Munoz et al., 2001 Imai et al., 1990 Konczal et al., 1992 Letinski and Halek, 1992 Moshonas and Shaw, 1989 Nielsen et al., 1992 Sadler and Braddock, 1991 Safa and Bourelle, 1999 van Willige et al., 2000, 2002, 2003). There are fewer studies looking at the effect that this absorption has on the sensory quality of the food. The few sensory studies that have been... 

Polymer packaging material is easy to seal, allowing the contents to remain fresh for longer times and during transportation. 

Sorted plastic packaging materials are shipped, usually in bales, to processing plants to be converted to polymer resins. The bales are broken and the bottles sorted to ensure that only one type of polymer is further processed. Processing consists of chopping and grinding the bottles into flakes. These flakes are washed. Processing steps such as flotation are used to remove polymeric contaminants from the flakes (15,16). The flakes are melted and converted into pellets. 

Packaging. Because of the extremely broad demands on the mechanical properties of packaging materials, the entire range of ceUular polymers from rigid to flexible is used in this appHcation. The most important considerations are mechanical properties, cost, ease of appHcation or fabrication, moisture susceptibUity, thermal conductivity, and aesthetic appeal. 

Fabrication. Flexible packaging materials may be mono- or multilayer. Monolayer materials are usually films that have been produced by polymer resin melting and extmsion. 

Certain bacterial species produce polymers of y-hydroxybutyric acid and other hydroxyalkanoic acids as storage polymers. These are biodegradable polymers with some desirable properties for manufacture of biodegradable packaging materials, and considerable effort is being devoted by ICI Ltd. and others to the development of bacterial fermentation processes to produce these polymers at a high molecular weight (66). 

Compared with more common plastics used as packaging materials, the compound does have some disadvantages, such as a high water vapour permeability and limited heat resistance, losing dimensional stability at about 70°C. It is also substantially more expensive than the high-tonnage polyolefins. Last but not least its biodegradability means that it must be used in applications that will have completed their function within a few months of the manufacture of the polymer compound. 

The methods of analysis of polymer additives and chemicals, such as hydrocarbons, alcohols, etc., are not only restricted to the field of polymer chemistry but can also be applied for the analysis of such materials in the field of food chemistry. In addition, the analysis of polyaromatic hydrocarbons in edible oils has been of extreme importance. Polymeric packaging materials that are intended for food-contact use may contain certain additives that can migrate into the food products which are actually packaged in such products. The amounts of the additives that are permitted to migrate into food samples are controlled by government agencies in order to show... 

A major difficulty is that so many applicahons employ polymers as though they were readily disposable, despite the fact that they are, in reality, among the more inert of chemical pollutants. In particular, plashc packaging tends to make a single use of a fabricated polymer which is then thrown away. Even when disposed of responsibly, packaging materials are the source of a serious pollution problem. Municipal authorities dispose of such materials by one of two routes, landfilling and incineration, of which the latter cannot be readily used for chlorinated polymers, such as PVC, because of the additional problems caused by organochlorine species in the atmosphere. 

It is likely that excellent gas barrier properties exhibited by nanocomposite polymer systems will result in their substantial use as packaging materials in fumre years. 

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