The aim of this paper is to provide a framework, whereby gas permeation rates through plastic packaging walls, and hence, food shelf life may be estimated. Although the approach is quite general, specifi c attention is given to the case of liquid-fi lled polyethylene terephthalate (PET) bottles with oxygen as the permeating gas.Two situations are considered: when the walls simply provide a passive resistance to the fl ux (as is the case for standard PET or PET blended with some other low permeability material) and when an active gas scavenger is incorporated within the boundary material.For the passive wall, permeability data relative to oxygen have been collected from literature sources and also measured using specifi c oxygen transmission rate experiments. For the active walls, scavenger kinetic constants were estimated from data obtained using test bottles prepared with varying scavenger concentrations. Numerical predictions in both cases have been verifi ed by comparison with data on gas concentration in water-fi lled bottles maintained under controlled conditions for periods of up to 6 months.
Since the last decade, the whole world is facing a sharp increase in energy consumption in conjunction with a fast growth in world population and an increasing demand in emerging economies. The vast majority of energy sources are actually derived from fossil. Chemical industry also uses fossil sources, primarily oil and gas, both for the manufacturing of chemical products and base chemicals and also for its internal energy consumption. Since late 1990s, according to the Kyoto protocol, a decision was taken to reduce greenhouse gas (GHG) emissions on a global basis. Consequently, many countries have started relevant processes to implement national policies ultimately aimed at reduction of GHG emissions, at improving energy security, and at less reliance on fossil fuels. According to those policies, resources with no or minimal environmental impact have been indicated as alternatives to fossil ones for energy production. Vegetable or animal biomasses can be an option provided that they do not compete with food or with feed because of lack of food availability in developing Countries and potential risk of unacceptable agricultural commodities price increase. A new kind of chemistry, based on the use of natural renewable resources, such as vegetable biomasses, widely available, inexpensive and with marginal environmental impact, is developing. This so‐called “bio‐based chemistry” will contribute to address some of the main concerns of the chemical industry. The depletion of nonrenewable and polluting oil resources, the effect of chemicals on human health, and the increase evidence of global warming can be the drivers to boost a new positive trend in the future for the entire chemical industry. In particular, the development of novel polymeric matrices from renewable resources for bio‐based composites appears very attractive as demand is expected to grow rapidly and significantly in next decades.
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