Packaging materials film permeability

Subramaniam, 1988]. Hydrochlorination, usually carried out at about 10°C, proceeds by electrophilic addition to give the Markownikoff product with chlorine on the tertiary carbon (Eq. 9-33) [Golub and Heller, 1964 Tran and Prud homme, 1977]. Some cyclization of the intermediate carbocation (XXVI) also takes place (Sec. 9-7). The product, referred to as rubber hydrochloride, has low permeability to water vapor and is resistant to many aqueous solutions (hut not bases or oxidizing acids). Applications include packaging film laminates with metal foils, paper, and cellulose films, although it has been largely replaced by cheaper packaging materials such as polyethylene. 

Debeaufort, R, Tesson, N., Voilley, A. 1995. Aroma compounds and water vapour permeability of edible films and polymeric packagings. In Food and Packaging Materials—Chemical Interactions, Ackermann, R, Idgerstad, M., and Ohlsson, T. (eds.). The Royal Society of Chemistry, Cambridge, U.K., pp. 169-175. 

The gas permeability of 1, 2-PBD depends on the film thickness, as shown in Fig. 2. When the film thickness is increased to several few millimeters, the gas permeability of 1, 2-PBD is reduced and approaches that of LDPE. In this film the gas permeability of 1, 2-PBD is hl, which is assumed to be attributable to the good solubility of CO2, 2 and ethylene oxide gas in the 1, 2-PBD film surface, in view of the small gas diffusion coefficient of 1, 2-PBD measured by J.D. Ferry et aJ.(2), From these fundamental physical properties aM nontoxic in respect to food hydiene described previous paper, the 1, 2-PBD will be suitable for food packaging materials. Because of its good gas permeability in this film, 1, 2-PBD is used, as the most superior application example, for stretched film as a wrapping for fresh vegetables, fruits and others. 

Poly(vinylidene chloride) (PVDC). The homopolymer is intractable in the conventional plastics processing techniques. For this reason, copolymers of vinylydene chloride with vinyl chloride or terpolymers with vinyl chloride and acrylonitrile are used. Due to its exceptionally low vapour, gas, and aroma permeability, PVDC films are used for packaging and for the barrier layer in composite films. Paper varnished by PVDC is a widespread packaging material. Trade names Diofan (FRG), Ixan (B), Saran (USA). 

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