Packaging material characterization

These properties concern paraffins that are part of food packaging materials. Their potential toxicity could be attributable to aromatic residues. The latter are thereby characterized directly or indirectly by ... 

Dense Symmetrical Membranes. These membranes are used on a large scale ia packagiag appHcations (see Eilms and sheeting Packaging materials). They are also used widely ia the laboratory to characterize membrane separation properties. However, it is difficult to make mechanically strong and defect-free symmetrical membranes thinner than 20 p.m, so the flux is low, and these membranes are rarely used in separation processes. Eor laboratory work, the membranes are prepared by solution casting or by melt pressing. 

The 10 volumes in the Series on characterization of particular materials classes include volumes on silicon processir, metals and alloys, catalytic materials, integrated circuit packaging, etc. Characterization is approached from the materials user s point of view. Thus, in general, the format is based on properties, processing steps, materials classification, etc., rather than on a technique. The emphasis of all volumes is on surfaces, interfaces, and thin films, but the emphasis varies depending on the relative importance of these areas for the materials class concerned. Appendixes in each volume reproduce the relevant one-page summaries from the Encyclopedia and provide longer summaries for any techniques referred to that are not covered in the Encyclopedia. 

The American Society for Testing and Materials (ASTM) has many test procedures for the characterization of packaging materials. These methods are available individually or in specific books of ASTM standards. A list of typical tests may be found in Table 15. 

Dense nonporous isotropic membranes are rarely used in membrane separation processes because the transmembrane flux through these relatively thick membranes is too low for practical separation processes. However, they are widely used in laboratory work to characterize membrane properties. In the laboratory, isotropic (dense) membranes are prepared by solution casting or thermal meltpressing. The same techniques can be used on a larger scale to produce, for example, packaging material. 

Soderhjelm, L. and Eskelinen, S. (1985). Characterization of packaging materials with respect to taint and odour. Appita 38(3), 205-209. 

A provisional list of additives for the production of food-contact plastics has been published, anticipating an EC Directive on these additives, and their characterization by several techniques, including NMR, is described.273 The problem of the interactions of food with packaging materials has also been addressed by a study of the migration of some food additives into packaging materials, using NMR in tandem with UV-Visible spectrophotometry.274... 

Violette Ducruet is a Senior Scientist at the National Institute for Agricultural Research (INRA), in Massy, France. In 1981, she earned her PhD in Food Science. Since 1991, she works on mass transfer between food and petrochemical packaging material implying food safety and sensorial impacts. She is involved in the characterization of the structure/barrier properties relationship of biobased polymers. 

Similarity in chemical structure between the sorbate and the polymeric packaging material enhances sorption. As the molecular weight distribution (MWD) of the polymer broadens, sorption also tends to increase. LLDPEs produced with metallocene catalysts, which are characterized by a narrow MWD, have a reduced tendency to sorb volatile compounds, compared to LDPE. Sorption studies on benzaldehyde, citral, and ethyl butyrate revealed that sorption by ionomers is similar to sorption by LDPE. As in the case of migration, the extent to which the sorption process occurs depends on the initial concentration of the sorbate and the partition coefficient between the polymer and the product, as well as on the rate of transfer. 

---