The Structure-Function Relationships in Laminated Barrier Films

Polymer films have been used in food packaging since the 195O’s, their useage and application becoming more diverse with the increasing demand for convenience foods. The specific areas of interest to this research program are the polymeric films and laminates used in 'boil-in-bag' manufacture, and the relationship between the physical properties of the polymer and its structure. The polymer films of interest fall into 3 categories, polyamides, polyesters and polyolefins, as well as laminated films using these polymers. A wide variety of additives are used both in polymers and foodstuffs. Four additives were used in this study water, 3% acetic acid, butylated hydroxytoluene (BHT) and e-caprolactam. Techniques were developed to determine, the diffusion (D), solubility (K), and permeability (P) coefficients for each additive through each polymer film and laminate at 100°C. The main technique used was permeation by gravimetry, and covered all permeants through all films studied. A structural study was carried out to determine the effect boiling in water had on the films. X-ray diffraction was used as a qualitative method backed up by density and differential scanning calorimetry (DSC) for quantitative analysis. It was found that all single films were permeable to water; though no time-lags were evident. The permeability to BHT and e-caprolactam varied, polyethylene being most permeable, PETP impermeable with nylon lying between. Adhesives as used in laminates were studied as films and were permeable to water. Water uptake was lower than expected for these adhesives. Laminated films reflected the permeability coefficients of the single films from which they were constructed, hence justifying the use of the resistance in series equation for binary laminates. Structural studies showed that water had little affect on crystallinity, except for nylon. Here X—ray diffraction and density suggested an increase in crystallinity. DSC results did not confirm this.

Name dc:type.qualificationname

PhD

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

De Montfort University

Year dc:date.issued

1987

Author dc:creator

• Werrett, Margaret Rankin

Licence

• https://dora.dmu.ac.uk/bitstreams/53330bc5-4a69-49a5-bbbc-6e16736ad1ae/download