The Influence of High Pressure Treatment and Thermal Pasteurization on the Surface of Polymeric Packaging Films (original) (raw)
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IOP Conference Series: Materials Science and Engineering
The purpose of this study was to assess the changes induced by pressure-assisted thermal processing (PATP) treatment in two multilayer polymer films used as packaging material by the meat industry. The changes induced by the treatment at 600 MPa, 70 ºC for 10 minutes on the structural, mechanical and thermal properties of two multilayer polymer films (Pev-70 coextruded high barrier multilayer film with the structure PA / EVOH / PA / PE and Pob-60 combination of biaxially oriented polyamide with a co-extruded barrier film of the polyethylene / EVOH / m-polyethylene structure) were studied. Numerous changes induced by the PATP treatment on the structural, mechanical and thermal properties of the two multi-layered polymer films used as packaging materials in the meat industry have been identified. The choice of a packaging material according to the PATP treatment requires a better understanding of all the changes induced by this treatment. So, this study has preliminarily identified a part of those changes that occurs and could irreversible affect the quality of foods.
Microstructural changes of some multilayer polymer films applied in patp food treatment
2013
Pressure Assisted Thermal Processing (PATP) provides an alternative to classical processing that can provide safe products without loss of sensory quality or nutrients. The objective of the present work was to study the behaviour of two commercially available multilayer polymeric films exposed to PATP treatment in order to assess their usefulness as food packaging materials. The microstructural changes during the treatment were monitored by Scanning Electron Microscopy (SEM). Two commercially multilayer polymeric films: I (combination of biaxially oriented polyamide with coextruded barrier film of the structure PE/EVOH/PE) and II (coextruded high barrier multilayer film with the structure PA/EVOH/PA/PE) were PATP treated (600 MPa for 10 min. at 70°C). The surface topography was evaluated after the PATP and compared to the control samples. The results showed that the combined pressure-heat treatment can compromise the integrity of tested multilayer films
Packaging Technology and Science, 2013
As high-pressure processing is used increasingly for the treatment of packed products, different packaging has been investigated with respect to their structural behaviour and stability under high-pressure processing. Often, failures and changes of the polymeric structure occur. Common damage symptoms of high-pressure-treated packaging materials are defined and classified in this review. These damage symptoms are allocated to the physico-chemical effects that created them. The effects may be separated into direct effects induced by the action of the high-pressure alone and indirect effects that are mediated via compressed contents of the package, i.e. filled product and gaseous headspace. The direct effects split up again in reversible and irreversible structural changes. The indirect effects are generated by compressed headspace gases, other compressed substances and the consequences of increased amounts of gases dissolved in the polymers. If applicable, current theoretical approaches have been allocated to the different categories of damage.
Temperature dependent surface properties of thin polymer films
1998
Variable temperature Scanning Force Microscopy of mixed polystyrene (2000-100000 g/mol) and poly(methylmethacrylate) (100000 g/mol) thin films was used to probe mechanical properties such as surface stiffness and pull-offforces. Adhesion data can be explained by the molecular properties of the constituents. The adhesion of Polystyrene samples was measured by force distance curves and using the Pu!sed Force Mode. lt can be shown that surface tension is not the dominant part ofthe tip-surface interaction, but the mechani ca! properties of the material will influence the measured adhesive force. Wetting of the tip by polymer molecules at higher temperatures due to increasing mobility is one possible model .
Journal of Food Engineering, 2019
The effect of high-pressure processing on the morphological, thermal and mechanical properties of flexible packages was evaluated. The packages were composed of PET/Al/PA/PP (sample A) and PET/printing/ metallization/PET/LDPE-coex (sample B), were processed under three different conditions (600 MPa/25 � C for 10 min, 600 MPa/90 � C for 10 min and 0.1 MPa/90 � C for 10 min), with an unprocessed sample being used as a control. Sample A showed visual and microscopic defects after processing at 600 MPa/90 � C in 20% of the processed packages, and the melting temperature of the PA layer was significantly lower (p < 0.05) after processing at 600 MPa/25 � C and 90 � C compared to control. In addition, high-pressure processing influenced the mechanical property results. For sample B, no changes were observed in thermal and morphological properties after varying process conditions. However, in the 90 � C processes there was a reduction in elongation of the material, bond strength and heat sealing strength.
Packaging Technology and Science, 2008
Pouches of the different materials containing distilled water or olive oil as food simulants, as well as empty ones, were subjected to 400 MPa for 30 min, at temperatures of 20 or 60°C. Delamination and wrinkling were a general consequence of the high-pressure processing of multilayer polymeric systems. However, no signifi cant changes were observed regarding the mechanical properties of PE containing laminates after pressurization. PPSiOx underwent signifi cant modifi cations as SiOx completely broke down. Neither thermal property was affected by pressure, as it was the processing temperature that induced tempering effects on the crystallization behaviour of polymeric components. Only PE/EVOH/ PE, when in contact with water as a simulant, presented a decrease in the melting point temperature.
On the Effect of Non-Thermal Atmospheric Pressure Plasma Treatment on the Properties of PET Film
Polymers
The aim of the work was to investigate the effect of non-thermal plasma treatment of an ultra-thin polyethylene terephthalate (PET) film on changes in its physicochemical properties and biodegradability. Plasma treatment using a dielectric barrier discharge plasma reactor was carried out in air at room temperature and atmospheric pressure twice for 5 and 15 min, respectively. It has been shown that pre-treatment of the PET surface with non-thermal atmospheric plasma leads to changes in the physicochemical properties of this polymer. After plasma modification, the films showed a more developed surface compared to the control samples, which may be related to the surface etching and oxidation processes. After a 5-min plasma exposure, PET films were characterized by the highest wettability, i.e., the contact angle decreased by more than twice compared to the untreated samples. The differential scanning calorimetry analysis revealed the influence of plasma pretreatment on crystallinity c...
Effect of Cold Plasma Treatment on Surface Roughness and Bonding Strength of Polymeric Substrates
Key Engineering Materials, 2014
For an effective application of polymers, it is essential to have good adhesion behaviour to ensure good mechanical properties and durable components. Unfortunately, in general terms, polymers are characterized by high chemical inertness, which leads to very low surface energy values and, consequently, poor adhesive properties; this is particularly true for polyolefins. In this study, the effects of low pressure plasma treatment on surface roughness of polyethylene and polypropylene samples and on shear properties of adhesive bonded joints based on these substrates have been investigated. In particular, the optimization of three plasma process parameters, exposure time, voltage and working gas, were studied performing roughness measurement, contact angle evaluation and lap-shear tests. The experimental results show that the optimized plasma process may remarkably change the surface morphology, increasing wettability properties of the surfaces and shear strength of the bonded joints. These good properties remain almost unchanged even after some days of storage in the laboratory.
The mechanism of adhesion and printability of plasma processed PET films
Materials Research Innovations, 2003
Of the several techniques available for the surface modification, plasma processing has proved to be very appropriate. The low temperature plasma is a soft radiation source and it affects the material only over a few hundred deep, the bulk properties remaining unaffected. Plasma surface treatment also offers the advantage of greater chemical flexibility. PET films are widely used for packaging and electrical insulation. The studies of adhesion and printability properties are important. In the present study PET films are treated in air plasma for different time of treatment. The improvement in adhesion is studied by measuring T-peel and Lap shear strength. In addition, printability of plasma treated PET films is studied by cross test method. It has been found that printability increases considerably for plasma treatment of short duration. Therefore it is interesting to study the surface composition and morphology by contact angle measurement, ESCA and AFM. Surface energy and surface roughness can be directly correlated to the improvement in above-mentioned surface related properties. It has been found that the surface oxidation occurs containing polar functional groups such as C-O, COO. A correlation of all such observations from different techniques gives a comprehensive picture of the structure and surface composition of plasma treated PET films.