-
[show abstract]
[hide abstract]
ABSTRACT: The moisture barrier and heat sealability properties of polylactide (PLA) extrusion-coated paperboard were investigated. The first part of the study focused on the influences of coating weight and surroundings temperature and relative humidity on the water vapour transmission rate (WVTR) of the structure. The outcome arising from this part was a simple and practical equation that allows calculating the WVTR as a function of PLA coating weight under specific thermo-hygrometric conditions. The second part of the study investigated the effect of heat treatments between 100 and 150°C on the WVTR and heat sealability of a 20 g/m2 PLA-coated paperboard. According to the results, the lowest WVTR values achieved were about 2.5 times lower than the WVTR of the untreated structure. Presumably, the PLA coating experienced two types of reordering mechanisms: crystalline growth and packing of the amorphous structure. The greatest barrier improvement was achieved when both of these mechanisms were accumulated effectively. This was observed from the samples after a 40 min treatment at 130°C. Ultimately, the crystalline growth was experienced by PLA at 100–130°C temperatures. The packing of the amorphous section, which was also accumulated at higher temperatures, was suggested to be the decisive factor influencing WVTR. According to the heat sealing results, the heat treatments causing crystalline growth resulted in considerably increased sealing temperatures and reduced applicability of the material in high-speed packaging applications. The treatments at 140–150°C caused only a slight increase in the sealing temperature and maintained the sealing performance of PLA. Copyright © 2009 John Wiley & Sons, Ltd.
Packaging Technology and Science 07/2009; 22(8):451 - 460. · 1.01 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Regression analysis was used to develop a prediction model for moisture barrier properties of extrusion-coated papers. Practically, water vapor transmission rates (WVtr) of extrusion-coated papers are affected by three factors: coating weight (or squared mass) of a studied polymer, temperature, and moisture concentration of surroundings. The created model finds mathematical connections between WVtr and these variables covering the detected region of variables with a continuous WVtr estimation. By using mixing ratio as a variable of humidity, the model accurately estimates across the field of experiments and represents a fast and easy-to-use tool for the prediction of WVtr for extrusion-coated papers.
Tappi Journal 09/2008; 7(9):8-15. · 0.47 Impact Factor
-
International Journal of Polymer Analysis and Characterization 01/2005; 10(1-2):71-83. · 1.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: One of the most promising areas for the industrial application of atomic layer deposition (ALD) is for gas barrier layers on polymers. In this work, a packaging material system with improved diffusion barrier properties has been developed and studied by applying ALD on flexible polymer based packaging materials. Nanometer scale metal oxide films have been applied to polymer-coated papers and their diffusion barrier properties have been studied by means of water vapor and oxygen transmission rates. The materials for the study were constructed in two stages: the paper was firstly extrusion coated with polymer film, which was then followed by the ALD deposition of oxide layer. The polymers used as extrusion coatings were polypropylene, low and high density polyethylene, polylactide and polyethylene terephthalate. Water vapor transmission rates (WVTRs) were measured according to method SCAN-P 22:68 and oxygen transmission rates (O2TRs) according to a standard ASTM D 3985. According to the results a 10 nm oxide layer already decreased the oxygen transmission by a factor of 10 compared to uncoated material. WVTR with 40 nm ALD layer was better than the level currently required for most common dry flexible packaging applications. When the oxide layer thickness was increased to 100 nm and above, the measured WVTRs were limited by the measurement set up. Using an ALD layer allowed the polymer thickness on flexible packaging materials to be reduced. Once the ALD layer was 40 nm thick, WVTRs and O2TRs were no longer dependent on polymer layer thickness. Thus, nanometer scale ALD oxide layers have shown their feasibility as high quality diffusion barriers on flexible packaging materials.
Thin Solid Films 519(10):3146-3154. · 1.89 Impact Factor
