Düşük yoğunluklu polietilen ve polimetil penten polimerlerinden taze gıda ambalaj malzemesi üretimi

As a result of population growth and global warming, fertile soil lands are decreasing and occurrence rate of natural disasters such as drought and flood are increasing. Because of these reasons millions of people around the world cannot reach the staple food products. Therefore, food supply is one the most urgent problems which is awaiting a solution nowadays. In order to overcome that problem, agricultural harvest is needed to increase or shelf lives of harvested products are needed to extend. Despite the limited arable soil lands, the quantity of product per unit area can be already increased due to increase in fertilisation. In spite of this enormous increase in fertilisation, the food requirements of population growth cannot be met. The main reason of this situation is the loss of post-harvest products which is said approximately 40% by weight. In order to overcome this problem completely, this losses should be eliminated. In order to eliminate these losses, new searches have been focused on new packaging methods. Active packaging and modified atmosphere packaging are new methods which were recovered from these studies. Fundamental principle of these methods is obtaining a balanced internal atmosphere between the respiration rate of preserved product and the gas permeabilities of packaging materials in order to extend the shelf lives of post-harvest products. However, the commercial plastics which are used in packaging industry cannot provide these high gas permeability values and because of this reason they cannot offer longer shelf lives. In accordance with this purpose, in order to obtain high gas permeability values and selectivity properties of packaging material, polymethylpentene (PMP) copolymer was added in different loading levels into low density polyethylene (LDPE) matrix by using a laboratory scale co-rotating twin screw extruder. In this study, LDPE/PMP copolymer blends which were containing 10%, 25%, 50%, 75%, and 90% PMP copolymer ratios were prepared by using extrusion. Also, for blends' structural, morphological, thermal and mechanical evaluations, neat LDPE and PMP copolymer were extruded under the same conditions in order to obtain standard materials which were exposed the same thermal treatment. The package samples were produced by using cast film extrusion method. The most important parameter of this study is O2 and CO2 permeabiltiy values of the package samples. In order to investigate this property entirely, under 90% relative humidity conditions, O2 and CO2 permeability values were determined at 3 different temperatures. Beyond these analysis, according to loading ratio of PMP copolymer into LDPE matrix was increased gas permeability values up to 600%. Increase in gas permeability values can be explanied with DSC and XRD analysis. The tetragonal symmetry of PMP copolymer and phase separations between PMP copolymer and LDPE which can be seen in SEM images led to obtain high gas permeability values in our opinion. The results of shelf life analysis was indicated that the package sample was containing 25% PMP copolymer could extend the shelf lives of banana and marrow fruits 2 times. Thus, the extension of shelf life of preserved products used in this study could be achieved.