The diploma thesis introduces the meaning and the function of packaging and envirnomental problems concerning waste packaging. Paper packaging, coated with the synthetic polymers is not biodegredable and is not easy to recycle, so the solution is in the natural biodegradable coating. One of the possible biodegredable polymers is polylactid acid or polylactide (PLA), which is suitable for applications in the food industry (citlery, cups, packaging of bakery products, bags, etc.). In diploma thesis used materials, i.e. paper and polymer PLA are described, the procedure of PLA dissolving in three different solvents: xylene, ethyl acetate and dichloromethane and the procedure of paper coating with PLA solution in different concentrations by a manual coating machine are presented. Certain basic, surface and absorbent characteristics were determined on both types of paper – coated and non-coated one. The bags for bakery wares of two different manufacturers were tested in order to gain reference values for barrier characteristics of coated packaging paper.
The basic goal of the diploma thesis was to find a suitable solvent for PLA granulat dissolving and the most proper concentration of PLA solution for paper coating. By comparing the characteristics of paper before and after coating with various concentrations and PLA coating applications the purpose was to determine optimum concentration and application quantity to provide good barrier characteristics of paper. The analysis of basic, absorbent and surface characteristics showed that PLA coating filled up the surface well, reduces porosity, wetabilty and makes it water tight. The comparison with packaging paper characteristics has shown that 15% concentration of PLA in dichloromethane with a bigger application achieves the same or even better barrier characteristics than both paper bags analyzed.
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