Influence of the additive on the properties of thermoplastic starch

Tijekom prošlog stoljeća plastika se kao sintetski polimer smatrala materijalom budućnosti no danas predstavlja globalni ekološki problem. Zahvaljujući porastu ekološke osviještenosti i jačim restrikcijama jedan od ciljeva jest smanjiti štetan utjecaj plastičnih proizvoda na okoliš te smanjiti potrošnju neobnovljivih izvora za njihovu proizvodnju. Zbog tih se razloga sve više traga za kvalitetnim alternativama kao što su biopolimeri koji su biorazgradivi ili su proizvedeni iz obnovljivih izvora. U posljednje vrijeme njihova proizvodnja i primjena su povećane što doprinosi smanjenju ekoloških problema povezanih s otpadnim polimernim materijalima. Jedan od biopolimera koji zahtijeva pažnju u ovoj primjeni jest škrob, točnije, termoplastični škrob (TPS). TPS je plastificirani škrob koji posjeduje amorfnu strukturu umjesto kristalne, zahvaljujući primjeni topline i smičnog naprezanja. S obzirom da svojstva samog TPS-a nisu dovoljno dobra da bi se mogao koristiti umjesto plastike, dodaju mu se razni aditivi, plastifikatori i punila. Navedeni dodaci se koriste kako bi se TPS-u modificirala uporabna svojstva: toplinska, mehanička i barijerna te kako bi se utjecalo na proces retrogradacije i površinsku napetost. U ovome radu izrađeni su tanki filmovi TPS-a uz dodatak raznih plastifikatora koristeći metodu lijevanja iz otopine i prešanja. Na pripravljenim filmovima ispitana su površinska, toplinska, mehanička i barijerna svojstva. Rezultati su pokazali da na svojstva filmova TPS-a znatno utječe vrsta plastifikatora, odnosno njihova struktura i sposobnost ugrađivanja u strukturu škroba.In the last century, synthetic polymers such as plastics were considered the materials of the future; however, today they pose a global environmental challenge. With increased environmental awareness and stricter regulations, one of the goals is to reduce the harmful effects of plastic products on the environment and reduce the consumption of non-renewable resources for their production. As a result, there is an increasing search for high-quality alternatives such as biopolymers that are biodegradable or come from renewable sources. Recently, their production and use have increased, helping to reduce the environmental problems associated with polymer waste. One of the biopolymers that needs attention in this context is starch, particularly thermoplastic starch (TPS). TPS is a plasticized starch that has an amorphous structure instead of a crystalline one, which is achieved by applying heat and shear stress. Since the inherent properties of TPS are not sufficient to replace plastic, various additives, plasticizers and fillers are added. These additives are used to modify the service properties of TPS, including thermal, mechanical, and barrier properties, as well as to affect the retrogradation process and surface tension. In this work, thin TPS films were prepared by solution casting and compression molding processes with the addition of various plasticizers. The prepared films were investigated for their surface, thermal, mechanical and barrier properties. The results showed that the properties of TPS films are significantly influenced by the type of plasticizer, i.e., its structure and its ability to bind into the starch structure