Talanyuk V. «Relationships of formation and biodegradation of welded joints of biodegradable polymers»

The thesis is devoted to the formation and research of biodegradation of the welded joints of biodegradable polymers PHB (polyhydroxybutyrate), PLA (polylactide), their mixtures PHB / PLA and their modifier, mainly synthetic thermoplastic elastomer (TPE) block copolymer SEBS (styrene-ethylene-butylene-styrene). In this work, the peculiarities of welding and biodegradation of the welds of two most studied biopolymers – PLA and PHB, as well as their modifier, mainly synthetic thermoplastic elastomer (TPE) block copolymer SEBS (styrene-ethylene-butylene-styrene rubber) have been investigated. Experiments on degradation of the biopolymer welds have shown that all welds decompose, but at different rates, especially significant less for the PHB biopolymer comparing to the basic materials. The reason of that is structurization of biopolymers (similar to synthetic polymers) with formation of a higher crystallininty inside the welded joints and longer decomposition process of their crystalline phase. The obtained results made it possible to develop technological recommendations for welding of the studied biopolymers PHB and PLA, which are currently the most common among biopolymers and used in industry, the purpose of which is to form the structure of the welds similar to the structure of the basic biopolymers and, accordingly, similar properties, such as ability to biodegradation. The results of mechanical tests and studies of the morphology of TPE SEBS welds suggest that TPE SEBS has sufficient welding ability to be used as a modifier of PHB and PLA in terms of the formation of their quality welds.