Abstract
The use of (bio)degradable polymers, especially in medical applications, requires a proper understanding of their properties and behavior in various environments. Structural elements made of such polymers may be exposed to changing environmental conditions, which may cause defects. That is why it is so important to determine the effect of processing conditions on polymer properties and also their subsequent behavior during degradation. This paper presents original research on a specimen’s damage during 70 days of hydrolytic degradation. During a standard hydrolytic degradation study of polylactide and polylactide/polyhydroxyalkanoate dumbbell-shaped specimens obtained by 3D printing with two different processing build directions, exhibited unexpected shrinkage phenomena in the last degradation series, representing approximately 50% of the length of the specimens irrespective of the printing direction. Therefore, the continuation of previous ex-ante research of advanced polymer materials is presented to identify any possible defects before they arise and to minimize the potential failures of novel polymer products during their use and also during degradation. Studies on the impact of a specific processing method, i.e., processing parameters and conditions, on the properties expressed in molar mass and thermal properties changes of specimens obtained by three-dimensional printing from polyester-based filaments, and in particular on the occurrence of unexpected shrinkage phenomena after post-processing heat treatment, are presented.
Highlights
Semicrystalline polylactide (PLA) is one of the best-known polymers with the ability to change its morphology
The purpose of this paper is to describe the defect that occurs during the degradation processes, how that impacts on the degradation mechanism and to provide explanations of these results
It was originally found that the processing conditions, in particular, the contact time of the
Summary
Semicrystalline polylactide (PLA) is one of the best-known polymers with the ability to change its morphology. The PLA morphology can be altered either during processing or under load. PLA exhibits a glass transition temperature (Tg ) in the range of 55–70 ◦ C and melting temperature (Tm ) in the range of 150–170 ◦ C. The main disadvantage of PLA is its deformation at relatively low temperatures (above the Tg ) [1]. The high degree of crystallinity contributes to a significant improvement in PLA stability at higher temperatures [2]. PLA, which is the most widely used and the best-known polymer among bio-based and/or (bio)degradable polymers, is a suitable material for three-dimensional (3D) printing [3,4]. Polyhydroxyalkanoates (PHAs) are non-toxic bio-based, biodegrade, and biocompatible polyesters.
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