Analysis of structure transition and compatibility of PTT/PC blend without transesterification

The Development of Poly(lactic acid) (PLA)-Based Blends and Modification Strategies: Methods of Improving Key Properties towards Technical Applications-Review

The widespread use of poly(lactic acid) (PLA) from packaging to engineering applications seems to follow the current global trend. The development of high-performance PLA-based blends has led to the commercial introduction of various PLA-based resins with excellent thermomechanical properties. The reason for this is the progress in the field of major PLA limitations such as low thermal resistance and poor impact strength. The main purpose of using biobased polymers in polymer blends is to increase the share of renewable raw materials in the final product rather than its possible biodegradation. However, in the case of engineering applications, the focus is on achieving the required properties rather than maximizing the percentage of biopolymer. The presented review article discusses the current strategies to optimize the balance of the key features such as stiffness, toughness, and heat resistance of PLA-based blends. Improving of these properties requires molecular structural changes, which together with morphology, crystallinity, and the influence of the processing conditions are the main subjects of this article. The latest research in this field clearly indicates the high potential of using PLA-based materials in highly demanding applications. In the case of impact strength modification, it is possible to obtain values close to 800 J/m, which is a value comparable to polycarbonate. Significant improvement can also be confirmed for thermal resistance results, where heat deflection temperatures for selected types of PLA blends can reach even 130 °C after modification. The modification strategies discussed in this article confirm that a properly conducted process of selecting the blend components and the conditions of the processing technique allows for revealing the potential of PLA as an engineering plastic.

Development of Thermal Resistant FDM Printed Blends. The Preparation of GPET/PC Blends and Evaluation of Material Performance

The paper discusses the preparation of polymer blends based on the polyethylene terephthalate copolymer/polycarbonate (GPET/PC). Materials have been prepared in order to assess their applicability in the fused deposition modeling (FDM) 3D printing process. The tested key feature was the thermomechanical resistance, measured by head deflection temperature (HDT) and Vicat softening temperature (VST), the mechanical tests and dynamic mechanical thermal analysis (DMTA) were also performed. A clear relationship between the increasing content of PC in the blend properties was observed. DMTA analysis revealed significant changes in the glass transition temperature, which indicates the miscibility of this type of polymer system. The mechanical tests indicate a clear trend of stiffness and strength improvement along with the increasing share of PC phase in the structure. The increase in impact strength is also clear, however, compared to the results for a pure PC, the results obtained for GPET/PC blends are significantly lower. As part of the research, reference samples based on polyethylene terephthalate homopolymer (PET) and composite samples with addition of 10% talc were also prepared. The structure analysis for PET/PC(50/50) samples did not show miscibility. However, due to the formation of the PET crystalline phase, the thermomechanical resistance of these materials was visibly higher. Scanning electron microscopy (SEM) analysis confirmed a high degree of compatibility of the GPET/PC blend structure as indicated by the lack of visible signs of phase separation. This phenomenon is not observed for PET/PC blends, which confirms the different thermomechanical interactions of both tested polymer systems.