Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-V) has not been used for demanding technical applications yet due to its limited mechanical properties, particularly its high brittleness. An appropriate route to overcome these limitations is the implementation of plasticizers in the PHB-V matrix via compounding. In this paper the use of different types of fatty acids esters as PHB-V plasticizers were investigated. The study describes how the difference in the fatty acid esters structure (mainly fatty acid hydrocarbon chain length) affects their plasticizing effect and thus the PHB-V ductility performance. The best impact properties of PHB-V compounds were obtained for oleic acid methyl ester, palmitic acid methyl ester or lauric acid ethylene glycol monoester. The increase of notched impact strength from 1.4 (for neat polymer) to 4.0–4.1 kJ/m² was observed. At the same time stiffness and strength of the polymer decreased but remain on a level sufficient for technical applications. Additional drawback of PHB-V materials is increasing the brittleness over time. Moreover this study shows that the use of oleic acid ethylene glycol monoester or stearic acid ethylene glycol monoester as plasticizers significantly reduces the increase of the brittleness of PHB-V over time. It is relevant that this drawback of PHB-V materials can be significantly improved by plasticizer addition.

In this study, the production of stereocomplex PLA formulations (sc-PLA) by compounding and subsequent injection moulding at different mould temperatures was investigated. Several selective nucleating agents were identified and compounded with different poly(L-lactide)/poly(D-lactide) (PLLA/PDLA) ratios on a co-rotating twin screw extruder. The effect of nucleating agents (NA) on the crystallisation behaviour of the compound was systematically investigated by DSC analysis. The crystallisation behaviour of NA-21 (aluminium complex of a phosphoric ester), also in combination with talc, under cooling rates of up to 70 K/min was analysed. The wide-angle X-ray diffraction (WAXD) results showed a complete stereocomplex (sc) crystal formation on all specimens containing NA-21 even at the highest cooling rates. The thermo-mechanical testing of sc-PLA shows a Young’s modulus of approx. 3 GPa, yield stress of 30–40 MPa, elongation of 1%, and a heat deflection temperature (HDT-B) up to 180 °C. Processing sc-PLA exclusively via the processing route of compounding and injection moulding will open new areas of application for PLA at higher temperatures.

Biopolymers such as Polylacticacid (PLA) by politicians and the press are often referred as the materials of the future. However, this overlooks the fact that the material properties of many biopolymers are not yet equal to those of conventional industrial polymers. For this reason, their use is currently limited to the packaging and medical sectors. Unmodified PLA has relatively low heat and impact resistance, which is insufficient for most technical applications. The aim of this work is to improve the characteristics of PLA by optimizing the crystallization properties through the addition of novel nucleating agents (twin-screw compounding). The assessment is carried out using DSC analysis and the resulting calculated thermodynamic parameters. Subsequently chosen compounds are selected for measuring mechanical properties. The methods used for measuring these properties are tensile tests, the Charpy impact test, and the measurement of the heat deflection temperature (HDT). The results show that sorbitol is the most effective nucleating agent for the nucleation of PLA 4032D, with regard to the optimization of the heat resistance and toughness of the material. However the best crystallization rates from the melt can only be achieved by the further addition of polyethylene glycol (PEG) as a plasticizer. The combined influence of sorbitol and PEG in PLA 4032D, can improve the impact properties by more than 500 % to a value of 131.3 kJ/m² (reference sample 21.8 kJ/m²) and the heat resistance by about 20 % to 65.9 °C (reference sample 54.0 °C).

In this paper a promising way to improve the material characteristics of virgin PLA for technical applications, e. g. profile extrusion, is described. Thereby PLA is combined with other biopolymers such as cellulose esters and different functional additives to create new biobased blend systems. To verify the improved properties of the new materials several mechanical (tensile test, Charpy impact test), thermal (heat deflection temperature) and dimension accuracy tests have been performed. Furthermore a case study shows that the developed PLA materials are suitable to be processed on standard profile extrusion equipment to produce profiles with a good surface geometrical accuracy and quality.