No abstract

The crystallization of polymers from organic solvents is a common phenomenon. Poly(2-isopropyl-2-oxazoline) (PIPOx) is known to crystallize in aqueous or aqueous/organic solvent solutions. This process is associated with the dehydration of polymer chains above the polymer’s lower critical solution temperature (LCST). In this work, the ability of PIPOx to crystallize in nonaqueous media is presented. The annealing of a solution of PIPOx in organic solvents, such as acetonitrile, dimethyl sulfoxide, or propylene carbonate, leads to the precipitation of insoluble material. DSC and WAXS studies confirm the formation of a crystalline phase in the solution, with the degree of crystallinity dependent on the solvent and the polymer concentration. SEM analysis reveals micron-sized fibril structures of the PIPOx crystalline fraction. The glass transition temperature (T g) and the melting temperature (T m) of PIPOx crystallized in organic solutions are equal to those of the polymer crystallized in bulk. The enthalpy of melting (ΔH) of the PIPOx crystalline fraction versus its degree of crystallinity (χc) is shown. The value of the enthalpy of melting for hypothetical, fully crystalline PIPOx (ΔH 100%) is determined.

This paper presents ex-ante examination of advanced polymer materials to detect defects and define and minimize the potential failure of novel polymer products before they arise. The effect of build directions on the properties of dumbbell-shaped specimens obtained by three-dimensional printing from polylactide and polylactide/polyhydroxyalkanoate commercial filaments was investigated, as well as the hydrolytic degradation of these specimens at 50 ºC and 70 ºC. Taking into account previous studies, we have found further dependences of the properties of 3D printed species before and during abiotic degradation from the orientation of printing. The initial assumption that only the contact time with the 3D printer platform leads to an increase in the crystalline phase during printing turned out to be insufficient. Further investigations of individual parts of the dumbbell-shaped specimens showed that the size of the specimens' surface in contact with the platform also affected the structural ordering of the material.