Roland Vogel

Effect of multiblock copolymers in polymer blends

The use of multiblock copolymers for the compatibilization of immiscible polymer blends is controversially discussed in the literature. Investigations have been carried out to estimate the effect of multiblock copolymers containing segments of a liquid crystalline polyester (LCP) and polysulfone (PSU) segments in blends of the based homopolymers. One goal was to determine whether multiblock copolymers provide an opportunity for compatibilizing PSU/LCP blends. By using PSU/LCP multiblock copolymers with different molecular weights of the blocks in the appropriate binary, solution-casted blends, it was shown that the interpenetration of the polysulfone phase of the block copolymer and the PSU matrix leads to an improved miscibility of the blend. This effect is retained in ternary blends of PSU, LCP, and the multiblock copolymer, assuming a certain critical molecular weight of the multiblock copolymer segments. In addition, some mechanical characteristics of PSU/LCP melt blends such as the E-modulus and fracture strength are improved by adding long-segmented multiblock copolymers.

LC multiblock copolymers containing polysulfone segments. II. Material properties

The synthesis of multiblock copolymers containing liquid crystalline, semi-aromatic polyester segments of poly(ethylene terephthalate-co-oxybenzoate), and polysulfone segments with different segment molecular weights was recently described. Such block copolymers should make it possible to combine properties of the base homopolymers, e.g., the high strength of liquid crystalline polymers (LCP) with the high thermostability of polysulfone (PSU). Investigations of melt rheology and relaxation behavior discussed here demonstrated that the properties of the block copolymers are intermediate between those of the homopolymers and can be tailored by using PSU and LCP segments of suitable molecular weight. The high melt viscosity of PSU is lowered by block copolymer formation, allowing good processability by injection molding. The material properties of the resulting samples are characterized by a combination of PSU thermostability and improved strength.

Melt Spinning of Poly(3‐hydroxybutyrate) for Tissue Engineering Using Electron‐Beam‐Irradiated Poly(3‐hydroxybutyrate) as Nucleation Agent

Electron-beam-irradiated poly(3-hydroxybutyrate) was used as a nucleating agent for poly(3-hydroxybutyrate) in a melt-spinning process. Molecular data and thermal properties of the irradiated samples were determined. The thermal properties of the nucleated melts were determined to assess the influence of the nucleation agents, and then spinning tests were carried out. Thermal and textile properties of the spun fibers were also determined. Estimations of the improvement of the crystallization in the spinline and of the inhibition of secondary crystallization in the fibers from the use of the described blood-compatible nucleation agents are given.

Acicular precipitated calcium carbonate as inorganic whisker for reinforcing of polypropylene fibers

Abstract Acicular precipitated calcium carbonate (PCC) was used as appropriate inorganic whisker for improving the mechanical properties of melt spun polypropylene fibers. Nucleation effects of the PCC in dependence to concentration, surface coating and pre-shearing were analyzed. Melt-spinning experiments were carried out in order to determine the reinforcing effect.

Precipitated calcium carbonate as carrier particles of ‘dry liquids’ for post-processing crosslinking reactions

Abstract Precipitated calcium carbonates (PCC) of different particle morphologies were used as appropriate carrier particles for post-processing crosslinking reactions. Optimum particle morphology and size were estimated for preparation of dry liquids (DLs). The DLs were tested in three different typically crosslinking reactions of polymers.