Composites 3. Reinforcement of biodegradable matrices by helical polypeptides

Blends of poly(e-caprolactone) as the matrix material and 1,2,4, or 8 wt.-% of a poly-peptide were prepared by dissolution in a cosolvent and coprecipitation into cold methanol. A low-and a high-molecular-weight poly(γ-benzyl L-glutamate), a poly(γ-methyl L-glutamate) and a poly(D,L-phenylalanine) were used as reinforcing components and compared with a liquid-crystalline (LC) polyester derived from a double-substituted terephthalic acid. Films of all blends were subjected to stress-strain measurements. A weak reinforcing effect was found for the poly(γ-benzyl L-glutamate)s, a somewhat stronger influence for the other polypeptides and the strongest effet for the LC-polyesters 1.