Abstract
The morphology and mechanical properties of blends prepared from poly(3-hydroxybutyrate) (P(3HB)) and ionomers formed by copolymerization of ethylene and methacrylic acid, either in the acid form (I-H) or partially neutralized with Zinc (I-Zn) and Sodium (I-Na) were investigated. Blends containing 5 to 30% of I-H, I-Zn and I-Na were prepared in an internal mixer and in a twin screw extruder. Specimens were prepared by compression and injection molding and submitted to SEM analysis and tensile and impact tests. During processing of the mixture P(3HB) with I-Na degradation of the polymer took place, with gas evolution. P(3HB)/I-H and P(3HB)/I-Zn blends presented phase separation morphologies, with the ethylene copolymer domains forming cylindrical structures. Both the Young's modulus and stress decreased and were dependent on the blend processing method and the ionomer used. The elongation at break increased by 120% as a result of the second component addition. The best impact resistance was noticed in blends containing 30% of I-Zn, with an increase of 53%. There was a strong indication that exchange reactions occurred during the mixing process. The extent of these reactions was dependent on residence time and the ionomer content of the blends.