Synthesis, thermal and mechanical properties and biodegradation of branched polyamide 4

A series of linear and branched polyamide 4 were prepared and characterized in order to study the effect of the structure on thermal and mechanical properties. Polybasic acid chlorides were effective initiators for the synthesis of the branched polyamide 4. The melting points of the polyamide 4 for the high molecular weight region were near 265 °C and showed no significant difference depending on their chain structure. On the other hand, it was found that the branched polyamide 4 showed remarkable increase of tensile strength, compared to similar molecular weight of the linear polyamide 4 (e.g. four-branched type Mw=9.28×104, tensile strength=72 MPa).When the initiator having branched structure were used, gel was also formed at the initiator concentration over a certain value (e.g. 3.0 mol% for 4-branched type).The biodegradation of the branched polyamide 4 was evaluated using a standard activated sludge (e.g. four-branched type Mw=8.25×104, biodegradation 41%).