To improve the flame retardancy, mechanical properties and degradation rate of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) by divinybenzene-maleic anhydride microsphere

Abstract

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB), as a bio-originated and biodegradable polyester, is expected to be developed to substitute traditional petroleum-based plastics. However, its flammability restrains its application, intumescent flame retardant (IFR) has been used in P34HB. Herein, a rigid microsphere divinylbenzene-maleic anhydride (DM) copolymer was used as a synergistic agent with IFR together in P34HB. The LOI of the 83wt% P34HB/16wt% IFR/1wt% DM reached 30.0%, and the composite also passed the UL-94V-0 rating. In the cone calorimeter test, the peak heat release rate (PHRR) of the control P34HB was 727 kW/m2, which was reduced to 281 kW/m2 for the 83wt% P34HB/16wt% IFR/1wt% DM. The total smoke production (TSP) of the control P34HB was 12.1 m2, however, the TSP value of 83wt% P34HB/16wt% IFR/1wt% DM was reduced to 8.4 m2. The results showed that DM acted as an ideal synergist flame retardant. For the 75wt% P34HB/25wt% IFR, the tensile strength and impact strength were 13.7 MPa and 4.2 KJ/m2, respectively and for the 83wt% P34HB/16wt% IFR/1wt% DM, they were increased to 18.1 MPa and 9.1 KJ/m2, respectively. In the degradation process, the weight loss rate of control P34HB was 0.1 mg/h, and that was 0.56 mg/h for 83wt% P34HB/16wt% IFR/1wt% DM, which indicated that the IFR/DM accelerated the degradation of P34HB. All the work documented that DM improved the flame retardant, mechanical properties, and degradation rate of P34HB.