Mechanical properties and biodegradation of thermoplastic starches obtained from grafted starches with acrylics

The mechanical properties and rate of biodegradation of thermoplastic starch obtained from acrylic grafted starch were evaluated. Thermoplastic starch from ungrafted starch (TPS) and grafted starch (TPGS) were obtained by mixing ungrafted or grafted starch with water and glycerol in a mixer camera. The TPS and TPGS with starch-g-PMMA behave as rigid materials with a high Youngʹs modulus. However, TPGS with starch-g-(PBA-co-PMMA) showed less rigidity. Using dynamic mechanical analysis (DMA), an increase in the flexibility of starch was observed due to the addition of a plasticizer. The susceptibility of TPS and TPGS to biodegradation was evaluated with Aspergillus niger. Good fungus growth was observed after 45 days of incubation on TPS probes, whereas lower fungus growth was observed on TPGS probes. Starch biodegradation was confirmed by minor decomposition temperatures obtained by TGA, which indicated a decrease in the molecular weight of the starch due to enzymatic attack.