Effects of hectorite loading on tear properties and biodegradability of thermoplastic starch films

Abstract

Development of bio-based polymers can reduce human dependence on fossil fuel and move to a sustainable material resource. In this work, thermoplastics starch (TPS) films were produced by plasticization process, in which the crystalline structure of the starch granules was destroyed and reformed by water and glycerine through mechanical stirring and heating process. Hectorite was employed as filler to reinforce the TPS films. The hectorite was subjected to ultrasonication process for reducing the size and aggregation of particles. The ultrasonicated hectorite was added into the TPS solution to produce the TPS/hectorite bio-composite by film casting method. The TPS films with hectorite loading in the range of 1% to 5% were prepared. The morphology, tear strength and soil biodegradability of the TPS/hectorite bio-composite films were studied by altering the loading of hectorite incorporated into the TPS films. Results showed that the TPS/hectorite bio-composite films have higher tear strength compared to the pure TPS films. The tear strength of the bio-composite films slightly increased with hectorite content 1% and 2%. However, as the filler loading increased to 3%, there was a drastic increase of the tear strength. The maximum tear strength value was achieved by the TPS film when 4% hectorite filler was employed. The TPS/4% hectorite (ultrasonicated) has the lowest rate of soil biodegradation due to its lower moisture uptake and greatest interface interaction between starch and hectorite, inhibiting diffusion of bacteria into the films.