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

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.

Mechanical Properties of Phormium Tenax Reinforced Natural Rubber Composites

The introduction of natural fibers as a filler in a natural rubber (NR) matrix can be of relevance for their eco-friendly and sustainable nature as the substitute for carbon-based fillers. In this work, short Phormium tenax fibers were introduced in random orientation into a NR matrix in different lengths (6, 10, and 14 mm) and various amounts (10, 20, and 30%, taking 100 as the NR weight). The composite was fabricated using a two-roll mill according to American Society for Testing and Materials (ASTM) D3184-11 standard. Several properties were determined, namely tensile and tear characteristics, hardness, and abrasion resistance. The results suggest that the shortest fiber length used, 6 mm, offered the best combination between loss of mechanical (tensile and tear) properties and hardness and the most acceptable resistance to abrasion, with the properties increasing with the amount of fibers present in NR. As a consequence, it is indicated that a higher amount of fibers could be possibly introduced, especially to achieve harder composites, though this would require a more controlled mixing process not excessively reducing tensile elongation at break.

Improving the Tensile and Tear Properties of Thermoplastic Starch/Dolomite Biocomposite Film through Sonication Process

In this work, dolomite filler was introduced into thermoplastic starch (TPS) matrix to form TPS-dolomite (TPS-DOL) biocomposites. TPS-DOL biocomposites were prepared at different dolomite loadings (1 wt%, 2 wt%, 3 wt%, 4 wt% and 5 wt%) and by using two different forms of dolomite (pristine (DOL(P) and sonicated dolomite (DOL(U)) via the solvent casting technique. The effects of dolomite loading and sonication process on the mechanical properties of the TPS-DOL biocomposites were analyzed using tensile and tear tests. The chemistry aspect of the TPS-DOL biocomposites was analyzed using Fourier transform infrared spectroscopy (FTIR) and X-Ray Diffraction (XRD) analysis. According to the mechanical data, biocomposites with a high loading of dolomite (4 and 5 wt%) possess greater tensile and tear properties as compared to the biocomposites with a low loading of dolomite (1 and 2 wt%). Furthermore, it is also proved that the TPS-DOL(U) biocomposites have better mechanical properties when compared to the TPS-DOL(P) biocomposites. Reduction in the dolomite particle size upon the sonication process assisted in its dispersion and distribution throughout the TPS matrix. Thus, this led to the improvement of the tensile and tear properties of the biocomposite. Based on the findings, it is proven that the sonication process is a simple yet beneficial technique in the production of the TPS-dolomite biocomposites with improved tensile and tear properties for use as packaging film.