Thermal, morphological, and structural characterization of starch-based bio-polymers for melt spinnability

Abstract

The demand for sustainable textiles has increased research on bio-based biopolymers. Fiber spinning from starch biopolymer and its blends was widely attempted using electro-spinning; however, it is less attempted using melt spinning which is an industrially feasible method. In this study, native tapioca starch is converted into thermoplastic starch (TPS), blended with polylactic acid (PLA), and is attempted for melt spinnability in its neat and blended form TPS/PLA (70/30) with the intention of checking the possibility of melt spinning. The results from characterization of the prepared biopolymers show that thermal analysis of neat TPS does not reveal clear thermal transitions, glass transition (T g), and melting (T m), in the second heating curve, rather it influenced crystallization behavior of PLA as seen from differential scanning calorimetry result and degradation temperature (T d) was found to be in the range of 296–352°C from thermogravimetric analysis showing that addition of PLA improved thermal stability of TPS. Morphology analysis with AFM images revealed the presence of granular starch in neat TPS and phase separation in TPS/PLA blends with finer phase distribution in the presence of additives. Fourier transform infrared spectroscopy result shows the interaction between starch, glycerol, and PLA showing the effect of thermoplasticization of starch which brings rupture or weakening of the strong glycosidic bonds in between starch molecules and interaction between TPS and PLA as it can be seen from peak shift and peak intensity. The melt spinning trials show the possibility of melt spinning TPS-based biopolymers into fibers even with higher content of TPS as well as neat TPS giving an insight and motivation for more research engagement. The melt-spun fibers were found to have a diameter in the range of 160.0–117.0 μm. However, additional experiments and investigations are required to improve the mechanical and other properties of the fibers.

Keywords

• biodegradable polymers
• thermoplastic starch
• melt-spinning
• bio-polymer fibers
• melt extrusion