vlastnosti materiálů --- polymery

Textile industry generate significant amount of waste fibers in form of short lengths during mechanical processing. However these short fibers possess excellent properties suitable for many other applications. The objective of this work was to use them for the preparation of nanoparticles/nanofibrils, as fillers in biodegradable composite applications such as food packaging, agriculture mulch films, automotive plastics, etc. In the present study, waste jute fibers generated in textile industries, were wet pulverized to the scale of nanofibrils of 50 nm diameter using high energy planetary ball milling for three hours.The rate of refinement of uncleaned jute fibers having non-cellulosic contents was found slower than the cleaned jute fibers. This tendency is attributed to the strong holding of fiber bundles by non-cellulosic contents which offered resistance to the defibrillation during wet milling. In addition, the presence of water during wet pulverization found to reduce the rising temperature of mill, which prevented sticking of nanofibrils on the mill wall and resulted in unimodal size distribution. In the subsequent stage, 1 wt %, 5 wt % and 10 wt % of jute nanofibrils were incorporated in poly lactic acid (PLA) matrix to prepare nanocomposite films by solvent casting. The reinforcement of nanofibrils was investigated from the improvements in mechanical properties based on tensile tests, dynamic mechanical analysis and differential scanning calorimetry. The maximum improvement was observed in case of 5 wt % nanocomposite film where initial modulus and tensile strength increased by 217.30 % and 170.59 % respectively compared to neat PLA film. These improvements are attributed to the increased interaction between nanofibrils and matrix as well as to the increased crystallinity of PLA in composites. The improvements in load bearing capacity of nanocomposite films were significant at 60oC than 35oC, which showed ability of jute nanofibrils to improve the softening temperature of PLA matrix. In the end, experimental results of Initial modulus were compared with predicted modulus of mechanical models. A good level of agreement was observed up to 5 wt % loading of jute nanofibrils.

Renewable Nanoscale Reinforcement of Biodegradable Polymers