(499d) Development of Nylon Biocomposites Through the Torrefaction of Waste Stream Agricultural by-Products

In the last several years the use of biobased materials for fillers in thermoplastics has seen a remarkable increase. The desire to produce lighter, stronger, and more ecologically friendly materials being key driving forces behind the movement. While the focus has thus far been on producing biobased composites out of commodity polyolefins or bio-derived resins, little work has been done in the realm of engineering thermoplastics. For engineering thermoplastics, the increased processing temperatures are unfavorable for biocomposite production, causing significant damage to the biobased fillers. As the automotive industry is one of the largest consumers of nylon and the ever increasing push to make cars green, there is a natural fit for research into producing biobased nylon composites. Finding a way to drive off the constituents within the biomass that degrade above the traditional processing temperatures of polyolefins would provide a new biomass that could withstand the processing of engineering thermoplastics. 

From previous studies into the use of biobased materials for energy production it is known that torrefaction, conducted between 220-300 °C, will drive off the hemicellulose, fats, waxes, and other constituents yielding a biomass consisting of mostly cellulose, degrading between 300-375 °C, and lignin, degrading slowly over 250-500 °C. As cellulose is the constituent in biomass that acts as a reinforcing agent in the biocomposite, this is a potential method to prepare biobased fillers for introduction in to engineering thermoplastics. This study describes the development of nylon based biocomposites using torrefied sunflower hulls (TSFH), oat hulls (TOH), and flax shive (TFS). 

To prepare the biocomposites, nylon was blended with each of the torrefied biomasses analyzed based on weight percentage. This study looks at three grades of the biocomposite; neat nylon-6, 16 wt% filler in nylon-6, and 20 wt% filler in nylon-6. The biocomposite samples prepared were tested for static and dynamic properties in addition to characterizing their resistance to moisture uptake as a function of torrefied biomass loading. Correlations between biomass input and loading are discussed.