Discipline: Technology and Engineering
Subcategory: Materials Science
Boniface J.Tiimob - Tuskegee University
Co-Author(s): Shaik Jeelani and Vijaya K. Rangari, Tuskegee University, Tuskegee, AL
The need for compostable alternative packaging materials is an urgent one, due to the inevitable demand in copious quantities by the increasing consumer population. Unfortunately, the mostly used polymeric materials are recalcitrant to degradation, and contribute significantly to climate change issues now confronting the world. Common polymers used for flexible packaging include polypropylene (PP) and polyethylene (PE). The demands for such materials have surged in commensurate proportions to match the increasing demand by growing global population. Worldwide yearly plastics production is estimated to exceed 300 million tons by 2015. This represents trillions of dollars in terms of global economic returns. The over dependence on petroleum resources can be alleviated by bioplastics development from renewable resources. Currently, the bioplastics market is surging up and capturing the plastics consumer market by a rate of 30% annually. Hence, the development of more compostable substitute plastics will immensely help in offsetting the demand on petroleum resource consumption while curtailing the complex issues related to the environmental waste management and climate change. In this research, extruded compostable poly (butylene adipate-co-terephthalate) (PBAT)/agro-based polylactic acid (PLA) blend films were studied to select a suitable blend for further investigations. These blend films (90/10, 80/20, 70/30, 60/40 and 50/50) were characterized using DSC, TGA, Raman spectroscopy, XRD, SEM and tensile testing. After this screening, the 70/30 blend was selected and further studied by reinforcing with eggshell nanoparticles (>30 nm in diameter by TEM analysis) engineered through mechanical attrition and ultrasound irradiation. Eggshell nanoparticles have shown great potential in tailoring of weak polymer properties toward their enhancement, at the same time the inherent egg proteins in the shells are capable of serving as biocides in the polymer matrix. DSC results revealed that the two polymers are immiscible, due to the presence of distinct melting points. Raman spectroscopy revealed frequency vibrations and intensities unique the individual polymers. Also, SEM micrographs of the blends showed heterogeneous mixtures of the two matrixes with distinct phase separation. The mechanical test showed that PLA lead to improvement in tensile strength and modulus whiles PBAT led to significant improvement in train to failure of the blends systems. Inclusion of nano eggshell led to improvement in thermal stability of the 70/30 blend whereas tensile testing revealed significant improvement in strain to failure and strain at maximum load. The presence of eggshell crystals in the blend matrix was confirmed by XRD analysis. Further studies are in progress to test the suitability of the 70/30/eggshell blends for potential bactericidal packaging applications.
Reference: Arruda C. L.; Magaton M.; Bretas E. S. R.; Ueki M. M. Influence of chain extender on mechanical, thermal and morphological properties of blown films of PLA/PBAT blends. Polymer Testing 43 (2015) 27-37Not Submitted
Funder Acknowledgement(s): The authors truly acknowledge NSF-CREST#1137681 and NSF-RISE#1459007 grants for funding this work, ERN for the travel award and American Dehydrated Foods Inc. Atlanta GA for supplying the eggshells.
Faculty Advisor: Vijaya K. Rangari, email@example.com