Title: Incorporation of poly(glycidylmethacrylate) grafted bacterial cellulose nano-whiskers in poly(lactic acid) nanocomposites: improved barrier and mechanical properties Authors
|Martinez-Sanz, Marta -|
|Abdelwahab, Mohamed -|
|Lopez-Rubio, Amparao -|
|Lagaron, Jose -|
|Chiellini, Emo -|
Submitted to: European Polymer Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 29, 2013
Publication Date: May 22, 2013
Citation: Martinez-Sanz, M., Abdelwahab, M.A., Lopez-Rubio, A., Lagaron, J., Chiellini, E., Williams, T.G., Wood, D.F., Orts, W.J., Imam, S.H. 2013. Incorporation of poly(glycidylmethacrylate) grafted bacterial cellulose nano-whiskers in poly(lactic acid) nanocomposites: improved barrier and mechanical properties. European Polymer Journal. 49:2062-2072. DOI: http://dx.doi.org/10.1016/j.eurpolymj.2013.04.035. Interpretive Summary: Biodegradable polymers and materials from renewable resources have attracted increased attention for sustainable development and environmental conservation. Biobased and biodegradable polymers are available, however, in their present forms, they have low functionalities compared to their petroleum-based counterparts. The incorporation of nano materials into these polymers has been shown to result in plastics with improved functionality over that of the biobased polymer alone. In this work, we produced a material with epoxy-like functionality via the incorporation of cellulose nanowhiskers derived from bacteria. The nanowhiskers had better adhesion to the bio-based polymer than previously developed material which led to improved barrier and mechanical properties. This research will eventually lead to the availability of better environmentally-friendly plastics on the market that may be used in a multitude of ways.
Technical Abstract: Poly(glycidyl methacrylate) (PGMA) was grafted onto bacterial cellulose nanowhiskers (BCNW) by means of a redox-initiated free radical copolymerization reaction. The incorporation of PGMA chains decreased the thermal stability and crystallinity of BCNW. The neat and the PGMA-grafted BCNW were subsequently incorporated as fillers into the PLA matrix. PGMA grafting improved both matrix-filler adhesion and the dispersion of cellulose nanocrystals. However, the dispersion of the nanofiller was still not completely optimized and loadings higher than 3 wt.-% resulted in increased agglomeration. The incorporation of both neat and PGMA-grafted BCNW significantly reduced the oxygen permeability of PLA for low relative humidity conditions. However, due to the moisture sensitivity of cellulose, smaller improvements were attained when increasing the water activity. The detrimental effect of moisture on the oxygen permeability of nanocomposites was limited by the grafting copolymerization since PGMA-grafted BCNW seemed to present a more hydrophobic behavior. Furthermore, increased elastic modulus and tensile strength were observed for all the nanocomposites, especially when the concentration of nanocrystals was around the percolation threshold, i.e. 3 wt.-%, but only nanocomposites containing PGMA-grafted BCNW preserved the ductility of neat PLA.