Photonic crystals in biology - NanoTR-VI

Poster Session, Thursday, June 17Theme F686 - N1123Preparation and Characterization of Corn Zein Nanocomposite Filmsfor Food Packaging ApplicationsIl KURTULU 1 , Onur ÖZÇALIK 1,2 and Funda TIHMINLIOLU 1,2,*1 Department of Chemical Engineering, zmir Institute of Technology, zmir 35430, Turkey2 Materials Science and Engineering Interdisciplinary Master’s Programme , zmir Institute of Technology, zmir 35430, TurkeyAbstract – Potential of novel corn zein-nanocomposite (CZNC) stand-alone films for gas and water vapor barrier applicationsin food packaging was investigated. Nanocomposites were prepared by dispersing organomodified layered silicate (OMLS)nanoclays within corn zein biopolymer matrix utilizing solution intercalation and melt intercalation methods together.Characterization results showed exfoliated structures of nanoclays within the zein matrix. Improvements in mechanical,thermal and water vapor barrier properties due to exfoliated nanoclays were obtained.Biopolymers offer a noticeable potential of replacingconventional petroleum based polymers in food packagingmaterials. In the last decades extensive research on biobasedmaterials have been conducted and today biopolymerapplications began to be used instead of conventionalpolymers in the industry. Recent advances in nanotechnologyand nanocomposite applications are also remarkable andattractive for biopolymer materials.Food packaging holds an indispensable part of modernlife. As distinct from the past, most of the food products usedtoday are being consumed far from their origin and also aftermonths as well for most of the products. Since introduction ofcheap and useful thermoplastics such as polyethylene andpolypropylene in 1950s, polymers replaced conventionalpackaging materials such as glass or metal and introduced newsolutions and high standards for food packaging. Today theamount of polymeric food packaging waste generated is aserious problem. The amount of waste generated is huge, andrecovery of polymeric materials is very low even compared toglass and metal packaging wastes. For example, in the case ofpolypropylene; which is used in single and multi-layerpackaging with other polymers so characterized as a materialhard to separate and identify in the waste; the recovery ratio isjust about 0.25% according to EPA 2006 statistics [1].Advances in the biopolymeric materials field, which arecapable of complete degradation in the nature, madebiopolymers advantageous alternatives over non-degradableconventional polymers.Protein based biopolymers including corn zein can beprocessed in to films and have excellent barrier to gases andmoderate barrier to water vapor. Characteristic disadvantagesof biopolymers such as low mechanical strength anddependency of their characteristics to moisture should beimproved by utilization of nanocomposite applications thatdraw attention in many fields of material science.Nanocomposite applications enabled researchers andindustry to produce a new era of polymeric compositematerials with enhanced mechanical, barrier, thermal andfunctional properties. Ordered dispersion of nano-sizedparticles, named exfoliated structures, lead to significantimprovements in polymer properties that can not be achievedby conventional composites.Although there are some studies concerning the utilizationof nanocomposite applications of protein based polymers suchas wheat gluten and soy protein [2,3,4], to our knowledgethere is no study related to corn zein nanocomposite films.In this study, novel corn zein nanocomposite stand-alonefilms were developed to examine their feasibility with varyingnanoclay content as an alternative food packaging material forbarrier needs. The (OMLS) content of the samples waschanged from 0% to 5% (weight clay/weight corn zein).Desirable barrier properties of zein films were enhanced byusing two widely used nanocomposite production techniques;solution and melt intercalation; together. First solutionintercalation method was used in the preparation of thesamples. Sonication was utilized for the dispersion of OMLSnanoclays within the corn zein biopolymer chains. Then theprepared solution was poured in to icy water and corn zeinnanocompositeprecipitates were collected and kneaded afterthey dry in an oven with controlled humidity. In the later partof the preparation, a twin-screw extruder suitable fornanocomposite applications with L/D ratio of 40 and 10heating zones integrated with a granule blade was used toprocess the organoclay intercalated precipitates in to granules.Finally, the nanocomposite compounds were pressed in hotpress (Carver) in order to obtain the films to be cut in therequired dimensions for the analysis.Results of the study showed good dispersion ofnanoclays, predicted as successful intercalated and exfoliatedstructures depending on the clay content characterized byXRD analysis. Mechanical tests showed increased YoungModulus in CZNC and decreases in elongation at break valuesas was reported by many researchers for nanocomposites. Thewater vapor permeability of the CZNC showed significantdecreases depending on the clay content. Enhanced propertiesin characterized films are believed to be due to the presence ofordered dispersed clay nanoparticle layers with large aspectratios and good interaction of clays with corn zein chains inthe polymer matrix.*Corresponding author: fundatihminlioglu@iyte.edu.tr[1] Marsh , K., Bugusu, B., 2007. “Roles, Materials, and EnvironmentalIssues”, Journal of Food Science. Vol. 72, pp. 39-55[2] Chen, P. and Zhang, L., 2006. “Interaction and Properties of HighlyExfoliated Soy Protein/ Montmorillonite Nanocomposites”,Biomacromolecules,7 (6), pp. 1700-1706[3] Yu, J., Cui, G., Wei, M., Huang J., 2007, “Facile Exfoliation of RectoriteNanoplatelets in Soy Protein Matrix and Reinforced BionanocompositesThereof”, Journal of Applied Polymer Science, Vol. 104, 3367–3377[4] tunc, S., Angellier, H., Cahyana, Y., Chalier, P., Gontard, N., Gastaldi, E.,2007, “Functional properties of wheat gluten/montmorillonite nanocompositefilms processed by casting”; Journal of Membrane Science, Vol.289, pp.159–1686th Nanoscience and Nanotechnology Conference, zmir, 2010 737