Photonic crystals in biology - NanoTR-VI

andPCPPoster Session, Thursday, June 17Preparation and Characterization of Poly (3-Hydroxybutyrate) Homo and CopolymersNanocomposite Films1111Onur GökbulutP P, Burcu KayaP P, Okan AknP Pand UFunda TihminliogluUP P*1PDepartment of Chemical Engineering, zmir Institute of Technology, Urla, 35430, TurkeyTheme F686 - N1123Abstract- This study aims to prepare and investigate the characteristic properties of Poly (hydroxybutyrate) (PHB) andpolyhydroxybutyrate-co valerate (PHB/HV) copolymers layered silicate nanocomposites. Nanocomposites were prepared via meltintercalation method by dispersing orgonamodified layered silicate nanoclays. The effects of clay loading and the polymer type on the watervapour, OR2R COR2R barrier properties were measured. In addition, Differential Scanning Calorimetry (DSC) and mechanical properties ofthe films were performed. Mechanical properties of the chitosan composites were enhanced with the addition of clay . The enhancement inthe barrier properties were obtained upto certain clay content in composites.Among many different materials that mankind is dependenton plastics are the most important ones considering theirwidespread usage in food packaging, textile, communication,transportation, construction, medical industries. Currently,plastics and synthetic polymers are mainly produced usingpetrochemical materials that cannot be decomposed. Inaddition the amount of plastic waste increases every year.Therefore in the last decades there has been a significantincrease in the development of biodegradable thermoplasticpolyesters due to ongoing concerns about the disposal ofconventional plastics and the increasing difficulty inmanaging solid wastes.Poly (hydroxyalkanoates), PHAs, comprise a family ofbiopolymers that has attracted much attention recently due tosimilar properties to conventional materials such aspolypropylene, polyethylene, polystyrene, and PET. Bacterialbiopolymers such as Poly (3-hydroxybutyrate) (PHB) and itscopolymers with valerate (PHB/HV) are biodegradablethermoplastic polyesters and one of the most widelyinvestigated members of the family of PHAs. PHB and itscopolymers present good mechanical, thermal and barrierproperties. PHB is a partially crystalline thermoplastic andhas a high melting temperature. However PHB suffers fromlow melting stability, brittleness and lack of transparency [1].Thus, recent studies are objected to improve the properties ofPHB and its copolymers by addition of nanoclays. Surfacemodified clays have been studied as advanced additives toimprove or balance thermal, mechanical, fire resistance,surface, or conductivity properties of nanocomposite due totheir high surface to volume ratios and the subsequentintimate contact that they promote with the matrix at lowfiller additions [2]. In essence, three different methods areused to synthesize polymer-clay nanocomposite; meltintercalation, solution and situ polymerization.PHB and PHB-HV /layered silicate nanocomposites in thepresent study are prepared via melt extrusion. Natural PHBand its copolymer PHB-HV (2% and 12%) were purchasedfrom Goodfellow Inc. and dried under vacuum at 80°C fortwo days before use. As clay, organophilic surface modifiedmontmorillonite called Cloisite® 15A purchased fromSouthern Clay Products, Inc. Polymers and nanoclay aremelted extruded by using a Thermofisher twin screw extruderwith varying weight percentages of clay at a temperature of180 °C and a screw speed of 50 rpm. The extrudedcomposites are dried under vacuum at 50 °C. The samples ofPHB, PHB-HV and their nanocomposite are finallytransformed into films by compression molding in a hot-plateohydraulic press at 175 P PC and 5 Metric tons of pressureduring 5 min. The polymer sheets are cooed to roomtemperature under constant pressure.The effect of filler concentration on the water vapor, OR2Rand COR2 Rpermeability, mechanical and thermal properties ofthe composite films were evaluated. The structure ofnanocomposites and the state of intercalation of the clay werecharacterized by Phillips X’Pert Pro MRD with Cu Kradiation (=1.54 nm) under a voltage of 40 kV and a currentof 40 mA. Samples were scanned over the range ofdiffraction angle 2 = 0.25-30°. Thermal properties of thepolymer and the nanocomposite films are studied by a DSCtechnique with a Shimadzu Calorimeter at a heating rate 10oP/min. Morphology of polymers and their nano compositesare analyzed by XRD and TEM. As a result of morphogicalanalyses , intercalated structure were obtained . The extent ofintercalation depends on the amount of silicate and the natureof organic modifier present in the layered silicate .According to results of permeability measurements; thenanocomposite films exhibit good barrier properties ascompared to their unfilled polymer films. The water vaporand gas permeability values of the composite films decreasedsignificantly depending on the filler concentration and thetype of filler used. The decrease in water vapor and gaspermeability of PHB and PHB-HV- clay nanocompositefilms are believed to be due to the presence of ordereddispersed clay nanoparticle layers with large aspect ratios inthe polymer matrix. This causes an increase in effective pathlength for diffusion of water vapour and gas into polymermatrix.*Corresponding author: HTfundatihminlioglu@iyte.edu.trT[1] M. D. Sanchez-Garcia ; E. Gimenez ; J. M. Lagaron ,Morphology and Barrier Properties of Nanobiocomposites ofPoly(3-hydroxybutyrate) and Layered Silicates Wiley InterScience2008 , DOI 10.1002/app.27622[2] Reguera, J.; Lagaron, J. M.; Alonso, M.; Reboto, V.; Calvo, B.;Rodriguez-Cabello, J. C. Macromolecules 2003, 36, 8470.[3] Cabedo L.; Plackett D.;Gimenez E.; Lagaron J.M., Studying theDegradation of Polyhydroxybutyrate-covalerate during Processingwith Clay-Based Nanofillers Received 31 March 2008; accepted 22September 2009, DOI 10.1002/app.29945[4] Pralay Maiti, Carl A. Batt, and Emmanuel P. Giannelis, NewBiodegradable Polyhydroxybutyrate/Layered SilicateNanocomposites , Biomacromolecules 2007, 8, 3393-34006th Nanoscience and Nanotechnology Conference, zmir, 2010 734