Preparation and investigation of mechanical and antibacterial properties of poly(ethylene terephthalate)/chitosan blend Mahmood Masoomi, * Masoud Tavangar and Seyed Mohammad Reza Razavi The aim of this work was to evaluate the anti-bacterial and mechanical properties of chitosan based solvent-cast blends with synthetic poly(ethylene terephthalate) (PET). The amount of chitosan loading was varied from 1% to 9% (w/w). Chitosan and PET were homogeneously dissolved in a ternary solvent system with different mass ratios in a trifluoroacetic acid, chloroform, and acetic acid solution and processed into uniform films. Molecular interactions between chitosan and PET were investigated using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy. Morphology and tensile properties of these blend films were investigated. The antibacterial activity of the samples was evaluated utilizing the colony forming unit method against three typical human pathogenic microorganisms, Escherichia coli, Klebsiella pneumonia, and Staphylococcus aureus. The results indicated that the PET/chitosan films showed a significantly higher growth inhibition rate compared with the PET film. Chitosan release from a wide range of blends was studied using the ninhydrin method. The release tests revealed that dissolution of the biocide glucosamine groups, i.e. the chitosan water soluble fractions, also increased with the increase in the amount of chitosan content. Results obtained from ATR-FTIR spectra suggested that there exist pronounced interactions that probably resulted from hydrogen bond formation between different components. SEM micrographs showed that the compatibility of the two polymers was reduced when the fraction of chitosan was increased. Tensile strength and elongation at break of the blends reduced with the increase in chitosan content. These results indicated that the blends became brittle upon increasing the chitosan content. 1. Introduction Recent studies have focused on the development of antibacte- rial surfaces and bulk to attain high functionality and high value products. 1,2 Since microbial contamination of foods occurs primarily at the surface, direct applications of antibac- terial substances onto foods have limited benets as they could be neutralized upon direct contact or diffuse rapidly from the surface into the food mass. 3 The use of packaging or coating lms containing antimicrobial agents could be more efficient by slow migration of the bactericidal agents from the carrier lm structure to the food surface, maintaining a high concen- tration where it is needed. 4 As the release occurs during a continuous period, the antimicrobial action can also be main- tained during the transport and storage period of the product. 5 In this sense, chitosan (CS) is a linear cationic natural poly- saccharide composed of randomly distributed b-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). It is derived from chitin, the second most abundant polysaccharide on earth aer cellulose. 6–9 Chitin is one of the most abundant natural biopolymer derived from exoskeletons of crustaceans. It can be also obtained from cell walls of fungi which becomes a basis for biotechnological production of this material. Chitosan is a product derived from N-deacetylation of chitin in the presence of hot alkali. The degree of deacetylation and the degree of polymerization (DP), which in turn decides molecular weight of polymer, are two important parameters dictating the use of chitosan in many applications, in pharmaceutical, cosmetics, biomedical, biotechnological, agricultural, food, and non food industries as well (water treatment, paper, and textile). 10 Excellent properties such as non-toxicity, 11,12 biocompatibility, 13,14 antimicrobial properties, 5,15–20 biodegradability and bioactivity mean that CS is widely used in biomedical elds. 5,21 This biopolymer is mostly available from waste products in the shellsh industry, and therefore, abundant commercial supplies are currently offered. It can also be obtained from the chitin component of fungal cell walls. Several studies have already demonstrated the antibac- terial and antifungal action of this compound for both bioactive preservative and bioactive packaging applications. 22–24 On the other hand, many efforts have been tried to produce new bio functional materials from chitosan in non-woven fabric, Department of Chemical Engineering (Polymer group), Isfahan University of Technology, Isfahan 84156-83111, Iran. E-mail: mmasoomi@cc.iut.ac.ir; Fax: +98- 31-33912677; Tel: +98-313-3915646 Cite this: RSC Adv. , 2015, 5, 79200 Received 9th April 2015 Accepted 4th September 2015 DOI: 10.1039/c5ra06372h www.rsc.org/advances 79200 | RSC Adv. , 2015, 5, 79200–79206 This journal is © The Royal Society of Chemistry 2015 RSC Advances PAPER