Structural, thermal and antibacterial properties of polyamide 11/polymeric biocide polyhexamethylene guanidine dodecylbenzenesulfonate composites

Antimicrobial polyamide 11 (PA-11) films containing low-cost, thermally stable and water resistant polymeric biocide polyhexamethylene guanidine dodecylbenzenesulfonate (PHMG-DBS) have been obtained by compression moulding. The structure of the modified PA-11 films containing from 3 to 10 wt% of PHMG-DBS was characterized using Raman and FTIR spectroscopy and atomic force microscopy (AFM). The surface properties were evaluated both by contact angle and contactless inductive method. The introduction of PHMG-DBS into PA-11 films was found to increase positive surface charge density to 5.5.10(-11) C/cm(2) for 10 wt% of PHMG-DBS. Antibacterial activity of PA-11/PHMG-DBS films against both Gram-positive (Escherichia coli) and Gram-negative (Bacillus subtilis) bacteria was demonstrated for films containing from 5 to 7 wt% of polymeric biocide. According to thermal investigations data, PA-11/PHMG-DBS composite has excellent thermal stability to at least 390 degrees C both in air and in argon atmosphere which indicates on its availability for the melt processing by common methods. It has also been found that polymeric biocide is highly resistant to leaching from PA-11 film.