Title: Effects of nanoclay type on the physical and antimicrobial properties of PVOH-based nanocomposite films Authors
|Liu, Guichao -|
|Song, Ye -|
|Wang, Jiamei -|
|Ma, Lei -|
|Li, Can -|
|Liu, Yao -|
|Zhang, Jianhao -|
Submitted to: LWT - Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 2014
Publication Date: N/A
Interpretive Summary: Growth of environmental concerns over non-biodegradable plastic packaging materials has raised interests in the application of biodegradable alternatives. Polyvinyl alcohols (PVOH) are synthetic polymers that are extensively applied in a wide range of industrial since the early 1930s because of its biodegradability. However, some of its properties, such as mechanical property, thermal characteristics, and water vapor permeability, need to be improved for food packaging applications. Nanoclays are, derived from montmorillonite, a mineral deposit that has layered structure of dimension around 1 nm thick and a specific surface area of 700-800 m2/g13. Nanoclays are currently being used to improve modulus and tensile strength, barrier properties, flame resistance, and thermal properties of many plastics. The objective of this study was to investigate effects of different types of nanoclay on properties of PVOH-based films. Results showed that the effects of nanoclays on properties of PVOH films, such as transmittance, tensile strength, elongation at break, water solubility, swelling ratio, water vapor uptake ratio, and water vapor permeability, varied with nanoclay type. Hydrophilic nanoclays were more compatible with PVOH than hydrophobic nanoclays and the nanoclays made of quaternary ammonium salt provided PVOH with antimicrobial activity. These results demonstrate that nanoclays can significantly change physical and antimicrobial properties of PVOH films.
Technical Abstract: Polyvinyl alcohols-based nanocomposite films were fabricated with four types of montmorillonite (MMT) nanoclay, including 18-amino stearic acid (I.24TL), methyl, bis hydroxyethyl, octadecyl ammonium (I.34TCN), di-methyl, di-hydrogenated tallow ammonium/siloxane (I.44PSS) organically modified MMT, and a natural MMT (Na+-MMT by using a solution-intercalation, film-casting method. Effects of the nanoclays were evaluated on physical properties [including transmittance, tensile strength (TS), elongation at break (E), water solubility (WS), swelling ratio (SR), water vapor uptake ratio (WVUR), and water vapor permeability (WVP)] and antimicrobial activity of the polyvinyl alcohols-based films. Transmittance, WS, SR, WVUR, WVP of the nanocomposite films were significantly reduced by nano-composition compared to a pure polyvinyl alcohols film. The WVP decreased by 11.8%-20.7%, and WS, SR and WVUR decreased by 19.9%-41.8%, 9.1%-26.4%, and 4.8%-12.8%, respectively. The extent of changes was dependent on nanoclay type. X-ray diffraction patterns revealed that intercalation was formed in nanocomposite films. Overall among all the tested nanoclays, Na+-MMT showed more impact on physical properties of polyvinyl alcohols films, and the polyvinyl alcohols film compounded with quaternary ammonium group displayed remarkable antimicrobial activity against Gram-positive bacteria.