Biodegradable polymers and their layered silicate nanocomposites: In greening the 21st century materials world

https://www.alice.cnptia.embrapa.br/bitstream/doc/579864/1/PA09005.pdf

Nanocomposites for food packaging applications

Four different types of chitosan-based nanocomposite films were prepared using a solvent-casting method by incorporation with four types of nanoparticles, that is, an unmodified montmorillonite (Na-MMT), an organically modified montmorillonite (Cloisite 30B), a Nano-silver, and a Ag-zeolite (Ag-Ion). X-ray diffraction patterns of the nanocomposite films indicated that a certain degree of intercalation was formed in the nanocomposite films, with the highest intercalation in the Na-MMT-incorporated films followed by films with Cloisite 30B and Ag-Ion. Scanning electron micrographs showed that in all of the nanocomposite films, except the Nano-silver-incorporated one, nanoparticles were dispersed homogeneously throughout the chitosan polymer matrix. Consequently, mechanical and barrier properties of chitosan films were affected through intercalation of nanoparticles, that is, tensile strength increased by 7−16%, whereas water vapor permeability decreased by 25−30% depending on the nanoparticle material teste...

Preparation and characterization of chitosan-based nanocomposite films with antimicrobial activity.

Concerns on environmental waste problems caused by non-biodegradable petrochemical-based plastic packaging materials as well as the consumer's demand for high quality food products has caused an increasing interest in developing biodegradable packaging materials using annually renewable natural biopolymers such as polysaccharides and proteins. Inherent shortcomings of natural polymer-based packaging materials such as low mechanical properties and low water resistance can be recovered by applying a nanocomposite technology. Polymer nanocomposites, especially natural biopolymer-layered silicate nanocomposites, exhibit markedly improved packaging properties due to their nanometer size dispersion. These improvements include increased modulus and strength, decreased gas permeability, and increased water resistance. Additionally, biologically active ingredients can be added to impart the desired functional properties to the resulting packaging materials. Consequently, natural biopolymer-based nanocomposite packaging materials with bio-functional properties have a huge potential for application in the active food packaging industry. In this review, recent advances in the preparation of natural biopolymer-based films and their nanocomposites, and their potential use in packaging applications are addressed.

Natural Biopolymer-Based Nanocomposite Films for Packaging Applications

Novel anticorrosion coatings prepared from polyaniline/graphene composites

Preparation and properties of poly(vinyl alcohol)–clay nanocomposite materials

A series of polymer−clay nanocomposite (PCN) materials that consisted of poly(methyl methacrylate) (PMMA) and layered montmorillonite (MMT) clay were prepared by effectively dispersing the inorganic nanolayers of MMT clay in an organic PMMA matrix via in situ thermal polymerization. Organic methyl methacrylate monomers were first intercalated into the interlayer regions of organophilic clay hosts followed by a typical free radical polymerization. The as-synthesized PCN materials were characterized by infrared spectroscopy, wide-angle powder X-ray diffraction, and transmission electron microscopy. PCN coatings with low clay loading (e.g., 1 wt %) on cold-rolled steel were found much superior in anticorrosion over those of bulk PMMA based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current, and impedance spectroscopy in 5 wt % aqueous NaCl electrolyte. The molecular weights of PMMA extracted from PCN materials and bulk PMMA were determined by gel pe...

Anticorrosively Enhanced PMMA−Clay Nanocomposite Materials with Quaternary Alkylphosphonium Salt as an Intercalating Agent

A series of polymer–clay nanocomposite (PCN) materials that consist of poly(N-vinylcarbazole) (PNVC) and layered montmorillonite (MMT) clay are prepared by effectively dispersing the inorganic nanolayers of MMT in an organic PNVC matrix via in situ photoinitiated polymerization with triarylsulfonium salt as the initiator. Organic NVC monomers are first intercalated into the interlayer regions of the organophilic clay hosts, followed by one-step UV-radiation polymerization. The as-synthesized PCN materials are typically characterized by Fourier transform IR spectroscopy, wide-angle X-ray diffraction, and transmission electron microscopy. The molecular weights of PNVCs extracted from the PCN materials and the bulk PNVC are determined by gel permeation chromatography analysis with tetrahydrofuran as the eluant. The morphological image of the synthesized materials is observed by an optical polarizing microscope. The effects of the material composition on the optical properties and thermal stability of PNVCs and a series of PCN materials (solution and fine powder) are also studied by UV–visible absorption spectra measurements, thermogravimetric analysis, and differential scanning calorimetry, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1904–1912, 2004

Ching-Yi Lin

Papers

Preparation and properties of poly(vinyl alcohol)–clay nanocomposite materials

Anticorrosively Enhanced PMMA−Clay Nanocomposite Materials with Quaternary Alkylphosphonium Salt as an Intercalating Agent

Poly(N-vinylcarbazole)-clay nanocomposite materials prepared by photoinitiated polymerization with triarylsulfonium salt initiator