Citation: Gaikwad KK, Ko S (2015) Overview on in Polymer-Nano Clay Composite Paper Coating for Packaging Application. J Material Sci Eng 4: 151. doi:10.4172/2169-0022.1000151
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are also efficient in this respect [41]. Improvement of barrier properties by up to four orders of magnitude upon incorporation of nanoclays in a polymer coating has been reported. The lack of a completely exfoliated structure has been used to explain why an efficient reduction in WVTR could not be observed when montmorillonite clays were dispersed in a barrier latex [42]. The incorporated clay particles can inhibit crystallization of the polymer matrix by restricted chain mobility through the association with the clay plates. This has led to an increase in the tensile strength of starch/polyester blends with increased montmorillonite content. Fischer et al. reported the blend of a thermoplastic starch with clay particles using a modifier (e.g. cat ionized starch) which is compatible with both the clay and the matrix. The results observed were a homogeneous incorporation of clay particles in the starch matrix, followed by an easier processing and a strong decrease in hydrophobicity. The stiffness, strength and toughness of the film could also be changed by changing the water content. Homogeneous dispersion of nanoparticles in nematic crystal matrices of liquid crystalline polymers has also been observed [40]. Nanoclays have been demonstrated to reduce both the water vapor and the OP of PLA and PLA–PCL films. The use of nanosized materials in food packaging should be approached so as to minimize the potential risks with inhalation or ingestion of small particles that can have unhealthy effects on the human body [41]. However, overall migration tests and analysis of specific metals (Fe, Mg and Si) have shown no change in the quantity of these species in food that has been in contact with a potato starch/clay nanocomposite film (Figure 4). Characterization and Test Methods The coated specimens should condition for 24 h at 23 q C and 50% relative humidity before any measurements, this is as per ISO standards. Scanning electron micrographs (SEM) SEM of the surfaces of the samples is obtain with a Digital Scanning Electron Microscope. X-ray diffraction (XRD) is employ to estimate the degree of orientation of the clay particles in the polymer film. The measurements should perform in the cross-direction of the coating. Electron spectroscopy for chemical analysis (ESCA) is use to assess the chemical composition of the surface of the coatings on paper. Water vapor transmission rate , WVTR, is measure using gravimetric cups according to TAPPI method T 448 om-97. Silica gel, 35 ± 0.1 g in each cup, as the desiccant WVTR g/ (m 2 day −1 ) is calculate
by dividing the slope of total weight and number of days by the sample area. All samples need conditioning as per ISO conditions for at least 24 H prior to measurements. OTR: Oxygen transmission measurements is perform with Oxygen Permation Analyser The tests were carried out at 23°C and 0, 50, and 80% relative humidity as per ISO standards Water contact angle: Water contact angles of the coated surface is measure in test conditions of 23°C and 50% relative humidity. Contact angle values is measure as a function of time. Cobb test: This is important test to determine the water resistant properties of paper. This test can be done by Cobb tester. Conclusions Polymer-nano clay is good choice in the development of new functionality of paper by coating. While there is still further research needed to reach the requirements set on all types of functional properties as well as on material availability, process ability, suitability for product contact, etc., the remaining hindrance to be overcome is, in most cases, the cost. Although the price for materials and processing will increase with increased modification of polymers and clay. Reduction of the final price for each package should be achievable by increased volume of production. However, there exists no universal barrier chemical that covers all potential applications and still fulfil is all possible requirements. Future functional surface treatment of Paper will most likely involve multilayer coatings where each single layer makes its own specific, property-based contribution with its specific properties to the overall performance of the coated products. Replacing one or more barrier layers consisting of plastic film in demanding packaging especially with bio-based polymers. References 1. Cynthia C (2011) Paper coatings opportunities abound. C&I Magazine. 2. *XJJHQKHLP60DUWLQ57 'H¿QLWLRQR f clay and clay mineral: Joint Report of the AIPEA nomenclature and CMS nomenclature committee’s. Clay minerals 43: 255-256. 3. Priolo MA (2013) Precisely Tuning the Clay Spacing in Nanobrick Wall Gas Barrier Thin Films. Chem. Mater 25: 1649-1655. 4. Lehtinen E (2000) Pigment Coating and Surface Sizing of Paper. (1 st ed) Fapet Oy, Helsinki. 5. Hagemayer R (1997) Pigments for Paper. Tappi Press, Atlanta. 6. Alexandre M, Dubois P (2000) Polymer-layered silicate nanocomposites: Preparation, properties and uses of a new class of materials. Mater. Sci. Eng 28: 1-63. 7. Giannelis EP (2003) Polymer layered silicate nanocomposites. Advanced Material 8: 1539-1641. 8. Sinha Ray S, Okamoto M (2003) Polymer/layered silicate nanocomposites: A review from preparation to processing. Progress in Polymer Science 28: 1539- 1641. 9. Kawasumi M (2004) The discovery of polymer-clay hybrids. Journal of Polymer Science Part A: Polymer Chemistry 42: 819- 824 10. Gullichsen J (2000) Pigment coating and surface sizing of paper. Paper Making Science and Technology, Fapet/Tappi Series. 11.Rissa K (2000) Coating and paper structure Orientation of talc particles in dispersion coatings. Nord. Pulp Pap. Res. J 15: 357 12.Rissa K, Vaha-Nissi M, Lepisto T, Savolainen A (2002) Top layer coatability on barrier coatings. Paperi Puu 84 :467. 13.Andersson C, Ernstsson M, Jarnstrom L (2002) Barrier properties and heat sealability/failure mechanisms of dispersion-coated paperboard .Packag. Technol. Sci 15: 209-224.
Microcomposite
Intercalated nanocomposite
Polymer
Exfoliated nanocomposite
Layered silicate
Figure 4: Dispersion of nanoclayina polymer matrix.
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