DEVELOPMENT OF FOODSERVICE PAPERBOARDS WITH ENHANCED GREASEPROOF PROPERTY USING CELLULOSE NANOMATERIALS

The overall goal of this research is to develop cost-effective foodservice paper products with greaseproof coating for enhanced functionality and recyclability. Three specific objectives are proposed below. (1) Develop a functional coating system which provides a film possesing greaseproof property using eco-friendly and renewable cellulose nanomaterials. Specifically, we will use two types of cellulose nanomateirals most commonly researched for making films: nanofibrillated cellulose (NFC) and cellulose nanocrystal (CNC) (Hubbe et al. 2017). NFC is commonly obtained through mechanical methods, such as extensive refining, homogenizing, and grinding of pulp fibers to decrease the fiber size to nanoscale. During this process, many fine particles are generated and also large size fibers are still exist during the processing (Peng et al. 2012). The fibril shape of NFC make it relatively flexible (Aulin et al. 2010; Belbekhouche et al. 2011; Hubbe et al. 2017). CNC is generated through chemical digestion of the amorphous regions of cellulose fibers and microcrystalline cellulose is a common feedstock. The obtained CNC is a stiff fiber in a needle shape (Moon et al. 2011; Bras et al. 2011; Peng et al. 2012, Nelson et al. 2016). There are important structural differences between NFC and CNC. CNC was reported to have crystallinity of 85% (Aulin et al. 2009; Czaja et al. 2004) while the crystallinity of NFC was around 60-70% (Aulin et al. 2009). CNC has much smaller fiber length than NFC (Siró and Plackett 2010; Nelson et al. 2016; Hubbe et al. 2017). The film formation of the two nanoscale cellulose fibers will be studied in detail in this research and the greaseproof properties of the films formed from them will be characterized. The potential of using the combination of the two cellulose nanomaterials will also be explored with regard to the film formation process and the film structure and properties. The objective is to use these renewable and eco-friendly nanomatierials to develop a functional film providing health-promoting foodservice packaging and benefiting the environment. (2) Apply the functional coating system developed in objective (1) on paper substrate at a laboratory scale using available industrial paper coating mechanisms. Under this objective, we will focus on the paper substrate of solid bleached board (SBB). SBB is made exclusively from several layers of bleached chemical pulp and usually has a mineral pigment-coated top surface for excellent surface and printing characteristics (Kirwan 2013). The back surface is also coated for some grades. The most common applications of SBB in foodservice segment are fast food packaging, such as paper trays for french fries, hot-dog, burgers, and other fried foods. Inside of the SBB will be contacting with food which could be the bleached chemical pulp layer or mineral pigment-coated surface. The commercial grade of SBB will be used in this study as the substrate. Mineral pigment-coating has been applied on paper substrate very successfully for a long time to obtain good printing quality (Lehtinen 2000). Appropriate technologies from pigment-coating, including formulation development techniques and coating application skills, will be adopted to deposit the developed coating layer from the objective (1) on SBB. The goal in this section is to make sure the functionalities of the coating developed in objective (1) will be directly transferred to the top of SBB substrate. Addtionally, mechanical performance of the coated SBB, including tensile, compression, bending, foldability, creasing, and embossing will be evaluated to check the flexibility of the coating layer. (3) Evaluate the recyclability of coated paper product. Foodservice packaging recycling is always a challenging topic due to the contamination of food residues, inks, grease or oil, and others (Geueke et al. 2018). For this objective, the recycling behaviors of the coated SBB will be comprehensively characterized using the conventional paper recycling technologies.