Recipient Organization
AUBURN UNIVERSITY
108 M. WHITE SMITH HALL
AUBURN,AL 36849
Performing Department
School of Forestry and Wildlife Sciences
Non Technical Summary
The proposed research is to prompt health of individuals, families, and our communities,through developing a cost-effective, health-promoting, and eco-friendly food service paper packaging product possessing enhanced greaseproof property and recyclability.There are four categories of greaseproof paper products on the market: (1) vegetable parchment, (2) greaseproof paper and glassine, (3) polymer coated paper and paperboard, and (4) fluorochemical treated paper and paperboard. Each category has their own limitations. Vegetable parchment and polymer coated paper and paperboard are not recyclable using conventional paper technology. Greaseproof paper and glassine have a high cost to produce. Fluorochemical treated paper and paperboard cause a safety concern to the consumers. Development of an economically viable, health-promoting, and eco-friendly food service packaging life cycle that prevents the contamination of greases or oils in food service packaging is an urgent need. This study is to develop a coating system for paper and paperboard that delivers greaseproof property. Cellulose nanomaterials will be used to form a solid layer on paper surface, blocking the penetration of oil or grease into the paper structure.The proposed research includes three specific objectives. Firstly, a greaseproof film mainly consists of cellulose nanomaterials will be developed. Two cellulose nanomateirlas will be studied: nanofibrillated cellulose (NFC), and cellulose nanocrystal (CNC). The film thickness, flexibility, and greaseproof properties will be balanced through formulation designs. The relationship between cellulose nanomaterial film formation and greaseproof property of the film will be reported. Secondly, the film developed in the step one will be coated on a paper surface. The same greaseproof property will be delivered to the paper surface. The coating thickness and performance on paper surface will be optimized depending on paper and paperboard grades. Thirdly, the recyclability of coated paper and paperboard will be characterized using conventional paper technology. The recyclability of post-consumer food service paper packaging with the same coating developed in this study will also be evaluated. A critical outcome of this work will be the cellulose nanomaterial coated paper and paperboard performance regarding mechanical and greaseproof properties. A detailed examination of the film formation mechanism from cellulose nanomaterial suspensions will be provided. The recyclability of the coated paper and paperboard for food service packaging applications will be critical for promoting health and eco-friendliness of this product developed in this proposal. The greaseproof paper product meets the demand of sustainability claim of the food service packaging industry and promote the rural health, including the health of individuals, families, and our communities.
Animal Health Component
20%
Research Effort Categories
Basic
50%
Applied
20%
Developmental
30%
Goals / Objectives
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.
Project Methods
The method proposed for the three specific objectives are describe in below. (1) Develop a functional coating system which provides a film possesing greaseproof property using eco-friendly and renewable cellulose nanomaterials. We will start by developing a monolayer film on a non-porous substrate as a phase one study. The main objective of the phase one study is to characterize the film surface morphology and greaseproof property. The film will be casted from the aqueous suspensions of cellulose nanomaterials. Three different aqueous suspensions will be studied: NFC, CNC, and NFC + CNC. During film formation process, the effect of different film drying rate controlled at different temperatures in an oven and different suspension pH values on film formation will be investigated.The film performance of greaseproof property will be characterized by the standard TAPPI method T559 cm-12 (kit test) and contact angle analysis. Other properties of the films, including oxygen and moisture barrier properties will also be evaluated. In this study, the suspension viscosities will be controlled to be at the same level for all samples to do the film casting experiments. To minimize the effect of film thickness on the greaseproof property, relatively thick films are designed to be formed at this phase.The phase two study will be investigating the effect of plasticizer and binder on the film properties formed from cellulose nanomaterial suspensions. From the phase one, we may select one or two suspensions from which the best greaseproof property films have been formed. Based on the selected suspension(s), different plasticizers, including starch and glycerol will be added, respectively. The main functionality of the plasticizer is to increase the flexibility of the film which in turn helps the paper packaging converting process, like creasing and foldability in folding cartons. Starch and glycerol are common plasticizer used in coatings and have been found to be able to increase the flexibility of biobased films. The film formed with plasticizer will be deposited on a high-density polyethylene plate and then will be peeled off for qualitative assessment on foldability. Additional dynamic mechanical analysis (DMA) measurement in tension mode will be conducted on the thin film for quantitative evaluation. The other part formulated into the cellulose nanomaterial suspension will be the binder which functions as a glue to bind the nanoscale cellulose fibers to the paper substrate and to each other, closing the pores on the surface. In this case, the binder of polyvinyl alcohol (PVOH) will be studied and the optimum amount of PVOH in the formulation will be reported. The effect of the plasticizer and binder on the film greaseproof property will be researched. We will finalize the formulation for the film possessing greaseproof properties after the phase two study.The last phase study is to understand the relationship between the film thickness and the cellulose nanomaterial suspension characteristics, including viscosity and concentration. A dip-coating process will be employed to deposit the film from the suspension on a non-porous substrate. Then the sample will be dried at the selected drying conditions to constant weight. The thickness of the obtained film will be characterized. Different dip-coating withdrawal speeds will be used to study this relationship between film thickness and suspension properties. The film surface morphologies and greaseproof property at different thicknesses will be evaluated. This information will be crucial for the next section to develop coating layers on paper substrate.(2) Apply the functional coating system developed in objective (1) on paper substrate at a laboratory scale using available industrial paper coating mechanisms. Deposition of the film developed in objective one on SBB will be managed in three different routes. The first route is to coat three times the same film using the same suspension selected from the objective one study. After each coating SBB will be dried through a laboratory sheet dryer.The second route is to develop a three-layer film on the paper substrate. This is to simulate the paperboard coating process with triple coating of precoating, middle coating, and top-coating. The method proposed here is to develop the three coating layers consisting of cellulose fibers. Cellulose fibers at different size scales will be generated using microfluidizer with sulfite pulps as the raw materials. Precoating layer will have the largest particle size cellulose fibers, followed by the middle layer coating. The top-coating will be nanoscale cellulose fiber based coating developed in the objective one study. Precoating layer will be designed to fill inconsistencies and roughness of the base paper substrate. The middle coating layer provides a base sheet for the final topcoating layer and provide the surface properties for holding the topcoating. The same binder system (PVOH) developed in objective one will be used. The coating weight will be controlled in the range of 20 - 25 g/m2 for good coating layer quality.The third route is to deposit the film developed in the objective one study on top of pigment coated SBB. The pigment coating is very-well studied system and is commonly used in the graphic industry. Kaolin and calcium carbonate will be used as the main component for precoating and middle coating of the pigment coating layers. The binder of PVOH will be used here.The coating deposition will be applied to SBB using a laboratory-scale curtain coating process. The coating process will be optimized through controlling the rheology of the coating formulations and other curtain coating factors. After coating, the effect of drying on the coating layer properties be investigated. The coating layer structure will be studied using microscopy. The coated paperboard will be tested on surface morphologies, greaseproof property, mechanical properties, cutting, and creasing. The option(s) giving the best greaseproof and mechanical performance will be determined.(3) Evaluate the recyclability of coated paper product. One important indicator of inferior performance of foodservice paperboard in recycling is that the paper made from recycled fibers from the food service paperboard has much lower mechanical properties, such as lower properties in tensile, tearing, burst, etc. There are two steps to investigate the recyclability of the coated SBB using the conventional paper recycling method. The first step is to characterize the repulpability of the coated SBB. A laboratory-scale pulper will be used. The pulping process of the coated and uncoated SBB will be compared in parallel. The fiber yield and the mechanical properties (tensile, tearing, and burst) of the handsheets made from the recycled SBB fibers will be measured. The effect of cellulose nanomaterial coating on the yield and mechanical properties will be reported.The second step is to check the recyclability of SBB with the coating under conventional paperboard recycling stream when the coated SBB exposes to foodservice environment. The exposure to oil or grease is the main concern for this study. The SBB contacting with grease or oil will be simulated to the real-life situation in which the SBB will be contacting with fast food and pizza. SBB without cellulose nanomaterial coating will be used as a control sample. The recycled fibers will then be used to make handsheets and the mechanical properties, including tensile, tearing, and burst of the handsheets will be characterized. The effect of the coating layer on the recyclability of the SBB will be assessed through evaluating mechanical properties of the handsheets made from the recycled SBB fibers. The recyclability of the coated and uncoated SSBB will be reported.