Graduate Thesis Or Dissertation
 

Investigation of Eco-friendly, Bio-based Methods to Produce High Quality and Water-resistant Apple Pomace Biocomposites Using Molded Pulp Technology

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/3n2046333

Descriptions

Attribute NameValues
Creator
Abstract
  • The overall goal of this study was to utilize apple pomace, the byproduct from juice processing, as a renewable source of fiber to create sustainable packaging using molded pulp technology. The goal was accomplished through two studies: 1) to modify apple pomace fibers for increasing relative cellulose composition and improving compatibility with recycled newspaper fibers that are conventionally used in molded pulp packaging, and 2) to improve water resistance of the apple pomace based molded pulp biocomposites (boards). First, chemical treatments of apple pomace were studied to eliminate hydrophilic cell wall materials (hemicellulose and pectin) for increasing apple pomace fiber cellulose ratio and compatibility with newspaper fibers, thus enhancing overall properties of apple pomace based board. A completely randomized experimental design was applied to compare traditional (hydrochloric acid, sodium hydroxide, or step-wise process of both) and eco-friendly (citric acid, sodium bicarbonate, or step-wise process of both) treatments based on their effect on composition and water retention value of apple pomace fibers, and mechanical properties of produced molded pulp boards. For preparing the board, newspaper fibers were utilized as a reinforcing agent at a 2:1 ratio of apple pomace to newspaper fiber with incorporation of glycerol (0.15% w/w of fibers) to enhance flexibility of the board. It was found that citric acid was a superior chemical treatment based on eco-friendly status and ability to significantly (P < 0.05) decrease extractives from apple pomace and improve board flexural strength compared to the control (untreated apple pomace). A Taguchi design was further employed to determine the most influential factors in respect to citric acid treatment and use of cellulose nanofiber (CNF) on produced board properties, including pH (2, 2.5, 3) and temperature (75, 85, 95 ºC) of citric treatment, and CNF incorporation (0, 0.15%, and 0.3%). It was found that pH (2.5, 3) and CNF addition (0.15% and 0.3%) were the most impactful conditions, which were then optimized using a 2x2 factorial design at treatment temperature of 75 ºC. The optimum treatment conditions were identified as: citric acid treatment at 75 ºC and pH 2.5 and CNF concentration of 0.15% based on dimensional stability and mechanical properties of the board. Scanning electron microscope analysis demonstrated clean fiber morphology (indicating removal of extractives) and minimal voids in the boards (indicating increased fiber interactions) as the result of citric acid treatment. Additionally, thermal analysis validated the increase in cellulose content, crystallinity, and thermal stability of treated apple pomace fibers compared to control. This study provides a foundation for utilizing eco-friendly treatments to improve apple pomace fiber quality and functionality of produced board, which could be expanded to other byproducts for creating sustainable molded pulp packaging. The second study produced practical solutions to improve water resistance of apple pomace based molded pulp board via formulation modifications and superhydrophobic coating application. Cardboard fibers were introduced into this study as a reinforcement agent owning to rising production of cardboard boxes following the COVID-19 pandemic. Rhubarb pomace was used together with apple pomace considering its high lignin content for improving water resistance of produced board. First, composition, morphology, and water retention value of rhubarb pomace, apple pomace, cardboard, and newspaper fibers were investigated since these properties directly affect the water retention value of the pulp and board properties. Control board was produced based upon 2:1 ratio of apple pomace to cardboard fibers. Secondly, response surface methodology was utilized to identify optimum formulation of apple pomace based board considering three input factors, including rhubarb pomace (15-40% w/w, dry basis), chitosan (5-13% w/w, dry basis), and glycerol (1.3-5% w/v, wet basis) considering their water resistant properties. The optimum formulation was identified as: 2:1 ratio of apple pomace to cardboard fiber at a 3% solid content of pulp, and incorporation of 26.9% w/w of rhubarb pomace, 0.039% w/v of glycerol, and 15.7% w/w of chitosan in the pulp. The optimized board showed significant increase in water contact angle (85.3 °) and decrease in water absorption (166.5%) compared to 19.2 ° and 275.7% for the control board, respectively. A one-step, bio-based coating (5:2 ratio of precipitated calcium carbonate to beeswax) was applied on the surface of board to create nanostructure and low energy surface for achieving superhydrophobic sliding angle of 6.38 ° and hydrophobic contact angle of 137.9 °. Compostability study using soil burial test reported that the control board degraded within 40 days in soil and the optimized board degraded over 80% within 60 days. This study provided new insights on the principles of using fruit pomace as alternative fiber substitution and developed effective approaches to improve water resistance of pomace based molded pulp packaging, which could be applied to a wide variety of cellulose based packaging applications, especially for liquid foods and at humid environment.
License
Resource Type
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Rights Statement
Publisher
Peer Reviewed
Language

Relationships

Parents:

This work has no parents.

In Collection:

Items

Thumbnail Title Date Uploaded Visibility Actions
file details LangClaraV2021.pdf 2021-12-09 Public Download