Hydrophobicity Improvement of Cellulose-Based Material

Abstract

The environmental challenges of plastic pollution and increasingly stringent legislative regulations have directed leading packaging companies to explore more sustainable and eco-friendly packaging materials. As part of these efforts, there has been a significant focus on developing bio-based and biodegradable materials. Among these, cellulose fiber-based materials have emerged as a highly promising alternative due to their renewable nature, biodegradability, and abundant availability. However, the materials are inherently susceptible to water, and to be effectively used as a packaging material they necessitate modifications to enhance their hydrophobic properties.
This degree project investigates the optimization and application of alkenyl succinic anhydride (ASA) emulsion as a sizing treatment to improve the hydrophobicity of cellulose-based material. The study is divided into two phases: the first focuses on characterizing ASA emulsion, and the second assesses the sizing performance of cellulose fiber-based material treated with the ASA emulsion.
In the first phase, nine emulsion samples were prepared using varying shear rates and pH levels. The stability of these emulsions was evaluated through visual assessment, particle size analysis, and zeta potential measurements. Additionally, Nuclear Magnetic Resonance (NMR) spectroscopy was employed to determine the extent of ASA hydrolysis. Results indicated that the most stable emulsion was achieved at a shear rate of 18500 rpm and a pH of 4.
The second phase involved applying the optimized ASA emulsion to cellulose samples and evaluating the sizing performance through the Cobb Test. The experimental trials revealed that the curing step improved water resistance, although the overall Cobb values were higher than those achieved with alkyl ketene dimer (AKD) sizing. Moreover, the infrared spectroscopy method was used to determine chemical variations of ASA after application to the samples. The IR spectra revealed the absence of ester bond formation between ASA and cellulose, correlating with the observed water resistance performance.
Based on the obtained results, the stable emulsion was not an index of the efficacy of ASA as a sizing agent. A stable emulsion was obtained at the high shear rate and acidic pH level; however, such ASA treatment could not provide sufficient sizing. More parameters must be taken into consideration, such as the formulation of the emulsion, as well as cellulose sample processing that could be addressed in future studies. Nevertheless, the sizing evaluation demonstrated the importance of the curing step in the process. Additionally, the findings contribute valuable insights into optimizing ASA emulsion for industrial application, promoting improved hydrophobicity in cellulose-based material.

Popular Abstract

To reduce the negative environmental impact, food packaging companies are increasingly seeking sustainable alternatives to plastics. One promising option is cellulose-based material, which is abundant in nature, biobased and biodegradable. However, a significant challenge is that cellulose easily absorbs water, limiting its use in food packaging applications. This project explores a method called sizing to make cellulose-based material more water-resistant.
Sizing involves applying chemical additives known as sizing agents onto the material to decrease its wettability. The focus of the project is on alkenyl succinic anhydride (ASA). ASA, a highly reactive liquid oil, that must be mixed with water and emulsifier before use. In this system, ASA can react with both cellulose and water. When ASA reacts with cellulose, it protects the material and provides it with water barrier properties. However, if ASA reacts with water, it forms sticky deposits and loses its effectiveness. Therefore, controlling ASA reactivity with water is critical to ensure a proper and successful sizing.
This degree project aims to achieve two main objectives. First, it investigates the stability of the ASA emulsion as a means to evaluate and potentially control its reaction with water. Second, it assesses whether the optimized ASA emulsion can improve the water resistance properties of cellulose material. Consequently, the experimental study of the study is divided into two phases. The first phase focuses on making and analysing ASA emulsions by adjusting pH levels and mixing speeds, and then evaluating their stability through various measurements. The evaluation methods include visual assessment, particle size and zeta potential measurements, and NMR spectroscopy. Results showed that the most stable emulsion was created under acidic conditions and high mixing speeds. The second phase tests how well the treated cellulose resists water. The findings revealed that the treated material had higher water resistance ability comparing to non-treated material. However, when compared with other sizing agent, ASA treated material did not achieve the desired levels of water resistance. Further investigation is required to conclude viability of ASA in the industrial use of food packaging applications.

• author: Auyelbekova, Alina
• supervisor: Daniel Hellström
• organization: Packaging Logistics
• alternative title: Optimizing the Sizing Agent Emulsion
• course: MTTM01 20241
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: alkenyl succinic anhydride, cationic starch, hydrophobicity, emulsion, acidic sizing
• language: English
• id: 9162972
• date added to LUP: 2024-06-19 16:34:51
• date last changed: 2024-06-19 16:34:51