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Subject: search.filters.subject.401610 Timber, pulp and paper

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    Development of a process to convert paper towel fibre waste destined for landfill into viable construction materials : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Chemical and Bioprocess Engineering at Massey University, Palmerston North, New Zealand. EMBARGOED until 18th March 2026.
    (Massey University, 2023) Payne, Caleb
    This thesis covers the continued development of a Precycle NZ product made from paper towel waste fibre. The initial product by Precycle NZ was a rigid board made from paper towels destined for landfill, with the idea of using it as a building product. This Master’s project covered the development of this board, which included the literature review where manufacturing methods, similar products, and standards and certifications like the Building Code were researched. Development was done on the manufacturing methods outlined by Precycle NZ through fine-tuning, optimising, and trialling adhesives from the literature. This development resulted in various panels, such as starch glue panels, casein panels, and regular panels of different sizes, before filtering some out based on structural failings internally, while others continued for testing. The tests included measuring the moisture content and observing the mould growth under different humidity, which was important to the Building Code’s internal moisture requirements, its insulative properties, which was vital as it had the potential to be used as an insulative panel, and mechanical properties where the compressive strength, bending strength, and impact resistance were tested, as structure and durability were outlined in the Building Code. The testing found that the tapioca starch glue–pulp panel was the best overall compared to the other manufactured pulp panels. However, this was not durable enough to justify using this as a structural panel compared to industry standards. It was found to have good insulative properties, though insufficient to replace industry insulation products or meet roof insulation requirements, and comparable mould growth to wood products like MDF. The panel should be considered non-load-bearing for future development and placement but can be paired with a load-bearing material. It can provide insulative properties as part of a prefabricated wall system and be converted into alternative uses like furniture or some other use case. Future development should cover other tests that still need to be performed, such as acoustic testing and breathability, to determine airflow. This will also involve scaling to larger panels by determining their cost-effectiveness and researching new manufacturing methods before scaling to a pilot plant.
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    Acoustic non-destructive testing for wood : a thesis by publications presented in fulfillment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Albany, New Zealand
    (Massey University, 2023) Abu Bakar, Adli Hasan Bin
    The ability to measure the stiffness of wood is important as it can be used to determine the optimal usage of the timber sample to maximise profitability and increase sustainability. The stiffness of trees and logs is measured in order to segregate them into different grades. Stiffness measurements are also made on juvenile trees and seedlings for breeding trials to improve the stiffness quality of future plantations. The traditional static bending test is considered the gold standard for measuring the stiffness of wood. However, this method is destructive, costly and difficult to use. Non-destructive testing (NDT) techniques have therefore been developed to mitigate these issues. Acoustics is the most common NDT technique used to measure wood stiffness. The time-of-flight method is the only acoustic method which can be used on standing trees. However, literature has shown that stiffness measurements obtained using the time-of-flight method can have a significant overestimation. Studies have reported the potential causes of this overestimation but the exact cause is still not known. In recent years, NDT techniques such as guided wave techniques have been developed for other industries. Guided wave testing is extensively used on metallic structures such as pipes and bars. However, there have been very few studies that utilize guided waves for wood. This thesis investigates the use of guided wave knowledge to identify the cause of the overestimation and to obtain improved NDT measurements. This thesis contains some of the first reported works to perform guided wave measurements on cylindrical wood samples. The results from guided wave experiments show that enhancement and suppression of desired wave modes can be achieved using a ring array of shear transducers. The effects of dispersion on ToF measurements are investigated and it was found that dispersion can be a potential cause of overestimation. Guided wave techniques were developed to obtain acoustic velocity and stiffness measurements for wood. The measurements were compared with the traditional resonance, ToF and static bending methods and improved measurements were obtained. More work can be done to further develop guided wave tools and techniques to be used in the wood industry.