Polymer Bulk Functionalization by Cold Plasma Treatment
Recycling polymeric materials has many challenges, and some of those we hope to solve include food-contaminated plastics, mixed plastics, and hard-to-recycle plastics. Through a novel plasma treatment process, we seek to modify the chemical structure of these types of polymeric waste to allow the production of high-performance polymer blends, creating new recycling paths and reducing the amount of plastics that end up in landfills. We are currently developing a plasma-enhanced polymer bulk functionalization, where an atmospheric pressure plasma jet will be applied to a continuous reactive extrusion process, enabling the production of graft copolymers and compatibilization of polymeric blends. Preliminary experiments already revealed the possibility of controlling the polymer’s viscosity by creating a semi-crosslinked network, indicating the plasma effectiveness in generating radicals in the polymeric chain, thus opening the possibility for plasma-enhanced melt grafting processes, which is another significant step in this project.
Academic leader: Prof. Johan Verbeek
Plasma enhanced carbon fibre reinforced thermoplastic
Today, we agree that natural, human, social and financial capital must be considered in manufacturing for a more sustainable future. For this reason, raw material cost remains important, but other metrics, such as embodied energy, are becoming widely used. Manufacturing composites from low embodied energy waste thermoplastics is becoming more attractive, but blended or contaminated waste introduces manufacturing challenges. In some cases, the strong fibres can bond well to a single type of thermoplastic but adhere poorly to others. To address the bonding issue, we study surface modification processes which improve the compatibility of blended waste polymers and reinforcing fibres. Our research efforts have shown that the interface bond strength of carbon fibre to nylon and polypropylene is enhanced after continuous plasma treatment. We aim to integrate the in-line surface treatment to produce carbon fibre prepreg with a waste thermoplastic matrix.
Academic leader: Prof. Simon Bickerton
Novel Recycling Methods to Allow Silicone Product Stewardship in Aotearoa
While the world has made great progress with technical solutions towards grappling the plastics and polymer crisis, silicones remain a polymer with no industry-proven recycling techniques. Several chemical and mechanical strategies show promise in degrading both elastomers and oils, but further work is required to promote circularity in the area. This project aims to demonstrate successful degradation of silicone elastomers and regeneration of similar products from the resulting residues. We have investigated several chemical and mechanochemical degradation routes, and selected a facile and low-cost hydrolysis method that has demonstrated great utility for degradation of both oils and elastomers into volatile siloxanes and lower molecular weight oligomers/polymers. The objective of this project is to optimize this technique, minimise solvent and energy use, as well as tailor the product mixture towards useful precursors for elastomer production.
Academic leader: Prof. Johan Verbeek
Chicken feathers to the rescue of polypropylene composites under fire
The practical use of waste materials as an economically viable waste management alternative has been emphasised by research into the influence of treated chicken feathers as flame retarding and reinforcing adjuvants for polypropylene composites. Objectively quantifying the sustainability of treating chicken feathers reinforced polypropylene composites mechanically, while exhibiting acceptable flame retardancy characteristics compared to their commercial counterparts. Using chicken feathers from poultry waste in polymeric composites makes sense as a cost-effective substitute for pricy phosphorous-flame retardant additives like ammonium polyphosphate. A costly waste management solution is avoided thanks to the conversion of feathers into a high-value product as flame-retardant bio-filler.
Academic leaders: Dist. Prof. Debes Bhattacharyya and Dr. Nam Kyeun Kim
Effects of Extracellular Biopolymers from Wastewater Activated Sludge on Flammability Characteristics of Composites
The activated sludge process is an outstanding method for wastewater treatment (WWTPs) and has been used for 74% of the total serviced population in New Zealand. The amount of activated sludge (AS) from this process is an environmental threat due to its complex structure. Extracellular polymeric substances (EPS), a polymer matrix with high protein and polysaccharide contents, could be recovered from AS. Many applications of EPS have developed, but the correlation of EPS components with its properties has not been fully reported yet, especially flammability. In this study, EPS is extracted from AS by different methods to optimize the flammability of EPS. The correlations of the EPS component and its fire performance are also explored. As a result, the EPS-based composites are fabricated for flame retardant application. The study could be the prime for processing AS in WWTPs and increasing the value of AS following the circular economy concept.
Academic leader: Dr. Nam Kyeun Kim
Impacts of Stitching Pattern on Fibre Alignment and Compression Performance of Stitched Glass Fabric Composites
Stitched glass fabrics are widely used to manufacture a variety of different components and products. The stitching is used to hold the glass tows in alignment to for manufacturing, but may also produce undesirable fibre misalignment. This misalignment can detrimentally affect the mechanical performance, especially in compression. This project aims to investigate the influence of the choice of stitching pattern on the fibre misalignment, and then on the compression strength and stiffness of composite materials manufactured form these fabrics. Automated image analysis techniques have been developed to measure fibre alignment in photographs of stitched fabrics, which have been compared to predictions of fibre alignment from sub-tow-scale numerical models. Both methods suggest that common tricot or tricot-chain mixed stitching patterns tend to produce greater fibre misalignment than a straight chain pattern. Future static and cyclic compression testing will investigate how the observed fibre alignment may impact the final composite compression behaviour.
Academic leader: Assoc. Prof. Mark Battley
Effects of printing-induced defects on mechanical response of polymeric lattices
Due to their multi-functional characteristics, including lightweight design, load-bearing capacity, energy absorption, impact mitigation, heat exchange, and fluid transfer capabilities, lattice structures have gained considerable research interest. However, these structures which are crafted through additive manufacturing technologies are not free of imperfection and these manufacturing processes often yield products with disparities when compared to their design specifications. In our study we investigate the impact of additive manufacturing induced defects (i.e. geometry related defects and internal voids) resulting from additive manufacturing on the mechanical properties of polymeric lattice samples. By utilizing X-ray computed tomography technique as well as image processing procedure to process the X-ray images, geometric irregularities such as strut cross-section variations, waviness, and internal voids were identified. By incorporating such defects in FE models, we are going to advance our comprehension of the influence of AM caused defects on mechanical behaviour of polymeric lattice structures.
Academic leader: Prof. Mark Battely and Dr. Maedeh Amirpour
Transverse Liquid Composite Moulding processes for Advanced Composites Material Manufacturing
Many recent developments in Liquid Composite Moulding (LCM) manufacturing processes have focused on through-thickness (transverse) resin flow for the impregnation of thicker parts, reducing the flow length to the thickness of the fibrous preform, therefore resulting in short filling times. In this case, the flow and deformation are coupled: the flow induces deformation of the fibre stack, and this deformation influences the fluid flow. Fibrous reinforcement materials show viscoelastic behaviour, meaning that the compaction response is strain-, strain-rate- and time-dependent. A detailed computational model has been developed in one dimension to simulate the coupled flow/deformation and viscoelastic behaviour for the entire family of transverse LCM processes.
Academic leader: Prof. Piaras Kelly
Verification and Characterisation of Thermoplastic Through-Thickness Liquid Composite Moulding Manufacturing
Thermoplastic continuous fibre composites are appealing to high-performance industries due to their favourable mechanical performance, no requirement for curing and recycling opportunities. Unfortunately, the exceptionally high viscosity of advanced thermoplastic polymers presents a significant textile impregnation challenge. While thermoplastic manufacturing methods exist, they are slow and limit the final part complexity. The understanding, governing phenomena, and thermoplastics manufacturing techniques have generally been derived from thermoset processing research. While similar, they operate in entirely different processing conditions and different assumptions. For example, effects such as non-Newtonian flow, hydromechanical deformation and air entrapment are of essential importance. Using a through-thickness infiltration die, we can produce low-void content thermoplastic continuous fibre composites to investigate the processing conditions that affect the flow front behaviour in thermoplastic, high-pressure, high-viscosity flow regimes.
Academic leader: Prof. Simon Bickerton
Enhancing the Bond Strength of Hybrid Composite Structures by Design and Additive Manufacture of Substrate Surface Topologies
In the ever-evolving landscape of manufacturing, our research journey embarks on a compelling story of innovation and sustainability. At its heart lies a quest to transform the way we craft hybrid composite structures, merging additive manufacturing with composite materials. Imagine a future where the production of high-performance components becomes not only more efficient but also more sustainable. By harnessing the power of Powder Bed Fusion (PBF) technology, we are exploring a groundbreaking approach – the direct 3D printing of continuous fiber-reinforced polymers onto substrates. In this narrative, each layer of polymer and fiber is carefully deposited, like building blocks in a grand design. The result? Lightweight, yet incredibly strong, structures with properties tailored to specific applications. From aerospace to automotive, these components offer a harmonious blend of strength, durability, and customization, paving the way for a more sustainable manufacturing future.
Academic leader: Prof. Simon Bickerton
The Centre for Advanced Materials, Manufacturing and Design Additive Manufacturing Lab is a modern research facility for product development and manufacturing technologies, and a place where you can easily turn your ideas into reality. The Lab is open to all University staff and students. The access philosophy for the Lab is one of open access with a welcoming attitude that encourages staff, students and industry partners to extensively use the facility to its maximum potential and explore new areas of use for the technologies.
The lab has a wide range of high-tech metal, polymer, and other, additive manufacturing equipment. For a full list of equipment, click HERE
We encourage you to come into the Lab to ask questions and to explore ways in which AM can benefit you.
For more information, please visit the AM Lab website.
Design for Additive Manufacturing
AM is not simply a replacement manufacturing technology to make conventionally designed parts. Instead, it can be used to add great value to products. But, for this to occur, users must change their design approach to be AM-centric right from the start of the project. Working with AM requires a new design-thinking approach that can add great innovation to products.
We provide the knowledge and education required to increase the industrial adoption of AM in NZ, help to initiate innovative start-up and spin-off companies, and promote the entrepreneurial drive that helps NZ compete internationally. But, most importantly, we make the creative application of AM not only valuable but also fun!
For more information, please visit the AM Lab website.
Academic leader: Prof. Olaf Diegel
Hybrid Injection molding tools with conformal cooling channels
Conformal cooling? Why bother? Here’s a good example of why conformal cooling is such a powerful feature that additive manufacturing brings to the world of injection molding. And to make it even more cost-effective, we used a ‘hybrid’ approach to tooling in which the usually simple bottom part of the tool is CNC machined, and that is then mounted into the AM system, and the complex part of the tool, with its conformal cooling channels, is grown directly on top of the machined blank. Then a quick finishing cut to give it the right surface finish for injection molding.
This tool insert, for a bottle cap, was done by CDAM Lab staff member Simon Chan, in collaboration with local tool manufacturer CAMEX. The CNC machined substrate is 17-4 PH stainless, and the AM part of the tool is maraging steel. This was done as the replacement for a worn out 4-cavity tool. The new tool reduced the tool cooling time from 4.5 seconds to 2.5 seconds. This reduced cooling time translates to more shots per minutes, which translates to cost savings.
For more information, please visit the AM Lab website.
Academic leader: Dr. Simon Chan
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