Papers by Keyword: Thermoplastic Polyurethane

Abstract: This study investigates the assessment of stresses in a Thermoplastic Polyurethane (TPU) disk under diametral compression relying on full-field strain measurements by Localized Spectrum Analysis (LSA). A checkerboard pattern was first laser-engraved on the disk surface. The LSA processing of the checkerboard images captured in the undeformed (reference state) and deformed (at –8 kN) configurations allowed the determination of the two in-plane principal stretch ratios and the corresponding principal directions. An incompressible behavior was assumed to derive the out-of-plane stretch ratio. Using a neo-Hookean constitutive model, the maps of the Cauchy stress tensors and the First Piola-Kirchhoff stress tensors were deduced. This study demonstrates the potential of the LSA strain measurement technique for deriving stress maps in soft materials, which will be used in future work to feed into the Virtual Fields Method (VFM) for identifying interparticle contact forces in soft granular systems.

Abstract: In this study, several samples of nanocopper fiber fabrics with different proportions of copper content were used. Among them, black copper antibacterial staple Polyamide fiber (PA) and 6 wt.% copper antibacterial fabric were selected. Positron emission tomography (PET) and other fabrics containing nanocopper components were used as experimental control samples. In the process, a raw material containing blending slurry, a nanometal solution, several inorganic particles, and thermoplastic polyurethane colloidal particles were used. The raw material was mixed and stirred before being dried and hot-melted. In the first stage of the process, the wire was cooled vigorously for conversion into the second stage form where it became a final product, a nanocopper fiber yarn. Taguchi analysis was used to compare the antibacterial property of the nanocopper powder between different particle sizes under the same distribution, weight, and fiber granulation characteristics. Two bacterial species, specifically Escherichia coli and Staphylococcus aureus, were used to investigate the antibacterial property of the fabric. In addition, we investigated the mechanical properties of the fabric and observed its surface structure. The copper content in the nanocopper fiber fabrics was detected using an X-ray fluorescence spectrometer. This finding indicate that the samples contained copper antibacterial components fabrics. Subsequently, the uniformity and aggregation degree of the copper distribution on the fiber fabrics were compared between different fiber polyester materials.

Abstract: Electrically conductive fibers are required for numerous fields of application in modern textile technology. They are of particular importance in the manufacturing of smart textiles and fiber composite systems with textile-based sensor and actuator systems. Elastic and electrically conductive filaments can be used as strain sensors for monitoring the mechanical loading of critical components. In order to produce such sensorial filaments, thermoplastic polyurethane (TPU) is compounded with carbon nanotubes (CNT) and melt spun. The mechanical performances of filaments produced at different spinning speeds and containing different amounts of CNT were tested. Furthermore, the correlation between the specific electrical resistance of the filaments and the mechanical strain were analyzed depending on the CNT-content and the spinning speed.

Abstract: The spokes of airless tire or non-pneumatic tire (NPT) are normally made with thermoplastic polyurethane (TPU), which is highly elastic material, to replace inflation pressure in conventional pneumatic tire. However there are limitation in designing of complex spoke geometries due to difficulty in manufacturing process, which normally involve molding process. Recently, the 3D printing technique has been improved and can be used to create highly complex geometries with wide range of materials. However the mechanical properties of printed spoke structure using 3D printing technique are still required to design and development of NPT. This research aim to study the mechanical properties of TPU while varying in printing conditions. The specimens were prepared from actual NPT spoke using waterjet cutting technique and 3D printing technique according to the testing standard ASTM D412 and D638, respectively. The tensile tests were performed on the specimens with corresponding crosshead speed. The testing speed of 3D printed specimen were also varied to 100 and 200 mm/min to study the effects of strain rate on mechanical properties. The stress-strain relationships were obtained from tensile testing and the important mechanical properties were then evaluated. The mechanical properties of specimens prepared from actual NPT spokes and 3D printed specimens were then compared. The ultimate stress of specimens prepared from actual NPT spokes in radial direction and 3D printed specimens with 100% infill were found to be 32.92 and 25.47 MPa, respectively, while the breaking strain were found to be 12.98 and 10.87, respectively. Thus, the information obtained from this research can be used to ensure the possibility in creating NPT spoke using 3D printing technique based on elastic material such as TPU.

Abstract: Conducting polymer blends Polyaniline-Dodecylbenzene sulfonic acid (Pani.DBSA) and thermoplastic polyurethane (TPU) were prepared using in-situ emulsion polymerization method by dissolving both components in DMF. Ani.DBSA/TPU blends were prepared with different compositions 20/80, 30/70, 40/60 and 50/50 wt%. Theses blends have good conducting and mechanical properties. Blends were characterized by Potentiostate, Thermogravimetric analysis (TGA), Infrared spectroscopy (FTIR) and Dynamic mechanical thermal analyzer (DMTA). The electrical conductivity increases up to 30 wt% loading of aniline.DBSA after that it decreases gradually. The uniform dispersion of aniline.DBSA showed in SEM images which is the indication of a strong connection between aniline.DBSA and TPU which increase the conductivity. These blends can be used as strain sensors.

Abstract: Natural fibers of trees, fruit skins and so on are considered as recyclable and are used as filler materials in polymer composites. For decades, natural fibers have become the attention of researchers as an alternative to commercial, synthetic and costly fibers. Therefore, this study has used 7 types of natural fibers from local fruit waste parts in Malaysia, as fillers in TPU. This composite was produced via melt mixing technique, with different filler loading from 5wt% to 20wt%. Different types of natural fiber and its loading, showed different mechanical properties which resulted through tensile strength and elongation at break. Also, it is found that each of these natural fibers gives maximum tensile strength to the optimum loading between 5wt% and 10wt%. The composite with pineapple fiber is the composite with the highest tensile strength value at 5wt% filler load, as well as the most elastic composite with the highest elongation at break percentages.

Abstract: The aim of this study is to improve the physical properties of poly(lactic acid) (PLA) by incorporating thermoplastic polyurethane (TPU), organo-montmorillonite (OMMT) and/or nanosilica (nSiO₂). PLA was first melt mixed with five loadings of TPU (10–50 wt%) on a twin-screw extruder, followed by injection molding. The addition of TPU was found to increase the impact strength, elongation at break and thermal stability of the blends, but decrease the tensile strength and Young’s modulus. Based on a better combination of the mechanical properties, the 70/30 (w/w) PLA/TPU blend was selected for preparing both single and hybrid nanocomposites with a fix total nanofiller content of 5 parts per hundred of resin (phr), and the OMMT/nSiO₂ weight ratios were 5/0, 2/3, 3/2 and 0/5 (phr/phr). The Young’s modulus and thermal stability of the nanocomposites were all higher than those of the neat 70/30 PLA/TPU blend, but at the expense of reducing the tensile strength, elongation at break and impact strength. However, all the nanocomposites exhibited higher impact strength and Young’s modulus than the neat PLA. Among the four nanocomposites, a single-filler nanocomposite containing 5 phr nSiO₂ exhibited the highest impact strength and thermal stability, indicating that there was no synergistic effect of the two nanofillers on the investigated physical properties. However, the hybrid nanocomposite containing 2/3 (phr/phr) OMMT/nSiO₂ possessed a compromise in the tensile properties.

Abstract: Thermoplastic polyurethane/graphene nanocomposites were successfully prepared by mixing masterbatches with neat polymers using the melt compounding process. Graphene was obtained from graphite by the chemical mean. Graphite was initially converted into graphite oxide which was then converted to graphene oxide. Graphene oxide was then reduced by L-ascorbic acid to obtain graphene. The effects of graphene addition on thermal and morphological properties of nanocomposite were studied by a differential scanning calorimeter, a thermal gravimetric analyzer and a scanning electron microscope. TPU/graphene nanocomposites showed higher melting temperature compared to TPU. On the other hand, heat of fusion of nanocomposites was lowered. TPU and TPU/graphene nanocomposites have two steps of decomposition. The first degradation of TPU occurred at higher temperature compared with nanocomposites but the second degradation showed the opposite results. The percentage of residue after thermal degradation of nanocomposites was lower than that of TPU. For surface morphology, nanocomposite exhibited the rougher surface comparing with TPU and well graphene dispersion in TPU phase was achieved. Nevertheless, there were some agglomeration of graphene.

Abstract: In consideration of environmental aspects and limited availability of resources, the focus of automotive and aerospace industry lies on significant weight optimisations especially for moving loads. In this context, innovative lightweight materials as well as material combinations need to be developed. A considerable potential for lightweight structures can be found in fibre- or textile-reinforced semi-finished products. Due to their specific characteristics and extraordinary structural diversity, thermoset and thermoplastic matrix systems can be used. In particular, carbon fibres as reinforcing components combined with a thermoplastic matrix polymer are able to create new high-performance applications. Besides the significant lightweight characteristics of the fibre-plastic-composites, in some instances contrary requirements must be satisfied in many areas, such as strength and ductility. In this field, the combination of fibre-reinforced polymers with aluminium or titanium sheets creates unique composite materials, so called hybrid laminates, which fulfil the unusual expectations.The focus of the current study lies on the development of a new thermoplastic hybrid laminate named CATPUAL (CArbon fibre-reinforced Thermoplastic PolyUrethane/ALuminium laminate). The structure of the laminate is an alternating sequence of thin aluminium sheets (EN AW 6082-T4) and fibre-reinforced thermoplastic polyurethane (TPU). The individual layers are consolidated to each other by using a hot pressing process. First results showed that the impregnation capability of thermoplastic polyurethane surpasses any other commercially available hybrid laminates. Furthermore, the mechanical properties regarding bending strength and interlaminar shear strength are exceeding the state of the art drastically.

Abstract: Blending method of two or more polymer is well-established strategy to modify the physical properties without synthesizes the new polymer system. While adding magnetic filler will change the magnetic properties of the polymer as an insulator to the materials that are magnetic. The TPU/NR blends as matrix was prepared from thermoplastic polyurethane (TPU) and natural rubber (NR) in the ratio 85/15 with 1-5 wt% NiZn ferrites. The value of saturation magnetization (M_s), remanance (M_r) increased, while coercive force (H_c) decreases with increasing filler loading. For the electrical properties, resistivity decreased and conductivity increased with the increase of NiZn ferrite loading in the blends.