• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.129-129
• /
• 2006

Conventional solvent-based polyurethane (PU) is well established for wide applications, such as textile treatments, surface coating, adhesive and so on. Due to the demands of safety, economic, and environmental protection, the solvent-based PU is restricted and has been phasing out and aqueous-based PU is becoming the world market trend, which is an environmental friendly product. The chemical resistance, physical and mechanical properties of aqueous-based PU are still not competible with solvent-based PU. Because of aqueous-based PU is a linear thermoplastic polymer with lower average molecular weight. Their improvements are normally performed by a post-curing reaction or a polymer hybridization to enhance the polymer cross-linking density. Hybridization of PU with aqueous-based epoxy resin or acrylate emulsion and then cured by a curing agent for improving the performance properties and reducing the cost of aqueous-based PU.Furthermore, a special function is added to aqueous-based PU increasing the application value, for examples, flame retardation, polymeric dyes, hydrophilic and etc.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.11
• /
• pp.85-91
• /
• 2009

A lip seal is widely used not only to prevent leakage of fluids from an actuator or a rotating shaft but also to exclude outside substances. Recently, TPU(Thermoplastic Polyurethane), which is one of the sealing materials, has been frequently used due to its excellent mechanical properties and wear resistance. The material constants for finite element analysis through the experiment on stress relaxation are presented. The reaction forces of a shaft as well as the contact pressures of a lip seal under condition before and after stress relaxation using finite element analysis were obtained, The results show that stress relaxation has not a little effect on the performance of a lip seal.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.8
• /
• pp.847-853
• /
• 2013

Micro-dimples on sliding surfaces have been investigated to reduce the frictional forces on metal bearing surfaces; however, for an elastomer, such as thermoplastic polyurethane (TPU), this has not been studied. The material properties of an elastomer are affected by temperature, and this can shorten the life of the elastomer. In this paper, micro-dimples were applied on the surface of an elastomer in order to reduce the frictional heating, which was experimentally investigated using pin-on-disk apparatus while the surface temperature was measured. To obtain optimal design parameters, the design of the experiment was applied, and the shape of the section, size, depth and density of micro-dimples were selected as the design parameters. The results show that the size of the dimple is the most important design parameter.

• Proceedings of the Korean Fiber Society Conference
• /
• 2003.10b
• /
• pp.269-270
• /
• 2003

Thermoplastic polyurethane is a engineering plastic with elasticity, abrasion resistance and good resistance to oil, grease and many solvents. Characteristics of poly(vinyl chloride) (PVC) are good general chemical resistance, excellent weatherablility, good insulate. properties, and self-extinguishing or flame resistance, etc. So it is used in widespread industrial fields[2]. (omitted)

• Journal of the Society of Naval Architects of Korea
• /
• v.43 no.1 s.145
• /
• pp.128-133
• /
• 2006

This study is focused on the skill to prevent RIB (Rigid Inflatable Boat) from sinking. For better ability to prevent sinking, single hypalon tube is replaced by double TPU (Thermoplastic Polyurethane) tube that is excellent at frictional wear strength and oil-resisting qualities. High buoyant materials are arranged in empty spaces of ship so that ship's spare buoyancy is increased. And for restoration of stable position of ship, the self-righting system is installed. Aluminium alloy is used for increasing hull strength.

• Journal of Adhesion and Interface
• /
• v.7 no.3
• /
• pp.16-25
• /
• 2006

Water vapour permeable and water resistant film was laminated to made footwear woven fabric and non-woven fabrics by screen type with thermosetting reactive hot melt adhesive. Optimum conditions of each process were investigated, and the properties of film laminated fabric with optimum conditions are evaluated. The results are as follows. Thermosetting reactive polyurethane hot melt is retain proper heat resistance differently thermoplastic hot melt. Optimum melting adhesive process conditions are as follows ; drum temperature $95^{\circ}C$, hose temperature $97^{\circ}C$, feeding pipe temperature $100^{\circ}C$, screen temperature $105^{\circ}C$, pressure of opposite roller $1kgf/cm^2$, pressure of laminating roller $3kgf/cm^2$, finishing speed 15 m/min, melting temperature $120^{\circ}C$, cooling time 20 s, pressing temperature $130^{\circ}C$, pressing time 30 s. As the thickness of film was increased, the water vapour permeability was decreased but water resistance was increased, and the effect of film is dominant over all the others in the air permeability.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.17 no.3
• /
• pp.120-126
• /
• 2018

In the present study, the multi-nozzle electrospinning process is investigated for the fabrication of uniform polymer nanofiber mats. Electrospinning has been one of the simple and efficient methods to manufacture polymer nanofibers and their mats. Although a typical electrospinning has many advantages such as simple system and operation, various materials, and cost-effectiveness, a relatively low productivity prevents it from being used in practical applications. Thus, the multi-nozzle electrospinning system with the adjustable nozzle position and rotating drum collector is designed and produced in this study. In particular, the effects of the inter-nozzle distance and spatial arrangement of nozzles on the uniformity of the electrospun nanofibers are investigated. With this multi-nozzle electrospinning process, the maximum flow rate of the supplied polymer solution for a uniform electrospinning increases, which indicates the enhanced productivity.

• The Journal of the Convergence on Culture Technology
• /
• v.4 no.1
• /
• pp.331-335
• /
• 2018

A pillow was fabricated through CAE(Computer Aided Engineering) and 3D printing, which can adjust automatically the height of the pillow when lying sideways and backwards according to the sleeping posture. The target height difference of the pillow was about 1.0 cm ~ 1.5 cm when the head weight difference was about 1.2 kg. Instead of using a complex mechanical device, it was based on an arch structure made of TPU. From the simulation, the optimum model was designed through series combination and the results were compared with the experimental ones. The final product had a height difference of about 2 cm according to the lying posture.

• Textile Coloration and Finishing
• /
• v.33 no.4
• /
• pp.269-279
• /
• 2021

In this study, the laminating of TPU film after coating of primer adhesive on the fabrics was applied in order to secure the strength to withstand a fall from a higher altitude by increasing the adhesion between the fabric and the film layer. It seems that the fineness of the yarn and the weave construction have a greater effect than the type of the laminating films. The order of superiority of the laminated fabrics by film type and thickness was the same for 1000 denier and 210 denier fabrics, and the tendency was consistent with the order of superiority in the film properties and peel strength tests. The tear strength of laminating fabrics increased three to four times for 1000 denier fabrics compared to the fabric alone, but it decreased by 2 times for the 210 denier fabrics. Summarizing the above results, it is most appropriate to combine 1000d fabric with three types of laminating films(100~200㎛ thickness) of A(0.2T) or B(0.15T) or D(0.1T) considering the air pressure resistance, the impact resistance during the fall, and the durability against damage during use.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.2
• /
• pp.79-86
• /
• 2022

Numerous fabrication techniques have been used to mimic cylindrical natural tissues, such as blood vessels, tendons, ligaments, and skeletal muscles. However, most processes have limitations in achieving the biomimetic properties of multilayered and porous architectures. In this study, to embrace both features, a novel self-assembly method was proposed using electrospun microfibrous sheets. A bilayer microfibrous structure, comprising two sheets with different internal stresses, was fabricated by electrospinning a polycaprolactone (PCL) sheet on a uniaxially stretched thermoplastic polyurethane (TPU) sheet. Then, by removing the stretching tension, the sheet was rolled into a hollow cylindrical structure with a specific internal diameter. The internal diameter could be quantitatively controlled by adjusting the thickness of the PCL sheet against that of the TPU sheet. Through this self-assembly method, biomimetic cylindrical structures with multilayer and porous features can be manufactured in a stable and controllable manner. Therefore, the resulting structures may be applied to various tissue engineering scaffolds, especially vascular and connective tissues.