PSI - Issue 52

Hideaki Katogi et al. / Procedia Structural Integrity 52 (2024) 611–617 Hideaki Katogi/ Structural Integrity Procedia 00 (2019) 000 – 000

612

2

1. Introduction There are many products for sustainable development Goals (SDGs). Some companies are announced many electronic personal mobility. The electronic personal mobility is usually used in European Union. Recently, the flying system of personal mobility has been developed for new product [1]. The mechanical properties of constituent materials of products under outdoor exposure environment should be investigated for comfort. There are many products using natural leather such as car ’ s sheet, shoes, cloth, belt, bag and leader suit so on. The natural leather has good performance. But, the alternative material of natural leather should be considered for SDGs of many products. The synthetic leather has been used for many products. The mechanical properties of synthetic leather are similar to those of natural leather. So, many researchers are examined mechanical properties of synthetic leather for long-term use. Mitsui et al. [2] reported about effect of show materials on wear comfort and microclimate between shoes and skin. This study is used shoes using natural, synthetic and artificial leather. Effects of temperature and humidity between the first and second toes on those subjective sensations were very high. Tsubokura et al. [3] reported about mechanical properties of leather board made of chrome and vegetable leather dusts. Mechanical properties of leather boards for shoe insole were improved by addition of vegetable leather dust in comparison with chrome leather dust. Enomoto et al. [4] reported on physical properties of polyurethane resin using isosorbide-containing polycarbonate diol for synthetic leather. The glass transition temperature of the synthesized polyurethane resin was 78°C. When the synthesized polyurethane resin was mixed with conventional polyurethane resin, the wrinkles could be occurred on the surface of synthetic leather. Rodriguez et al. [5] reported on biological solubilisation of leather industry waste. The solubilisation of chromium-free shavings was good performance. And, the low temperature treatment on the chrome-tanned shavings could be delivered good solubilisation. Tian et al. [6] reported on the preparation and application of synthetic leather from coffee grounds. The synthetic leather has good moisture performance and breathability compared with that of genuine leather. The softness of coffee-ground added synthetic leather was similar to that of traditional solvent-based and water-based soft-package leather. The tensile property of synthetic leather is also important for development of product. Some papers published about tensile property of synthetic leather. Xing et al. [7] reported about mechanical properties of polyurethane synthetic leather nanocomposite. The polyurethane synthetic leather nanocomposite has high tensile strength. Sun et al. [8] reported about curing process of polydimethylsiloxane coating for synthetic leather. The divinyl-terminated polydimethylsiloxane and polymethylhydrosiloxane with side hydrogen atoms enhance the tensile strength and thermal properties. Also, the effect of outdoor exposure environment on mechanical property of constituent material of product should be investigated for SDGs. Fujimoto et al [9] reported on analysis of photodegradation mechanism of polyurethane using FT-IR-ATR and DMA. The polyurethane molecules were broken when the ultraviolet irradiation was conducted for longer than 72 hours. And, the photodegradation of polyurethane using MDI hard segments and long soft segments depended on the mechanism of photo-fries rearrangement type. Katogi et al. [10] reported about effect of short-term outdoor exposure environment on abrasion property of cotton fabric. The 2-week outdoor environment exposure affected the cotton knit fabric shrinkage because cotton fiber has a hydrophilic group of cellulose. The structural changes of cotton knit fabric affected the fabric abrasion properties during outdoor exposure environment. The synthetic leather consists of polymer matrix and fibers like fiber reinforced composite materials. There are many papers about mechanical properties of the composite materials for wider applications [11-23]. The leader suit using synthetic leather is used for comfort under outdoor exposure environment. However, there are few papers about tensile property of synthetic leather under outdoor exposure environment of recent weather for comfort when flying system of personal mobility can be used for next products. So, the aim of this study was the effect of outdoor exposure environment on tensile property of synthetic leather for personal mobility. In this study, static tensile test of synthetic leather were conducted before and after outdoor exposure tests. Results showed that tensile property of synthetic leather using polyurethane and polyester was probably affected by optical degradation under outdoor exposure environment.