scholarly journals Effects of peeling and steam-heating treatment on mechanical properties and dimensional stability of oriented Phyllostachys makinoi and Phyllostachys pubescens scrimber boards

2018 ◽  
Vol 64 (5) ◽  
pp. 625-634 ◽  
Author(s):  
Min Jay Chung ◽  
Sheng Yang Wang
BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 5342-5354
Author(s):  
Chia-Ju Lee ◽  
Min-Jay Chung

Effects of bamboo species, adhesives, and steam-heating treatment (SHT) were examined relative to mechanical properties and dimensional stability of oriented bamboo scrimber board (OBSB) made from makino bamboo (Phyllostachys makinoi Hayata) and moso bamboo (P. pubescens (Mazel)) strips. Results indicated that OBSB produced using makino bamboo culms bonded with water-soluble phenol formaldehyde resin (PF) had significantly higher ultrasonic wave velocity (Vu (//)), tap tone sound velocity (Vt (//)), dynamic modulus of elasticity (DMOEu (//)), and DMOEt (//) than that produced using moso bamboo bonded with water-soluble urea formaldehyde resin (UF) (p < 0.05). The two types of OBSB showed the same trend of DMOEu > DMOEt > modulus of elasticity (MOE). In addition, OBSB made using steam-heated makino bamboo and PF had the largest modulus of rupture (MOR) (210.5 MPa), exceeding that of OBSB made using laminated bamboo timber and wood-plastic composite (WPC). However, OBSB made using steam-heated moso bamboo and UF exhibited the highest screw holding strength (SHS). Improvement in dimensional stability was observed in OBSB manufactured using steam-heated culms. Finally, OBSB glued with UF had lower water absorption, thickness swelling, and volumetric swelling than that glued with PF.


2020 ◽  
Vol 66 (1) ◽  
Author(s):  
Yoko Okahisa ◽  
Keisuke Kojiro ◽  
Hatsuki Ashiya ◽  
Takeru Tomita ◽  
Yuzo Furuta ◽  
...  

Abstract Age is an important factor that dictates bamboo’s mechanical properties. In Japan, bamboo plants aged 3–5 years are selected for use as materials because of their robustness and decorative or craft-friendly characteristics. In this study, the age-dependent and radial sectional differences in bamboo’s dynamic viscoelastic properties in relation to lignin structural variation, were evaluated. We used Phyllostachys pubescens samples at the current year and at 1.5, 3.5, 6.5, 9.5, 12.5, and 15.5 years of age. There was a clear age dependence in the peak temperature of tan δ and in the yield of thioacidolysis products derived from β-O-4 lignin structures. The highest peak temperature tan δ value was detected in 3.5-year-old bamboo, which contained the highest amount of the thioacidolysis products. Moreover, tan δ’s peak temperature was always higher on the outer side, and the ratio of S/G thioacidolysis products was always higher on the inner side of bamboo plants of all ages. These results suggest that changes in bamboo’s thermal softening properties from aging are caused by the maturation and degradation of lignin in bamboo.


Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2622
Author(s):  
Malcolm Griffiths

Austenitic stainless steels are used for core internal structures in sodium-cooled fast reactors (SFRs) and light-water reactors (LWRs) because of their high strength and retained toughness after irradiation (up to 80 dpa in LWRs), unlike ferritic steels that are embrittled at low doses (<1 dpa). For fast reactors, operating temperatures vary from 400 to 550 °C for the internal structures and up to 650 °C for the fuel cladding. The internal structures of the LWRs operate at temperatures between approximately 270 and 320 °C although some parts can be hotter (more than 400 °C) because of localised nuclear heating. The ongoing operability relies on being able to understand and predict how the mechanical properties and dimensional stability change over extended periods of operation. Test reactor irradiations and power reactor operating experience over more than 50 years has resulted in the accumulation of a large amount of data from which one can assess the effects of irradiation on the properties of austenitic stainless steels. The effect of irradiation on the intrinsic mechanical properties (strength, ductility, toughness, etc.) and dimensional stability derived from in- and out-reactor (post-irradiation) measurements and tests will be described and discussed. The main observations will be assessed using radiation damage and gas production models. Rate theory models will be used to show how the microstructural changes during irradiation affect mechanical properties and dimensional stability.


2015 ◽  
Vol 74 (2) ◽  
pp. 177-184 ◽  
Author(s):  
Youming Dong ◽  
Yutao Yan ◽  
Kaili Wang ◽  
Jianzhang Li ◽  
Shifeng Zhang ◽  
...  

Author(s):  
Wellington da Silva Mattos ◽  
George Edward Totten ◽  
Lauralice de Campos Franceschini Canale

This article describes the concept of uphill quenching process applied in the heat treatment of aluminum alloys. Uphill quenching is interesting since residual stress reductions of up to 80% has been reported. In addition, substantial improvements in dimensional stability have been achieved for several types of aluminum parts. Often, uphill quenching is applied after quenching and before aging during the heat treatment of aluminum alloys. The uphill quenching process consists of the immersion of the part in a cryogenic environment, and after homogenization of the temperature, the part is transferred to the hot steam chamber to obtain a temperature gradient that will maintain the mechanical properties gained with this process. The results obtained are lower residual stress and better dimensional stability. The aim of this article is to provide a review of this process and to compare it with conventional heat treatment.


2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Jinguang Wei ◽  
Fei Rao ◽  
Yuxiang Huang ◽  
Yahui Zhang ◽  
Yue Qi ◽  
...  

Natural wood has certain advantages such as good processability and high specific strength and thus has been used for millennium as a structural material. But the mechanical performance and water resistance, particularly for fast-growing species, are unsatisfactory for high-end applications. In this study, the “new-type” scrimber technology was introduced to radiata pine (Pinus radiata D. Don) scrimbers. The structure, mechanical properties, and dimensional stability of the scrimber panels were investigated. Results showed that OWFMs as basic units of scrimber had been very even in size and superior permeability. The scrimbers exhibited a three-dimensional porous structure, and the porosity had a decrease with increasing density. Both OWFMs and densification contributed to the high performance in terms of mechanical properties and water resistance. The flexural, compressive, and short-beam shearing strength were significantly enhanced with increasing density. As the density was 0.80 g cm−3, the flexural strength (MOR) was approximately 120 MPa, much larger than many selected wood-based panels. Moreover, the water resistance and dimensional stability also were closely related to the density. At the density of 1.39 g cm−3, the water absorption rate and thinness swelling rate of the panels in boiled water were only 19% and 5.7%, respectively.


2019 ◽  
Vol 14 ◽  
pp. 155892501989056
Author(s):  
Eui Kyung Roh

As a lot of time is spent in the car, the comfort of not only the car seat but also the car seat cover itself has become of increasing importance. With increasing use of ventilated seats, the control of the physical and mechanical properties of leather in response to punching has become of prime importance in the design of car seats. This study evaluated the changes in the physical and mechanical properties of leather due to punching and proposes optimum punching intervals for car seats. Sixteen types of leather, punched at three spatial intervals (2, 3, and 5 mm), were evaluated in terms of their apparent density, softness, coefficient of friction, warm-cool feeling, and mechanical properties. Leather punching affected its physical and mechanical properties. However, there were differences in punching intervals that significantly affected each property, including the mechanical properties. Depending on the performance required when developing a product, a suitable punching interval must be selected. Therefore, punching at 5 mm intervals is preferred for obtaining physical and mechanical properties similar to those of untreated leathers, and punching at 3 mm intervals is recommended for achieving more softness. On the contrary, punching at 2 mm intervals increases air permeability but decreases dimensional stability.


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