Effect of hydrothermal aging on the dynamic mechanical performance of the room temperature-cured epoxy adhesive

2019 ◽  
Vol 58 (1-2) ◽  
pp. 9-19
Author(s):  
Hui Li ◽  
Yingshe Luo ◽  
Donglan Hu ◽  
Dazhi Jiang
2021 ◽  
Vol 143 ◽  
pp. 106403
Author(s):  
Hoang Nguyen ◽  
Valter Carvelli ◽  
Wolfgang Kunther ◽  
Mirja Illikainen ◽  
Paivo Kinnunen

2020 ◽  
pp. 095400832097759
Author(s):  
Ke Li ◽  
Hua Yin ◽  
Kun Yang ◽  
Pei Dai ◽  
Ling Han ◽  
...  

Designing novel low-melting, high-rigidity phthalonitrile resin is of great significance in the current context of development. In this study, rigid spirocycle acetal structure was introduced into phthalonitrile to reduce the melting point and maintain their thermal stability. The chemical structure of resins was confirmed by nuclear magnetic resonance (NMR) spectrometry, matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry and Fourier-transform infrared (FTIR) spectroscopy. The curing behaviors were studied by differential scanning calorimetry (DSC). Thermal stability and mechanical properties of the cured resins were investigated by dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The processability was studied by rheological analysis. The results indicated the three monomers had a low melting temperature, wide processing windows and low viscosities. These polymers did not exhibit Tg from room temperature to 400°C, exhibited superb dynamic mechanical property and thermal stability.


Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5856
Author(s):  
Pragya Mishra ◽  
Pia Åkerfeldt ◽  
Farnoosh Forouzan ◽  
Fredrik Svahn ◽  
Yuan Zhong ◽  
...  

Laser powder bed fusion (L-PBF) has attracted great interest in the aerospace and medical sectors because it can produce complex and lightweight parts with high accuracy. Austenitic stainless steel alloy 316 L is widely used in many applications due to its good mechanical properties and high corrosion resistance over a wide temperature range. In this study, L-PBF-processed 316 L was investigated for its suitability in aerospace applications at cryogenic service temperatures and the behavior at cryogenic temperature was compared with room temperature to understand the properties and microstructural changes within this temperature range. Tensile tests were performed at room temperature and at −196 °C to study the mechanical performance and phase changes. The microstructure and fracture surfaces were characterized using scanning electron microscopy, and the phases were analyzed by X-ray diffraction. The results showed a significant increase in the strength of 316 L at −196 °C, while its ductility remained at an acceptable level. The results indicated the formation of ε and α martensite during cryogenic testing, which explained the increase in strength. Nanoindentation revealed different hardness values, indicating the different mechanical properties of austenite (γ), strained austenite, body-centered cubic martensite (α), and hexagonal close-packed martensite (ε) formed during the tensile tests due to mechanical deformation.


Author(s):  
Xia Zhengbing ◽  
Zhang Kefeng ◽  
Deng Yanfeng ◽  
Ge Fuwen

Recently, engineering blasting is widely applied in projects such as rock mineral mining, construction of underground cavities and field-leveling excavation. Dynamic mechanical performance of rocks has been gradually attached importance both in China and abroad. Concrete and rock are two kinds of the most frequently used engineering materials and also frequently used as experimental objects currently. To compare dynamic mechanical performance of these two materials, this study performed dynamic compression test with five different strain rates on concrete and rock using Split Hopkinson Pressure Bar (SHPB) to obtain basic dynamic mechanical parameters of them and then summarized the relationship of dynamic compressive strength, peak strain and strain rate of two materials. Moreover, specific energy absorption is introduced to confirm dynamic damage mechanisms of concrete and rock materials. This work can not only help to improve working efficiency to the largest extent but also ensure the smooth development of engineering, providing rich theoretical guidance for development of related engineering in the future.


2019 ◽  
Vol 137 (13) ◽  
pp. 48492
Author(s):  
Nur Haslina Nasirah Abdul Hadi ◽  
Hanafi Ismail ◽  
Muhammad Khalil Abdullah ◽  
Raa Khimi Shuib

2019 ◽  
Vol 17 (1) ◽  
pp. 206-219 ◽  
Author(s):  
Manawwer Alam ◽  
Naser M Alandis ◽  
Naushad Ahmad ◽  
Mohammad Asif Alam ◽  
Eram Sharmin

AbstractJatropha oil [JO] based poly (esteramide-urethane) coatings embedded with fumed silica nanoparticles were prepared. JO was converted to N,N-bis(2-hydroxy ethyl) JO fatty amide (HEJA) and was further modified by a tetrafunctional carboxylic acid(trans 1,2 diaminocyclo-hexane-N,N,N’,N’,-tetraacetic acid) to form poly (diamino cyclohexane esteramide) (PDCEA). PDCEA was then treated with toluene 2,4-diisocynate and fumed silica to prepare poly(diamino cyclohexane urethane esteramide) (PUDCEA) nanocomposite. The formation of PDCEA and PUDCEA nanocomposites was confirmed by FTIR, 1H &13C NMR spectroscopic techniques. The thermal behavior and morphology of PUDCEA nanocomposite coatings were investigated by TGA/DTG, DSC, SEM, EDX spectroscopy. PUDCEA nanocomposites were applied on carbon steel and their coatings were produced at room temperature. The properties of these nanocomposite coatings were investigated by standard analytical methods. The PUDCEA-3 nanocomposite showed good anticorrosion and physico-mechanical performance. These naocomposite coatings can be employed safely upto 200oC.


Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5789
Author(s):  
Olga Mysiukiewicz ◽  
Mateusz Barczewski ◽  
Arkadiusz Kloziński

Polylactide-based composites filled with waste fillers due to their sustainability are a subject of many current papers, in which their structural, mechanical, and thermal properties are evaluated. However, few studies focus on their behavior in low temperatures. In this paper, dynamic and quasi-static mechanical properties of polylactide-based composites filled with 10 wt% of linseed cake (a by-product of mechanical oil extraction from linseed) were evaluated at room temperature and at −40 °C by means of dynamic mechanical analysis (DMA), Charpy’s impact strength test and uniaxial tensile test. It was found that the effect of plasticization provided by the oil contained in the filler at room temperature is significantly reduced in sub-zero conditions due to solidification of the oil around −18 °C, as it was shown by differential scanning calorimetry (DSC) and DMA, but the overall mechanical performance of the polylactide-based composites was sufficient to enable their use in low-temperature applications.


2017 ◽  
Vol 52 (18) ◽  
pp. 2477-2482 ◽  
Author(s):  
Hei-Lam Ma ◽  
Xiaoqing Zhang ◽  
Kin-tak Lau ◽  
San-qiang Shi

Nanoclay has been a popular kind of nanofiller for polymer-based nanocomposites in industries since adding a small amount of it can effectively enhance the mechanical properties of polymer. In the present study, a suitable sonication time was first found for manufacturing nanoclay/epoxy adhesive. Then, the lap joint shear strengths of nanoclay/epoxy adhesives with different nanoclay content (0, 1, 3, 5 wt%) conditioned at both room temperature and cryogenic temperature environment were investigated. The main failure mechanism of all samples was interfacial failure between the first layer of glass fiber and adhesive due to peeling. Results showed that 1 wt% was the optimal nanoclay concentration for cryogenic temperature. Scanning electron microcopy was used to examine the fracture surfaces of samples. Good exfoliation and dispersion were found in samples containing 1 wt% of nanoclay. Adding nanoclay into epoxy did not greatly affect the lap joint shear strength at room temperature but significantly influence the strength at cryogenic temperature. This was due to a clamping force induced on nanoclay by negative thermal expansion during conditioning from room temperature to cryogenic temperature. With good exfoliation and dispersion, the clamping force can be evenly distributed. Hence, 1 wt% nanoclay/epoxy adhesive is suitable for bonding composite lap joints, which will be servicing at low temperature environment.


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