Modification of the Mechanical Properties of Core‐Shell Liquid Gallium Nanoparticles by Thermal Oxidation at Low Temperature (Part. Part. Syst. Charact. 10/2021)

Low-temperature properties of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and their blends were studied. The analyzed low-temperature mechanical properties involve the deformation resistance and impact strength characteristics. HDPE is a bimodal ethylene/1-hexene copolymer; LDPE is a branched ethylene homopolymer containing short-chain branches of different length; LLDPE is a binary ethylene/1-butene copolymer and an ethylene/1-butene/1-hexene terpolymer. The samples of copolymers and their blends were studied by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), 13С NMR spectroscopy, and dynamic mechanical analysis (DMA) using testing machines equipped with a cryochamber. It is proposed that such parameters as “relative elongation at break at −45 °C” and “Izod impact strength at −40 °C” are used instead of the ductile-to-brittle transition temperature to assess frost resistance properties because these parameters are more sensitive to deformation and impact at subzero temperatures for HDPE. LLDPE is shown to exhibit higher relative elongation at break at −45 °C and Izod impact strength at −20 ÷ 60 °C compared to those of LDPE. LLDPE terpolymer added to HDPE (at a content ≥ 25 wt.%) simultaneously increases flow properties and improves tensile properties of the blend at −45 °C. Changes in low-temperature properties as a function of molecular weight, MWD, crystallinity, and branch content were determined for HDPE, LLDPE, and their blends. The DMA data prove the resulting dependences. The reported findings allow one to understand and predict mechanical properties in the HDPE–LLDPE systems at subzero temperatures.

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Effects of equal channel angular pressing and heat treatments on the microstructures and mechanical properties of selective laser melted and cast AlSi10Mg alloys

Archives of Civil and Mechanical Engineering ◽

10.1007/s43452-021-00246-y ◽

2021 ◽

Vol 21 (3) ◽

Author(s):

Przemysław Snopiński ◽

Mariusz Król ◽

Marek Pagáč ◽

Jana Petrů ◽

Jiří Hajnyš ◽

...

Keyword(s):

Mechanical Properties ◽

Low Temperature ◽

Equal Channel Angular Pressing ◽

Heat Treatments ◽

Electron Backscattered Diffraction ◽

Angular Pressing ◽

Low Temperature Annealing ◽

Transmission Electron ◽

Before And After ◽

The Impact

AbstractThis study investigated the impact of the equal channel angular pressing (ECAP) combined with heat treatments on the microstructure and mechanical properties of AlSi10Mg alloys fabricated via selective laser melting (SLM) and gravity casting. Special attention was directed towards determining the effect of post-fabrication heat treatments on the microstructural evolution of AlSi10Mg alloy fabricated using two different routes. Three initial alloy conditions were considered prior to ECAP deformation: (1) as-cast in solution treated (T4) condition, (2) SLM in T4 condition, (3) SLM subjected to low-temperature annealing. Light microscopy, transmission electron microscopy, X-ray diffraction line broadening analysis, and electron backscattered diffraction analysis were used to characterize the microstructures before and after ECAP. The results indicated that SLM followed by low-temperature annealing led to superior mechanical properties, relative to the two other conditions. Microscopic analyses revealed that the partial-cellular structure contributed to strong work hardening. This behavior enhanced the material’s strength because of the enhanced accumulation of geometrically necessary dislocations during ECAP deformation.

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Nanoscale Mechanical Properties of Core–Shell-like Poly-NIPAm Microgel Particles: Effect of Temperature and Cross-Linking Density

The Journal of Physical Chemistry B ◽

10.1021/acs.jpcb.1c04173 ◽

2021 ◽

Author(s):

Gen Li ◽

Imre Varga ◽

Attila Kardos ◽

Illia Dobryden ◽

Per M. Claesson

Keyword(s):

Mechanical Properties ◽

Effect Of Temperature ◽

Cross Linking ◽

Core Shell ◽

Microgel Particles

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Analysis of Mechanical Properties and Mechanism of Natural Rubber Waterstop after Aging in Low-Temperature Environment

Polymers ◽

10.3390/polym13132119 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2119

Author(s):

Lin Yu ◽

Shiman Liu ◽

Weiwei Yang ◽

Mengying Liu

Keyword(s):

Mechanical Properties ◽

Low Temperature ◽

Energy Dispersive Spectrometry ◽

Permanent Deformation ◽

Test Chamber ◽

Accelerate Aging ◽

Aging Mechanism ◽

Temperature Environment ◽

Freezing Test ◽

Temperature Water

In order to elucidate the aging performance and aging mechanism of a rubber waterstop in low-temperature environments, the rubber waterstops were placed in the freezing test chamber to accelerate aging, and then we tested its tensile strength, elongation, tear strength, compression permanent deformation and hardness at different times. Additionally, the damaged specimens were tested by scanning electron microscope, Fourier transform infrared spectroscopy and energy dispersive spectrometry. The results showed that with the growth of aging time, the mechanical properties of the rubber waterstop are reduced. At the same time, many protrusions appeared on the surface of the rubber waterstop, the C element gradually decreased, and the O element gradually increased. During the period of 72–90 days, the content of the C element in the low-temperature air environment significantly decreased compared with that in low-temperature water, while the content of O element increased significantly.

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Core@shell structured Ti3C2Tx@Ni-reinforced Al composites with enhanced mechanical properties and electromagnetic interference shielding performance

Journal of Materials Science ◽

10.1007/s10853-021-06162-z ◽

2021 ◽

Author(s):

Xiachen Fan ◽

Shibo Li ◽

Weimin Xu ◽

Jie Hu ◽

Shujun Hu ◽

...

Keyword(s):

Mechanical Properties ◽

Electromagnetic Interference ◽

Core Shell ◽

Electromagnetic Interference Shielding

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Interfacial Reactions and Mechanical Properties of Sn–58Bi Solder Joints with Ag Nanoparticles Prepared Using Ultra-Fast Laser Bonding

Materials ◽

10.3390/ma14020335 ◽

2021 ◽

Vol 14 (2) ◽

pp. 335

Author(s):

Gyuwon Jeong ◽

Dong-Yurl Yu ◽

Seongju Baek ◽

Junghwan Bang ◽

Tae-Ik Lee ◽

...

Keyword(s):

Mechanical Properties ◽

Low Temperature ◽

Printed Circuit Boards ◽

Solder Joints ◽

Interfacial Reactions ◽

Circuit Boards ◽

Ag Nps ◽

Laser Bonding ◽

Laser Soldering ◽

Low Temperature Bonding

The effects of Ag nanoparticle (Ag NP) addition on interfacial reaction and mechanical properties of Sn–58Bi solder joints using ultra-fast laser soldering were investigated. Laser-assisted low-temperature bonding was used to solder Sn–58Bi based pastes, with different Ag NP contents, onto organic surface preservative-finished Cu pads of printed circuit boards. The solder joints after laser bonding were examined to determine the effects of Ag NPs on interfacial reactions and intermetallic compounds (IMCs) and high-temperature storage tests performed to investigate its effects on the long-term reliabilities of solder joints. Their mechanical properties were also assessed using shear tests. Although the bonding time of the laser process was shorter than that of a conventional reflow process, Cu–Sn IMCs, such as Cu6Sn5 and Cu3Sn, were well formed at the interface of the solder joint. The addition of Ag NPs also improved the mechanical properties of the solder joints by reducing brittle fracture and suppressing IMC growth. However, excessive addition of Ag NPs degraded the mechanical properties due to coarsened Ag3Sn IMCs. Thus, this research predicts that the laser bonding process can be applied to low-temperature bonding to reduce thermal damage and improve the mechanical properties of Sn–58Bi solders, whose microstructure and related mechanical properties can be improved by adding optimal amounts of Ag NPs.

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