A Brief Introduction on the Development of Ti-Based Metallic Glasses

Ti-based metallic glasses (MGs) possess high specific strength, low elastic modulus, high elasticity, high wear and corrosion resistance, and excellent biocompatibility, which make them highly attractive as lightweight high-strength materials as well as biomaterials. However, the glass forming ability (GFA) of Ti-based MGs, particularly those bearing no toxic, noble, or heavy metals, that is, Be, Pd, or Cu alike, largely sets back their wide applications for the restricted critical glass forming size of these Ti-based MGs. In this review, the outlines in developing Ti-based MGs are delineated in order to provide an overall view on the efforts ever made to fabricate bulk size Ti-based MGs. The state of the art in the knowledge on the GFA of Ti-based MGs is briefly introduced, and possible directions for fabricating bulk size toxic and noble element free Ti-based MGs are discussed.

Phase Change Energy Storage Elastic Fiber: A Simple Route to Personal Thermal Management

A novel thermoplastic polyurethane (TPU) PCFs possessing a high loaded ratio and high elasticity was simply prepared by vacuum absorption following wet spinning, then coated by waterborne polyurethane (WPU). Octadecane (OCC), hexadecanol (HEO), and stearic acid (SA), which have different tendencies to form hydrogen bonds with TPU, were selected as PCMs, and their thermal behavior, thermal storge properties, and elasticity were systematically studied, respectively. The hierarchical pore structure though from the sheath to the core part of TPU filaments weakened the influence of the nonfreezing layer and hydrogen bond on the crystallization behavior of PCMs. The resulting HEO/TPU fiber has the highest enthalpy of 208.1 J/g compared with OCC and SA. Moreover, the HEO/TPU fiber has an elongation at break of 354.8% when the phase change enthalpy is as high as 177.8 J/g and the phase change enthalpy is still 174.5 J/g after fifty cycles. After ten tensile recovery cycles, the elastic recovery rate of HEO/TPU fiber was only 71.3%. When the HEO in the fiber was liquid state, the elastic recovery rate of HEO/TPU fiber promoted to 91.6%. This elastic PCFs have excellent thermal cycle stability, elastic recovery, and temperature sensitivity. It has great application potential in the fields of flexible wearable devices, intelligent fabrics, and temperature sensors.

Development of multi-angle fiber array for accurate measurement of flexion and rotation in human joints

Herein, we have proposed a method that uses a highly stretchable and conductive fiber-based multi-angle fiber array, which precisely measures human joint motion in various degrees of freedom (flexion and rotation) at the shoulders, knees, and wrists in real time. By embedding conductive carbon nanotubes (CNTs) within spandex fibers of high elasticity and shape recovery ratio, we monitored joint motion stably without degrading the fiber’s conductivity even during repeated stretching and contraction of different lengths. The strain occurring in a specific direction was monitored using mapping images generated due to the change in resistance that occurred when 12 CNT-embedded spandex fibers arranged in radial lines at intervals of 15° were stretched or contracted by an external force. The proposed high-precision joint-monitoring technology measures human motion accurately and is applicable for use in wearable healthcare devices that require precise measurements.

Bacteria Cell Hydrophobicity and Interfacial Properties Relationships: A New MEOR Approach

For microbial enhanced oil recovery (MEOR), different mechanisms have been introduced. In some of these papers, the phenomena and mechanisms related to biosurfactants produced by certain microorganisms were discussed, while others studied the direct impacts of the properties of microorganisms on the related mechanisms. However, there are only very few papers dealing with the direct impacts of microorganisms on interfacial properties. In the present work, the interfacial properties of three bacteria MJ02 (Bacillus Subtilis type), MJ03 (Pseudomonas Aeruginosa type), and RAG1 (Acinetobacter Calcoaceticus type) with the hydrophobicity factors 2, 34, and 79% were studied, along with their direct impact on the water/heptane interfacial tension (IFT), dilational interfacial visco-elasticity, and emulsion stability. A relationship between the adsorption dynamics and IFT reduction with the hydrophobicity of the bacteria cells is found. The cells with highest hydrophobicity (79%) exhibit a very fast dynamic of adsorption and lead to relatively large interfacial elasticity values at short adsorption time. The maximum elasticity values (at the studied frequencies) are observed for bacteria cells with the intermediate hydrophobicity factor (34%); however, at longer adsorption times. The emulsification studies show that among the three bacteria, just RAG1 provides a good capability to stabilize crude oil in brine emulsions, which correlates with the observed fast dynamics of adsorption and high elasticity values at short times. The salinity of the aqueous phase is also discussed as an important factor for the emulsion formation and stabilization.

Effect of Temperature on Tensile Curve of Polyaspartic Ester Polyurea and Its Activation Energy Analysis

The influence of ambient temperature on the tensile stress-strain curve of polyaspartic ester polyurea (PAE-PU) was investigated to discuss the yield and breakage mechanism of tensile deformation. Temperature has a significant effect on the tensile stress-strain curve of PAE-PU. At low temperature (27, 40 °C), it shows obvious yield and forced high elasticity. After the temperature exceeds 80 °C, the yield phenomenon disappears and shows high elasticity of rubber: the strain energy and breakage energy are significantly reduced. The yield activation energy of PAE-PU was calculated by yield strain time at different temperatures. It was found that the yield activation energy decreased with the increase of tensile rate. When the tensile rate is 500mm/min, among the activation energies calculated by breakage strength, yield strength and Young’s modulus at different temperatures, the ordinary elastic deformation activation energy is higher, while the yield and breakage activation energy are close and lower. The latter two are close to the hydrogen bond energy and one order of magnitude lower than the chemical bond energy of molecular chain.

Effective Polymer Protective Coatings

New protective coating compositions based on epoxy resins with high rates of chemical resistance to etching solutions are developed. The chemical resistance coefficient ranges from 0.7 to 0.96. The curing process was evaluated via IR spectroscopy. For each composition, the following parameters were determined: impact strength A, compressive strength σcompr and bending strength σbend, adhesion shear strength σshear, glass transition temperature Tgt, high elasticity modulus Eh and mesh density nm.