Search

The use of polylactic acid‐based composites as self‐fixing materials is a promising technology for various applications due to the shape memory effect of polylactide. In this study, hexagonal boron nitride (h‐BN) was mixed with polylactic acid (PLA) with concentrations of 0, 0.5, 1, 2, 5, and 10 wt% for subsequent film casting. The morphology, mechanical and thermal characteristics of the composite were investigated. With a high percentage of filler content, a decrease in thermal conductivity was observed. The recovery strain decreased with increasing the filler content. The amount of h‐BN had a mixed effect on the recovery stress of the composite. Thus, PLA/h‐BN composites represent a new research idea to study the influence of a heat‐conducting filler on a shape memory effect in polylactic acid. Highlights: Correlation between crystallinity, thermal and shape memory properties was describedDecrease in thermal conductivity was observed with the large percentage of fillingThe composite with 2 wt% of h‐BN exhibits optimal characteristics of SMERecovery strain decreased with the rise of filler contentAmount of h‐BN had a non‐trivial effect on the recovery stress of composite [ABSTRACT FROM AUTHOR]

This article presents the results of an interpretation of the territory of the Olon-Ovoot ore cluster using medium and high spatial resolution satellite images. The interpretation is based on the Sentinel-2 image, which has been orthorectified and reduced to a common spatial resolution (10 m). Indices of iron hydroxide and iron silicate in Sentinel-2 images are used for selecting areas. The subpixel structure is analyzed using high spatial resolution satellite images from the Google Earth computer program in order to identify the areas of concentration of quartz-carbonate veins in Sentinel-2 images. The structural and morphological interpretation with lineament extraction has not required spectral domain analysis in high-resolution images. Remote sensing data interpretation have made it possible to significantly clarify the geological structure of the territory and improve from the mapping scale from 1 : 200 000 to 1 : 20 000 for key areas. The fusion of satellite images of different functional scales has led to an order of magnitude increase in mapped geological features (e.g., dikes). Detailed mapping of the territory makes it possible to come close to geo-information modeling of geological structural elements, i.e., leading indicators. [ABSTRACT FROM AUTHOR]

Ultra-high molecular weight polyethylene (UHMWPE) fibers drawn at drawing ratio of 6 (pre-deformation strain 500%) demonstrating the obtained one-way shape memory effect. Artificial muscles have been manufactured in the form of coiled UHMWPE fibers. Isometric recovery stress and recovery strain of the fibers were measured during heating by using a dynamic mechanical analyzer (DMA). As a result, the fibers were capable to demonstrate large contraction of 78% (recovery strain of 93%) due to the entropic elasticity. The recovery stresses of the fibers reach up to 27 MPa. The work of stroke cycle for coiled artificial muscles with a constant stress of 1 MPa was recorded. Artificial muscles based on coiled UHMWPE fibers have a large stroke of 64 %. The structural mechanisms of muscle-like behavior were discussed. [ABSTRACT FROM AUTHOR]

Solid-state formation method of polyimide (PI) blends based on polyphenylene sulfide (PPS) and fluorinated ethylene propylene (FEP) was elaborated. Recycled thermoset PI powder was used as reinforcements. FEP/PI and PPS/PI blends were obtained by high-energy ball mill without using compatibilizer. PI content in blends was of 25, 50 or 75 wt%. Bulk samples were obtained by sintering at 330 °C during 25 min, with consequent disposition of sample into hot mold between two cold plates and loading the pressure of 20-35 MPa for 10 min. Morphology structure and thermal properties of powder blends were studied by tapped density measurements, DSC and XRD analyses. Thermal and mechanical properties of bulk samples were studied by DMA, hardness measurements and compressive tests. Strong chemical interaction between FEP matrix and PI filler was observed, whereas in case of PPS/PI samples nearly no interaction between components was found. Mechanical tests show that optimum filling degree for PPS/PI system is of 25 wt% PI, whereas in FEP/PI system it is of about 50 wt%. [ABSTRACT FROM AUTHOR]

The paper represents storage modulus and internal friction modulation upon cyclic loading of Zr61Cu27Fe2Al10 bulk metallic glassy samples within quasi-reversible deformation regime. The structure of the samples was studied by X-ray diffraction and transmission electron microscopy including high-resolution imaging and selected-area electron diffraction. It is found that kinetically frozen anelastic deformation accumulates on mechanical cycling at room temperature and causes an increase in the storage modulus and even nanocrystallization of a metallic glassy phase after a certain number of cycles. The study has shown that even a minor cyclic deformation in an elastic region can lead to the changes the atomic structure and in turn affect the elastic modulus. [ABSTRACT FROM AUTHOR]

Ball milling technique was used for deposition of the polytetrafluoroethylene (PTFE) coating on the powder of TiFe intermetallic compound. Measurement of pressure-composition hydrogen absorption isotherms revealed that the polymer-coated TiFe intermetallic compound kept its hydrogen storage ability. The TiFe/PTFE material demonstrated resistance to surface poisoning even after a prolonged exposure to air and was not subjected to pulverization during multiple hydrogenation-dehydrogenation cycles. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The equiatomic intermetallic compound TiFe has been prepared by elemental mechanochemical synthesis in a planetary ball mill from Fe and Ti powders. The structural and phase transformations during synthesis were followed using X-ray diffraction. The reaction of the synthesized compound with hydrogen was studied volumetrically. The results demonstrate that the hydrogen capacity of the mechanochemical TiFe is 1.2 wt % at 2.5 MPa. Its absorption isotherm has an extended plateau in the range 1.6-1.7 MPa at room temperature. [ABSTRACT FROM AUTHOR]

The development of adaptive medical structures is one of the promising areas of bioengineering. Polymer composite materials based on polylactide (PLA) are interesting not only for their properties, such as biocompatibility, mechanical properties, biodegradation, and convenience of use, but also for demonstrating shape memory effect (SME). In this study, reducing the activation initiation temperature and the SME activation energy was achieved by forming a composite based on PLA containing 10% poly (ε-caprolactone) (PCL). The effect of the plasticizer on the structure, mechanical properties, and especially SME of the composite, was studied by DSC, SEM, FTIR spectroscopy, compression tests, and DMA. By varying the composition, the beginning of the SME activation was reached at 45 °C, and the apparent activation energy of the process decreased by 85 kJ/mol, ensuring safe and effective use of the material as a precursor for temporary self-fitting scaffolds for reconstructive surgery. [ABSTRACT FROM AUTHOR]