Preparation and properties of fluffy high-shrinkage polyester/polyamide 6 hollow segmented pie microfiber nonwovens

Bicomponent spunbond hydroentanglement technology can break the interface between the two components by physical extrusion and shearing, thereby realizing the green and efficient production of high-strength microfiber nonwoven materials. Herein, we report a soft and fluffy bicomponent spunbond hydroentanglement nonwoven material using high-shrinkage polyester/polyamide 6 (HSPET/PA6) as the bicomponent. HSPET/PA6 hollow segmented pie composite fibers with different volume ratios were prepared by spunbond technology, the HSPET and PA6 segments were alternately arranged, and the interface was flat. The composite fibers were split by heat treatment. The dry heat shrinkage rates of the composite fibers were 8.45% (50/50) and 10.57% (70/30), and the boiling water shrinkage rates were 10.02% (50/50) and 12.27% (70/30). HSPET/PA6 hollow segmented pie microfiber nonwovens were prepared by hydroentanglement technology. After heat treatment, the fibers of nonwovens were further split and the HSPET fibers curled, giving the nonwovens a fluffy characteristic. By comparing the properties of HSPET/PA6 after heat treatment, the shrinkage effect of the water bath was obviously better than that of dry heat, and the split degree of fibers reached 81.97% (50/50) and 84.65% (70/30). Compared with polyester/PA6 nonwovens, the softness of HSPET/PA6 nonwovens increased by 45.1% (50/50) and 49.3% (70/30) after boiling water shrinkage. At the same time, the mechanical properties of HSPET/PA6 nonwovens were also improved. The successful fabrication of HSPET/PA6 microfiber nonwovens provides a new method for enhancing the softness of bicomponent spunbond hydroentanglement nonwovens.

Research of deformation compensation method in laser metal deposition process of 316L stainless steel product

It is exists the problem of big product manufacturing with minimal dimensions tolerances. To solve this problem it is necessary to compensate the deformations influence. In researching of method, it became clear that deformation degree has changed and depended on size and form of part. However, the amount of deformation degree to dimension of part is still independent of size. This fact has observed after production of axis-symmetrical parts. The simple axis-symmetrical part was built up. The dimensions of part was measured, and the compensation coefficient was calculated. The dimensions of part was scaled on this coefficient for compensation of shrinkage effect. After that the experiment was repeated.

Synthesis and Optical Properties of B-Mg co-Doped ZnO Nanoparticles

Doping impurity into ZnO is an effective and powerful technique to tailor structures and enhance its optical properties. In this work, Zn1−xMgxO and Zn1−x−yMgxByO nanoparticles (x = 0, 0.1, 0.2, 0.3, 0.4; y = 0, 0.02, 0.04) were synthesized via one-pot method. It shows that the Mg and B dopants has great influence on crystallinity and surface morphology of ZnO nanoparticles, without changing the wurtzite structure of ZnO. The band structure study indicates that the competition of Conductive Band (CB) shift, Burstein–Moss (B-M) shift and Shrinkage effect will cause the band gap energy change in ZnO.

Gas flow rate evaluation in coal coupling the matrix shrinkage effect caused by water extraction

Estimating production in coal accurately is crucial for promoting the process of safe, efficient and green coal mining. It has been gradually recognized that horizontal wells with multiple fractures are employed to develop the coal reservoir, which signifies that the linear flow regime will dominate for a rather long time. However, the traditional analysis approaches of transient linear flow regime may yield the overestimation of coal reservoir property. In this work, a new analytical model was proposed to estimate the rate-transient of wells with multi-fractures in coal reservoir that produce at a constant flowing-pressure, which takes multiple flow mechanisms into consideration. Especially, the matrix shrinkage effect caused by water extraction from microscopic pores was incorporated, which has never been investigated by current production analysis models. In comparison with the conventional reservoir, the advanced pseudo-pressure and pseudo-time equations incorporating above critical mechanisms were established, including the four effects of gas slippage, effective stress, and matrix shrinkage caused by gas desorption/water extraction. In addition, the excellent agreement between the predicted rate by the proposed model and field data was achieved to validate the reliability of proposed models. Furthermore, the sensitivity analysis was carried out to clarify the influence of a series of factors on the seepage mechanism and productivity curve. Results demonstrated that the matrix shrinkage effect caused by water extraction may increase the well production rate in coal reservoir. Selecting one field case as an example, the production rate predicted by the red curve is obviously higher than that by the green curve, the average discrepancy yields around 39.5%. The relative humidity in coal matrix will present a positive impact on well production performance. Taking a field case as an instance, when the relative humidity varies from 8% to 14%, the well production sharply increases by about 11.6%.

Fluid Performance in Coal Reservoirs: A Comprehensive Review

The fluids in coal reservoirs mainly consist of different gases and liquids, which show different physical properties, occurrence behaviors, and transport characteristics in the pore-fracture system of coal. In this study, the basic characteristics of fluids in coal reservoirs are firstly reviewed, consisting of coalbed methane (CBM) components and physical properties of CBM/coalbed water. The complex pore-fracture system mainly provides the enrichment space and flow path for fluids, which have been qualitatively and quantitatively characterized by various methods in recent years. Subsequently, this study has summarized CBM adsorption/desorption behaviors and models, the CBM diffusion-seepage process and models, and gas-water two-phase flow characteristics of coal reservoirs. Reviewed studies also include the effects of internal factors (such as coal metamorphism, petrographic constituents, macroscopic types, and pore structure) and external factors (such as pressure, temperature, and moisture content) on CBM adsorption/desorption and diffusion behaviors, and the relationship between three main effects (effective stress, gas slippage effect, and coal matrix shrinkage effect) and the CBM seepage process. Moreover, we also discuss in depth the implication of fluid occurrence and transport characteristics in coal reservoirs for CBM production. This review is aimed at proposing some potential research directions in future studies, which mainly includes the control mechanism of the microscopic dynamics of fluids on CBM enrichment/storage; enhancing CBM desorption/seepage rate; and the synergistic effect of multiple spaces, multilevel flow fields, and multiphase flow in coal reservoirs. From this review, we have a deeper understanding of the occurrence and transport characteristics of fluids in pore-fracture structures of coal and the implication of fluid performance for CBM production. The findings of this study can help towards a better understanding of gas-water production principles in coal reservoirs and enhancing CBM recovery.

Influence of the binder technological shrinkage on the strength of composite reinforcement

A structural and mechanical analysis of the effect of polymer binder technological shrinkage on the destruction mechanisms and strength at break of construction composite reinforcement has been carried out. Using the results of our own experimental studies, as well as published data of other researchers, the differences in the destruction mechanisms of fiberglass and carbon fiber reinforcement are shown. A calculated assessment of the polymer shrinkage effect in the anchor sleeve on the appearance of additional shrinkage stresses in the interface between the reinforcement bar and the test anchor sleeve has been made. The results obtained make it possible to modernize the methodology for predictive assessment of the strength of composite construction reinforcement and can be used by engineering and technical workers of manufacturers and consumers of such reinforcement, as well as in the educational process in the preparation of engineering personnel for the construction profile.

Production accuracy of polymer composite material components

The main conditions of manufacturing support of the quality of polymer composite material components are set out. The life cycle, functional, design and technological tolerances, the surface layer quality and methods for providing preset accuracy are discussed. The classification of manufacturing types is given. The shrinkage effect is considered on an example of polymer composite components produced with different accuracy. The quality characteristics of the surface layers and the quality class values are presented for components based on the thermoplastic and thermosetting matrixes.

Optical Absorption and Photoluminescence in Defect-Stannite-Type Semiconductor ZnGa2Se4

Optical absorption and photoluminescence (PL) spectra were measured on defect-stannite-type semiconductor ZnGa2Se4 at temperatures T from 11 to 300 K. The square of the absorption coefficient spectra showed distinct two absorption edges, which were E0A,B and E0C,D transitions at Γ point in the Brillouin zone. The temperature dependence of the direct-gap energies, E0A,B and E0C,D, of ZnGa2Se4 were determined and fit using the analytical four-parameter expression developed for the explanation of the band-gap shrinkage effect in semiconductors. The PL emissions at near band-edge and at higher energy than band-edge were also observed at T ≤ 150 K.