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Injection molding is a widely used method for production of plastic components, offering both simplicity and high strength. In this study, secondary injection molding was utilized to weld polyamide 6 (PA6). The welded samples were evaluated for the welding strength via a shear tensile test. Three process parameters of mold temperature, injection temperature, and injection speed were varied to determine the optimal conditions for welding. A polarizing microscope analysis of the welding interface revealed formation of a shish kebab layer (SKL) structure, which significantly contributed to the welding strength. A differential scanning calorimetry analysis of the welded samples showed that changes in the crystallinity at the interface were closely related to the welding strength under different injection molding conditions. To analyze the crystal phase of the interface after welding, we propose the use of Fourier-transform infrared spectroscopy area scanning to obtain the relationship between the phase transformation and welding strength. Additionally, microhardness testing is proposed as a means of evaluation of the welding effect. Overall, this study highlights the importance of optimization of process parameters in secondary injection molding to achieve strong welds in PA6, where the SKL structure and crystallinity changes at the interface have crucial roles. Highlights * The high welding shear strength reaches 80% of the base material. * The interfacial crystalline structure has a significant impact on the strength. * The crystalline changes were analyzed using FTIR region scanning. * The relationship between microhardness and welding strength was obtained. * The wide-ranging conditions have reference value for industrial production. KEYWORDS crystalline phase, Fourier-transform infrared, injection molding, interface, microhardness, polyamide 6, welding strength, 1 | INTRODUCTION Plastics have a significant economic value. Injection molding is used to process more than 33% of all plastics. (1) Thermoplastic resins may be effectively melted and joined [...]

X65 pipeline steel is widely used in the field of offshore oil and gas exploitation due to its excellent performance. However, due to the complex environment in the ocean, X65 pipeline steel is faced with a great risk of microbial corrosion failure. Therefore, it is of great significance to study the corrosion mechanism of X65 pipeline steel by microorganisms. In this paper, the corrosion effect of Pseudomonas aeruginosa (P. aeruginosa) secreting phenazine compounds on X65 pipeline steel was studied by the weight loss method, biofilm scanning electron microscopy analysis, surface corrosion morphology observation, electrochemical testing and medium pH test corrosion products. The results showed that the inoculation of P. aeruginosa accelerated the corrosion of X65 steel. After knocking out the phzM and phzS genes that regulate the synthesis of PYO, P. aeruginosa can still produce biofilms on the surface of X65 steel consistent with the morphology of wild-type P. aeruginosa, but the corrosion of X65 steel is significantly reduced. It is proved that PYO plays an important role in the corrosion process of P. aeruginosa on steel. [ABSTRACT FROM AUTHOR]

Taking Zhushantang Coal Mine as the research background, based on the thermal cycle theory, the original ventilation system of mine central pump room was reformed. The auxiliary shaft was used as the inlet air shaft of the central pump room, the fresh air shaft was used as the return air shaft, and the multi-stage spray room system was set at the wellhead of the auxiliary shaft to construct the thermal cycle system, and the feasibility of the system stability was demonstrated. Finally, the influence of wellbore friction coefficient and wellbore average thermodynamic temperature on the stability of thermal cycle system is analyzed. The results show that: the total ventilation resistance of the thermal cycle system is 131.03 Pa, the ventilation power is 168.63 Pa, the system is stable and reliable; after completion of the thermal cycle system, the air volume load of the mine fan will be released directly by 56.67 m3/s. The total ventilation resistance is positively correlated with the friction resistance coefficient of auxiliary shaft and fresh air shaft. Reducing the friction resistance coefficient of shaft can effectively reduce the total ventilation resistance. The ventilation power is negatively correlated with the average thermodynamic temperature of auxiliary shaft. The lower the average thermodynamic temperature of the auxiliary shaft is, the higher the average thermodynamic temperature of the fresh air shaft is, which is more conducive to the stable operation of the thermal cycle system.

Pour point depressant (PPD) is a crucial addition in the petroleum industry which can significantly enhance the flow properties of crude oil by preventing wax from precipitating out of it. The flow assurance effect of PPD on crude oil is impacted by its molecular structure. As a result, we concentrate on the PPD with various molecular structures, such as carboxyl and benzene rings, to investigate its impact on the flow behavior of crude oil. Then, FTIR and contact angle test were used to describe the characteristics of PPD (SAF-n and SAFS-m). The Karamay crude oil was tested using the following items: pour point, rheology, viscosity, viscoelasticity, and POM. When the crude oil was treated with 1000 ppm SAFS-1, the pour point decreased from 12 to −14 °C and the viscosity decreased from 40.1 to 6.3 pa·s at 0 °C. Meanwhile, the results show that the more variety polar groups PPD has, the more its dispersion increases and the stronger its interactions with crude oil are when its molar ratio of non-polar groups are suitable. These effects may be caused by the PPD changing the crystallization characteristics of wax and the aggregate state of resin and asphalt. [ABSTRACT FROM AUTHOR]

ZnZrOx has been used in large quantities for the preparation of light olefins from CO2, but the relationship between structure and performance remains unclear at present. In this paper, ZnZrOx were prepared by co-precipitation method, and a series of oxides with different sizes were prepared by varying the calcination temperatures. Subsequently, these oxides were combined with SAPO-34 to create a composite bifunctional catalyst for the synthesis of light olefins by CO2 hydrogenation, in which the impact of nanocrystal size effect was examined. The catalytic performance significantly increased as the nanocrystal size reduced from 18 to 12 nm. However, when the nanocrystal size was further decreased to 8 nm, the catalytic performance decline. Characterizations revealed a gradual increase in the number of oxygen vacancies with decreasing nanocrystal size. However, the oxide with the smallest nanocrystal size, prepared by varied calcination temperatures, did not yield the optimal catalytic performance due to sintering occurring during the reaction process. The results show that the assumption that smaller nanocrystal sizes inherently equate to improved catalytic performance is not universally valid, and stability must be considered when the nanocrystal size is decreased. The bifunctional catalysts used in this paper for the prepared light olefins from CO2 in yield as high as 13.8%, which is higher than most previous reports. [ABSTRACT FROM AUTHOR]