Effect and mechanism of reductive polyaniline on the stability of nitrocellulose

The search for new green and efficient stabilizers is of great importance for the stabilization of nitrocellulose(NC). This is due to the shortcomings of traditional stabilizers, such as high toxicity. In this study, reduced polyaniline(r-PANI), which has a similar functional structure to diphenylamine(DPA) but is non-toxic, was prepared from PANI based on the action with N_(2)H_(4) and NH_(3)-H_(2)O, and used for the first time as a potential stabilizer for NC. XPS, FTIR, Raman, and SEM were used to characterize the reduced chemical structure and surface morphology of r-PANI. In addition, the effect of r-PANI on the stabilization of NC was characterized using DSC, VST, isothermal TG, and MMC. Thermal weight loss was reduced by 83% and 68% and gas pressure release by 75% and 49% compared to pure NC and NC&3%DPA, respectively.FTIR and XPS were used to characterize the structural changes of r-PANI before and after reaction with NO_(2). The 1535 cm^(-1) and 1341 cm^(-1) of the FTIR and the 404.98 eV and 406.05 eV of the XPS showed that the -NO_(2) was generated by the absorption of NO_(2). Furthermore, the quantum chemical calculation showed that NO_(2) was directly immobilized on r-PANI by forming -NO_(2) in the neighboring position of the benzene ring.

A green method for synthesizing novel nanoparticles and their application in flexible conductive patterns

A general and unified approach to synthesize Ag,Cu and Au nanoparticles(NPs)is developed at room temperature in air atmosphere under ultrasonication in poly(N-vinylpyrrolidone)(PVP)solutions with ascorbic acid and glucose as the reducing and nucleation agents,respectively.XRD,TEM,and HR-TEM analysis of the Ag,Cu,and Au NPs confirm purity and average diameters of 15.5±2.0 nm,50±3.0 nm,and 10±1.0 nm,respectively.An ultrasonic-assisted mechanism,wherein reduction occurs readily and produces anti-oxidation particles,is proposed and discussed.Fast infrared sintering was used to avoid damaging the substrate of conductive patterns whose resistivity at 10 W(~50℃)sintering power for less than 6 min reached up to 10±0.5 μΩ cm,40±3.0 μΩ cm,and 280±5 μΩ cm for Ag,Cu,and Au patterns,respectively.Paper-based electrodes were produced successfully and exhibited excellent flexibility and good conductivity.The potential of this method for large scale production is discussed.

Engineering crystal phase of polytypic CuInS2 nanosheets for enhanced photocatalytic and photoelectrochemical performance

Crystal phase engineering on CulnS2(CIS)nanocrystals,especially polytypic structure,has become one of the research hotspots to design the advanced materials and devices for energy conversion and environment treatment.Here,the polytypic CIS nanosheets(NSs)including zincblende/wutzite and chalcopyrite/wurtzite types were first time achieved in a hot-injection system using oleic acid and liquid paraffin as the reaction media.As-obtained polytypic CIS NSs exhibit significantly enhanced light-absorption abillty and visible-light-driven photocatalytic performance originating from the rational hetero-crystalline interfaces and surface defect states,which efficiently inhibit the recombination of photo-generated carriers.Meanwhile,the polytypic CIS NSs were spin-coated onto the surface of fluorinated-tin oxide glass substrate and used as the photoelectrode,which shows an excellent photoelectrochemical(PEC)activity in aqueous solution.The present work not only provides a facile,rapid,low-cost,and environmental-friendly synthesis strategy to design the crystal phase and defect structure of ternary chalcogenides,but also demonstrates the relationships between the polytypic structure and photocatalytic/photoelectrochemical properties.

Digital high-efficiency print forming method and device for multi-material casting molds

Sand mold 3D printing technology based on the principle of droplet ejection has undergone rapid development in recent years and has elicited increasing attention from engineers and technicians.However,current sand mold 3D printing technology exhibits several problems,such as single-material printing molds,low manufacturing efficiency,and necessary post-process drying and heating for the manufacture of sand molds.This study proposes a novel high-efficiency print forming method and device for multi-material casting molds.The proposed method is specifically related to the integrated forming of two-way coating and printing and the shortflow manufacture of roller compaction and layered heating.These processes can realize the high-efficiency print forming of high-performance sand molds.Experimental results demonstrate that the efficiency of sand mold fabrication can be increased by 200%using the proposed two-way coating and printing method.The integrated forming method for layered heating and roller compaction presented in this study effectively shortens the manufacturing process for 3D-printed sand molds,increases sand mold strength by 63.8%,and reduces resin usage by approximately 30%.The manufacture of multi-material casting molds is demonstrated on typical wheeled cast-iron parts.This research provides theoretical guidance for the engineering application of sand mold 3D printing.

Preparation of P2O5-SiO_(2) hollow microspheres in the presence of phosphoric acid

Silica hollow microspheres containing phos-phorous have been prepared by a sol-gel/emulsion method which uses tetraethoxysilane(TEOS)as the precursor for the SiO_(2) and phosphoric acid(H3PO4)as the precursor for P2O5.The hollow structure forms an emulsion system which is composed of an oil phase(kerosene,sorbitan monooleate(Span 80))and an aqueous phase(a viscous sol solution of ethanol,TEOS and H3PO4).Some of the phosphorous remains in thefinal silica shell structure even after calcination at 650°C.The hollow structure of the P2O5-SiO_(2)(silicophosphate)was characterized by X-ray diffraction(XRD),polarized optical microscopy(POM),scanning electron microscopy(SEM),nitrogen adsorption measurement and Fourier transform infrared spectroscopy(FTIR).