Optimization study on wet electrostatic powder coating process to manufacture UHMWPE/LDPE towpregs

In the present study, an attempt has been made to coat the non-conductive Ultra-high Molecular Weight Polyethylene (UHMWPE) fibers with Low-Density Polyethylene (LDPE) powder. In order to enable the deposition of electrostatically charged LDPE powder onto the fiber surface, UHMWPE fibers are dipped into a surface modification bath to impart momentary conductivity. Further, Box Behnken’s experimental design is used to optimize the processing parameters for Fiber Volume Fraction (Vf) for this wet electrostatic spray coating process. An experimental multi-parametric equation is acquired through response surface methodology to ascertain the association amid the process parameters such as processing temperature (A), conveying air pressure (B), and gun nozzle angle (C) on the output response of Vf. The process parametric values for A, B, and C are varied from 225°C to 245°C, 0.2 bar to 0.4 bar, and 0° to 120° respectively. The Vf obtained is in the range of 37.02%–56.28% depending on the combination of process parametric values. Powder pick-up increases with an increase in the gun nozzle angle. An increase in conveying air pressure and temperature of the hot air oven leads to an increase in powder deposition. The values predicted from the model are observed to be in close proximity (94.59%) to the experimental results. Gun nozzle angle is the principal parameter affecting the matrix deposition on the fiber surface in comparison to other process parameters.

A study on the processing technology for Rhizoma Coptidis

Background The present study intends to optimize the processing technology for the wine-processing of Rhizoma Coptidis, using alkaloids as indicators. Method In the present study, the Box–Behnken design method was adopted to optimize the processing technology for Rhizoma Coptidis, using the alkaloid component quantities as the index. 100 g of Rhizoma Coptidis slices and 12.5 g of Rhizoma Coptidis wine were used. After full mixing, box-Behnken design method was used to optimize the processing time, processing temperature and processing time of coptis chinensis by taking alkaloid content as index. After mixing well, these components were fried in a container at 125 °C for 6 min and exhibited good parallelism. Results The content of alkaloids in coptis chinensis was the highest after roasting at 125 °C for 6 min. The characteristic components were berberine hydrochloride, and the relative content was about 15.96%. And showed good parallelism. The effective components of Rhizoma Coptidis were primarily alkaloids. Conclusion The optimized processing technology for Rhizoma Coptidis is good.

Influence of Different Carbon Content on Reduction of Zinc Oxide via Metal Bath

Electric arc furnace dust (EAFD) is an important secondary resource for the zinc industry. The most common process for its recycling is the pyro-metallurgical treatment in the Waelz process. However, this process focuses on the recycling of the zinc, whereas the recovery of other metals from the EAFD—such as iron and other alloying elements—is neglected. An up-to-date version of reprocessing can involve multi-metal recycling by means of a metal bath containing carbon. The use of a liquid iron alloy requires a higher processing temperature, which enables the reduction and melting of iron oxides as well as other compounds occurring in the dust. Furthermore, the Zn yield is higher and the reduction kinetics are faster than in the Waelz process. This paper is only focused on the zinc reduction in such a metal bath. In order to determine the influence of the carbon content in the molten metal on the reduction rate, experiments were carried out on the reduction behavior of zinc oxide using a synthetic slag. This slag, with a basicity B2 = 1, was applied to an iron bath with varying carbon contents. (0.85%, 2.16%, 2.89%, and 4.15%) The decrease in the zinc oxide concentration was monitored, along with the reaction rates calculated from these data. It was found that the reaction rate increases with rising carbon content in the melt.

Joint Analysis and Reliability Test of Epoxy-Based Nano Silver Paste Under Different Pressure-Less Sintering Processes

Recent years, the sintered silver paste was introduced and further developed for power electronics packaging due to low processing temperature and high working temperature. The pressure-less sintering technology reduces the stress damage caused by the pressure to the chip, improves reliability, and is widely applied in manufacturing. Currently, most existed studies are focused on alcohol-based sintered silver pastes while resins have been demonstrated to improve the bonding properties of solder joints. Hence, the performance and sintering mechanisms with epoxy-based silver paste need to be further explored. In this work, a methodology for multi-factor investigation is settled on the epoxy-based silver paste to reveal the relationship between the strength and the different influence factors. We firstly analyzed the characteristics of commercialized epoxy-based silver paste samples, including silver content, silver particle size, organic paste composition, sample viscosity, and thermal conductivity. Samples were then prepared for shear tests and microstructure analysis under different pressure-less sintering temperatures, holding time, substrate surface, and chip size. Full factor analysis results were further discussed in detail for correlation. The influence factors were ranked from strong to weak as follows: sintering temperature, substrate surface, chip size, and holding time. Finally, a thermal cycling test was carried out for reliability analysis. Epoxy residues are one of the possible reasons which result in shear strength decreasing exponentially.

Influence of Thermal Processing for 3D Printed Components

In the medical field the additive manufacturing process by fused deposition modeling has gained a great importance given the ability to create complex, organic geometries, in a short time period and the possibility of high customization. By fused deposition process the part is created layer by layer and the resulting part is characterized by high anisotropy, dictated mostly by printing parameters. To alleviate the anisotropy and to study the mechanical behavior of the 3D printed parts thermal processing is used. The materials used as filament is a poly (lactic acid) with copper particles embedded for antibacterial purposes. Samples were 3D printed using a commercial printer, thermally processed and tested in compression. On the failed specimens fracture investigations were performed to understand mechanical behavior during compression. The mechanical characteristics showed improvement and the anisotropy decreased as the processing temperature increased, but the samples became brittle. The mechanical behavior changed drastically on the thermally processed samples because of structural changes: a discontinuity between exterior layers and infill layers was created post layer fusion, the first region being the one stressed and failed first during tests.

Low temperature and high performance ZnSnO thin film transistors engineered by in-situ thermal manipulation

Thin film transistors (TFT) with low cost, high mobility and low processing temperature are key enablers for practical application, which are always contradictory. In this work, we achieved high performance...

Three-dimensional printing of ramipril tablets by fused deposition modeling

Introduction. Arterial hypertension is one of the main risk factors for the development of cardiovascular diseases. Drug treatment of arterial hypertension is associated with a number of difficulties: often requires combination therapy, also a possible change in either dosages or drugs during treatment during the patient's life. Three-dimensional printing allows to create individual medicines on-demand.Aim. Study suitability of Kollidon® VA 64 as a matrix-polymer for the preparation of immediate release ramipril printing tablets.Materials and methods. Substance: ramipril; excipients: Kollidon® VA 64, Kollidon® CL-F, Soluplus®, PEG 1500, sodium carbonate anhydrous, Poloxamer 188, sodium stearyl fumarate, mannitol; reagents: hydrochloric acid, acetonitrile for ultra-HPLC, sodium octanesulfonate for HPLC, orthophosphoric acid 85 %, sodium perchlorate analytical grade, triethylamine, standard: ramipril USP (№1598303). Ramipril filaments were prepared by hot melt extrusion on the extruder Haake™ miniCTW (Thermo Fisher Scientific). The tablets were printed on a hand-made 3D printer. The printlets were studied for friability and hardness. Uniformity and quantitative determination of ramipril and impurities in tablets and filaments were determined by high performance liquid chromatography on a Shimadzu Prominence LC liquid chromatograph. Stability of ramipril was studied on a DSC 3+ Mettler Toledo by differential scanning calorimetry. Also, the stability of ramipril was determined by the Raman spectroscopy on an analytical system ORTES-785TRS-2700.Results and discussion. Ramipril filaments with a diameter of 1.75 mm were obtained by melt extrusion at a temperature of 105 °C. They were homogeneous in quantitative content of the active substance. From the resulting filaments, tablets were printed in five configurations with three filling densities: 30 %, 50 % and 100 %. Degradation of ramipril in filaments and tablets is not observed. The melting point of the selected mixture is lower than the melting point of matrix-polymer. It makes possible to lower the processing temperature. Tablets with 100 % filling provide an immediate release of ramipril.Conclusion. Kollidon® VA 64 is suitable as a matrix-polymer for the development of immediate release ramipril printlets. Kollidon® VA 64 provides the necessary physical and processing properties of the filament required for FDM printing.

Improved interfacial performance of carbon fiber/polyetherimide composites by polyetherimide and modified graphene oxide complex emulsion type sizing agent

In the field of interfacial enhancement of composite, sizing method has attracted extensive attention. In this research, a new complex emulsion type sizing agent containing polyetherimide (PEI) and covalently chemical functionalized graphene oxide (GO) was first proposed to further improve the interfacial adhesion of carbon fiber (CF)/PEI composites, adapt to the high processing temperature, and overcome the shortcomings of the solution type sizing agent. The emulsion was prepared by the emulsion/solvent evaporation method. In order to avoid the agglomeration of nanomaterials on CF surface, the monomer and polymer structure of PEI was used to functionalize GO, so as to achieve better compatibility and dispersion of GO in PEI. The physicochemical state of CF surface was characterized and the successful introduction of GO was verified. The microbond test revealed that the introduction of GO further improved the IFSS compared with only PEI sizing. When GO grafted with PEI was used as the main component of the sizing agent, the IFSS reached the largest with an increasement of 55.96%. The mechanism of interfacial reinforcement was proposed. Increased ability of mechanical interlocking, the mutual solubility between PEI molecular chains, and the improvement in wettability may be beneficial to the interfacial strength. This mild and effective modification method provided theoretical guidance for the interfacial enhancement of composites and was expected to be applied in industrial production.

Effects of Injection Molding Parameters on Properties of Insert-Injection Molded Polypropylene Single-Polymer Composites

The reinforcement and matrix of a polymer material can be composited into a single polymer composite (SPC), which is light weight, high strength, and has easy recyclability. The insert injection molding process can be used to realize the multiple production of SPC products with a short cycle time and wide processing temperature window. However, injection molding is a very complicated process; the influence of several important parameters should be determined to help in the future tailoring of SPCs to specific applications. The effects of varying barrel temperature, injection pressure, injection speed, and holding time on the properties of the insert-injection molded polypropylene (PP) SPC parts were investigated. It was found that the sample weight and tensile properties of the PP SPCs varied in different rules with the variations of these four parameters. The barrel temperature has a significant effect, followed by the holding time and injection pressure. Suitable parameter values should be determined for enhanced mechanical properties. Based on the tensile strength, a barrel temperature of 260 °C, an injection pressure of 127.6 MPa, an injection speed of 0.18 m/s, and a holding time of 60 s were determined as the optimum processing conditions. The best tensile strength and peel strength were up to 120 MPa and 19.44 N/cm, respectively.

Effect of transglutaminase on fresh cheese quality propertises using citric acid as a coagulant

The purpose of this study was to evaluate the effect of microbial transglutaminase (MTGase) on cheese quality properties using citric acid as a coagulant agent. The experimental results showed that citric acid has a temperature-dependent ability to agglomerate milk proteins. The process of protein coagulation at 50°C by citric acid (2.0%) gave fresh cheese with yield production (% H), dry matter content (% TS) and cheese solids yield (CSY) of 12.81%, 41.17%, 38.73%, respectively. The reconstituted milk was incubated with MTGase under different conditions of enzyme concentration (0-6.0 IU / g protein), processing temperature (30-50 °C) and time (60-180 min.). Enzyme treatment at 37 °C with enzyme concentration of 2 IU/g protein for 2 hrs showed the highest values of yield (15.03%), dry matter content (46.96%) and cheese solids yield (46.83%). Analytical results of the sensory score, acidity, whey separation and color difference of fresh cheese samples during storage (28 days) showed that using MTGase better maintained the quality of the product. Furthermore, MTGase also improved water holding capacity (reduced whey separation) during storage and did not affect the color of fresh cheese products. Moreover, the physicochemical and microbiological parameters of the product were also determined. The results showed that the quality of fresh cheese coagulated by citric acid met CODEX STAN 221-2001 for unripened cheese including fresh cheese.