Holding Pressure Time Research Articles

Ultra-high pressure assisted extraction of water-soluble polysaccharides from Moringa oleifera seed husks and their antioxidant activities

ABSTRACT The process conditions and antioxidant activity of ultra-high pressure assisted extraction of polysaccharides from Moringa oleifera seed husks were studied. Taking the yield of polysaccharides as the index, the effects of degree of crushing, extraction pressure, holding pressure time and material-to-liquid ratio on the yield of polysaccharides from Moringa oleifera seed husks were investigated. The optimal extraction conditions were determined by single-factor test and orthogonal test: a holding time of 10 min, a material-to-liquid ratio of 1:25, an extraction pressure of 350 MPa, and a polysaccharide yield of 0.264%. Its antioxidant activity can be determined by measuring the total antioxidant capacity and their ability to scavenge DPPH and ·OH radicals. The results showed that the IC50 of Moringa oleifera seed husk polysaccharides on DPPH and hydroxyl radicals were 0.0662 g/L and 0.0844 g/L, respectively. The total antioxidant capacity was 0.1826 mm/g (expressed as the equivalent concentration of ferrous sulfate). Compared with hot water extraction methods, ultra-high pressure assisted extraction methods can shorten extraction time, improve extraction efficiency. The water-soluble polysaccharides extracted from Moringa oleifera seed husks by ultra-high pressure assisted extraction technology also have higher antioxidant activity than that by hot water extraction method at the same concentration.

Determination of electromagnetic traveling path in polymer/multi‐walled carbon nanotube nanocomposite foams and analysis by Taguchi technique

AbstractThe attenuation of electromagnetic (EM) energy with polymeric nanocomposite foams is significant because the microwave energy is diminished by multiscattering of EM into microcellular structure. In this study, acrylonitrile butadiene styrene (ABS) and multi‐walled carbon nanotubes (MWCNTs) nanocomposite foams were fabricated via a chemical foaming in an injection‐molding process. It was demonstrated that the skin depth in foamed ABS/MWCNT specimens was fallen dramatically compared to their solid counterparts. The diminution of skin depth for foamed ABS/1 wt% of MWCNT nanocomposite was 21.7% compared to solid pure ABS. The reflectance of pure ABS was decreased by foaming but it was increased in foamed ABS/MWCNT nanocomposite. The absorption of microwave was improved by foaming and adding MWCNTs in ABS matrix. The utmost value of the experimental absorption shielding effectiveness (SEA. experimental), 14.26 dB, was found for the foamed ABS/1 wt% of MWCNT, holding pressure of 2 s and cooling time of 60 s F8, at 8.7 GHz. It was demonstrated that traveling path of EM wave was prolonged by the introduction of microcellular structure in ABS/MWCNT nanocomposite. Moreover, the contribution of MWCNT, holding pressure time, and cooling time to traveling path were achieved 76.7%, 8.5%, and 7.3%, respectively.Highlights ABS/MWCNTs nanocomposite foams were fabricated by chemical foaming process. Skin depth in foamed nanocomposite samples was fallen compared to solids. Reflectance of pure ABS was decreased by foaming. Absorption of microwave was improved by foaming and MWCNTs. Traveling path of EM wave was prolonged by microcellular structure.

Finite Element Analysis and Experimental Study on Magnetorheological Fluid Seal of the Hydraulic Cylinder

In order to solve the leakage problem of the engineering mechanical hydraulic cylinder, a magnetorheological fluid (MRF) seal structure with a multistage source is designed. The magnetic field in the gap of the sealing structure is analyzed by ANSYS finite element analysis method, the influence about the number of magnetic sources and the length of pole teeth on the pressure capability of the MRF seal is studied, and the results are analyzed. The results show that the suitable number of magnetic sources is 10; The length of the pole teeth with the best magnetic concentrating effect is 0.7 mm. Then, the influence of the MRF injection volume, reciprocating speed, reciprocating distance and holding pressure time of the hydraulic cylinder on the MRF sealing pressure capability is studied. The experimental results show that the maximum pressure capacity can be achieved when the MRF injection volume is 12 ml. With the increase of reciprocating speed, the pressure capability of the MRF seal decreases obviously. With the increase of reciprocating distance and holding time, the sealing pressure capability has no obvious change. Through the finite element analysis and experimental study of the MRF seal, it is of great significance to develop a device with high sealing performance suitable for the hydraulic cylinders.

High pressure treatment and green tea extract synergistically control enteric virus contamination in beverages

Consumers are driving food production toward the use of natural preservatives and minimal processing technologies. Green tea extract (GTE) at low concentration could be combined with high pressure processing (HPP) for reduced treatment times and quality impact on foods in a hurdle concept for synergistic effects on foodborne viral pathogens, specifically human norovirus and hepatitis A virus (HAV). Viral inactivation by HPP (at 300, 400, and 500 MPa for 5 min) combined with 3.3 mg/mL aged-GTE was initially evaluated in buffer (PBS) against murine norovirus (MNV), a culturable human norovirus surrogate, and HAV. Furthermore, human norovirus inactivation was evaluated by the novel human intestinal enteroid system (HIE) and a capsid integrity binding assay (ISC-RT-qPCR). HPP treatment completely inhibits human norovirus GII.4 infectivity when applied at 500 MPa alone and at 400 MPa combined with aged-GTE. Additional experiments investigated the reduction of MNV and HAV infectivity in apple and horchata juices exposed to combined aged-GTE and HPP treatments. Results demonstrated that the addition of aged-GTE to the juices exposed to HPP significantly inactivated MNV and HAV at reduced holding pressure time. This synergistic effect of aged-GTE combined with HPP treatments represents a hurdle technology that could be exploited as a control measure to improve the food safety of beverages.

사출성형해석을 이용한 ASTM 굴곡시편의 사출조건 결정방법 연구

An essential condition for minimizing the cost of quality loss by mass-producing high-quality injection molded products in a short period is the optimization of the injection process condition. As an ASTM D790 flexural strength specimen of PA46 TW341 raw material, molding analysis was performed using the Taguchi method and Minitab to determine the injection weight, which is a factor for optimal quality condition. In addition, the quality of the flexural strength of the specimen was verified by injection molding into the specimen mold and conducting a flexural strength test. The optimum conditions, such as injection time, injection pressure, holding pressure, and holding pressure time, which are key factors of injection molding, were predicted and verified. Good quality was confirmed by evaluating the flexural strength of the injection-molded specimen.

Induced network-based transfer learning in injection molding for process modelling and optimization with artificial neural networks

The necessity of an abundance of training data commonly hinders the broad use of machine learning in the plastics processing industry. Induced network-based transfer learning is used to reduce the necessary amount of injection molding process data for the training of an artificial neural network in order to conduct a data-driven machine parameter optimization for injection molding processes. As base learners, source models for the injection molding process of 59 different parts are fitted to process data. A different process for another part is chosen as the target process on which transfer learning is applied. The models learn the relationship between 6 machine setting parameters and the part weight as quality parameter. The considered machine parameters are the injection flow rate, holding pressure time, holding pressure, cooling time, melt temperature, and cavity wall temperature. For the right source domain, only 4 sample points of the new process need to be generated to train a model of the injection molding process with a degree of determination R2 of 0.9 or and higher. Significant differences in the transferability of the source models can be seen between different part geometries: The source models of injection molding processes for similar parts to the part of the target process achieve the best results. The transfer learning technique has the potential to raise the relevance of AI methods for process optimization in the plastics processing industry significantly.

Effects of pressure densification on strength and properties of cassava waste briquettes

Cassava waste has the potential to be used as an energy source. The aim of this study was to analyze the effects of pressure densification on the properties of cassava residue briquettes, especially on the strength of the briquettes. It was used three compaction pressures: 102, 153, and 204 MP A and three pressing hold times: without holding pressure time, 60s, and 120 s, to produce briquettes without heating and verify their formation concerning the compaction. The proximate analysis provided 72.50% to volatile, 13.10% to Fixed carbon, and 14.45% to ash; the higher heating value (HHV) was 17.12 MJ/kg. The cassava rhizome waste (bulk density) showed an energy density of 2.04 GJ/m3. With densification, it obtained an energy density of 15.7 GJ/m3, representing an increase of up to 7.7 times. We obtained higher durability (94,1%) for time pressing of 120s and pressure of 204 MP A. The briquette volumetric stabilization occurred 24 h after production, and we observed that the briquettes produced with a higher compaction pressure showed greater density and resistance. Cassava rhizome biomass showed good energy properties. The densification process can be an alternative to solving transportation, handling, and cassava rhizome residues.

Effect of Forming Technology on the Properties of Quartz Sands Porous Materials via Dry Pressing Method

The effect of forming technology on the properties of quartz sand porous materials were researched with the low grade quartz sand along the Yangtze River via the pressureless sintering method in this paper, which lay technology foundation for researching new heat insulating materials. The wear of ball milling media is investigated through adjusting the ball milling parameter via the weigh methods. The results are shown that the porosity of quartz sand porous materials are decreased with increasing a forming pressure. The porosities of Φ30 and Φ50 materials are decreased with increasing a holding pressure time, however, the porosity decreasing rate of Φ30 is slower than that of Φ50. The porosity of Φ50 is higher than that of Φ30 under same forming conditions. Through optimized the forming conditions, the porosity of sintered Φ50 quartz matrix porous materials reaches 54.52% under the forming pressure for 5MPa and the holding pressure time for 5min.

Optimizing Glass Fiber Molding Process Design by Reverse Warping.

The purpose of this study is to clarify the influence of changes in glass fiber properties on warpage prediction, and to demonstrate the importance of accurate material property data in the numerical simulation of injection molding. In addition, this study proposes an optimization method based on the reverse warping agent model, in which the thermal conductivity of the plastic material is reduced, and the solidified layer on the surface of the mold is reduced and transferred from the molding material to the mold wall. This means that by the end of the cooling phase, the shrinkage of the molten zone within the component will continue, resulting in warpage. Based on the optimal process parameters, the sensitivity of the warpage prediction to the relationship between the two most important material properties, the glass fiber and holding pressure time, was analyzed. The material property model constants used for numerical simulations can sometimes vary significantly due to inherent experimental measurement errors, the resolution of the test device, or the manner in which the curve fit is performed to determine the model constants. This model has been developed to intelligently determine the preferred processing parameters and to gradually correct the details of the molding conditions. Thus, the cavity is separated in the critical warpage region, and a new cavity geometry with a reverse warped profile is placed into the mold base slot. The results show that the hypothetical and reasonable variation of the glass fiber model constant and the holding pressure time relationship may significantly affect the magnitude of the warpage prediction of glass fiber products. The greatest differences were found as a result of the warping orientation of the glass fiber material.

Effect of Molding Processing on Properties of YAG Porous Ceramics via Dry Pressing Molding Method

YAG materials have a number of unique properties, the application is very extensive. In order to improving the properties of YAG porous materials, the effect of forming processing on the properties of YAG porous ceramics is investigated. Through the results and analysis, the conclusions showed that the porosity of YAG porous ceramics gradually decreased with the molding pressure increases, and the compressive strength of YAG porous ceramics shows a rising trend. The size and number of pores in the microstructure are reduced with increasing the forming pressure, there are inherently many voids in the YAG porous ceramics body at low forming pressures. The porosity of YAG porous ceramic decreases with the increase of dwell time, however, the process of extending from 5 min to 10 min is much faster than the rate of descending from 10 min to 15 min. The size and number of pores in the microstructure are reduced with extending the holding pressure time, which also makes YAG porous ceramics pose the higher mechanical strength. Through the analysis of the results, when the forming pressure is 10MPa, the porosity of YAG porous ceramics is 41.11% and the compressive strength is 5.8MPa, the porosity and compressive strength of YAG porous ceramics is better.

Preparation and Characterization of Al<sub>2</sub>O<sub>3</sub>-Al Cermet with Coated Microstructure Using Powder Metallurgy Method

Cermet includes the excellent properties of ceramic materials and the advantages of metal materials, so it is an important new engineering material. In this paper, Al2O3-Al cermet is prepared using different molding process via the powder metallurgy method to study the properties of Al2O3-Al cermet. The conclusion are shown the increasing density of Al2O3-Al cermet is not obvious with increasing the forming pressure of cermet body during the initial and late processing, but the increasing density is more obvious under the forming pressure for 20-30MPa. The density of cermet materials are increased with prolonging holding pressure time, the initial increase speed is faster, and the later growth rate becomes weaker. When the molding pressure is 30MPa, the holding time is 10min, the sintering temperature is 900°C, the holding time is 1h, the prepared Al2O3-Al cermet adding sintering aids has a coated microstructure, which indicates that the large number of particles is migrated on the grain boundary. The sample density is 2.26g/cm3, the density is highest, the distribution of Al2O3 and Al phase is the most uniform. The buried sintering method is more suitable for the preparation of Al2O3-Al cermet composites than the nudity sintering method.

Effect of Molding Processing on Properties of Al<sub>2</sub>O<sub>3</sub>-Al Cermet Prepared via Powder Metallurgy Method

Cermet while maintaining the excellent properties of ceramic materials, but also have the advantages of a metal material, is an important new engineering materials. In this paper, Al-Al2O3 cermet is prepared using different molding process via the powder metallurgy method to study the properties of Al-Al2O3 cermet. The conclusions are shown the density of the initial and late increase is not obvious with the cermet body forming pressure increases, but the increase in density of 20-30MPa is more obvious. The density of the cermet material increases with prolonging holding pressure time is shown, the initial increase speed is faster, and the later growth rate becomes weaker. In the different molding pressure, the pressure is 40MPa and 15min, sintering temperature is 700°C and 1h, the sample density is 2.084g/cm3, the highest density, the best performance, aluminum and alumina distribution is the most uniform.

The Effects of Processing Parameters and AC Foaming Agent on the Mechanical Properties and Morphology of Foamed Wood-Polylactic Acid (PLA) Composites

Wood flour, PLA, and other additives were mixed evenly in a high speed mixing machine. The granules were prepared by melt blending and extrusion granulating with a twin-screw extruder, and test specimens were molded by a plate curing machine. By changing the heating temperature, the molding pressure, the holding pressure time, and azodicarbonamide (AC foaming agent) contents, the influences of four factors on the apparent density, the mechanical properties, and the morphology of the biodegradable foamed WPCs were investigated. The best processing parameters and the optimum AC foaming agent content were obtained. When heating temperature was 178 °C, heating time was 10 min, holding pressure time was 25 s, and molding pressure was 7 MPa, the test specimen was lighter in color, with a smooth surface and dense, uniform cross section. The mechanical properties (flexural strength and impact strength) of the foamed WPCs were relatively good. When adding 1% AC foaming agent, the foamed WPCs showed uniformly distributed microcellular structure, and the average pore diameter was about 67 µm. The density was reduced by 18.6%, and the flexural strength and impact strength were increased by 128.6% and 40%, respectively, compared with non-foamed WPCs.

Densification Mechanism of Al<sub>2</sub>O<sub>3</sub>/Al Metallic Ceramics Prepared via Powder Metallurgy Method

Alumina ceramics with good mechanical and corrosion resistance, is one of the most widely used engineering ceramics. The aluminum has a high strength, high conductivity, high plasticity, etc. than aluminum ceramics used in more and more industries. In this paper, aluminum and alumina powder as raw material, mixing, forming, sintering and a series of processes for preparing the alumina/aluminum metallic ceramic materials, through performance testing and analysis can be found in the ratio of raw materials 50wt% Al, 50wt % Al2O3 relatively good moldability. After sintering, after measuring the density contrast is found better density in the pressing process pressure of 20MPa and holding pressure time for 20min. By comparing the sintering process, after the interface structure by scanning electron microscopy and found help improve density through the secondary sintering metallic ceramic materials.

Injection Molding of Beverage Container Caps Made of a Composite Consisting of Wood Cellulose Fiber and an Ethylene-Acrylic Acid Copolymer

Abstract The influence of processing parameters on injection-molded bottle caps consisting of 20 wt% of cellulose fibers and an ethylene-acrylic acid copolymer was studied. The study included three cylinder barrel temperatures and three mold temperatures. For each combination of temperatures, the holding pressure time was varied and the mold sealing time was determined. High density polyethylene caps were also produced as reference material, and injection-molded tensile test bars were also produced in order to assess the tensile mechanical properties. The results showed no major differences in sealing time for the caps containing cellulose fibers, except for the highest melt and mold temperatures where a slightly longer time was observed. The viscosity of the composite material was higher than that of the polymeric matrix. For the highest temperature and high shear rates, the viscosity of the composite material was close to the viscosity of the matrix material. The moisture content of the injection-molded bars was less than 1 %, showing that almost no water was absorbed during the compounding or after several months. The crystallinity decreased when the fibers were included but was not influenced by the mold temperature. Enhanced mechanical properties were obtained by using the fibers compared to the pure ethylene-acrylic acid copolymer, both in the tensile test bars and in the caps. The reference high density polyethylene had, however, a higher mechanical performance than the composite.

Investigation of the effect of nanoclay and processing parameters on the tensile strength and hardness of injection molded Acrylonitrile Butadiene Styrene–organoclay nanocomposites

Polymer–clay nanocomposites have attracted considerable interest over recent years due to their dramatic improved mechanical properties. In the present study, compatibility of Acrylonitrile Butadiene Styrene (ABS) and organically modified montmorillonite nanoclay (Cloisite 30B) and composition capability of them are investigated. Polymethylmethacrylate (PMMA) in varying amount (0, 2, and 4wt%) is used as the compatibilizer. In order to produce nanocomposite parts, the material is first compounded using a twin-screw extruder and then injected into a mold. The effect of the nanoclay percentage and processing parameters on the tensile strength and hardness of nanocomposite parts is also explored using Taguchi Design of Experiments method. Nanoclay content (in three levels: 0, 2 and 4wt%), melt temperature (in three levels: 190, 200 and 210°C), holding pressure (in three levels: 80, 105 and 130MPa) and holding pressure time (in three levels: 1, 2.5 and 4s) are considered as the variable parameters. Moreover, distribution of nanoclay layers is analyzed using Wide Angle X-ray Diffraction (XRD) test. XRD results displayed that with the presence of PMMA, nanoclay in ABS matrix is compounded in more exfoliated and less intercalated dispersion mode. Adding PMMA also leads to a remarkable increase in the fluidity of the melt during injection molding process. Results also illustrated that nanocomposites with medium loading level (i.e. 2%) of nanoclay have the highest tensile strength, while the highest hardness number belongs to nanocomposites with 4wt% nanoclay. Obtained results also indicated that injection temperature has the most important effect on tensile strength and hardness of ABS–clay nanocomposites.

COMPARISON OF METHODOLOGIES FOR IDENTIFICATION OF PROCESS PARAMETERS AFFECTING GEOMETRIC DEVIATIONS IN PLASTIC INJECTION MOLDING OF HOUSING USING TAGUCHI METHOD

This paper examines parameters that could influence geometric part deviation (shrinkage and warpage) of the Housing (Cycoloy, PC/ABS, Grade C2800) produced by plastic injection molding. Five parameters (temperature of molded plastic, injection time, cooling time, holding pressure, holding pressure time). Influence of the parameters is compared by simulation and real experiment with the results measured at five points. Taguchi's orthogonal array method is used. The simulation leads to unreliable results, with too many parameters influencing geometric deviation. Factor that has major influence is holding pressure time (HPT). The real experiment identifies holding pressure (HP) as a parameter with major influence. For further examination, the real experimentation is recommended, whenever it is possible.DOI: http://dx.doi.org/10.5755/j01.mech.18.6.3166

Research on Process Optimization of Thin-Wall Plastics Injection Based on Moldflow and Orthogonal Experiment

Warpage makes the plastic products deviate from the shape of the mold cavity that is one of the common weaknesses of plastics. In this paper, the melt temperature, mold temperature, packing pressure and holding pressure time are chosen as the study objects, and the use of Moldflow combined with orthogonal experiment method determine the best combination of molding process parameters to obtain the minimum warpage value, which improves the quality of injection products.

Optimization of Injection Molding Process Parameters to Increase the Tensile Strength in Polyamide-Specimen Using the Taguchi Method

Mechanical properties of plastic play an important role in defining the quality of injection molded products. Many studies have shown that mechanical properties of a product are influenced by the process parameters governing the injection-molding processes .This study employs Taguchi design parameters, to systematically investigate the influence of injection molding processing parameters on the tensile strength of Commercial grade Polyamide (PA-6). The result shows that the holding pressure time has main effect on the tensile strength, followed by cooling time, and holding pressure. Finally, a specimen produced according to the general form of the predictive equation of process parameters and verification test is performed on that. Test results show that the experimental value of tensile strength is very close to the estimated value.

INACTIVATION OF STAPHYLOCOCCUS AUREUS EXPOSED TO DENSE‐PHASE CARBON DIOXIDE IN A BATCH SYSTEM

ABSTRACT The inactivation of Staphylococcus aureus exposed to dense‐phase carbon dioxide (DPCD) was investigated, and the kinetics of come‐up time (CUT) in pressurization was monitored with come‐down time (CDT) and temperature fluctuation in depressurization. CUT was about 2.5, 3.5, 4.0 and 4.0 min; CDT was 3.4, 3.7, 4.5 and 4.5 min; lowest temperature of samples in depressurization was 4, −1, −15 and −22C, corresponding to 10, 20, 30 and 40 MPa at 37C. The inactivation behavior of S. aureus was closely related to the variables of process pressure, holding‐pressure time (HPT), process temperature and process cycling. The log reduction of S. aureus at 40 MPa for 30‐min HPT was significantly greater (P < 0.05), but the inactivation effect at 10, 20 and 30 MPa was similar. The log reduction of S. aureus at 30 and 40 MPa for 60‐min HPT was similar and significantly greater (P < 0.05), while the inactivation effect at 10 and 20 MPa was similar. The inactivation of S. aureus against HPT conformed to a fast–slow biphase kinetics; the two stages were well fitted to a first‐order model with higher regression coefficients R2 = 1.000 and 0.9238; their respective D values (decimal reduction time) were 16.52 and 70.42 min. As the process temperature increased, the log reduction of S. aureus increased significantly (P < 0.05); the inactivation kinetics of S. aureus versus process temperature was characterized with a fast inactivation rate from 32 to 45C and a slow inactivation rate from 45 to 55C. As compared to one‐process cycling for a total of 60‐min HPT, four‐process cycling resulted in a significant reduction of S. aureus, and its maximal reduction was near to 5 log cycles, indicating that more process cycling caused more inactivation of S. aureus under identical pressure and temperature with equal HPT. However, the maximal reduction was 0.09 and 0.12 log cycles for two‐ and four‐process cyclings with 0‐min HPT, indicating that pressurization and depressurization had a lesser effect on the inactivation of S. aureus, while HPT was significant in DPCD to inactivate S. aureus.PRACTICAL APPLICATIONSDense‐phase carbon dioxide (DPCD) is a novel technology to achieve cold pasteurization and/or sterilization of liquid and solid materials, and is likely to replace or partially substitute currently and widely applied thermal processes. This study showed that DPCD effectively inactivated Staphylococcus aureus inoculated in 7.5% sodium chloride broth, and the inactivation behavior of S. aureus was closely related to the pressure, holding‐pressure time, temperature and process cycling. Based on this observation, the technology of DPCD can be applied in the pasteurization of foods such as milk and various fruit juices, especially thermal‐sensitive materials.