Soaking Test Research Articles

Effects of Maleic Anhydride Grafted Polypropylene on the Physical, Mechanical and Flammability Properties of Wood-flour/Polypropylene/Ammonium Polyphosphate Composites

In this study, maleic anhydride grafted polypropylene (MAPP) was incorporated as coupling agent in the wood-flour/polypropylene/ammonium polyphosphate composites (flame-retardant WPCs). The effects of MAPP content (5 wt.%, 10 wt.% and 15 wt.%) on the physical, mechanical and flammability properties of flame-retardant WPCs were investigated. The water soaking tests showed that the incorporation of MAPP could reduce the hygroscopicity of flame-retardant WPCs. The mechanical properties of WPCs were evaluated by three-point bending tests, unnotched Izod impact strength tests, and dynamic mechanical analysis. The results showed that the flame-retardant WPC containing 10 wt.% MAPP (WPC/APP/MAPP-10 %) performed the best flexural properties, the highest impact strength, E′ value, and tan δ at room temperature. The limiting oxygen index (LOI) tests and cone calorimetry tests showed that the incorporation of 10 wt.% MAPP endowed the flame-retardant WPC with the highest LOI value, the lowest peak-heat release rate, total heat release, CO/CO2 weight ratio and total smoke release. Moreover, the characterization of the WPCs combustion residues performed that WPC/APP/MAPP-10 % had the most complete carbonaceous structure with the highest graphitization degree after combustion. In general, the addition of 10 wt.% MAPP could impart the flame-retardant WPC with the optimum physical-mechanical properties and flame-retardant performance.

Deformation characteristics of sedimentary rock due to continuous changes of moisture content in wetting process

In recent years, the number of cases where tunnels are constructed in sedimentary rock layers has increased. It is essential to investigate the deformation characteristics of sedimentary rocks for predicting tunnel deformation. The mechanical properties of sedimentary rocks are widely varied due to moisture content. The rocks are dried by tunnel excavation and wetted by groundwater gushing or backfilling. It is necessary to grasp the changes of deformation characteristics of sedimentary rocks due to moisture changes. In this study, soaking tests were conducted on Neogene period Japanese tuff sampled at Utsunomiya, Japan. In the test, the cylindrical tuff specimens are air dried by over 240 hours at first. Then the tuff specimens are taken in pure water with measuring deformations in detail. There are no effective stress increases by soaking and only uniform matric suction are acted on the specimen without any restraints. The results demonstrated that strain tensor was reached to stable state for 2 - 3 days, and the value of the normal strain perpendicular to the bedding plane is greater than the other normal components and shear strains are also observed in both cases. Although the orientation of the maximum principal strain is in the near of the bedding orientation at the initial dry state, the orientation are suddenly rotated to the normal orientation of the bedding plane. It means that the principal orientation of anisotropy are rotated due to continuous moisture changes.

Experimental Study on Mechanical Properties of Q690 High Strength Steel in Marine Corrosive Environment

In order to study the mechanical property degradation rule of Q690 high-strength steel in the ocean wave splash area, the rusted specimen is obtained by indoor damp heat surrounding soaking environment corrosion test. The scanning electron microscopy, uniaxial tensile and cyclic loading tests of corroded steel are performed. This paper analyzes the steel from elastic modulus, yield strength, ductility and law of hysteresis degradation under different corrosion cycles and establishes the constitutive model of HSS. The results show that the appearance of HSS is obviously affected by the corrosion cycle. With the increase of the corrosion cycle, reddish-brown flaky corrosion products are formed on the surface of the steel and there are obvious corrosion pits. After 100 days of corrosion, the corrosion rate of steel reached 7.21%; the elastic modulus and yield strength under uniaxial tension load decreased by 10.2% and 4.9%. Under the effect of cyclic reciprocating load, the hysteretic energy is reduced by 15.3%; at the same time, the test curve is fitted by the secondary plastic flow model and the Ramberg–Osgood model and it is found that the shape parameter S1 and the cyclic strengthening coefficient K' are reduced by 20.1% and 10.2%, While the shape parameter S2 and the cycle strengthening index n' have no obvious changes.

Thermal degradation behavior of thin films of fatty acid methyl ester

Thermal degradation of FAME was performed on the low carbon steel coupon by a thin film method. Impact of the film thickness on FAME physical and chemical properties was evaluated. It showed that FAME film degradation ratio depends on its thickness and the thermal treatment duration. It was determined that the 200 µm film degraded faster than the 500 µm film. The soaking test, which performed using three solvents (xylene, heptane, fresh FAME) showed that better solubility of degraded FAME was achieved in xylene, followed by fresh FAME and then heptane. The swelling effect was observed than soaking test of FAME films were performed in fresh FAME. The acid values into the degraded FAME films were achieved and lower values were obtained in the 500 µm than in 200 µm films, respectively. The iron content into 200 µm film was 3 times higher, compared with 500 µm film thickness.

Wood Permeability Assessment of Young Teak (Tectona grandis L.f.)

Wood properties of young teak (Tectona grandis L.f.) is inferior, and then preservative treatment is one possible solution to enhance its service life. The uptake and movement of preservatives through wood cell structure is directly connected to the wood permeability. There are two simple methods to identify wood permeability: water soaking and bubble test methods. This paper assesses the young teak permeability by water soaking and bubble test methods. The assessment was conducted into five cm thick young-teak discs by soaking in the red-dye water and blowing air into the discs which had been coated with soap. Results show that the heartwood is less permeable than sapwood. Red-dye penetrates almost 100% of the sapwood area, and the red-dye did not penetrate in the heartwood. Red-dye only penetrates in the cracked heartwood through the void volume in the cracking heartwood. There is a transition zone between sapwood and heartwood, and it is refractory. Bubble test with air pressure from compressor could open the air-pathway in the heartwood and sapwood of young-teak discs taken from Bogor. The bubble test result of young-teak discs from Madiun showed air-pathway only in the sapwood, but heartwood. The air pressure is not capable of moving the vapour through the wood cell. It indicates that the heartwood of young-teak from Madiun is less permeable and less possibility for pressure treatment.

Titanium Bioactive Surface Formation Via Alkali and Heat Treatments for Rapid Osseointegration

Titanium and its alloys are widely used as implant materials and many studies to accelerate the osseointegration have been performed. This work aims to evaluate the formation of a bioactive surface in commercially pure titanium (cp-Ti) grade 4 after alkali (AT) and heat treatments at 600 °C (AHT600) and 900 °C (AHT900). Characterization techniques were SEM, AFM, Raman, TF-XRD, wettability, nanoindentation and indentation adhesion. Additionally, SBF soaking tests were performed to evaluate apatite growth and showed that alkali and heat treatment accelerates apatite growth. The AT samples formed sodium hydrogen titanate (1 µm thick), and AHT600 and AHT900 formed sodium titanate (1 µm thick), while rutile TiO2 increased with temperature, reaching up to 5 µm thick and the surface changed from slightly hydrophilic to fully hydrophilic. Roughness and surface area increased, especially in AHT900. The hardness of the surface layer was significantly increased by the heat treatment.

Biological evaluation of the modified nano-amorphous phosphate calcium doped with citrate/poly-amino acid composite as a potential candidate for bone repair and reconstruction

Large numbers of research works related to fabricating organic–inorganic composite materials have been carried out to mimic the natural structure of bone. In this study, a new modified n-ACP doped with citrate (n-ACP-cit)/poly (amino acids) (PAA) composite (n-ACP-cit/PAA) was synthesized by employing high bioactive n-ACP-cit and the biodegradable and biocompatible PAA copolymer. Its basic structure was characterized by X-ray diffraction spectroscopy, Fourier transformed infrared spectroscopy, and X-ray photoelectron spectroscopy. Moreover, the degradability, bioactivity, biocompatibility, and osteoconductivity of n-ACP-cit/PAA composite were evaluated in vitro and in vivo, using simulated body fluid (SBF) solution soaking test, mouse bone marrow mesenchymal stem cells proliferation and differentiation, morphological observation test, expression of genes associated with osteogenesis, and bone defect model repair test, respectively. The modified n-ACP-cit/PAA composite exhibited a much higher weight loss rate (36.01 wt.%) than that of PAA (23.99 wt.%) after immersing in SBF solution for 16 weeks and the pH values of local environment restored to neutral condition. Moreover, cells co-culturing with composites exhibited higher alkaline phosphatase activity, more calcium nodule-formation, and higher expression levels of osteogenic differentiation-related genes (Bmp-2, Colla I, OCN, OPN, and Runx-2) than that of PAA. Furthermore, the bone defect model repair test revealed that the composite could be intimately incorporated with the surrounding bone without causing any deleterious reaction and capable of guiding new bone formation. Together, these results indicated that the new modified bone repair n-ACP-cit/PAA composite material with specific characteristics may be designed for meeting diverse requirements from biomedical applications.

Comparative performances of nature-based dyes extracted from Baobab and Shea leaves photo-sensitizers for dye-sensitized solar cells (DSSCs)

Dye-sensitized solar cells (DSSCs) were fabricated using dye extracts from Baobab and Shea leaves as photo-sensitizers. The photoanode was made from spin-coating of titanium dioxide (TiO2) and annealed at 450°C for 1 ​h. The TiO2 shows good optical absorption capability in the ultraviolet region with a band gap of 3.3 ​eV and surface morphology that revealed grains that are spherical and randomly oriented with average particle size of (26±4.0) nm. The Shea and Baobab dyes have shown absorption at the blue-yellow region of the visible light with energy band gap of 1.66 ​eV and 1.89 ​eV respectively. The Shea-based DSSC (SDSSC) yielded power conversion efficiency (PCE) of (0.25±0.13) % with short current density, Jsc, open-circuit voltage, Voc and fill factor, FF of (2.66±1.61)mAcm−2, (0.158±0.0877) V and 0.596 ​± ​0.389, respectively while Baobab-based DSSCs (BDSSCs) gave lower PCE of (0.11±0.028) % with Jsc, Voc and FF of (0.286±0.0483)mAcm−2,0.676±0.0622 V and 0.592±0.0339. Light soaking tests show that SDSSCs are more stable in photoelectric performance than BDSSCs for 5 ​h. Hence, preferred as a sensitizer for better performance in dye-sensitized solar cells than Baobab dye extract.

Kinetics of Quality Changes in Soaking Water during the Retting Process of Pepper Berries (Piper nigrum L.)

There are organic matters and bioactive compounds naturally present in pepper that may have leached out into the soaking water due to a prolonged retting process that caused changes in water quality. This study was carried out to determine the influences of different quantities of mature pepper berries and soaking time on the quality of soaking water during the retting process. The soaking test was conducted by having three tanks with different quantities of pepper berries soaked in the 18 L of water. The results show that the tank with the highest quantities of pepper berries has the highest increment of turbidity from 21.80 ± 1.90 NTU to 1103.30 ± 23.10 NTU (98%), the highest reduction in pH from 6.99 ± 0.02 to 3.67 ± 0.02 (47.50%), the highest reduction in dissolved oxygen from 5.19 ± 0.17 mg/L to 1.05 ± 0.02 mg/L (79.77%) and the highest increment of chemical oxygen demand from 21.67 ± 1.15 mg/L to 3243.33 ± 5.77 mg/L (99.33%) compared to other tanks. Furthermore, the zero, first and second-order kinetic models fitted well with the experimental data of the quality of soaking water for three conditions using the Arrhenius law approach. Thus, these findings are useful for estimating water quality during the retting process.

Molecular-scale descriptions and experimental characterizations of nitrocellulose soaked in pure liquid ethanol or diethyl ether respectively at room temperature

Studies on nitrocellulose (NC) mixtures with little solubilities were neglected in many cases previously. This investigation was performed to provide supplemental characterizations of NC and its soaked state with pure liquid ethanol or diethyl ether by simulations and practical methods. Above all, a short-chained NC model (polymerisation degree: 8) and a dried NC specimen were characterized for their substitution of nitrate and microstructure. It was confirmed that both the numerical model and practical specimen belonged to low-nitrated NC. The bonding information of a glycosyl unit and nitrate ester were summarized via first-principle calculations. Then, ReaxFF potential based Molecular Dynamic (MD) simulations and soaking tests on binary organic mixtures demonstrated that both ethanol and diethyl ether had limited solubility for our specified NC. However, potential energies and diffusion coefficients of both computational models showed that the interactions from ethanol molecules were relatively stronger than diethyl ether molecules. The viscosities of saturated NC solutions also proved this consequence, as the difference between pure ether and its filtered NC solution was only 0.02 mm2 s−1. Finally, the strong volatility of diethyl ether itself could keep the wetness of NC upper surface shortly, because this was an upward volatilization effect. Due to this effect, the penetration of NC-diethyl ether mixture was higher in the early period of penetration tests.

Investigation of gastric disintegration of carrot during digestion in vitro by a Low-Field Nuclear Magnetic Resonance device

Abstract Knowledge of the process and kinetics of solid food disintegration in the human stomach is essential for assessing bioaccessibility of nutrients and understanding gastric emptying. It is desirable to develop advanced techniques for non-invasively and non-destructively studying the kinetics of gastric disintegration and nutrient release during digestion. The main objective of this study was to verify the feasibility of monitoring gastric disintegration of carrot sample during digestion in vitro by a Low-Field Nuclear Magnetic Resonance (LF-NMR) device. Static soaking in different liquid medium was also carried out using as comparison with the LF-NMR data to validate the feasibility. The wet and dry weight retention ratio, water content, hardness and effective diffusivity of the carrot were measured during the soaking tests following a course of time. The transverse relaxation time (T2) and magnetic resonance imaging (MRI) from the LF-NMR was employed to illustrate the transient water status throughout each sample. The T23 relaxation time at peak maximum migrated from ~1300 ms to 500 ms after static soaking in the simulated gastric juice with pH of 1.8 for 240 min, with the total peak area decreasing by 9.10% throughout the measurement of T2 quantitatively supporting the similar reduction of 8.89% in the wet mass retention ratio. Moreover, the time evolutions of the carrot sample size as shown from the MRI imaging results were also in line with the decrease of the solid loss during the static soaking. These consistent results indicate that the LF-NMR provides a non-invasive and non-destructive technique for potentially characterizing the disintegration of solid food samples during gastric digestion.

The making of Class C fly ash as high-strength precast construction material through geopolymerization

A study has been carried out to apply fly ash as a high strength, water-resistant precast construction material through geopolymerization. Experiment results show that the working conditions such as water content, the concentration of NaOH, curing temperature, and curing time significantly affect the mechanical property of geopolymer matrix. Through optimization, an above-100 MPa compressive strength has been achieved with the geopolymerization products. The optimum working conditions involves 10 M NaOH concentration, 14–15% water content, and curing at 90 °C in an oven for 1 day or at ambient condition for 3 weeks. Adding Ca(OH)2 does not help to increase the compressive strength of the specimen. Water soaking tests show that the geopolymerization product has a very high water resistance without losing noticeable compressive strength, even after a 1-month soaking time. To elucidate the geopolymerization mechanism, microscopic techniques such as SEM/EDS (scanning electron microscopy and energy-dispersive X-ray spectroscopy), XRD (X-ray diffraction) and ATR-FTIR (attenuated total reflectance Fourier transform infrared) are also applied to investigate the microstructure, the elemental and phase composition of geopolymerization products. The findings of the present work provide a novel method for applying fly ash as a high-strength water-resistant precast construction material.

Selected Properties of Overlaid Magnesium Based Composite Panels for Flooring

The objective of this work was to evaluate some of the mechanical and physical properties of the flooring materials manufactured from panels having magnesia substrate overlaid with oak veneer (Querqus alba) and linoleum sheets. Commercially manufactured panels were used in this work. Bending characteristics, internal bond strength, thickness swelling, and surface quality of the samples were evaluated. The highest modulus of elasticity (MOE) value of 4406 MPa for the sample type-A2 was loaded in the direction of the substrate followed by 3478 MPa for linoleum covered samples which were loaded in the same direction. Internal bond strength values of the panels did not show any significant differences from each other. Dimensional stability of the specimens in the form of thickness swelling for both 2-h and 24-h water soaking tests resulted in values ranging from 0.11 to 0.19%. The surface quality of the samples was not substantially influenced as a function of water exposure. Based on the results in this work magnesium substrate overlaid with oak veneer and linoleum panels could have potential to be used as flooring material with accepted properties.

Apatite formation and bacterial growth on raw silk fabric heated in argon gas

Raw silk has the potential to be a flexible, osteoconductive material because it forms bone-like apatite on its surface in acellular simulated body fluid with ion concentrations nearly 1.5 times greater than that of human plasma (1.5SBF). It has been reported that silk-which has many similarities to raw silk-develops antibacterial properties when heated in inert gas, which may be advantageous in preventing bacterial infection. Hence, raw silk heated in inert gas may be a flexible, osteoconductive material with antibacterial activity. Thus, we examined the effect of the heat treatment of raw silk fabric on its apatite-forming ability in 1.5SBF and on the growth of Escherichia coli. Raw silk fabric was heated in argon gas at several temperatures, to a maximum of 500 °C. The results of soaking tests in 1.5SBF indicate that the apatite-forming ability of raw silk decreases with increasing temperature. This may be because favourable structures for apatite formation, such as carboxyl groups, are thermally decomposed. The results of bacterial tests indicate that raw silk fabrics heated to 300 °C or 500 °C exhibit reduced bacterial growth compared to those that were not heated or were heated only to 100 °C. This might be because hydrophobic surfaces inhibit bacterial adhesion, or because the thermal decomposition of sericin-a component of raw silk-leads to a lack of available nutrients for the bacteria. Although this study did not demonstrate the expected material properties needed for clinical applications, this research contributes to a better understanding of silk biomaterials.

Experimental investigation of the interaction between water and shear-zone materials of a bedding landslide in the Three Gorges Reservoir Area, China

Most landslides induced by reservoir impoundment and rainfall in the Three Gorges Reservoir area of China are usually characterized by bedding-plane shear zones. This paper presents an experimental study of the interaction between water and shear-zone materials. A series of tests, including wetting-drying cycles and soaking tests, were carried out. The results show that the fluid-solid interaction not only reduces the shear strength of shear-zone soil but also accelerates the disintegration process of clastic rock from shear zone. After the fluid-solid interaction at different pH values, the clastic rock samples produce the most clay minerals in acidic solution. Similarly, the clay minerals of shear-zone soil samples increase dramatically after 45 days of soaking in acidic environment. According to the tests, it is found that the shear-zone soil in eluvium may originate from the weathered clastic rock near the shear zones under long-term fluid-solid interaction.

Stretchable and Healable Bioelectronics

Organic electronics, based on semiconducting and conducting polymers, have been extensively investigated in the past decades and have found commercial applications in lighting panels, smartphone and TV screens using OLEDs (organic light emitting diodes) technology. Many other applications are foreseen to reach the commercial maturity in future in areas such as transistors, sensors and photovoltaics.Organic electronic devices, apart from consumer applications, are paving the path for key applications at the interface between electronics and biology, such as in polymer electrodes for recording and stimulating neural activity in neurological diseases. In such applications, organic polymers are very attractive candidates due to their distinct property of mixed conduction: the ability to transport both electron/holes and ionic species. Additionally, conducting polymers offer the possibility to tune their surface properties (e.g., wettability or chemical reactivity) by changing their oxidation state, thus promoting or hindering the adhesion of biomolecules. This feature can be particularly useful for enhancing the biocompatibility of implantable electrodes.My talk will deal with processing and characterization of conducting polymer films and devices for flexible, stretchable and healable electronics as well as for implantable electrodes.Our group fabricated water-stable and flexible organic electrochemical transistors based on poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) on a plastic substrate using a new process based on a fluorinated photoresist. The PEDOT:PSS films, mixed solely with a biocompatible conductivity enhancer, show robust adhesion on plastic substrates, and exhibit unchanged electrical properties under extreme bending. This simplifies the fabrication of high-performance OECTs and places them in a highly competitive position for flexible electronics and healthcare applications.The fabrication of stretchable electronic devices is presently rather challenging due to both the limited number of materials showing the desired combination of mechanical and electrical properties and the lack of techniques to process and pattern them. My group reported on transfer patterning process to fabricate high-resolution metal microelectrodes on polydimethylsiloxane (PDMS) by using ultrathin Parylene films (2 μm thick). By combining transfer patterning of metal electrodes with orthogonal patterning of PEDOT:PSS on a pre-stretched PDMS substrate and a biocompatible “cut and paste” hydrogel, we demonstrated fully stretchable organic electrochemical transistors, relevant for wearable electronics, biosensors and surface electrodes to monitor body conditions.Self-healing electronic materials are highly relevant for application in biology and sustainable electronics. We observed mechanical and electrical healability of PEDOT:PSS thin films. Upon reaching a certain thickness (about 1 µm), PEDOT:PSS thin films damaged with a sharp blade can be healed by simply wetting the damaged area with water. The process is rapid, with a response time on the order of 150 ms. Significantly, after being wetted, the films are transformed into autonomic self-healing materials without the need of external stimulation. This reveals a new property of PEDOT:PSS and enables its immediate use in flexible and biocompatible electronics, such as electronic skin and bio-implanted electronics, placing conducting polymers on the front line for healing applications in bioelectronics.We have recently electropolymerized PEDOT coatings on sharp platinum-iridium recording and stimulating neural electrodes and demonstrated its mechanical and electrochemical stability Electropolymerization of PEDOT:tetrafluoroborate was carried out in three different solvents: propylene carbonate, acetonitrile and water. The stability of the coatings was assessed via ultrasonication, phosphate buffer solution soaking test, autoclave sterilization and electrical pulsing. Coatings prepared with propylene carbonate or acetonitrile possessed excellent electrochemical stability and survived autoclave sterilization, prolonged soaking and electrical stimulation without major changes in electrochemical properties. Stimulating microelectrodes were implanted in for 60 days. The electrochemical properties monitored in vivo demonstrated that coated electrodes show lower impedance and higher stability over time.

Superhydrophobic TC4 alloy surface fabricated by laser micro-scanning to reduce adhesion and drag resistance

Surface drag resistance would cause energy waste in transportation industrials and vascular stenosis in biomedicine field, which is still an urgent problem to be solved. Selecting widely used Ti-6Al-4V (TC4) alloy as research object, the grid-shape micro-nano structure was fabricated on the surface by laser micro-scanning, and the superhydrophobicity with low adhesion was achieved after further chemically modified to lower the surface free energy. The change of the wettability in this process indicated that the superhydrophobicity was ascribed to a combination of the micro-nano structure and chemical composition. The bounce behavior was analyzed by obtaining the trajectory of water droplet via image processing, and the rebound coefficient was maintained at about 0.85, which fully verified the superhydrophobicity. The prepared superhydrophobic surface shows enough stability after the abrasion tests, soaking tests, and water impinge tests. The slip length, which indicates the drag reduction capability, was measured based on torque measurements with various shear rates. The prepared superhydrophobic TC4 alloy surface reduced drag effectively, yielding slip lengths of 17 μm with pure water and 40 μm with 30% glycerin-water solution, respectively. It is worth believing that this laser-based method would show great application potential in the fields of transportation and biomedicine, necessary condition to achieving superhydrophobicity.

Water Absorption and Hygrothermal Aging Behavior of Wood-Polypropylene Composites.

Environmentally sound composites reinforced with natural fibers or particles interest many researchers and engineers due to their great potential to substitute the traditional composites reinforced with glass fibers. However, the sensitivity of natural fiber-reinforced composites to water has limited their applications. In this paper, wood powder-reinforced polypropylene composites (WPCs) with various wood content were prepared and subjected to water absorption tests to study the water absorption procedure and the effect of water absorbed in the specimens on the mechanical properties. Water soaking tests were carried out by immersion of composite specimens in a container of distilled water maintained at three different temperatures, 23, 60 and 80 °C. The results showed that the moisture absorption content was related to wood powder percentage and they had a positive relationship. The transfer process of water molecules in the sample was found to follow the Fickian model and the diffusion constant increased with elevated water temperature. In addition, tensile and bending tests of both dry and wet composite samples were conducted and the results indicated that water absorbed in composite specimens degraded their mechanical properties. The tensile strength and modulus of the composites reinforced with 15, 30, 45 wt % wood powder decreased by 5.79%, 17.2%, 32.06% and 25.31%, 33.6%, 47.3% respectively, compared with their corresponding dry specimens. The flexural strength and modulus of the composite samples exhibited a similar result. Furthermore, dynamic mechanical analysis (DMA) also confirmed that the detrimental effect of water molecules on the composite specimens.

Obtención y rendimiento del extracto etanólico de dos plantas medicinales


 
 
 
 En el presente trabajo de investigación se evaluó el porcentaje de rendimiento de la extracción etanólica de las plantas medicinales Alegría (Scutellaria incarnata) y Amansatoros (Justicia pectoralis), al aplicar dos métodos de maceración con y sin agitación, con el material vegetal entero y molido, además de realizarse pruebas en diferentes tiempos de maceración (6, 12, 24, 48 y 92 horas) hasta llegar a la estabilización de la extracción. Para el análisis de los datos se empleó un modelo de análisis estadístico correspondiente a un diseño experimental en bloques completos al azar con arreglo factorial (Anova), con el fin de determinar los valores estadísticos más relevantes en el proceso de extracción, de acuerdo con el factor tiempo, el método empleado y el tamaño de partícula. Tanto para la planta Alegría como para Amansatoros los resultados indican que, en la obtención del extracto etanólico, el mejor tiempo fue de 48 horas, con el uso de material molido y la aplicación de agitación. Estas condiciones permitieron obtener rendimientos del 37.000 y 37.600% para el extracto etanólico de Amansatoros y Alegría, respectivamente.
 
 
 

Evaluation of Launderability of Electrically Conductive Fabrics for E-Textile Applications

This article presents the studies on the launderability of conductive fabrics with four types of metal coatings (Cu, Ag, Ni/Cu, or Ni/Cu/Co), respectively, which are laminated to three common fabrics (spandex, nylon, and denim) using thermoplastic urethane (TPU) film. The electrical resistance as a function of laundry cycles is used to characterize the performance of these conductive materials. The laundry procedure follows the AATCC M6 test standard by using the AATCC compliant washer and dryer with control factors such as detergent, temperature, agitation speed, and spin speed. After the intended wash and dry cycles, the electrical resistance of the conductive fabrics is measured using a four-point probe method. The resistance stability over the laundry cycles is compared between these conductive fabrics with four metal coatings, respectively. In general, all the conductive fabrics show an increase in electrical resistance with laundry cycles, and the extent of the increase depends on the metal coating and the base fabrics to which the conductive fabrics are laminated. Further, the soaking test reveals that the AATCC certified detergent does not have a measurable effect on the performance of the conductive fabrics. To obtain an insight on the degradation of the conductive fabrics during laundry, further inspection and analysis are performed, including 3-D optical microscopy, scanning electronic microscopy (SEM), cross sectioning, and X-ray fluorescence (XRF). A significant peeling and fracture of metal coating layers, due to mechanical tumble or agitation stresses during laundry, are observed for the conductive fabrics with Cu, Ni/Cu, and Ni/Cu/Co coatings, leading to electrical resistance increase or even electrical open, whereas the conductive fabrics with Ag coating show a metal scratch instead of peeling and fracture, possibly due to silver's superior flexibility, ductility, and adhesion with the base fiber. Besides metal coatings, the mechanical properties of the base fabrics appear to significantly affect the laundry performance of the conductive fabrics, in which the more rigid base fabric causes higher mechanical stresses on the metal coating, leading to more damages and accordingly higher increases in resistances.