A General and Efficient Approach for the Dual-Scale Infiltration Flow Balancing in In Situ Injection Molding of Continuous Fiber Reinforced Thermoplastic Composites

In situ injection molding of continuous fiber reinforced thermoplastic composites is challenged by unbalanced dual-scale infiltration flow due to the pronounced capillary effect. In this paper, a general and efficient approach was proposed for dual-scale infiltration flow balancing based on numerical simulation. Specifically, Stokes and Brinkman equations were used to describe the infiltration flow in inter- and intra-fiber bundles. In particular, capillary pressure drop was integrated in the Brinkmann equation to consider the capillary effect. The infiltration flow front is tracked by the level set method. Numerical simulation and experimental results indicate that the numerical model can accurately demonstrate the unbalanced infiltration flow in inter- and intra-fiber bundles caused by the changes of the injection rate, the resin viscosity, the injection rate, the fiber volume fraction and the capillary number. In addition, the infiltration flow velocity in inter- and intra-fiber bundles can be efficiently tuned by the capillary number, which is mainly determined by the injection rate for a specified resin system. The optimal capillary numbers obtained by simulation and experiment are 0.022 and 0.026, which are very close to each other. Finally, one-dimensional in situ injection molding experiments with constant injection pressure were conducted to prepare fiber reinforced polymerized cyclic butylene terephthalate composite laminate with various flow rates along the infiltration direction. The experimental results confirmed that the lowest porosity and the highest interlaminar shear strength of the composite can only be obtained with the optimized capillary number, which is basically consistent with the simulation results.

Bleaching Flax Roving With Poly(Acrylic Acid) Magnesium Salt As Oxygen Bleaching Stabilizer For Hydrogen Peroxide

Alkali-oxygen one-bath scouring and bleaching process of the flax roving was studied by using a new type of synthesized non-silicon oxygen bleaching stabilizer Poly(acrylic acid) magnesium instead of sodium silicate. Based on the analysis of the effects of single factors such as sodium hydroxide concentration, hydrogen peroxide concentration, temperature, time and the amount of the synthesized non-silicon oxygen bleaching stabilizer poly(acrylic acid) magnesium salt on the performance of the bleached flax roving, including the whiteness, the breaking tenacity, the capillary effect and the weight loss ratio. The optimal process for the application of the stabilizer was determined by orthogonal test, namely, hydrogen peroxide concentration 8.5 g/L, sodium hydroxide concentration 5 g/L, sodium bisulfite 3 g/L, sodium carbonate 3 g/L, the synthesized non-silicon oxygen bleaching stabilizer poly(acrylic acid) magnesium 5.5 g/L, scoured and bleached at 90 ℃ for 60 min, and the bath ratio was 25:1. Compared with the traditional oxygen bleaching stabilizer sodium silicate, it not only has good ability to inhibit the rapid decomposition of hydrogen peroxide, but also has the advantages of higher whiteness, higher capillary effect, good feel and breaking tenacity, and can effectively solve the "silicon scale" problem and improve the quality of flax products.

Preparation of Cross-Linked Cellulase Aggregate and Application to Cool Finishing of Cotton Fabric

Cellulase was immobilized by cross-linked enzyme aggregation to improve the stability of cellulase. The prepared cross-linked cellulase aggregates (CLCAs) and ice silicone oil were used for the cool finishing of cotton fabric. The results showed that the CLCAs extended the cellulase stability compared to free cellulase. The surface softness, smoothness, moisture permeability, and air permeability of the cotton fabric increased after CLCAs and ice silicone oil treatment. Shearing rigidity of the treated sample was 0.44 cN/(cm·deg), bending rigidity was 0.0069 cN cm, and the drape coefficient was 29.3%. Coefficient of kinetic friction of the treated sample was 0.186. The capillary effect of the treated fabric was 12.1 cm/(30 min). Air permeability was 354.3 L/(m2·s). Moisture penetrability was 3.912 g/(m2·d). The thermal and water-vapor resistance were 0.0194 m2·°C/W and 4.691 Pa·m2/W, respectively.

Capillary effect on the tidal response of buried aquifers – an interaction between shallow and deep groundwater systems

<p>The interaction between the shallow and deep groundwater systems is important for a number of issues on water resources and the environment but is difficult to evaluate directly. Here we use two-dimensional numerical simulations to show that the tidal response of deep aquifers may be significantly affected by capillary force on the water table. We propose a criterion to evaluate the capillary effect and apply the model to interpret the tidal response of the Arbuckle aquifer in a USGS deep monitoring well in Oklahoma. Our study suggests that the shallow and deep groundwater systems may interact across thick layers of intervening aquitards and that the analysis of the tidal response of deep aquifers may be an effective means to evaluate such interaction.</p>

Capillary Effect Enhancement in a Plastic Capillary Tube by Nanostructured Surface

We investigated the enhancement of the capillary effect in a plastic capillary tube using only a nanostructured surface. Since plastic is a hydrophobic material, the capillary effect does not emerge without an additional coating or plasma treatment process. Therefore, capillary effect enhancement by the nanostructure fabrication method is expected to reduce the cost and minimise the contamination produced in the human body. By combining a hydrophilic nylon resin and a nanostructure at the tip of the plastic pipette, we could confirm that the capillary effect was produced solely by the tube fabrication process. The produced capillary effect increased linearly with increasing nanostructure height when a standard solution with a surface tension of 70 mN·m−1 was used. Thus, we can conclude that including the plastic part with nanostructure can be useful for biomedical applications. In addition, we suggest that the proposed method is highly effective in controlling the wetting properties of plastic surfaces, compared to the typical coating or plasma treatment processes.

Mathematical modeling for output yield obtained by single slope solar still integrated with sand troughs

The crises for potable water is inevitable, due to increasing population. Solar desalination is apt technology to convert brack water and sea water into potable one. In the current work a mathematical modelling of a single slope solar still integrated with sand troughs is presented. The model is validated with the experimental results of a solar still with 3cm of water level at the basin. The mathematical model findings and results obtained with the experimental investigations are within ?10% deviation. Capillary effect was proposed to obtain the yield daily basis and thermal effect model was integrated with the capillary effect model. From the results, it is understood that the yield obtained is more in the case of solar stills with sand troughs when compared to solar stills without sand troughs. Further the model is used for predicting yield for 1cm and 2cm of water levels at the basin. It is observed that the maximum yield was obtained for 1cm water level at the basin. There is a good agreement between theoritacal results and experimental results. It shows that the still produce better yield with the lower depth of water level at the basin, this may be because of the availability of more space in the sand for evaporation due to capillary effect in the troughs.