Stab resistance of flexible composite reinforced with warp-knitted fabric like scale structure at quasi-static loading

The stab-resistant fabric like scale structure has a promising application prospect for areas of stab prevention owing to its great flexibility and excellent stab-resistance performance. In this paper, a kind of novel stab-resistant fabric has been designed by coating with epoxy resin (ER) and silicon carbide (SiC) particles, which was based on the warp-knitted fabric like scale structure (WKFS). The uniformity of dispersion has been investigated with different diameter and mass fraction of SiC, and polymerization degree of polyglycols (PEG); the flexibility and quasi-static properties of different kinds of WKFS treated with different coating solution has been studied, and the coating solution was prepared by mixing SiC particles and ER at different ratios. The results showed that the dispersion uniformity of the dispersion was the best when the diameter of SiC is 1 μm, the content is 50%, and the polymerization degree of PEG is 600. The longitudinal flexibility of the stab-resistant fabric is greater than that of transverse due to the gap between the longitudinal scales, and the addition of SiC particles can increase the transverse and longitudinal flexibility of stab-resistant fabric, and the flexible properties were the greatest when SiC:ER = 50:30. In addition, the WKFS treated with SiC of 16.7% has fatigue resistance; the damage mechanism of the fabric treated with pure ER is thankful to the brittleness of the resin; the added SiC particles hinder the further crack propagation of the resin, and the failure mode is mainly in stretch.

Non-Solvent Influence of Hydrophobic Polymeric Layer Deposition on PVDF Hollow Fiber Membrane for CO2 Gas Absorption

The implementation of hydrophobicity on membranes is becoming crucial in current membrane technological development, especially in membrane gas absorption (MGA). In order to prevent membrane wetting, a polypropylene (PP) dense layer coating was deposited on a commercial poly(vinylidene fluoride) (PVDF) hollow fiber membrane as a method of enhancing surface hydrophobicity. The weight concentration of PP pellets was varied from 10 mg mL−1 to 40 mg mL−1 and dissolved in xylene. A two-step dip coating was implemented where the PVDF membrane was immersed in a non-solvent followed by a polymer coating solution. The effects of the modified membrane with the non-solvent methyl ethyl ketone (MEK) and without the non–solvent was investigated over all weight concentrations of the coating solution. The SEM investigation found that the modified membrane surface transfiguration formed microspherulites that intensified as PP concentration increased with and without MEK. To understand the coating formation further, the solvent–non-solvent compatibility with the polymer was also discussed in this study. The membrane characterizations on the porosity, the contact angle, and the FTIR spectra were also conducted in determining the polymer coating properties. Hydrophobic membrane was achieved up to 119.85° contact angle and peak porosity of 87.62% using MEK as the non-solvent 40 mg mL−1 PP concentration. The objective of the current manuscript was to test the hydrophobicity and wetting degree of the coating layer. Hence, physical absorption via the membrane contactor using CO2 as the feed gas was carried out. The maximum CO2 flux of 3.33 × 10−4 mol m−2 s−1 was achieved by 25 mg modified membrane at a fixed absorbent flow rate of 100 mL min−1 while 40 mg modified membrane showed better overall flux stability.

In Situ Polymerization to Boron Nitride-Fluorinated Poly Methacrylate Composites as Thin but Robust Anti-Corrosion Coatings

High-performance anti-corrosion coatings featuring easy processability and thin thickness are highly desired in industry. Yet, solution process coating often faces a sedimentation problem with particles which are used as reinforcement in coatings. In this contribution, boron nitride (BN) was modified by an acrylate silane coupling agent (KH-570) to obtain acrylated BN flakes. Afterwards, the acrylated BN flakes were in situ copolymerized with 2-(perfluorohexyl)ethyl methacrylate to synthesize BN-fluorinated poly methacrylate (PFBP) composites. The as-obtained PFBP composites can form stable coating solutions, in which sedimentation of BN flakes seldom happens. The coating solution can easily form uniform coatings on various substrates with nanoscale thickness, confirmed by scanning electron microscope (SEM). The corrosion resistance of the samples coated PFBP coatings in 3.5 wt.% sodium chloride solution was evaluated by electrochemical impedance spectroscopy (EIS). It is indicated that the incorporation of BN flakes greatly reduce the corrosion rate. Adhesion measurements and abrasion resistance test indicate the PFBP coating performs good adhesion to substrate and robustness. Through the in situ polymerization, acrylated BN flakes are connected with the polymer chain, which inhibits the sedimentation of BN in the coating solution. Additionally, the BN flakes dispersed in the fluorinated polymer act as barriers, improving the corrosion resistance of the coated samples.

Anti-bacterial Activity of Alginate Based Edible Coating Solution Added with Lemongrass Essential Oil Against Some Pathogenic Bacteria

Edible coating is a thin layer that can be made of several materials, one of which is polysaccharides, such as alginates, carrageenan, agar, chitin, chitosan, pectin, starch, cellulose derivatives, and gums. The application of food products with edible coatings has been widely carried out and has been proven to improve quality and extend the shelf life of the product. Antibacterial agent can be added to improve the performance of edible coating. This study was aimed to explore the potential of lemongrass essential oil as an antibacterial agent in alginate based antibacterial edible coating solutions, especially against pathogenic bacteria. Edible coating is made of alginate powder, modified cassava flour (Mocaf), beeswax, glycerol and antibacterial agent. The additional levels of lemongrass essential oil into edible coating formula were 0.25, 1.50 and 0.75%. The antibacterial activity of the edible coating solution produced was tested against Escherichia coli, Staphylococcus aureus, Salmonella, and Pseudomonas aeruginosa by employing a disk diffusion testing method. Antibacterial agents used in previous studies to develop alginate-based antibacterial edible coatings and potential applications of the developed alginate-based edible coatings incorporated with lemongrass essential oil were identified by browsing through the internet. The results showed that various antibacterial agents have been explored to improve the performance of alginate based edible coatings. An antibacterial activity study exhibited that the highest antibacterial activity was found in the edible coating with the addition of 0.50% lemongrass essential oil, except for S. aureus at the addition level of 0.75%. This study suggests that the addition of lemongrass essential oil for the manufacture of alginate based edible coating solution is 0.50%. The potential uses of edible coatings made from alginate with the addition of lemongrass essential oil are to coat various animal and plant based food products.

Characteristics of corn starch-based edible coating enriched with curry leaf extract on quality of the strawberry (Fragaria x ananassa Duch.)

Strawberry is one of the most popular tropical fruits in Indonesia. The fruit has a concise shelf life and quickly deterioration after harvesting due to mechanical injury, physiological disorders, water loss, fungal growth, and high respiration rates. Postharvest technology is one technique that can maintain fruit quality and extend shelf life, one of which is a coating technique called edible coating. The edible coating layer of corn starch with the addition of curry leaf extract has antibacterial activity that can inhibit the growth rate of microorganisms. This study aimed to determine the characteristics of the edible coating solution produced from corn starch with the addition of curry leaf extract to produce the best edible coating layer. This study used a factorial completely randomized design experimental method, which consisted of treatment with curry leaf extract concentration (8%, 10%, and 12%) and dipping time (4, 5, and 6 minutes) with three repetitions. The result showed a significant delay in weight loss and total dissolved solids in strawberries compared to the uncoated control strawberries. In addition, the edible coatings had positive results in organoleptic based on panelists’ acceptance of color, aroma, taste, texture, and overall. These findings suggest that using 8% curry leaf extract with 4 minutes dipping time could be favorable to extend the shelf-life and maintain the quality of strawberry fruit.

Influence of Two Different Coating Application Methods on the Maintenance of the Nutritional Quality of Fresh-Cut Melon during Storage

This study aimed at evaluating the effects of two coating application methods, spraying and dipping, on the quality of fresh-cut melons. An alginate-based coating containing both ascorbic and citric acid was applied at two concentrations (5% and 10%) with both methods on fresh-cut melon. The nutritional quality of the products was investigated during 11 days of storage at 10 °C. The suitability and adaptability of the applied coatings on the fruit were evaluated based on rheological and microstructural properties. Moisture, carotenoids, total polyphenols and ascorbic acid content were analyzed on melon samples during storage. Results showed that the coating solution applied by the dipping method and at the highest concentration (10%), allowed to better maintain some quality characteristics of fresh-cut melon, thanks also to the better coating homogeneity and higher thickness observed through microstructural analysis.

Study of biological activities and physicochemical properties of Yamú (Brycon siebenthalae) viscera hydrolysates in sodium alginate-based edible coating solutions

The fishing industry produces waste such as viscera, which is an environmental problem for many countries. Obtaining protein from these wastes are useful for the food industry. In this study, the chemical composition, amino acid profile, solubility, digestibility and thermal properties of Yamú protein isolate (PI) and its hydrolysates obtained by enzymatic hydrolysis were characterized. The hydrolysates (0.05, 0.1, 0.5, 1 and 2% w/v) were mixed with a sodium alginate-based solution to form an edible coating solution (ECS). Antioxidant capacity antimicrobial activity, Zeta potential (ζ) and adsorption kinetics properties were determined. PI contains 88% (w/w) protein showing better solubility, digestibility and thermal stability properties. The hydrolysate concentrations with DPPH inhibitory ECS were 0.1 and 0.5% (w/v). The kinetic properties of ECS showed good stability and excellent adsorption. These results suggest that this Yamú protein has high nutritional potential as an ingredient for the production of functional foods.

Spray coating of cellulose aerogel particles in a miniaturized spouted bed

Aim of this work is to apply protective and homogeneous shellac coating layers on the surface of hydrophilic open-pore cellulose aerogel particles with low densities ≤ 0.1 g/cm3 and high specific surface areas in the range of ~ 400–450 m2/g while keeping the aerogels’ microstructure intact during processing. For this purpose, an innovative miniaturized spouted bed setup was used. Successful process settings for application of enclosed films on aerogel surfaces without intrusion of coating material into the pores were determined. Precise control of coating layer thickness in the range of 10–50 µm was achieved due to variation of coating solution amount without agglomeration and clogging events occurring during processing. Comparison of bulk densities and specific surface areas before and after coating proved the intactness of the porous structure. Coating of particles loaded with vanillin led to controlled release, enhancing release half-life times from 20 to 1600 min. Overall, a successful strategy for coating of organic low-density aerogels was developed.

A Study of the Localized Ceria Coating Deposition on Fe-Rich Intermetallics in an AlSiFe Cast Alloy

Corrosion inhibiting conversion coating formation is triggered by the activity of micro-galvanic couples in the microstructure and subsequent local increase in pH at cathodic sites, which in the case of aluminium alloys are usually intermetallics. Ceria coatings are formed spontaneously upon immersion of aluminium alloys in a cerium conversion coating solution, the high pH gradient in the vicinity of intermetallics drives the local precipitation of ceria conversion compounds. Cu-rich intermetallics demonstrate a highly cathodic nature and have shown the local precipitation reaction to occur readily. Fe-rich intermetallics are, however, weaker cathodes and have shown varied extents of localized deposits and are in focus in the current work. Model cast Al-7wt.%Si alloys have been designed with 1 wt.% Fe, solidified at different cooling rates to achieve two different microstructures, with big and small intermetallics, respectively. Upon subjecting the two microstructures to the same conversion coating treatment (immersion in a 0.1 M CeCl3 solution) for a short period of 2 h, preferential heavy deposition on the boundaries of the big intermetallics and light deposition on the small intermetallics was observed. Based on these observations, a mechanism of localized coating initiation at these Fe-rich intermetallic particles (IM) is proposed.