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This experiment involved the chemical conversion of pure stearic acid from buffalo adipose tissue to a waxy stearyl stearate, which was subsequently applied as a coating film to extend the shelf life of recently harvested fruits. Fat was extracted from minced adipose tissue using the dry rendering procedure, and it was then characterized. The extracted fat was hydrolyzed into a mixture of free fatty acids and glycerol. The supercritical CO2 extractor was used for stearic acid individual extraction in pure form from the free fatty acid mixture, and it was confirmed according to its melting point (69.2–70.0 °C), elemental analysis, GC–MS for esterified fatty acids. The isolated stearic acid was used for the synthesis of a new hydrophobic wax named stearyl stearate. The chemical structure of the prepared compound was established according to its elemental analysis and spectral data. The new hydrophobic wax was used as a coating film to enhance the shelf life of freshly harvested tomato fruits. Therefore, stearyl stearate solution (2.00% w/v diethyl ether) was used for tomato coating and compared to chitosan-coated tomatoes, where weight loss, pH, fruit firmness, ascorbic acid concentration, and total soluble solids were studied for a period of 15 days at 23 ± 1.0 °C and 65 ± 2.0% relative humidity. The results revealed that coating with stearyl stearate solution (2.00% w/v diethyl ether) could delay tomatoes’ ripening during the experiment condition. A sensory evaluation of the coated tomatoes was carried out and showed acceptable taste for the tomatoes that were coated with stearyl stearate. On the other hand, the acute oral toxicity of stearyl stearate using albino mice showed complete safety up to 25 g/kg mice weight.

Since the bioactive surface needs hydrophilic coating; and the high corrosion resistance needs a hydrophobic one, it is a challenge to design a bioactive film that exhibits corrosion protection. In...

In this work, pure stearic acid had been isolated from buffalo adipose tissue, and chemically converted to a waxy stearyl stearate, which was then used as a coating film for enhancing the shelf life of freshly harvested fruits. Where adipose tissue was minced, fat was extracted by dry rendering method, and then it was characterized. The extracted fat was hydrolyzed into a mixture of free fatty acids and glycerol. Supercritical CO2 extractor was used for stearic acid individual extraction in pure form from the free fatty acids mixture, and it was confirmed according to its melting point, elemental analysis, GC-MS and mass spectrometry (MS) of the corresponding methyl ester. The isolated stearic acid was used for synthesis of a new hydrophobic wax named as stearyl stearate, the chemical structure of the prepared compound was established according to its elemental analysis and spectral data. The new hydrophobic wax was used as a coating film to enhance the shelf life of freshly harvested tomato fruit. Therefore, stearyl stearate solution (2.00% w/v diethyl ether) was used for tomato coating, and compared to chitosan-coated tomatoes, where, weight loss, pH, fruit firmness, ascorbic acid concentration and total soluble solids were studied for a period of 15 days at 23±1°C and 65 ± 2% relative humidity. A sensory evaluation of the coated tomatoes was carried out. And the results revealed that coating with stearyl stearate solution (2.00% w/v diethyl ether), could delay tomatoes ripening during 15 days storing at 23±1°C and 65 ± 2% relative humidity. On the other hand, acute oral toxicity of stearyl stearate was achieved using albino mice of 21–25 g body weight to determine its safety.

In this study, a coating of ionic Zr integrated in 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) metalorganic-like complexes was applied on Mg for corrosion control. HEDP was first immobilized on alkaline pretreated Mg followed by an alternating dip-coating process of Zr ions and HEDP to build a complex coating on Mg. This coating was demonstrated to be homogeneous, compact and with a metalorganic-like framework firmly anchored on Mg. This coating led to reduced corrosion current densities and remarkably suppressed long-term in vitro degradation of Mg in phosphate buffer saline (PBS). This complex coating showed promise for surface modification of Mg in biodegradable applications.

Plasma electrolytic oxidation (PEO) process is proved to be an effective technique for forming highly protective oxide film on Mg alloy AZ31. A comparative study has been done to investigate the PEO films deposited from silicate solution with NaF, Al2O3 nano-additives. The surface morphology feature, phase composition and elemental composition were examined by field scanning electron microscope, energy dispersive X-ray, X-ray diffraction. Doping of additives showed an obvious effect mainly on the peak of MgO and the thickness of the PEO films. Fluoride has a promising role and its presence considerably resulted in thicker and compacter films with improved corrosion resistance. Vice versa unexpected negative results had been obtained in the presence of alumina additives. It is assumed that fluoride ions enhanced ions conductivity during PEO process therefore promoted the film growth rate. On the other hand, the bulk Al2O3 particles hindered the ions movement through the coating deposition leading to thinne...

Magnesium and its alloys are promising biodegradable materials because of their light weight and superior mechanical properties. However, the high corrosion susceptibility of magnesium is the main obstacle that hinders the application of Mg in biomedical applications. In this article, two approaches have been employed to fabricate hybrid films of hexamethylene diamine tetrakis (methylene phosphonic acid) (HMDTMPA) and hydroxyapatite (HA) on Mg. The direct dipping method involves an immersion in a single solution containing both calcium, phosphate, and the organic compound. However, it results in poor-quality loose films, due to unstable film of monocalcium phosphate monohydrate (MCPM). The other method involves immersion in two separated solutions: Ca-P solution and HMDTMPA solution. Our results showed that the corrosion resistance was enhanced about 12-times compared with HMDTMPA film due to the formation of a stable hybrid film of dicalcium phosphate dihydrate (DCPD). The mechanism of formation of anti-corrosion DCPD was discussed on the light of SEM, EDS, FTIR, XRD and XPS.

It remains challenging to build up a multifunctional coating onto biodegradable magnesium (Mg) for biomedical use. In this study, a small amount of titanium dioxide (TiO

This paper introduces a novel coating process based on micro-arc oxidation (MAO) for formation of ceramic MgO layer over some newly developed magnesium alloys in an environmentally friendly electrolyte by anodization. Electrochemical corrosion testing showed that the corrosion resistance of bare AMS4429 is much better than that of AZ31HP-O and MZ due to formation of protective Nd-rich oxide layer in AMS4429 compared to less protective Al- and Zn-rich oxide films for AZ31HP-O and MZ respectively. Surprisingly, the corrosion resistance of MAO coated MZ is about 50 times higher than the bare one. The deposition, characterization and electrochemical characteristics of the fine porous MgO protective layer formed due to MAO coatings were investigated in details.

It remains challenging to build up a multifunctional coating onto biodegradable magnesium (Mg) for biomedical use. In this study, a small amount of titanium dioxide (TiO2) has been incorporated in situ into phytic acid (PA) coating when it was chemically deposited on Mg substrate targeted to biodegradable implant applications. Ultraviolet (UV) irradiation was utilized in the liquid phase deposition of TiO2 to improve the quality of coating (PA&TiO2-UV). This PA&TiO2-UV coating was compact, thicker and more hydrophilic compared with sole PA or TiO2 coating. The PA&TiO2-UV coated Mg presented a seven times lower electrochemical corrosion current density as well as significantly slower in vitro degradation rate up to 500 h in phosphate buffer saline as compared to the direct PA coated Mg. In addition, the UV irradiation showed remarkably to promote the MC3T3-E1 pre-osteoblast cells adhesion and proliferation especially after 7 days of culture. Further, the PA&TiO2-UV coating adhered more firmly on Mg substrate after 90° bending than the other coatings, indicating a better mechanical compliance on Mg substrate. These results make this PA&TiO2-UV complex coating bodes well for biodegradation slowing-down, osteo-compatible as well as mechanical compliant modification of Mg for orthopedic implants applications.

The polymerized Hydroxyquinoline (HQ) coatings incorporated with corrosion inhibitor nano-Graphene Oxide (GO) particles were fabricated on treated magnesium AZ31 alloy. The effect of surface treatment of AZ31 using either oxidation or phosphating was much more effective than GO embedment on the corrosion resistance and self-healing functionality. Surface treatment prior to GO/HQ deposition plays a vital role in initiating more anchoring bonds between molecules to fasten any scratch healing. The anticorrosion behavior of the GO/HQ hybrid coating will be discussed in the light of SEM, XRD, XPS and FTIR analysis.

Injection molding is one of the most important forming processes for thermoplastic polymers. Setting the injection molding parameter such as injection pressure, injection speed, cooling time and packing pressure plays a very important role in controlling the quality of the products forming by injection molding process. Taguchi approach is a widely used technique for optimizing the molding process parameters. This paper presents a simple and efficient way to study the influence of injection molding parameters on defects percentage. Using Design of experiments and Taguchi approach, the significant parameters are optimized to minimize the defects percentage of the most common defects (inverted label and incomplete plastic filling) that appeared in thin walled containers for food packaging. The results of the experimental study indicate that Injection speed and Injection pressure are the dominant factors determining the quality. The injection speed of 300 CCm/Sec give lower inverted label defect and the injection pressure of 2000 bar give lower incomplete filling defect.

This chapter discusses a modified microarc oxidation (MAO) process using two kinds of nano-additives (Al 2 O 3 and NaF) doped in the alkaline electrolyte system in order to improve the performance of MAO ceramic coatings formed on magnesium alloy AMS4429. The surface morphology, phase composition, and elemental composition of the MAO ceramic coating were examined by field electron emission scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. electrochemical impedance spectroscopy and potentiodynamic polarization techniques were used to investigate the electrochemical behavior of MAO coatings. Results showed that the ceramic coatings formed are composed of pure MgO with porous surface structures. Nano-additives showed no significant effect on the elemental composition, while they strongly influenced the morphological features and corrosion resistance of the MAO coating formed. The addition of NaF to the electrolyte solution results in the formation of MAO coatings with finer uniform nodules than that of Al 2 O 3 nanoparticles leading to a successful protective MAO coating.