Papers by Keyword: Shellac

Abstract: The objective of this study was to assess feasibility of applying shellac as a biopolymer filament for using in fused deposition modeling (FDM) 3D printing. The shellac matrices were prepared through hot melt process by heating the ground shellac samples at 80°C in a silicone oil bath under continuous stirring for 15 min. Accelerated stability testing (annealing process) was also performed in order to evaluated thermal stability by re-heating shellac matrices at 80 °C for 12 h and 24 h in a hot air oven. The shellac matrices and annealed shellac matrices were then comparatively characterized. In the present study, all shellac matrices were investigated for physical appearance, acid value, insoluble solid, moisture content and also characterized by instrument analysis including Fourier-transform infrared (FTIR) spectroscopy, powder X-ray diffractometry (PXRD) and thermal analysis. The results demonstrated that shellac with initial heat (80°C, 15 min) and annealed at 80°C for 12 h had similar properties except the annealed shellac at 80°C for 24 h which shown the lower acid value and formed insoluble solid. The melting temperature, decomposition temperature and melting enthalpy of shellac were around 63-64°C, over than 200°C and 23 J/g, respectively. Furthermore, the extruded filament based on shellac was achieved by hot melt extrusion (HME) technique. The findings revealed that the shellac properties might be suitable to fabricate FDM filaments.

Abstract: Shelf life in ground and tree nuts are often assessed based on aesthetic appearance, nut integrity, color and most importantly, taste and edibleness. Nuts with considerable level of rancidity and free fatty acids due to degradation of oils indicate expiration or decay. We prepared a shellac-lemongrass oil blend coating using food-grade ingredients and assessed its potential to extend shelf life of Pili nut (Canarium ovatum) kernels. A glossy, hard but considerably brittle coating for the pili kernels were prepared with varying numbers of layers. On average, the mass of coating added per dip is 0.10 g, and the thickness of 5-layers of coating is 0.3 mm. The obtained reflectance spectra of the coated pili kernels implied the translucent nature of the coating, but becomes opaque as the number of layers are increased. Peroxide value (PV) and free fatty acid value (FFAV), were also measured at 10 days after application of coating. PV was lowest in the nuts with 5 coating layers, while this treatment did not reduce FFAV. These results indicate the effectiveness of our coatings in preventing peroxide production probably by blocking oxygen penetration and ultraviolet exposure, which are important triggers production of peroxide and other free radicals. Further tests and time-series experiments are planned to assess the dynamics of peroxide levels and the overall potential of our coating technology for Pili nut.

Abstract: A molded pulp is increasingly used as eco-packaging, but it has poor water resistance. Therefore, surface coating is common to perform on pulp or paper packaging to overcome this shortcoming. In this study, the bagasse (BG) molded pulp sheets were mono-and bilayer coated with nanofibrillated cellulose (NFC), modified NFC (mNFC), and shellac (S) by using a spin coating technique. Surface morphology, surface wettability, water absorption, and mechanical properties of the coated sheet samples were evaluated and compared to the uncoated sample. It was found that mNFC could effectively provide an even and complete coverage coating layer on the BG-based sheet (BG/mNFC), thanks to the partially substituted ester groups. On the contrary, NFC could not be coated evenly on the BG-based sheet surface (BG/NFC) due to its tendency towards agglomeration. The homogeneity of surface obtained from the first layer coating by NFC or mNFC affected the surface quality of the second layer coating by shellac. As a result, the BG/mNFC/S bilayer coated sample showed the smoothest surface and also the highest water resistance confirmed by SEM, contact angle measurement, and water absorption results. Furthermore, the tensile properties of both bilayer coated samples (BG/NFC/S and BG/mNFC/S) were significantly improved (p<0.05) as compared to the uncoated BG sample. This results suggested that the current bilayer coating system is very promising for advancing the performance of molded pulps in novel packaging uses.

Abstract: The aim of this study was to develop the electrospun shellac (SHL) and hydroxypropyl cellulose (HPC) blended nanofibers for drug carrier application. The effects of polymer solution and electrospinning parameters, including SHL-HPC ratio, HPC concentration, applied voltage and flow rate, on the appearance of fibers were investigated. Based on the results, electrospun fiber was not obtained when a solution of HPC alone was employed. However, the fibers would be obviously fabricated as SHL was added to the HPC solution. An increase in the SHL ratio in SHL-HPC blended solution could accordingly lead to a remarkable enhance in the fiber diameter. In addition, the continuous nanofibers with less beads were gradually formulated when the HPC concentration was increased. The electrospinning parameters seemed to be significant. The elevation of infusion rate from 0.5 to 1 mL/h would contribute to the preparation of thick fibers with the diameters enlarging from 666.9 to 843.5 nm. With the applied voltage increasing from 15 to 30 kV during the electrospinning process, the fabrication of small nanofibers with the diameters reducing from 843.5 to 741.6 nm would be conducted. In this study, monolaurin (ML), a broad antimicrobial agent, was encapsulated into the SHL-HPC carrier for the purpose of drug delivery application. Regarding the result, the loaded concentration of ML could not be enhanced by introducing HPC to the SHL fibers.

Abstract: Shellac is a natural product which has been presumed as a fragile polymer due to itschemical properties. The objective of this study was to improve chemical properties of shellac by themodification with different concentration of glycerol and acrylic acid. Shellac was reacted withglycerol at various temperature and amounts of glycerol. The intermediate product was reacted withacrylic acid at different concentration. Acid value, hydroxyl groups, and free glycerol concentrationof modified shellac was determined. The result showed that acid value gradually decrease alongincreasing temperature for each ratio of glycerol and acrylic acid to shellac. The concentration ofhydroxyl groups rise as temperature and ratio increases. Furthermore, free glycerol concentration felldown along with the rise temperature. Modification chemical properties of shellac with glycerol andacrylic acid can be applied for the further study to enhance shellac properties.

Abstract: Electrospun shellac nanofibers might be potentially used for wound dressing application due to its natural origin and excellent protective properties. In this study, a full factorial design with three replicated center points was performed in order to investigate the main and interaction effects of shellac content (35-40% w/w), applied voltage (9-27 kV) and flow rate (0.4-1.2 mL/hr) on the morphology of shellac nanofibers. A total of 11 experiments were conducted. The response variables were the diameter of nanofibers, the distribution of diameter and the amount of beads. The results showed that the concentration of shellac was the most significant impact on shellac nanofiber diameter, while applied voltage, interaction between shellac content and voltage, and feed rate were minor factors, respectively. Shellac content and applied voltage had negative relationships with bead amount. When reducing the concentration of shellac and voltage, the amount of beads was increased. However, the influence of these parameters on diameter distribution seemed to be not significant. Based on response surface plot, nanofibers with thinner diameter (~493 nm) and less number of beads (~0.47) could be obtained at the optimum conditions; the shellac content of 38.5% w/w, the voltage of 21 kV and the feed rate of 0.4 mL/hr.

Abstract: This work reports on the effect of shellac coated hydroxyapatite (HA) on the compression strength. The HA was processed from bovine bone. Shellac was derived from the resinous secretion of the lac insect. The aims of the addition of shellac solution is to improve the mechanical properties of the material, especially when this material is implanted as a bone filler in order to not easily broken.The four different of shellac solutions (2,5%; 5%; 7,5%; and 10% weight) coated HA scaffold and one ratio as a control. It was found that the compression strength is influenced by the shellac solution. The greater of shellac solution will increase the compression strength of HA. The highest compression strength ​​was obtained in a solution of 10%.The morphology of HA scaffold was analyzed by Scanning Electronic Microscopy (SEM).

Abstract: A modified coaxial electrospinning process is developed for producing medicated nanofiber membranes of shellac. With pure ethanol as a sheath fluid, high quality borneol-loaded shellac nanofibers have been successfully fabricated using the modified coaxial process. Electron scanning microscopic observations demonstrated that the nanofibers had better quality than those fabricated using a single fluid electrospinning in terms of nanofiber diameters and their distributions. The former had an average diameter of 570 ± 80 nm under a sheath-to-core flow rate ratio of 0.25, whereas the later was 940 ± 230 nm. X-ray diffraction results verified that borneol existed in the shellac matrix in an amorphous state. The medicated nanofiber membranes could significantly improved the physical stability of borneol due to the favorable hydrogen bonding between the drug and the polymer matrix, as demonstrated by the weight loss experiments. The modified coaxial electrospinning process described here expands the capability of electrospinning process in generating high quality functional membranes.

Abstract: The present study report two types of ultra-thin shellac fibers that were fabricated using a traditional single fluid electrospinning and a modified coaxial electrospinning. Ethanol was exploited as the solvent of shellac and also a sheath fluid of the coaxial process. A camera was used to observe the electrospinning processes and scanning electron microscope was taken to investigate the prepared shellac nanofibers. A single fluid electrospinning of 64% (w/v) shellac solutions not only clogged the spinneret now and then, but also resulted in fibers with a spindles-on-a-string morphology under a flow rate of 1.0 mL/h and an applied voltage of 12 kV. In sharp contrary, a coaxial electrospinning of 80% (w/v) shellac solutions (under a sheath and core flow rate of 0.2 and 0.8 mL/h, respectively, and an applied voltage of 12 kV) furnished linear nanofibers with an average diameter of 740 ± 60 nm. With the same outflows from the nozzles of spinneret, the ultrathine nanofibers from the modified coaxial process surpassed those from the single fluid process in terms of fibers’ morphology and size. The modified coaxial process described here expands the capability of electrospinning process and opens a new way to obtain thinner nanofibers with fine structural uniformity.

Abstract: In this paper, the compound shellac fruit wax was prepared by SiO₂ aerogel, shellac, sodium hydroxide, fungicide. The obtained fruit wax was used to preserve the mango in tropical area. The results show that the compound shellac fruit wax with 0.2% SiO₂ aerogel can suppresses water loss, adjust the respiration, reduce the rot rate, thus extending the preservation time of mango.