Bleaching Time Research Articles

Influence of applied voltage on optimal performance and durability of tungsten and vanadium oxide co-sputtered thin films for electrochromic applications

In this research, tungsten and vanadium oxide co-sputtered thin films are evaluated for electrochromic properties based on the effects of applied cyclic voltages of −0.7 V, −1.0 V and −1.3 V for 9600 s. XRD patterns reveal the appearance of new peaks after completion of −1.3 V cycles, these peaks are not seen after lower voltage scans. SEM images also verify severely damaged morphologies. Chronoamperometry (CA) scan of −1.3 V shows a drastic reduction in current density value to as low as 32% for bleaching and 26% for coloring respectively. This is because of the lesser intercalation and de-intercalation as a result of damaged and disturbed orientation. Whereas the films with −1.0 V testing cycles shows the current density drop to 93% and 88% for bleaching and coloring respectively. A remarkable discovery in switching times of WO3-V2O5 co-sputtered thin films is also achieved. Coloring and bleaching times are drastically reduced to 5.5 s and ‹1.3 s as compared to only WO3 films having these values as 13.4 and 4.1 s respectively. We further investigates electrochromic films for different states and concentrations by XPS, electrochemical impedance spectroscopy (EIS) for electronic/ionic conductivity comparison and visible spectroscopy to verify optical modulation and calculation of some optical constants.

An all-solid-state polymeric electrochromic device based on two well-matched electrodes with fast switching time and excellent cycling stability

All-solid-state polymeric electrochromic devices (ECDs) were fabricated based on anodic poly(4,4′,4″-tris[4-(2-bithienyl)phenyl]amine) (PTBTPA) and cathodic poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS). PEDOT:PSS films with various thicknesses were obtained to control their charge capacities and neutral transmittances. It is found that the compatibility between PTBTPA and PEDOT:PSS has an important influence on the driving potential and electrochromic properties of ECDs. Therefore, an ECD with well-matched color and charge capacity between PTBTPA and PEDOT:PSS exhibits excellent electrochromic properties under low driving potential ranges (0–1.4 V) with high optical contrast of 54.3%, fast switching time of 1.02 s (colored time) and 0.51 s (bleached time), large coloration efficiency of 812.1 cm2‧C−1 and good cycling stability (which retains 70.2% of its original optical contrast after 10,000 cycles). The optimized all-solid-state polymeric ECD has potential applications in smart windows, electronic-tags and rearview mirrors.

Pulsed electrodeposition of nanostructured polythiothene film for high-performance electrochromic devices

In this work, polythiothene (PT) films on indium tin oxide (ITO) substrate (PT-5/ITO, PT-10/ITO, PT-15/ITO, and PT-20/ITO) are prepared by pulsed electrodeposition, where + 1.5 V as the first square waveform pulse is applied to the cell for 5, 10, 15, and 20 s, respectively. These obtained electrodes are further assembled into the electrochromic devices (ECDs). We investigate the surface morphology, electrochemical properties of PT films, and EC performance of corresponding ECDs. The results indicate that PT films possess loose surface morphology, large surface area and high electrochemical activities. Among four kinds of films (PT-5, PT-10, PT-15 and PT-20), PT-10 film has the most uniform distribution of nanoparticles and smaller particle size. The EC properties of ECDs are significantly improved, which exhibits a large optical contrast, high coloration efficiency, short switching time, and stable cycling. The ECD based on PT-10/ITO (ECD-10) has the best EC performance, caused by the nanostructured morphology of PT-10 film that is most conducive to electron conduction, ion diffusion and migration. Compared with the ECD based on PT film obtained by potentiostatic deposition on ITO glass, the optical contrast of ECD-10 increases by 94% (17 → 33%), and its coloration efficiency increases by 88% (159 → 299 cm2/C). Among all ECDs, the response time of ECD-10 is the shortest, and its coloration and bleaching time are 1.12 and 0.80 s, respectively. This study suggests that pulsed electrodeposition might be a facile strategy for fabricating high-performance polymer-based ECDs.

Bleaching Process on Oil Palm Empty Bunches by Pulping Using Formacell Liquid Waste

The formacell process produces black liquor that damages the environment. Previous research has shown that black liquor can be used as a cooking solution for pulping. The pulping process using formacell waste on oil palm empty bunches produces a dark color; therefore, it requires a bleaching process. The aim of this study was to determine the effect of the type of cooking solution (fresh pulping solution and leachate residual from pulping) and bleaching time (0.5, 1, 1.5, 2, and 2.5 h) on pulp yield, cellulose content, permanganate number, and score on whiteness degree. The bleaching process used 35% peracetic acid and was conducted at 80�C. The best results were obtained at a bleaching time of 2 h, which resulted in yields of 76.1%�81.2%, cellulose contents of 53%�62.5%, permanganate numbers of 6.3�7.4, and scores of color of 3.78 (yellowish white) to 4.7 (white).

Conjugated polymer multilayer by in situ electrochemical polymerization for black-to-transmissive eletrochromism

A range of novel multilayer films were fabricated onto ITO-coated glass through the multilayer electrochemical polymerization (MEP) technology using three EDOT-based electrochromic polymers (P1, P2 and P3) with additive primary colors red, green and blue (RGB) respectively in the neutral state, and high transmissivity in the oxidized state. As expected, a highly desired black-to-transmissive electrochromic switching with low driving voltages (<1 V) was observed for the resulting multilayer films through straightforward color mixing of polymers P1, P2 and P3. Significantly, the fabricated multilayer films, such as “P1/P2/P3 Multilayer”, possessed the outstanding electrochromic performances, including high optical contrast (exceeding 40%), fast switching speed (coloration time and bleaching time of less than 1.5 s), and lasting cyclic stability (optical contrast retains 89% after 500 steps), which make them hold great potential in practical applications of electrochromic devices, like switchable displays, energy-saving windows, electronic papers and so on. Finally, this work provides a simple and efficient approach towards black-to-transmissive electrochromism, and indicates that it is viable and facile to achieve fine-tuning in colors of electrochromic polymers in virtue of MEP method

Effect of the grain size on the electrochromic properties of NiO films

The use of electrochromic materials is increasing, and nickel oxide is one of the most studied electrochromic materials. In this work, the effect of the current density and film thickness on the microstructure and electrochromic properties of a nickel oxide film was investigated. The number of cycles affected the optical modulation amplitude of the film. Ni thin films with different deposition parameters were prepared by electrodeposition, and NiO thin films were obtained by oxidization at 300 °C for the same time. When the thickness was 20 nm, an increase in the deposition current density from 1.25 mA/cm2 to 3.75 mA/cm2 increased the optical modulation amplitude by 25%, the colouring time by 2.1 s, and the bleached time by 1.2 s. With increasing current density, an inflection point representing the difference between the grain boundary fading rate and the grain fading rate appeared. When the thickness of the sample deposited at 2.50 mA/cm2 was increased from 10 nm to 50 nm, the optical modulation amplitude increased by 35%, and the cycle response time obviously increased. And the coloured state transmittance of the film could be reduced to 30%. Increasing the film thickness and deposition current density increased the grain boundary surface area of the NiO film. As a result, the optical modulation amplitude and cycle response time of NiO electrochromic films increased.

Interfacial Coordination Nanosheet Based on Nonconjugated Three-Arm Terpyridine: A Highly Color-Efficient Electrochromic Material to Converge Fast Switching with Long Optical Memory.

An electrochromic (EC) hyperbranched coordination nanosheet (CONASH) comprising a three-arm terpyridine (3tpy)-based ligand and Fe(II) ion has been synthesized by interfacial complexation at the liquid-liquid interface. The film can be easily deposited on the desired substrate such as indium tin oxide (ITO) glass. Characterization of CONASH deposited on ITO by microscopic methods reveals the homogeneous nanosheet film with an ∼350 nm thickness after 48 h of reaction. The fabricated solid-state EC device (ECD) undergoes a reversible redox reaction (Fe2+ → Fe3+) in the potential range of +3 to -2 V in ECDs accompanied with a distinct color change from intense pink to colorless for several switching cycles with a coloration time of 1.15 s and a bleaching time of 2.49 s along with a high coloration efficiency of 470.16 cm2 C-1. Besides, the nonconjugated 3tpy ligand restricts the easy electron redox conduction inside the EC film to enhance the EC memory in open-circuit condition as it shows 50% retention of its colorless state until 25 min. The long EC memory compared to other metallo-supramolecular polymers having a conjugated ligand suggests the potentiality of the 3tpy-Fe CONASH film to be used as a power-efficient EC material for modern display device applications.

Bleaching and coloration kinetics of electrochromic device based on PT/EG/AgNWs composite film

In this work, electrochromic polymer (ECP)/exfoliated graphene (EG)/silver nanowires (AgNWs) composite film on indium tin oxide (ITO) substrate (ECP/EG/AgNWs/ITO) is prepared, and further assembled into the electrochromic device (ECD). We investigate the performance, bleaching and coloration kinetics of device based on the composite film using polythiothene (PT) as model polymer. The results indicate that the ECD based on PT/EG/AgNWs/ITO possesses large optical contrast (36%), high coloration efficiency (234 cm2/C), fast response time (the coloration and bleaching time are 6.63 and 0.71 s), and exhibits stable cycling. In comparison with the device based on PT film on bare ITO (PT/ITO), the optical contrast of device based on PT/EG/AgNWs/ITO is doubled (18 → 36%), and its coloration efficiency increases by 42% (165 → 234 cm2/C). Additionally, we can find that the dynamic processes of bleaching and coloration are all divided into three parts: I, primary stage; II, middle stage; III, late stage. The primary bleaching and coloration are completed in the first two stages. In stage II, the rate constants of bleaching and coloration can be obtained from the linear regression curves, and these rate constants of ECD based on PT/EG/AgNWs/ITO are higher. This study lays a foundation for quantitative analysis of bleaching and coloration processes and the construction of EC kinetic model.

Fabrication of metal-supramolecular polymers of FeL/carbon nanomaterials with enhanced electrochromic properties

The metal-supramolecular polymers, with emerging state-of-the-art electrochromic materials (ECMs), have witnessed explosive developments due to wide promising applications in industry and military. Here, we report novel composites of metal-supramolecular polymer FeL (combining 1,4-bis(2,2':6′,2″-tribipyridin-4′-yl) benzene (L) with Fe) with 0D to 2D functionalized carbon nanomaterials (fullerene (C60), single-walled carbon nanotube (SWCNT) and graphene oxide (GO)), showing significant improved cyclic stability and response time. FTIR spectra indicate that a strong interfacial interaction occurred between FeL and carbon nanomaterials. SEM image clearly shows that the addition of carbon nanomaterials results in a large number of homogeneous micro-pores on the film surface morphology, especially for the FeL/SWCNT, which contributes to the ion migration during the electrochromic process. Consequently, the order of electrochemical activity of the as-prepared composites follows the order of FeL/SWCNT > FeL/C60 > FeL/GO > FeL. Compared with the pristine FeL, the three composites exhibit obviously improved cyclic stability and response time. In particular, the FeL/SWCNT composite displays the optimal electrochromic properties with the bleaching time of 1 s, and the coloring time of 0.9 s, and the highest cyclic stability.

A fast switching electrochromic performance based on poly(3,4-ethylenedioxythiophene)-reduced graphene oxide/metal-organic framework HKUST-1

Poly(3,4-ethylenedioxythiophene)-reduced graphene oxide/Cu-based metal-organic framework (PrGO/HKUST-1) was electrochemically synthesized via a chronoamperometry. Structural identification, functional groups characterization, morphology and charge transfer properties of the PrGO/HKUST-1 were studied using X-Ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), field emission scanning microscopy (FESEM) and electrochemical impedance spectroscopy (EIS). The PrGO/HKUST-1 exhibited a high coloration efficiency of 176.8 cm2C-1 at 500 nm with high optical contrast. An electrochromic coloration and bleaching times of 1.3 and 1.4 s were recorded at 500 nm which proved an excellent switching kinetics of PrGO/HKUST-1 compared to PEDOT (tc = 50.6 s, tb = 49.3 s), PrGO (tc = 4.6 s, tb = 5.5 s) and HKUST-1 (tc = 23.0 s, tb = 31.9 s). The charge retention of 83.4% over 900 cycles proved efficient Li+ ions diffusion into the PrGO/HKUST-1 throughout the coloration/bleaching process. Thus, the combination of PEDOT, rGO and HKUST-1 as a PrGO/HKUST-1 is a promising electrochromic display due to its excellent electrochromic performance.

A new mathematical approach to the bleaching process of edible oils

AbstractBACKGROUNDAs energy costs are constantly increasing, industries need to consider efficiency in all processes. Vegetable oils, which are among the daily staple foods, have large energy‐consuming processes during refining. Bleaching, one of the most important of these processes, is a process in which energy is used abundantly. In this study, system parameters of bleaching earths were experimentally investigated for a factory that processes soybean and sunflower oil.RESULTSThe bleaching earth used was characterized using X‐ray diffraction and Brunauer–Emmett–Teller (BET) techniques, while the oils at the process outlet were analyzed according to ASTM standards. The amount of bleaching earth used and bleaching time were used as independent parameters, and color, acid and peroxide number values were determined. Furthermore, through the use of gathered experimental data, a model was developed to predict the color of products under different operating conditions. Two different approaches were used to estimate the color values of oils. According to the polynomial and thin plate spline approaches, 2–2.5 wt% bleaching earth and 60–80 min bleaching time were determined as optimum conditions.CONCLUSIONIt was determined that the ratio of bleaching earth and the bleaching time had a serious effect on the color, but their effects on acid and peroxide numbers were limited in comparison. There was no linear relationship between the bleaching time and the color change, and the excess time had a negative effect on the bleaching process depending on the amount of the bleaching earth. © 2020 Society of Chemical Industry

Optimisation of bleaching time and H2O2 concentration of handmade paper from Areca catechu L. fibre

Areca nut (Areca catechu L.) is a type of palm used for commercial purposes because all parts of the plant -have high economic value. Areca nut fibre contains 53.2% cellulose and therefore, it can potentially be used as raw material for pulp for paper craft. Bleaching is conducted in order to make colourful paper craft. Some factors to be taken into account while bleaching the paper craft are levels of chemicals used for bleaching and length of bleaching time. The purpose of this study was to determine H2O2 level and optimum bleaching time to create quality paper from areca fibres and cardboard paper. Quality of the paper was evaluated based on tensile strength, thickness, grammage and brightness. Response surface method (RSM) is implemented optimize the estimated response. The model used in RSM is CCD (Central Design Composite) with 2 factors, namely bleaching time and H2O2. The upper and lower limit for the first factor were 90 and 150 minutes consecutively. Those for the second factor were 5% and 15% respectively. The evaluate responses were tensile strength and brightness level. The findings showed that the most suitable combination was 150-minutes bleaching time and 15% H2O2. The combination resulted in 69.50% brightness and 14.71 kN/m2 tensile strength. In addition, the paper grammage was 282 gr/cm2, its thickness was 0.88 mm and the moisture content was 6.5.

Flexible electrochromic thin films with ultrafast responsion based on exfoliated V2O5 nanosheets/graphene oxide via layer-by-layer assembly

Abstracts Flexible electrochromic (EC) display devices have received extensive attention due to their application in the new generation of smart and wearable devices. 2D ultrathin nanosheets are the promising structure to allow EC materials (such as V2O5, WO3) to be incorporated into flexible EC electronics owing to their surface-to-surface contact with the flexible substrate. Herein, the graphene-like V2O5 nanosheets (V2O5 NSs) with thicknesses ranging from few-layers (4 nm) to 40 nm are synthesized by liquid-phase exfoliation (LPE) method. To enhance the electronic conductivity and decrease the agglomeration of V2O5 NSs, graphene oxide (GO) is introduced to fabricate V2O5 NSs/GO films by layer-by-layer (LBL) assembly method. The composite films exhibit ultrafast coloring responsion time (1.6 s) and bleaching time (2 s) attributed to the reduced charge transport distances of 2D ultrathin structure. The LBL assembly structure accompanied by larger Li+ ions storage surface areas facilitates the superior transmittance contrast (ΔT) of 57.5% at 425 nm and reversible yellow/green/blue-grey color changes. Besides, the flexible V2O5 NSs/GO films on ITO/PET substrate still display rapid responsion speed (2.7 s/4.3 s) after bending 100 cycles with the bending angle of 90°, which manifests their potentially application for flexible EC devices.

Highly Stable and Rapid Switching Electrochromic Thin Films Based on Metal-Organic Frameworks with Redox-Active Triphenylamine Ligands.

Metal-organic frameworks (MOFs), known for their tailorable porous structures and large specific surface areas, are appealing for electrochromic applications as their abundant pores may greatly benefit the charge transport required for electrochromic switching. Herein, for the first time, a simple, scalable, and cost-effective electrochemical deposition method for fabrication of high-performance and durable MOFs-based electrochromic films with redox-active ligands was developed. The fabricated film can achieve rapid switching speed (both coloration and bleaching time <5 s) because the inherent cavities of the MOFs greatly facilitate ion insertion and extraction. In addition, the film constructed with optimized parameters shows a high optical contrast of 65%@700 nm and can be stably switched for 1000 cycles with <5% contrast attenuation, which is by far the best cycling performance for MOFs-based electrochromic materials ever reported. Furthermore, our method enables the scalable preparation of large-area MOFs-based electrochromic thin films without using large high-pressure reaction vessels, and the as-prepared film in this work could be switched well between colored and bleached states. This new method, therefore, opens up a new avenue to broaden the use of MOFs-based thin films for electrochromic applications.

Novel D-A-D conjugated polymers based on tetraphenylethylene monomer for electrochromism

A monomer (E)-4′,4‴-(1,2-diphenylethene-1,2-diyl)bis([1,1′-biphenyl]-4-carbaldehyde) (DDBC) with AIE properties and two novel DDBC-basing polyazomethines (coded as P1 and P2) were prepared. They were gained in short time, low cost and mild reaction conditions by a straightforward synthetic path. Fluorescent testing shows that DDBC owns an intense aggregation-induced emission (AIE) characteristics. But unfortunately, the polymers based on DDBC do not have AIE effect. It may be attributed that the molecules in the excited state consume light energy in the form of electron transfer, reducing the proportion of energy outputted from light, thus causing the disappearance of macroscopic fluorescence. Another guess is that the tetraphenylethylene (TPE) unit takes part of the conjugated backbone of the polymer. However, P1 have high coloration efficiency (346.94 cm2 C−1) and P2 have short response time (the color switching time is 3.43 s and the bleaching time is 1.41 s at 470 nm). Moreover, P1 has electrochromic properties in the near-infrared field. Thus, these features demonstrate that these two novel polymers have great potential as electrochromic materials in optoelectronics applications.

Study on electrochromic properties of TiO2 films under Co ion content fluctuations

In this paper, the Co doped TiO2 film with satisfactory electrochromic performances was prepared by a sol-gel method. To study the Co-doped influence on the TiO2 film for the electrochromic performances, we respectively regulated the Co ion content to 0, 0.4, 0.8 and 1.2 at%. Due to the Co ions doped into the TiO2 film, the synthesized film led to the generation of the oxygen vacancies. From the results, when the optimal Co ion content is 0.8 at%, the improved switching time (the bleached time of 2.9 s and the colored time of 5.1 s) and the improved coloration efficiency (18.89 cm2/C) compared to the other samples are obtained. These results can be due to the enhanced Li+ diffusion coefficient and electric conductivity, which result in the increase of the electrochromic reaction activity and the reduction of the optical band gap in colored state to improve the transmittance modulation. Thus, the new film can be a competitive electrochromic material to enhance the performances of the electrochromic device.

Exploration on Spent FCC Catalyst for Decolorization of Vegetable Oil

In the present work, an FCC equilibrium catalyst (E-cat) was used as a decolorizer in decolorization of vegetable oil. E-cat is an excellent and stable decolorizer, which can even be directly applied to the decolorization of vegetable oil after being discharged. The process conditions were investigated and optimized, mainly the bleaching temperature, time, and E-cat amounts. The spectrophotometric method was used to calculate the decolorization rate after detecting the absorbance of vegetable oil. As the bleaching time, temperature and E-cat amounts increase, the effects on the decolorization of rapeseed oil by E-cat were all improved to varying degrees. The best decolorization utility of E-cat was performed at 115°C and an E-cat ratio of 5wt% for 40min, the decolorization rate of the rapeseed oil was 93.3%. Compared with the fresh FCC catalyst with high catalytic activity, the decolorization capability of E-cat was not much reduced. It indicates that the structural characteristics of E-cat are more desirable in the decolorization of vegetable oil, as evidenced by the alkali treatment test.

Tunable graduated filters based on electrochromic materials for spatial image control

Passive graduated filters with fixed absorption profile are currently used in image recording to avoid overexposure. However, a whole set of filters with prescribed gradients is required to cope with changing illumination conditions. Furthermore, they demand mechanical adjustment during operation. To overcome these deficiencies we present a microfabricated active electrochromic graduated filter which combines multiple functionalities: The overall absorbance, the position of medium transmission as well as the magnitude of its gradient can be tuned continuously by electrical means. Live image control is possible using low operation voltages in the range of ±2 V to reach a high change in optical density ΔOD of 1.01 (400 nm to 780 nm) with a coloration and bleaching time 1.3 s and 0.2 s, respectively. Owing to their low volume and power consumption they are suitable for widespread applications like in smartphones, surveillance cameras or microscopes.

Synthesis, electrochromic properties and flash memory behaviors of novel D-A-D polyazomethines containing EDOT and thiophene units

A series of novel polyazomethines containing EDOT and thiophene units coded as PEDOTs (PEDOT-TPA, PEDOT-TDD, PEDOT-THIO, PEDOT-APM) and PTHIOs (PTHIO-TPA, PTHIO-TDD, PTHIO-THIO, PTHIO-APM) were synthesized successfully. They were gained in short time, low cost and mild reaction conditions by a straightforward synthetic path. It can be easily found from the electrochemical properties of these polymers that the polymers containing 3,4-ethylenedioxythiophene (EDOT) unit (PEDOTs) have lower initial oxidation potentials as compared to the polymers containing thiophene unit (PTHIOs). Spectroelectrochemical properties reveal that all of the polymer films exhibit outstanding multielectrochromic behaviors, distinct color contrast and excellent electrochemical stabilities. Kinetic studies show that the PEDOT-TPA film has the shortest response time (a color switching time of 4.54 s and a bleaching time of 3.88 s at 428 nm) and the PEDOT-THIO film exhibits the highest CE of 343.56 cm 2 C −1 . Typical I-V characteristics of the ITO/plymer/Al memory devices exhibit that all the memory devices based on PEDOTs and PTHIOs exhibited nonvolatile flash memory characteristics, with an ON/OFF current density ratio of 10 3 -10 4 and low threshold voltages (around 1 V). Thus, these characteristics illustrate that these novel polymers have great potential in optoelectronics applications as electrochromic materials and memory devices. • Eight kinds of novel polyazomethines were synthesized successfully by a straightforward synthetic path. • All of these polyazomethines exhibit outstanding electrochromic behavior and excellent electrochemical stability. • The polymers containing 3,4-ethylenedioxythiophene (EDOT) units (PEDOTs) have low initial oxidation potential. • Among these polymers, the PEDOT-TPA film has the shortest response time and the PEDOT-THIO film exhibits the highest CE. • All the memory devices exhibited nonvolatile flash memory characteristics.

Optimum condition of conventional bleaching process for bleached shellac

AbstractBleached shellac has attracted wide interest in many industries. Since bleaching using sodium hypochlorite is a vigorous process, it can possess a high impact on physicochemical properties causing the unstable bleached‐shellac. An investigation into optimum conditions of the bleaching process was, therefore, required to achieve sufficient whiteness, good mechanical properties, and the stable bleached‐shellac. The studied conditions were variations in solvents, volume, and time of bleaching. Studied parameters, such as color change, acid value, insoluble solid, polarity, water vapor permeability coefficient, mechanical properties, chemical structure, and crystallinity, were detected. The physicochemical properties depended on the bleaching conditions but no effect on the chemical and amorphous structures of shellac. With the proper control of bleaching process, the simple, and conventional method can be applied in bleaching. The optimum condition was the use of sodium carbonate as a solvent, 20‐ml sodium hypochlorite, and 2‐hr bleaching time.Practical applicationsShellac has long been used as an edible coating for extending product quality. Although shellac possesses an outstanding property in moisture protection, the dark color causes an unpleasant for applying in food and pharmaceutical industries. The bleaching process using sodium hypochlorite is commonly used to whiten the shellac. Due to the vigorous redox reaction of process, extreme changes in properties of shellac were obtained. The aim was to explore the optimum condition of bleaching process. The studied conditions were, solvent used, amount, and time of bleaching process. With a careful control of process, not only provided a high degree of whiten shellac but also obtained good physicochemical properties of bleached shellac. This study could be of help in adding the value of natural polymer without the use of high temperature and power consumption compared with other methods. The bleached shellac can then be used in wider applications.