Nano-TiO<Subscript>2</Subscript> based multilayer film deposition on cotton fabrics for UV-protection

Nano-TiO₂ based multilayer nanocomposite films were fabricated on cationically modified woven cotton fabrics by layer-by-layer molecular self-assembly technique. Cationization process was used to obtain cationic surface charge on cotton fabrics. Attenuated total reflectance Fourier transform infrared spectroscopy analyses were used to verify the presence of cationic surface charge and multilayer films deposited on the fabrics. Scanning electron microscope micrographs of poly(sodium 4-styrene sulfonate)/TiO₂, nano polyurethane/TiO₂, and TiO₂/poly(diallyldimethylammonium chloride) multilayer films deposited on cotton fabrics were taken. With nano-TiO₂ based multilayer film deposition, the protection of cotton fabrics against UV radiation is enhanced. The UV protection durability of the self-assembled multilayer films deposited on the cotton fabrics was analyzed after 10 and 20 washing cycles at 40 °C for 30 min. Air permeability and whiteness value analysis were performed on the untreated and multilayer film deposited cotton fabrics. The effect of layer-by-layer deposition process on tensile strength properties of the warp and weft yarns was determined.     

A Novel Green Stabilization of TiO<Subscript>2</Subscript> Nanoparticles onto Cotton

Facile embedding of TiO₂ nanoparticles onto cotton fabric has been successfully attained by ultraviolet light irradiations. The adhesion of nanoparticles with fibre surface, tensile behaviour and physicochemical changes before and after ultraviolet treatment were investigated by scanning electron microscopy, energy dispersive X-ray and inductive couple plasma-atomic emission spectroscopy. Experimental variables i.e. dosage of TiO₂ nanoparticles, temperature of the system and time of ultraviolet irradiations were optimised by central composite design and response surface methodology. Moreover, two different mathematical models were developed for incorporated TiO₂ onto cotton and tensile strength of cotton after ultraviolet treatment and used further to testify the obtained results. Self-clean fabric through a synergistic combination of cotton with highly photo active TiO₂ nanoparticles was produced. Stability against ultraviolet irradiations and self-cleaning properties of the produced fabric were evaluated.     

Ladder-Structured Polysilsesquioxane/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Nanocomposites for Transparent Wear-Resistant Windows

As a protective layer for deformable displays, we synthesized ladder-type polysilsesquioxanes (LPSQs) containing cyclic epoxy as a curable unit. The mechanical properties after photo- and thermal-curing of LPSQs with a small amount of added Al₂O₃ nanoparticles were compared with those of the pure LPSQs. The prepared LPSQ-Al₂O₃ nanocomposites and the pure LPSQs exhibited comparable optical transparencies and thermal stabilities. In addition, the degree of conversion of the applied epoxy units in LPSQs and the resulting mechanical properties, as monitored by Fourier transform infrared spectroscopy and nanoindentation tests, indicated that the addition of nanoparticles to LPSQs moderately enhanced the epoxy conversion rate and remarkably improved the wear resistance, including hardness, after photo-/thermal-curing processes. The LPSQ-Al₂O₃ nanocomposites achieved higher wear resistance than epoxy-silica nanocomposites containing similar curable functional groups and reinforcing fillers (silica). The excellent mechanical properties of the LPSQ-Al₂O₃ nanocomposites could be attributed to three-dimensionally interconnected networks of organic-inorganic hybrid-type chemical structures in the LPSQ as well as additional reinforcement from amine-functionalized Al₂O₃ nanoparticles covalently interconnected with the LPSQ. We believe that the devised LPSQ-Al₂O₃ nanocomposites could serve effectively as a wear-resistant platform for deformable display windows.     

Fabrication and characterization of nano Al<Subscript>2</Subscript>O<Subscript>3</Subscript> filled PVA:NH<Subscript>4</Subscript>SCN electrolyte nanofibers by electrospinning

Present paper reports a method of preparing polymer composite electrolyte nanofiber mat using polyvinyl alcohol (PVA), ammonium thiocynate (NH₄SCN) salt, and aluminium oxide (Al₂O₃) nano particles based on electrospinning technique. Two-stage process of preparation of nanofibers, namely, preparation of nano particles filled PVA electrolyte gel solution followed by its electrospinning has been used. The so obtained nanofibers have been characterized by XRD, DSC, SEM, and Conductivity measurements. XRD patterns affirm the formation of nanocomposite while SEM pictures reveal formation of fibers on a nano scale format (300–800 nm). Fibers of the electrolytes are seen to be thermally stable. Ionic conductivity of electrolyte fiber is seen to improve in the presence of nano filler at room temperature with a maximum at 5.31×10⁻³ Scm⁻¹ for 4 wt% filler concentration, which is comparable to that for corresponding dried gel electrolyte films.     

Preparation and characterization of inner-pressure hollow fiber composite membrane via two-way coating technique for CO<Subscript>2</Subscript>/CH<Subscript>4</Subscript> separation

High-selectivity inner-pressure hollow fiber composite (HFC) membrane for CO₂/CH₄ separation was prepared through the Two-way coating (TWC) technique. The blends of poly(vinylamine) (PVAm)/polyvinyl alcohol (PVA) were coated onto porous hollow fiber polysulfone (PSF) ultrafiltration (UF) membrane with an effective membrane area of 0.4 m². The effects of fabrication parameters on the permselectivity of the resultant HFC membrane were investigated and the optimum preparation conditions were obtained as follows: coating time for 30 min and air blowing time for 30 min after the coating. The prepared HFC membrane showed the typical characteristic of fixed carrier membrane with a high selectivity of CO₂ and CH₄: the separation factor of CO₂/CH₄ (40 vol% CO₂ at 25 °C and 0.2 MPa) was 36.6 and the CO₂ permeability was 56.3 GPU. Field emission scanning electron microscopy (FESEM) images indicated that the HFC membrane prepared by TWC technique had a uniform coating layer along the whole hollow fiber. Membrane permselectivity showed almost no difference between different membrane sections. The HFC membrane showed a good stability during the continuous testing process of 540 h. And the HFC membrane preserved at 30 °C and 40 % humidity exhibited a good durability with a basically unchanged separation factor after 30 days.     

Effect of phase transformation on physical and biological properties of PVA/CaFe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanocomposite

The thermal treatment method was employed to achieve higher homogeneity of calcium ferrite (CaFe2O4) and Poly (vinyl alcohol) (PVA) nanocomposites. The influences of phase transformation on physical and biological properties of calcined specimens were investigated by various experimental techniques including X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), high resolution Field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FT-IR). Heat treatment was conducted at temperatures between 723 and 923 K, so that a phase transformation occurred from cubic to orthorhombic spinel structure at 923 K. The chemical analysis of the PVA/CaFe₂O₄ nanocomposite was performed by energy dispersion X-ray analysis (EDXA), demonstrated the PVA/CaFe₂O₄ nanocomposites contained the elements of C, Ca, Fe, and O. The formed nanocomposites exhibited ferromagnetic behaviors which were confirmed by using a vibrating sample magnetometer (VSM). The calcined specimens were carried out to an antimicrobial or antifungal test.     

The effect of floating vegetation on CH<Subscript>4</Subscript> and N<Subscript>2</Subscript>O emissions from subtropical paddy fields in China

Duckweed (Lemna minor), a floating macrophyte belonging to the Lemnaceae family, is commonly found in subtropical paddy fields. This plant rapidly takes up nutrients from water and forms dense floating mats over the water surface that may impact the biogeochemical processes and greenhouse gas production in paddy fields. In this study, we measured CH₄ and N₂O emissions from duckweed and non-duckweed plots in a subtropical paddy field in China during the period of rice growth using static chamber and gas chromatography methods. Our results showed that CH₄ emission rate ranged from 0.19 to 26.50 mg m^?2 h^?1 in the duckweed plots, and from 1.02 to 28.02 mg m^?2 h^?1 in the non-duckweed plots. The CH₄ emission peak occurred about 1 week earlier in the duckweed plots compared to the non-duckweed counterparts. The mean CH₄ emission rate in the duckweed plots (9.28 mg m^?2 h^?1) was significantly lower than that in non-duckweed plots (11.66 mg m^?2 h^?1) (p < 0.05), which might be attributed to the higher water and soil Eh in the former. N₂O emission rates varied between ?50.11 and 201.82 µg m^?2 h^?1, and between ?28.93 and 54.42 µg m^?2 h^?1 in the duckweed and non-duckweed plots, respectively. The average N₂O emission rate was significantly higher in the duckweed plots than in the non-duckweed plots (40.29 vs. 11.93 µg m^?2 h^?1) (p < 0.05). Our results suggest that the presence of duckweed will reduce CH₄ emission, but increase N₂O flux simultaneously. Taking into account the combined global warming potentials of CH₄ and N₂O, we found that growing duckweed could reduce the overall greenhouse effect of subtropical paddy fields by about 17 %.     

Controlling the Properties of OPEFB/PLA Polymer Composite by Using Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> for Microwave Applications

Microwave-absorptive polymer composite materials provide protection against interference to communication systems caused by microwave-inducing devices. Microwave-absorptive polymer composites were prepared from polylactic acid (PLA) biocomposite blended with oil palm empty fruit bunch (OPEFB) fiber and commercial Iron oxide (Fe₂O₃) as filler using the melt-blending method. The composites characterization was carried out using the scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The coefficient of reflection S₁₁ and coefficient of transmission S₂₁ of the composites for various Fe₂O₃ filler percentages were determined using a rectangular waveguide in connection with microwave vector network analyser (HP/Agilent model PNA N5227). These coefficients were then used to calculate microwave-absorption properties (in decibels). XRD analysis showed that increasing amounts of reinforced material (Fe₂O₃) reduces the crystallinity of the composites. SEM data indicated that Fe₂O₃ filler ratio increased in the composites, and adhesion to the cellulose fiber grew gradually until the highest percentage of filler was added. The complex relative permittivity and relative permeability were obtained within the broad frequency range of 8–12 GHz at room temperature for various percentages of filler and were measured by the transmission/reflection method using a vector network analyser. Fe₂O₃ embedment in OPEFB/PLA was observed to have resulted in enhancing the dielectric and magnetic properties. The values of permittivity and permeability increased with increasing Fe₂O₃ filler content. Theoretical simulation studied the relation between ε′ and ε″ of the relative complex permittivity in terms of Cole-Cole dispersion law. The result indicated that the processes of Debye relaxation in Fe₂O₃/OPEFB/PLA, the unique dielectric characteristics of Fe₂O₃ cannot be accounted for by both the Debye dipolar relaxation and natural resonance. Results further showed that the material transmission, reflection, and absorption properties could be controlled by changing the percentage of Fe₂O₃ filler in the composites.     

Immobilization of Cationic Titanium Dioxide (TiO<Subscript>2</Subscript><Superscript>+</Superscript>) on Electrospun Nanofibrous Mat: Synthesis,Characterization, and Potential Environmental Application

We report a facile approach to fabrication and characterization of cationic titanium dioxide (TiO₂⁺) on poly (vinyl alcohol)/poly (acrylic acid) (PVA/PAA) composite electro-spun nanofibrous mat. The aim of this study is to develop a “functional electrospun nanofibrous mat” as a sustainable approach to superior photocatalytic degradation of organic colorants. For that, the PVA/PAA nanofibrous mat was prepared by electrospinning of PVA and PAA solution according to an aspect ratio of 1:1 and later water stability was induced by the thermal cross linking at an elevated temperature of 145 °C for 30 minute. By means of electrostatic layer-by-layer (LbL) assembly, cationic titanium dioxide (TiO₂⁺, ~19 nm) was immobilized on the surface of the water stable nanofibrous mat. As functionalized composited nanofibrous mat was characterized by using scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis and thermogravimetric analysis (TGA). Superior competency of the functionalized nanofibrous mat towards photocatalytic degradation of organic dye (methyl blue) in aqueous solution was observed by using UV-visible spectrophotometer with quantitative measuring method. The result indicates a complete degradation of methyl blue within 40 mins and superior reusability upto 5 cycles application. The study signifies the prospect of using electrospun nanofibers to manipulate the catalytic activity, which could be a foundation for further rational design of various composite nanofibrous materials.     

Effect of organic,inorganic and slow-release urea fertilisers on CH<Subscript>4</Subscript> and N<Subscript>2</Subscript>O emissions from rice paddy fields

Vietnam is one of the world’s top two rice exporting countries. However, rice cultivation is the primary source of agriculture’s greenhouse gas (GHG) emissions in Vietnam. In particular, strategies are required to reduce GHG emissions associated with the application of organic and inorganic fertilisers. The objective of this study was to assess the effects of various combinations of biochar (BIOC), compost (COMP) and slow-release urea (SRU) on methane (CH₄) and nitrous oxide (N₂O) emissions. In total, 1170 gas samples were collected from closed gas chambers in rice paddies at Thinh Long commune and Rang Dong farm in northern Vietnam between June and October 2014. The gas samples were analysed for CH₄-C and N₂O-N fluxes using gas chromatography. The application of BIOC alone resulted in the lowest CH₄ emissions (4.8–59 mg C m^?2 h^?1) and lowest N₂O emissions (0.15–0.26 µg N m^?2 h^?1). The combined application of nitrogen–phosphorus–potassium (NPK) + COMP emitted the highest CH₄ (14–72 mg C m^?2 h^?1), while ½NPK + BIOC emitted the highest N₂O (1.03 µg N m^?2 h^?1 in the TL commune), but it was the second lowest (0.495 µg N m^?2 h^?1) in the RD farm. Green urea and orange urea reduced N₂O emissions significantly (p < 0.05) compared to white urea, but no significant differences were observed with respect to CH₄ emissions. SRU fertilisers and BIOC alone measured the lowest greenhouse gas intensity, i.e. <2.5 and 3 kg CO₂ eq. kg^?1 rice grain, respectively. Based on these results, application of fertilisers in the form of BIOC and/or orange or green urea could be a viable option to reduce both CH₄ and N₂O emissions from rice paddy soils.     

Degradation and kinetic modeling of polyvinyl alcohol in aqueous solutions by a H<Subscript>2</Subscript>O<Subscript>2</Subscript>/Mn(II) system

This paper is about the degradation of polyvinyl alcohol (PVA) in aqueous solutions using a H2O2/Mn(II) system. Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC) were applied to analyze the degradation products of PVA, and the results revealed that the backbone chain of PVA could be effectively broken and oxidized. Several unsaturated degradation products, including carboxylic acids, ketones, aldehydes, olefins, and alkynes were also detected and identified by gas chromatography-mass spectrometry (GC-MS), which indicated that higher treatment temperatures would considerably promote the generation of lower molecular weight degradation products. According to the work presented in this paper, the degradation efficiency of PVA increased from 55 % at 60 oC to 99 % at 90 oC after treatment when the initial PVA concentration was 5 %, at pH=3 with a H2O2 and Mn(II) dose of 100 ml/l and 0.6 mol/l, respectively. In addition, kinetic modeling indicated that the experimental results were best fitted by the Page-modified model with an activation energy of 48.78 kJ/mol.     

Evaluating the Mechanical Behavior of Basalt Fibers/Epoxy Composites Containing Surface-modified CaCO<Subscript>3</Subscript> Nanoparticles

Polymer matrix composites (PMCs) owing to their outstanding properties such as high strength, low weight, high thermal stability and chemical resistance are broadly utilized in various industries. In the present work, the influence of silanized CaCO₃ (S-CaCO₃) with 3-aminopropyltrimethoxysilane (3-APTMS) coupling agent at different values (0, 1, 3 and 5 wt.% with respect to the matrix) on the mechanical behavior of basalt fibers (BF)/epoxy composites was examined. BF-reinforced composites were fabricated via hand lay-up technique. Experimental results from three-point bending and tensile tests showed that with the dispersion of 3 wt.% S-CaCO₃, flexural strength, flexural modulus, tensile strength and tensile modulus enhanced by 28 %, 35 %, 20 % and 30 %, respectively. Microscopic examinations revealed that the development of the mechanical properties of fibrous composites with the incorporation of modified CaCO₃ was related to enhancement in the load transfer between the nanocomposite matrix and BF as well as enhanced mechanical properties of the matrix part.     

Macropores regulate CO<Subscript>2</Subscript> behavior in an andisol soil

Macropores resulting from soil pedogenesis, biological activity, and agricultural practices play important roles in soil water, chemical and gas transport; however, seldom studies focus on the effect of soil macropores on CO₂ behavior. In this study, a 150-day soil column incubation experiment was conducted to investigate the CO₂ behavior in a homogeneous soil column and a soil column with an artificial macropore, which have the same total porosity. The results showed that the cumulative CO₂ fluxes observed in the soil with a macropore (57.2 g m^?2) were higher than those in the homogeneous soil (52.7 g m^?2). The soil cumulative CO₂ fluxes measured using column incubation can fit the kinetic model, and a higher carbon mineralization rate in the soil with the macropore was found. The results of the incubation experiment also suggest that macropore increased the gas diffusivities, and thus decreased the CO₂ concentrations in the soil profile. This study proposed a simulation experiment and quantified the effect of macropore on soil CO₂ behavior, which could help to understand the mechanism of CO₂ emission from soil with macropores especially caused by agricultural practices.     

Coloration and Decoloration of Textiles Using a TiO<Subscript>2</Subscript> Composite Pigment

A colorable pigment was prepared by dye adsorption onto titanium dioxide and subsequent silane coating. The effects of pH value, dye concentration, and adsorption times on dye adsorption were discussed. Large adsorption capacity of an anionic dye was obtained at pH value of 2 and the adsorption process was well described by the Langmuir isotherm model. Good dyeability and color fastness of pigment dyed fabric were achieved in the normal life cycle under sunlight. The decoloration of pigment was realized through photocatalytic degradation of dye molecules by titanium dioxide under ultraviolet irradiation when reusing the pigment dyed textiles after disposal. The new absorption peaks in the FTIR spectrum at 2924.95 cm^-1, 1714.91 cm^-1, 1461.17 cm^-1, and 1289 cm^-1 verified silane modification. Silane modification improved fixation of dyes onto the pigment and immobilization of pigments onto substrates. The close attachment of silane coating layer to titanium dioxide was conducive to photodegradation of dye molecules in the pigment.     

Synthesis of Ag-Loaded TiO<Subscript>2</Subscript> Electrospun Nanofibers for Photocatalytic Decolorization of Methylene Blue

Titanium dioxide (TiO₂) is one of the excellent photocatalysts used for degradation of environmetal pollutants. In this work, 2.5, 5.0 and 7.5 wt.% of silver (Ag)-loaded TiO₂ nanofibers of mean size 52–134 nm were synthesized by electrospinning method. These electrospun nanofibers were calcined at 500 °C to enable the transformation of Rutile (R) phase to Anatase (A), elimination of reaction moieties from the TiO₂ matrix and subsequently formation of Ag clusters. The effect of Ag loading on the morphology, crystal structure, phase transformation, and band gap of these electrospun nanofibers have been characterized by scannining electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), raman spectroscopy and UV-visible spectroscopy. These nanofibers exhibited a red-shift in the absorbance edge and a significant enhancement of light absorption in the wavelength range of 250–550 nm. These electrospun nanofibers were investigated for photodecomposition of methylene blue (MB), and photocatalytic decolorization rates were determined by pseudo-first-order equation. The rate constants for the pure and those of 2.5, 5.0, and 7.5 wt% Agloaded TiO₂ nanofibers were computed to be 0.1439 min^-1, 0.1608 min^-1, 0.1876 min^-1, and 0.2251 min^-1 respectively.     

Load of Ag<Subscript>3</Subscript>PO<Subscript>4</Subscript> Particles on Sulfonated Polyphenylene Sulfide Superfine Fibre with High Visible-light Photocatalytic Activity

Ag₃PO₄ was loaded on sulfonated polyphenylene sulfide (SPPS) superfine fibre by a facile precipitation method. Both the structure and properties of the as-synthesized Ag₃PO₄/SPPS composites were characterized via XRD, SEM, EDS, XPS, FTIR, and UV-vis. The photocatalytic performance of Ag₃PO₄/SPPS composites was investigated via degradation of Methylene blue(MB) solution under visible light irradiation. The degradation results revealed that the photocatalytic activity of Ag₃PO₄/SPPS composites was greatly enhanced by the incorporation of Ag₃PO₄ with SPPS superfine fibre. For concentrations of AgNO₃ and Na₂HPO₄ solutions of 0.3 M and 0.06 M in the preparation process, the Ag₃PO₄/SPPS composite showed higher photocatalytic activity under visible light irradiation.     

Experimental study on dyeing technical PET yarns having different TiO<Subscript>2</Subscript> contents

TiO₂ contents in yarns can influence color yield so that dyeing quality of industrial poly ethylene terephthalate (PET) yarns can be improved through the adjustment of TiO₂ contents. To evaluate the dyeing performance of color yield, the chips which included the different TiO₂ contents of 330, 550, and 1,100 ppm respectively were used to produce the yarns of different TiO₂ content by a spin-draft machine. The physical and structural properties of the yarns were measured to investigate effect of the TiO₂ contents on them. Dye uptake and dyeing rate were also evaluated using a colorimeter to compare the yarns having different TiO₂ contents. The experimental results showed that there were no appreciable variation in physical and structural properties among the yarn samples and no difference were observed among the dyed fabric samples with regard to dyeing uptake and dyeing rate. However, the color yield of dyed fabrics increased as TiO₂ contents decreased in the yarns especially when the fabric samples were dyed to pale shade. The physical reasoning could be proposed on why the yarns having low TiO₂ contents appeared to have higher color yield after dyeing.     

Electrospun in-situ hybrid polyurethane/nano-TiO<Subscript>2</Subscript> as wound dressings

By combining the organic-inorganic hybridization, wet phase inversion, and electrospinning, novel electrospun polyurethane (PU) membranes with in-situ generated nano-TiO₂ were prepared, which satisfied the requirements of an ideal wound dressing. The morphology of the PU-TiO₂ mats and the cross sectional morphologies of the membranes were characterized by a scanning electron microscopy (SEM). The average diameter of the individual fibers obtained from the solutions was 341±12 nm. SEM micrographs with higher magnification further showed that the in-situ generated TiO₂ particles were well-separated and dispersed homogeneously in the membranes. The average sizes of TiO₂ particles were increased from 31 to 57 nm, with the increase of nano-TiO₂ concentration. The water vapor transmission rates (WVTRs) of the membranes were in the range of 373.55–3121.86 g/m²·d and decreased gradually with the increase of nano-TiO₂ concentration. The water absorption of various PU membranes was in the range of 210.90–397.98 % which was enough to prevent wound beds from exudate accumulation. Shake flask testing indicated that the PU membrane exhibited antibacterial efficiency against Pseudomonas aeruginosa (Ps. aeruginosa) and Staphylococcus aureus (S. aureus) due to in-situ generated of nano-TiO₂. These electrospun nanofibrous membranes also had no toxic effect and showed good and immediate adherence to L929 cells.     

In situ loading TiO<Subscript>2</Subscript> and its photocatalysis and UV resistance on cotton fabric

Anatase TiO₂ nanoparticles was in-situ formed on the cotton fabric by using tetrabutyl titanate (TBT) as a precursor through the normal pressure hydrothermal method. X-ray diffraction (XRD), Scanning electron microscopy (SEM), UV visible spectra (UV-VIS), ATR-IR were used as the characterization techniques. Photocatalytic performance of TiO₂ on the fabric surface was evaluated by methylene blue (MB), 4 kinds of the common living stains and three dyes under ultraviolet and visible light radiation. XRD analysis found that the TiO₂ loaded on the fabric was mainly anatase crystalline phase with particle size of 6.4 nm. SEM observed that a large number of nano TiO₂ particles are distributed on the fabric surface. UV-VIS test indicated that theTiO₂-coated fabric possessed an obvious absorption for ultraviolet. ATR-IR analysis indicated that the nano-TiO₂ possesses a strong affinity with the hydroxyl group of the cotton fabric, and the soaping tests showed that the TiO₂ was firmly bonded with the fabrics. The treated fabrics have good degradation ability for MB aqueous solution, and could degrade azo, anthraquinone and phthalocyanine dyes. The order of degradation of the common life stains was: pepper oil> tea > coffee > soy sauce.     

Effect of UV irradiation on cellulase degradation of cellulose acetate containing TiO<Subscript>2</Subscript>

Cellulose acetate (CA) films containing anatase type titanium dioxide (TiO₂) nanoparticles were prepared by solution casting. The film surface was modified by UV irradiation using a grid type UV irradiator. The UV irradiation caused slight increase in photodegradation of the CA films with TiO₂ compared to the CA film alone. However, CA films irrespective of TiO₂ content did not show a significant enzymatic degradation by a cellulase fromAspergillus niger without UV irradiation. Upon UV irradiation, the biodegradability remarkably improved even in the CA film without TiO₂. The irradiation of CA films decreased both the water contact angle and the degree of substitution (DS) implying the decrease in acetyl groups of the CA film surface due to the photo-scission of the acetyl group and photooxidation, resulting in more facile biodegradation of the surface film layer. The substantial enhancement in biodegradation of the UV irradiated CA film containing TiO₂ was attributed to the increased hydrophilicity, lowered DS and zeta potential due to the photoscission and the photooxidation effect of UV light. Also the increased surface area of the CA film due to the photocatalysis of TiO₂ particles may encourage the facile biodegradation.