Chitosan-hybridized acrylic resins prepared in emulsion polymerizations and their application as interior finishing coatings.
Keywords: Acrylics, latexes, colloids, emulsions, waterborne, mechanical properties, architectural, water-based, air quality, emissions, VOC control
In the living environment, sick-building syndrome is a social health problem which occurs when the quality of indoor air diminishes due to harmful substances contained in it. (1) Volatile organic compounds (VOCs) such as formaldehyde cause sick-building syndrome because VOCs are contained in furniture and building materials. (2) To combat this problem, a considerable number of studies have been done to improve indoor air quality. (3,4) In interior materials, both the decomposition of formaldehyde using photocatalysts such as titanium oxide, and decomposition using chemical means or the physical adsorption of formaldehyde, have been studied. (5-10) Although the means for decomposing formaldehyde are effective, if sufficient ultraviolet radiation cannot be supplied throughout the indoor environment, undecomposed formaldehyde remains. In the case of physical adsorption with porous raw materials such as zeolite, diatomite, and charcoal, there is a problem in that adsorbed formaldehyde is emitted. On the other hand, chemical adsorption by reactions with formaldehyde can be efficiently removed and not re-emitted. Chemical adsorbents, however, are not sufficiently safe.
Recently, investigations using natural raw materials as adsorbents were carried out. Among the natural raw materials, chitosan is an environmentally friendly material with many superior properties. Chitosan powder was used to inhibit the emission of formaldehyde from plywood. (11-12) Ishimaru also reported that chitosan is effective in adsorbing formaldehyde. (13) Chitosan is a polysaccharide consisting of 2-amino-2-deoxy-D-glucopyranose as a repeating unit and is obtained by deacetylation of chitin, as shown in Figure 1. Chitin exists in crustacean shells, such as crabs and shrimps; in insects, such as beetles and grasshoppers; in cuttlefish bone; and in the cell walls of fungi, such as mushrooms. Compared to synthetic polymers, chitosan has several important advantages, including biocompatibility, biodegradability, and no toxicity. In addition, chitosan has reactive amino groups on pyranose rings and becomes a cationic polymer upon the protonation of its amino groups. However, chitosan simply added to waterborne coatings cannot uniformly disperse. Furthermore, when chitosan-acid solution is added to waterborne coatings using acrylic emulsions, precipitates are formed because chitosan is a cationic polymer. To resolve this problem, chitosan-hybridized acrylic resins were investigated in emulsion polymerizations between chitosan-acrylic acid ion complexes and acrylic monomers. In this study, the preparation of chitosan-hybridized acrylic resins in emulsion polymerization and their application to interior finishing coatings are discussed.
[FIGURE 1 OMITTED]
Chitosan (Kyowa Tecnos Co., Ltd., Japan C-60M) used in this study was deacetylated at 88.2%. Acrylic acid (AA), methylmethacrylate (MMA), 2-ethylhexylacrylate (2EHA) monomers, and the 2,2-azobis(2-aminopropane) dihydrochloride (ABAP) initiator were of reagent grade from Wako Pure Chemical Industries, Japan. Adeka Reasoap NE-20 and NE-30, which are reaction products of polyalkylene glycol alkyl ether with allyl glycidyl ether, used as reactively emulsifying nonionic surfactants, were obtained from Asahi Denka Co., Ltd., Japan. The numbers 20 and 30 in NE-20 and NE-30 are the contents of ethylene oxide component, respectively. An aqueous solution of 38% reagent grade formaldehyde was purchased from Wako Pure Chemical Industries. An aqueous solution of 28% reagent grade ammonia was also purchased from Wako Pure Chemical Industries. Hydrogen sulfide used in this study consisted of a balanced gas of 1.0 vol% hydrogen sulfide/nitrogen balance gas and was purchased from Nippon Sanso Co., Ltd., Japan.
[FIGURE 2 OMITTED]
[FIGURE 3 OMITTED]
Traditionally, most emulsion polymers used in architectural coatings have required the use of coalescing agents to optimize film properties. When the inside of an emulsion particle is homogeneous in composition, the minimum film-forming temperature (MFT) is mostly conformable to a glass transition temperature in an emulsion. In order to form a film at lower temperatures, it is wellknown that the MFT is predicted from the theoretical glass transition temperature. (14) The purpose of this study is the development of interior finishing coatings without coalescing agents. Therefore, the theoretical glass transition temperature from monomers composed of chitosan-hybridized acrylic resins is below 0[degrees]C.
Table 1 shows the components of emulsion polymerization. If all the AA, MMA, and 2EHA monomers are polymerized and there are no unreacted monomers, the content of chitosan in this emulsion would be about 4 wt% in solid. Chitosan-hybridized acrylic emulsion polymerizations were carried out by the following two methods: monomer dropping and pre-emulsion dropping. Figure 2 shows the processes for (a) the monomer dropping method and (b) the pre-emulsion dropping method, respectively.
In the monomer dropping method system, (15-17) 10.9 g of chitosan were added to 4.4 g AA to prepare a chitosan solution. In this solution, chitosan was dissolved as a chitosan-AA salt, as shown in Figure 3. Then, 88.4 g MMA and 179.2 g 2EHA were mixed into the chitosan solution to prepare a monomer mixture. First, 10% of the monomer mixture was added and stirred at 500 rpm with an aqueous solution consisting of 14.3 g NE-20, 4.2 g NE-30, and 540 g ion exchanged water in a separate one-liter flask equipped with a thermometer, a dropping funnel, and a condenser. Both the remaining 90% of the monomer mixture and 0.8 g of the initiator ABAP were continuously dropped and stirred at 60[degrees]C for two hours. After two hours, the initiator 0.2 g ABAP was added and the reaction mixture was kept at 70[degrees]C for two hours.
The pre-emulsion polymerization system (15-17) was performed in stages. In the first stage, 10.9 g of chitosan were added to 4.4 g AA to prepare a chitosan solution. Next, 88.4 g MMA, 179.2 g 2EHA, the chitosan solution, 1.7 g NE-20, and 240 g ion exchanged water were emulsified at 10,000 rpm using a homogenizer. In the second stage, the emulsified mixture and 0.8 g of the initiator ABAP were continuously dropped into an aqueous solution of nonionic surfactants, which was a mixture of 12.6 g NE-20, 4.2 g NE-30, and 300 g ion exchanged water in a separate one-liter flask at 60[degrees]C for two hours. After an additional two hours, 0.2 g of the initiator ABAP was added to the reaction mixture, which was kept at 70[degrees]C for two hours, as in the monomer dropping method.
Characterization of Chitosan-Hybridized Acrylic Emulsions
Solid contents of the chitosan-hybridized acrylic emulsions were determined gravimetrically after drying in an air oven at 105[degrees]C for three hours. Particle sizes in the chitosan-hybridized acrylic emulsions were measured by Microtrac-UPA (Nikkiso Co., Ltd.). Viscosities of the chitosan-hybridized acrylic emulsions were determined using a Brook-field Viscometer (model BM, Tokimec Inc.) at 25[degrees]C. Minimum film forming temperatures were determined using temperature gradient bars (Shimakawa Inc.) as specified by ISO 2115 standards.
Adsorption Tests for Formaldehyde, Hydrogen Sulfide, and Ammonia
Adsorption tests for various gases such as formaldehyde, hydrogen sulfide, and ammonia were performed in 20-L chambers at 23[degrees]C. Chitosan-hybridized acrylic emulsions were coated on 15 cm X 15 cm glass plates and dried at room temperature. The two glass plates were put into a chamber and test gas was injected into it. Atmospheric gas concentrations in the chamber were measured by high-performance liquid chromatography, gas chromatography, or ion chromatography.
Formaldehyde was analyzed as follows (18): A cartridge containing 2,4-dinitrophenylhydrazine (DNPH), which forms a derivative with formaldehyde, was connected to chamber outlets to measure the concentration of formaldehyde within the chamber. The DNPH derivative in the DNPH cartridge was dissolved using acetonitrile. Formaldehyde concentrations were measured by high-performance liquid chromatography (Shimadzu, LC-10A, column: Intersil ODS-3V 3 X 250 [micro]m, mobile phase: distilled water/acetonitrile = 45/55, detector: UV 360 nm).
Hydrogen sulfide was analyzed as follows: The atmosphere from 0.5 ml in the chamber was sampled using a gas-tight syringe. Hydrogen sulfide concentrations were measured by gas chromatography (Yokogawa Analytical Systems Inc. HP5890/HP5921A, column: Pora PLOTQ 25 X 0.32 mm I.D 10 [micro]m film, carrier gas: He, detector: AED wavelength S181 nm 320[degrees]C, He plasma).
Ammonia was analyzed as follows: The atmosphere from 1000 ml in the chamber was bubbled in 10 ml of an aqueous solution of 3-mM-methanesulfonic acid. Ammonia concentrations were measured by ion chromatography (Di-onex DX-500, column: ION Pac CS14, mobile phase: 8-mM-methanesulfonic acid, detector: electric conductivity).
[FIGURE 4 OMITTED]
The formulation of an interior finishing coating made from chitosan-hybridized acrylic resins is shown in Table 2. Interior finishing coatings were prepared by blending synthesized chitosan-hybridized acrylic emulsions, titanium dioxide, extender pigment, and additives, such as dispersing agents, thickeners, and deformers. Ingredients were blended with a mixer at 1200 rpm for 20 min.
Mechanical Properties and Coating Characterization
Tensile strengths and elongations at breaking points were measured using a universal testing instrument (Autograph AG-10TA from Shimadzu Co.). The tensile speed was 200 mm/min. Specimens were prepared to dumb-bell type 2 test pieces (length of narrow portion: 20 mm, width of narrow portion: 10 mm) at a thickness of 0.5 mm.
[FIGURE 5 OMITTED]
[FIGURE 6 OMITTED]
Tests for the interior finishing coating were evaluated. The drying time test was determined using Ballotini as specified by ISO 1517:1973. The water resistance test and alkali resistance test were conducted according to ISO 2812-1:1993. The whole test surface was examined for blistering according to ISO 4628-2:1982.
RESULTS AND DISCUSSION
Emulsion polymerizations were carried out by both the monomer dropping method and the pre-emulsion dropping method. In Table 3, characteristics of chitosan-hybridized acrylic emulsions obtained from each emulsion polymerization method and their resin film are shown. In the monomer dropping method, products consisted of high viscosity liquids (4000 mPaxs at 25[degrees]C) and a precipitate, such as a gel, was formed during the polymerization process. On the other hand, chitosan-hybridized acrylic resins prepared by the pre-emulsion dropping method had low viscosities (500 mPaxs at 25[degrees]C) without the formation of any precipitates. These results may reflect that the pre-emulsion dropping method gave homogeneous droplets of monomer mixtures with chitosan. Chitosan-hybridized acrylic resin film forming temperatures were below 0[degrees]C, had excellent water resistance, and did not exhibit water whitening. These results suggest that chitosan-hybridized acrylic resins are significantly effective materials for interior finishing coatings.
Adsorption Ability for Formaldehyde
The formaldehyde adsorption abilities by chitosan-hybridized acrylic resin films with various chitosan contents are shown as functions of time in Figure 4. In Figure 2, the initial concentration of formaldehyde in the chamber was 10 ppm and the chitosan content was for the emulsion solid. In the adsorption tests with chitosan-hybridized acrylic resin films, formaldehyde concentrations in the atmosphere lowered to almost 0 ppm in 25 min. On the other hand, in adsorption tests conducted on films without chitosan, formaldehyde concentrations gradually decreased, and after 180 min they reached 0 ppm. After the adsorption tests were finished, the atmosphere in the chamber was replaced with [N.sub.2] gas. Sample films with adsorbed formaldehyde were left at 60[degrees]C for two hours in the chamber, and the formaldehyde concentrations released from these films were measured (Figure 5). In films tested without chitosan, formaldehyde concentrations of about 4 ppm were recognized. This may be caused by the adsorption of formaldehyde onto film surfaces. In chitosan-containing films, formaldehyde was not detected in the least.
Figure 6 shows FTIR spectra of chitosan-hybridized acrylic resins before and after formaldehyde adsorption. In chitosan-hybridized acrylic resins (Figure 6c), strong and weak peaks based on acrylic resins and chitosan were observed at 1720 [cm.sup.-1] and 1150 [cm.sup.-1], respectively. Moreover, chitosan-hybridized acrylic resins had weak amino group bands at 1580 [cm.sup.-1]. On the other hand, in chitosan-hybridized acrylic resins, adsorbed formaldehyde (Figure 6d) peaks based on amino groups were not observed because of the combination of chitosan and formaldehyde. It was difficult to directly verify the combination of chitosan and formaldehyde in chitosan-hybridized acrylic resins because characteristic absorption bands from chitosan-hybridized acrylic resins overlap acrylic resins bands. Therefore, FTIR spectra of chitosan before and after adsorption tests for formaldehyde were measured (Figures 6a and 6b). Both chitosans had peaks based on pyranose rings and acetyl amino groups. Chitosan showed a peak based on the amino group band at 1580 [cm.sup.-1]. Chitosan-adsorbed formaldehyde did not show a peak from amino groups, but instead showed a peak based on a C=N stretch at 1550 [cm.sup.-1]. Schiff's bases (-N=C[H.sub.2]) were made from chitosan amino groups and formaldehyde, as shown in Figure 7. These results suggest that formaldehyde is not released from chitosan-hybridized acrylic resin films, which can be attributed to the fact that formaldehyde had reacted with chitosan amino groups in the resins.
Adsorption Ability for Hydrogen Sulfide and Ammonia
Adsorption performance results from chitosan-hybridized acrylic resin films with 5 wt% chitosan contents for hydrogen sulfide and ammonia gases are shown in Figure 8. Initial concentrations of hydrogen sulfide and ammonia were 50 ppm and 20 ppm, respectively. The concentration of hydrogen sulfide decreased with time and reached 30 ppm after 24 hr. In the case of ammonia, the ammonia concentration reached 0 ppm after 24 hr. However, a film-dispersed chitosan could not adsorb hydrogen sulfide and ammonia. From these results, it was found that hydrogen sulfide and ammonia could also be adsorbed into chitosan-hybridized acrylic resin films. It is presumed that hydrogen sulfide and ammonia may electrostatically interact with carbonyl groups in chitohan-hybridized acrylic resin film.
The mechanical properties of chitosan-hybridized acrylic resin films are summarized in Table 4. The percentages of chitosan listed in Table 4 are for the weight in the emulsion polymerization. Tests were performed at -5[degrees]C and 23[degrees]C. As can be seen from the results, mechanical properties were remarkably dependent on acrylic resin contents. The tensile strengths and elongations at breaking points of chitosan-hybridized acrylic resin films were lower than those of acrylic resin films and decreased with increasing chitosan contents. Decreases in tensile strength and elongation at breaking points with the addition of chitosan to emulsion polymerizations are due to the following: in copolymerizations of emulsion polymerizations of chitosan-AA salts, MMA, and 2EHA with chitosan, molecular weights of AA-MMA-2EHA copolymers are lower than that of copolymers in the emulsion polymerization of AA, MMA, and 2EHA without chitosan. This is because AA forms complexes with chitosan and, consequently, copolymerizations of AA with MMA and 2EHA are limited. It is presumed that decreases in the molecular weights of AA, MMA, and 2EHA copolymers causes a decrease in mechanical strength.
[FIGURE 7 OMITTED]
[FIGURE 8 OMITTED]
Characteristics of Chitosan-Hybridized Acrylic Resin Finishing Coatings
An interior finishing coating without volatile organic compounds, such as a film forming solvent, was prepared using chitosan-hybridized acrylic emulsions with 5 wt% chitosan contents. The pigment volume concentration in this coating was 60%. Table 5 shows the adsorption performance of the chitosan-hybridized acrylic resin finishing coating for formaldehyde in different concentrations. Under both conditions, formaldehyde concentrations became about 0.1 ppm after 24 hr. These results support that interior finish coatings with chitosan-hybridized acrylic resins have excellent adsorption abilities for formaldehyde.
Tests for interior finishing coatings with chitosan-hybridized acrylic resins were carried out. The results, summarized in Table 6, show that finishing coatings made from chitosan-hybridized acrylic resin emulsions have the necessary qualities for interior finishing coatings.
In the present work, chitosan-hybridized acrylic resins were developed for application in interior finishing coatings. We investigated emulsion polymerizations for chitosan, which is an effective natural polymer that has formaldehyde adsorption abilities. Chitosan-hybridized acrylic emulsions made by the pre-emulsion dropping method showed good stability. Chitosan-hybridized acrylic resin films showed high adsorption abilities for formaldehyde, hydrogen sulfide, and ammonia. Tensile strengths and elongation at breaking points of the chitosan-hybridized acrylic resins decreased with increasing chitosan contents. Nonetheless, interior finishing coatings made from chitosan-hybridized acrylic resin emulsions with 5 wt% chitosan contents have the necessary qualities for an interior finishing coating and showed excellent adsorption abilities for formaldehyde.
Table 1 -- Components of Emulsion Polymerization Component Content MMA 10.50 wt% 2EHA 21.27 wt% AA 0.52 wt% Chitosan 1.29 wt% Nonionic surfactants 2.20 wt% Ion exchanged water 64.10 wt% Initiator 0.12 wt% Total 100.00 wt% Table 2 -- Formulation of the Interior Finishing Coatings Ingredient wt% Chitosan-hybridized acrylic emulsions 45.0 Deionized water 4.4 Dispersant (Poise 521, Kao Co., Ltd., Japan) 1.0 Extender pigment (Whiting limestone powder, Maruo Calcium Co., 27.0 Ltd., Japan) Titanium dioxide (Tioxide TR-92, Tioxide Japan Co., Ltd., Japan) 21.0 Thickeners (Adekanol UH-420, Asahi Denka Co., Ltd., Japan) 0.8 Thickeners (Adekanol UH-472, Asahi Denka Co., Ltd., Japan) 0.8 Total 100.0 Table 3 -- Characteristics of Chitosan-Hybridized Acrylic Emulsions and Polymer Films Pre-Emulsion Test Monomer Dropping Method Dropping Method Viscosity 4000 mPa*s at 500 mPa*s at 25[degrees]C 25[degrees]C Polymer gel (on 100 mesh) Present Absent Solids content 27.0% 34.0% pH 5.8 5.7 Average particle size -- 204.6 nm Minimum film forming -- Below 0[degrees]C temperature Film appearance -- Clear film (Glossy) Table 4 -- Mechanical Properties of Chitosan-Hybridized Acrylic Resin Films with Different Chitosan Contents Tensile Strength Elongation at Breaking Point Chitosan (N/[mm.sup.2]) (%) Content wt% -10[degrees]C 23[degrees]C -10[degrees]C 23[degrees]C 0 13.5 1.3 260 610 1 12.0 1.2 230 600 2 10.5 1.2 210 590 3 10.0 1.2 190 560 4 9.3 1.2 170 400 5 7.4 0.6 150 380 Table 5 -- Adsorption Performance of Chitosan-Hybridized Acrylic Resins Finishing Coatings (a) for Formaldehyde Initial Concentration After 24 hr 3.32 ppm 0.11 ppm 19.65 ppm 0.14 ppm (a) Pre-emulsion method Table 6 -- Characteristics of Interior Finish Coatings with Chitosan- Hybridized Acrylic Resins Test Quality Standard Result In-can appearance Becomes homogeneous when Homogeneous stirred Application properties Forms a uniform dry film No impediment Low-temperature stability No deterioration No deterioration at wet paint Drying time Within 2 hr at 40 min 20[degrees]C Within 4 hr at 75 min 5[degrees]C Dry film appearance No appearance defects No deterioration Water resistance No failure when immersed Degree of in water for 96 hr blistering 0 (More than 168 hr) Alkali resistance No failure when immersed Degree of in calcium hydrate for blistering 0 (More 48 hr than 120 hr)
(1) "Indoor Air Quality and Its Impact on Man--Report No. 19: Total Volatile Organic Compounds (TVOC) in Indoor Air Quality Investigations," European Commission Joint Research Center for Environment Institute (1997).
(2) Imai, M. and Motohashi, K., "Measurement of Formaldehyde Emitted from Coating Materials and Wall Papers," Summaries of Technical Papers of Annual Meeting of Architectural Institute of Japan, A-1 Materials and Construction, 651-652 (2003).
(3) Uedaira, T., Motohashi, K., and Imai, H., "Emission of Chemicals from the Emission Paints Including Very Little Volatile Organic Compounds," Summaries of Technical Papers of Annual Meeting of Architectural Institute of Japan, A-1 Materials and Construction, 657-658 (2003).
(4) Miyamura, M., Murakami, N., Ohsawa, S., Okamoto, H., Hasegawa, T., and Kakui, K., "A Study on VOC Reduction of the Emulsion Paint. Part 1: Performance of the Emulsion Paint or Reduction of VOC and Reduction of a Bad Smell," Summaries of Technical Papers of Annual Meeting of Architectural Institute of Japan, A-1 Materials and Construction, 661-662 (2003).
(5) Miggli, D.S., Lowery, K.H., and Falconer, J.L., J. Catal., 180, 111 (1998).
(6) Obee, N.T. and Brown, T.R., "Ti[O.sub.2] Photocatalysis for Indoor Air Applications. Effects of Humidity and Trace Contaminant Levels on the Oxidation Rates of Formaldehyde, Toluene, and 1,3-Butadiene," Environ. Sci. and Technol., Vol. 29, No. 5, 1223-1231 (1995).
(7) Ching, H.W., Leung, M., and Leung, C.Y.D., "Solar Photocatalytic Degradation of Gaseous Formaldehyde by Sol-Gel Ti[O.sub.2] Thin Film for Enhancement of Indoor Air Quality," Solar Energy, Vol. 77, No. 2, 129-135 (2004).
(8) Gesser, D.H. and Fu, S., "Removal of Aldehydes and Acidic Pollutants from Indoor Air," Environ. Sci. Technol., Vol. 24, No. 4, 495-497 (1990).
(9) Motohashi, K. and Imai, M., "Reduction Effects of Interior Textured Coated Layers Containing Formaldehyde Catching Agents for Formaldehyde,". Summaries of Technical Papers of Annual Meeting of Architectural Institute of Japan, A-1 Materials and Construction, 649-650 (2003).
(10) Santamaria, J., Aguado, S., Polo, C.A., Bernal, P.M., and Coronas, J., "Removal of Pollutants from Indoor Air Using Zeolite Membranes," J. Membr. Sci., Vol. 240, No. 1/2, 159-166 (2004).
(11) Sato, K., "Suppressing Effect of the Diffusion of Formaldehyde from Plywood with Chitosan Powder," Chitin and Chitosan Research, Vol. 2, No. 2, 168-169 (1996).
(12) Sato, K., Ota, H., and Omura, Y., "Development of Functional Coating Reagent for Wood Based Materials by Using Chitosan," Adv. Chitin Sci., 897-901 (1997).
(13) Ishimaru, A., "Adsorption and Reduction of Formaldehyde of Various Industrial Materials," Kanagawa Industrial Technology Research Institute (2001).
(14) Brodnyan, J.G. and Konnen, T., J. Appl. Polym. Sci., 8, 687 (1964).
(15) Uragami, T., Wake, A., Inui, K., Matoba, Y., Ochi, I., Imajyo, H., and Irie, Y., Jpn. Kokai Tokyo Koho, JP 175876[2002 342283] (2004).
(16) Wada, T., Uragami, T., Matoba, Y., Inui, K., Imajyo, H., and Irie., Y., "Studies on Preparation of Chitosan-Complex Acrylic Resin in an Emulsion Polymerization System and Application to Indoor Environment Paint," Japan Society for Finishing Technology, 11-14 (2003).
(17) Wada, T., Matoba, Y., and Uragami, T., "Preparation of Chitosan-Hybridized Acrylic Resin in Emulsion Polymerization and Their Application to an Interior Finishing Coating," 6th Asia-Pacific Chitin Chitosan Symposium (2004).
(18) "Indoor Air--Part 6: Determination of Formaldehyde and Other Carbonyl Compounds--Active Sampling Method, ISO 16000-3.
(19) Wada, T., Uragami, T., Matoba, Y., Inui, K., and Kouno, K., "Application to an Interior Finishing Coating of Chitosan-Hybridized Acrylic Resin Prepared in an Emulsion Polymerization," Chitin and Chitosan Research, Vol. 10, No. 2, 118-119 (2004).
(20) Wada, T., Uragami, T., Matoba, Y., and Inui, K., "Preparation of Chitosan-Hybridized Acrylic Resins in Emulsion Polymerization and Their Adsorption Characteristics for Formaldehyde," EUCHIS'04 6th International Conf. European Chitin Society, Vol. 10, No. 2, 118-119 (2004).
Tamaki Wada ([double dagger]) -- Kowa Chemical Industries Co., Ltd.*
Tadashi Uragami -- Kansai University ([dagger])
Yasuhiro Matoba -- Kowa Chemical Industries Co., Ltd.**
* Ota-ku, Tokyo 144-0032, Japan.
([dagger]) Faculty of Engineering and High Technology Research Center, Suita, Osaka 564-8680, Japan.
** Toyonaka, Osaka 561-0815, Japan.
([double dagger]) Author to whom correspondence should be sent: Email: email@example.com.
|Printer friendly Cite/link Email Feedback|
|Comment:||Chitosan-hybridized acrylic resins prepared in emulsion polymerizations and their application as interior finishing coatings.|
|Date:||Jul 1, 2005|
|Previous Article:||Films formed from polystyrene latex/clay composites: a fluorescence study.|
|Next Article:||Metrology for characterizing scratch resistance of polymer coatings.|