Published Date February 2013, Vol.45:148–154,doi:10.1016/j.indcrop.2012.12.016
Author
Ilaria Santoni
Benedetto Pizzo,
CNR-IVALSA, Istituto per la Valorizzazione del Legno e delle Specie Arboree, National Research Council of Italy, via Madonna del Piano 10, I-50019, Sesto Fiorentino (FI), Italy
Received 24 September 2012. Revised 23 November 2012. Accepted 18 December 2012. Available online 9 January 2013.
Abstract
Adhesives industry is increasingly interested in products coming from natural and renewable resources, because of the limited reserve of oil, its prices variability and its negative impact on both environment and human health. However, soy crops are mainly concentrated in the Americas, and are not so widespread in Europe. Thus, it is interesting to evaluate if other vegetable proteins more common in Europe are compatible for their use as wood adhesives. In this study, zein, a protein component of maize (Zea maysL.), the pea (Pisum sativumL.) protein, and two products based on soy (Glycine maxL.) proteins, one treated with alkali and the other not, were compared in order to verify their utilisation as wood adhesives for indoor applications.
Dissolution tests in both water and ethanol/water mixture at different pH values, and FT-IR analysis in the same conditions were carried out. Also the effect of the addition of denaturing agents such us urea and guanidine hydrochloride was evaluated. Solubility results showed that, as expected, water soluble fraction of these proteins increased significantly by increasing pH: both the 2 soy proteins and the pea protein evidenced soluble fraction higher than 80% at pH 10, while for zein, this parameter was always lower than 30%.
Moreover, water seemed to be a better solvent than the ethanol/water mixture. In fact, in one case a solubility decrease was observed when ethanol was added to water.
Standard bonding tests on wood-to-wood joints were carried out according to EN 205, both in dry and in wet conditions, this latter after 4 days of immersion in water. Shear strength values were above the minimum threshold limit of 10 MPa required by the standard for both the 2 soy and the pea proteins. In contrast, all proteins were not suitable for wet conditions.
Pea protein seemed to be a valid alternative to soy proteins, which is realistic considering that the amino acid profiles of pea and soy proteins are similar. However, like for the soy protein, it is essential to improve the water resistance with an additive. In contrast, zein did not seem suitable as wood adhesive, because of its low solubility in all the considered conditions.
Highlights
► The protein of maize, the pea protein, and two soy proteins were evaluated. ► Dissolution tests at different pH, FT-IR analysis, and shear tests were carried out. ► Proteins became more unfolded and solvated after pH increase. ► Variations in the acidity level did not change the conformation of all proteins. ► Pea protein is a valid alternative to soy, zein is not suitable as a wood adhesive.
Published Date October 2013, Vol.46:14–20,doi:10.1016/j.ijadhadh.2013.05.007
Author
Cenk Demirkir a,,
Şükrü Özsahin a
Ismail Aydin b
Gursel Colakoglu b
aKaradeniz Technical University, Faculty of Technology of Woodworking Industry Engineering Department, Trabzon, Turkey
bKaradeniz Technical University, Faculty of Forestry, Forest Industry Engineering Department, 61080 Trabzon, Turkey
Accepted 16 May 2013. Available online 1 June 2013.
Abstract
Plywood is one of the most important wood based composites with its more than 81 million m3production and a market value of approximately 19 billion dollars in exports and imports in 2010. Bonding strength test is crucial for plywood panels, because it classifies boards as suitable/unsuitable for using areas. The most important factors affecting the bonding strength of plywood are wood species, adhesive type, wood density, veneer peeling temperature, veneer drying temperature and relative moisture content. Determining the optimum plywood manufacturing factors without any loss in bonding strength is also very important. However, a lot of values for these manufacturing parameters need to be tested to reach the optimum panel properties that cause losing much time, energy and cost. The aim of this study was to design an ANN capable of predicting the optimum manufacturing parameters without spending much time and loss bonding strength. For this aim; bonding shear strength values of plywood panels manufactured from the scots pine, maritime pine and European black pine veneers peeled at 32 °C and 50 °C and dried at 110 °C, 140 °C and 160 °C temperatures were obtained by experimental study, then it was predicted the intermediate bond strength values based on veneer peeling and drying temperatures by artificial neural network modeling. the optimum peeling and drying temperature ranges giving the highest bonding strength values were determined as 48–50 °C and 154–160 °C, respectively for panels with phenol formaldehyde and 32–50 °C and 110–124 °C for panels with melamine urea formaldehyde adhesive in scots pine. For maritime pine plywood panels, the optimum temperature ranges were 49–50 °C and 138–160 °C for phenol formaldehyde adhesive while the ranges were 38–50 °C and 110–125 °C for panels with melamine urea formaldehyde adhesive. The optimum temperature ranges for European black pine plywood panels were 32 °C and 126–123 °C for panels with PF adhesive and 32–50 °C and 110–112 °C for panels with MUF adhesive.
Published Date 15 May 2016, Vol.111:191–198,doi:10.1016/j.conbuildmat.2016.02.051 Author
T. Pulngern a,,
T. Chitsamran a
S. Chucheepsakul a
V. Rosarpitak b
S. Patcharaphun c
N. Sombatsompop d
aDepartment of Civil Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi (KMUTT), Thongkru, Bangmod, Bangkok 10140, Thailand
cDepartment of Material Engineering, Faculty of Engineering, Kasetsart University (KU), Chatuchak, Bangkok 10900, Thailand
dPolymer PROcessing and Flow (P-PROF) Group, School of Energy, Environment and Materials, King Mongkut’s University of Technology Thonburi (KMUTT), Thongkru, Bangmod, Bangkok 10140, Thailand
Received 23 July 2015. Revised 3 December 2015. Accepted 17 February 2016. Available online 23 February 2016.
Highlights
We presented effect of temperature on mechanical properties and creep responses of Wood/PVC composites.
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We provided empirical equation representing mechanical properties as a function of temperature.
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The creep models combining time–stress and time–stress–temperature dependencies were obtained.
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Good correlations between analytical models and experimental results were obtained.
Abstract
This work presents the effect of temperature on mechanical properties and tensile creep responses of Wood/PVC (WPVC) composite materials. The materials were produced by an industrial scale twin crew extruder using the weight ratio of wood and PVC compound of 1:1. The tensile, compressive, and flexural properties were determined at various temperatures (25 °C, 40 °C, 50 °C, 60 °C, and 70 °C). The tensile creep responses and creep models at these temperatures were also included in this work. The experimental results indicate that mechanical strength of WPVC composites decreased significantly at temperature higher than 50 °C while the modulus of elasticity was affected significantly at temperature higher than 60 °C. The material properties at large deformation as mechanical strength was found to be more sensitive to the temperature change than the mechanical modulus at small deformation. The empirical equation representing mechanical properties as a function of temperature was also provided together with recommended adjustment factors for the design phase. The creep models combining time–stress dependencies using power form and time–stress–temperature dependencies using Pickel’s form were obtained. Close agreement was observed representing adequacy of these models to predict the long-term deformation of the WPVC composites. This provided information would be useful for the design of WPVC composite member in structural and construction applications.
