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Canola Protein and Oil-based Wood Adhesives
Published in Zhongqi He, Bio-based Wood Adhesives, 2017
Ningbo Li, Guangyan Qi, Xiuzhi Susan Sun, Donghai Wang
Adhesion is the tendency of dissimilar particles and/or surfaces to cling to one another with the aid of adhesive by chemical or physical forces (Schultz and Nardin, 1999). In order to achieve bonding, adhesives spread and wet the surface of the substrate, penetrating into the fibers cells through the capillary path and acting as a mechanical anchor (Schultz and Nardin, 1999). Adhesives for wood bonding range from natural starch, protein, and lignin to very durable synthetic resins created from petrochemicals (Eckelman, 2010). Before World War II, essentially all adhesives used for wood bonding were originated from natural resources such as mud, dung, clay, or a mixture of these substances. However, better-performing synthetic resins with higher bonding strength and water resistance from petrochemicals, such as urea-formaldehyde (UF), melamine-formaldehyde (MF), and phenolformaldehyde (PF), quickly dominated the wood composite market and usage surpassed a majority of the previous natural glues for wood bonding (Koch et al., 1987). Recent environmental concerns and awareness of finite natural resources, however, have led to a resurgence in the development of biodegradable, durable, and sustainable bio-based adhesives such as protein-based adhesives, animal glue, blood-based adhesives, casein- based adhesives, lignin adhesives, and vegetable protein-based adhesives (Lin and Gunasekaran, 2010; Pizzi, 2006; Yang et al., 2006).
Composition and Technology of the 17th Century Stucco Decorations at Červená Lhota Castle in Southern Bohemia
Published in International Journal of Architectural Heritage, 2020
Jan Válek, Olga Skružná, Petr Kozlovcev, Dita Frankeová, Petra Mácová, Alberto Viani, Ivana Kumpová
Collagen proteins were identified by MALDI-TOF method in all analysed samples. Source of collagen is typically an animal glue which was traditionally used to modify the setting of gypsum (retard) and to influence its hardened performance (Elert, Benavides-Reyes, and Cardell 2019). In agreement with the expected usage, collagen was found in the lime-gypsum mortars, i.e. in the core mortar (LCL 5) and the coarse adhesive mortar (LCL 1). The fine adhesive mortar was not analysed for its presence. However, collagen was also identified in the mortars without gypsum, like in the small decorations (SCL 2 – leaf, 3 – cherry), in the stucco layer (SCL 5) and also in the older stucco decoration (SCL 16). The presence of collagen was also confirmed in the coating layers of the leaf (SCL 8) and the bead mould (SCL 6) samples. The analytical outcome confirmed a match of several protein chains that meant quite a high reliability of the result.
A Preliminary Study on the Characteristics of Lime-Based Mortars with Egg White Addition
Published in International Journal of Architectural Heritage, 2021
Kun Zhang, Liqin Wang, Fude Tie, Fuwei Yang, Yan Liu, Yue Zhang
Mortar hardness and strength were also improved with the addition of egg white. Figure 7 shows that within the first 7 d of curing under 50% RH, mortar specimens with egg white had higher surface hardness values and increasing rates than specimens without, which indicated that the addition of egg white could shorten mortar setting time, as was also reported by Pahlavan et al. (2018). Under 50% RH curing, the 28 d and 180 d compressive strength values (Figure 8) of the specimen with egg white (L-TD-EW-50%) reached respectively 2.21 ± 0.18 and 3.71 ± 0.23 MPa, higher than the values of L-TD-W-50% (0.8 ± 0.06 and 2.15 ± 0.18 MPa), which is with water only. Improved compressive strength in air lime mortars (cured under dry condition) with protein-based additives (e.g., animal glue, milk, and cactus) was previously reported in Alonso et al. (2002) and Ventolà et al. (2011). Centauro et al. (2017) and Chandra and Aavik (1987) found that protein functional groups such as -CONH-, -NH2, -COOH, and -OH can form strong interactions with inorganic compounds, increasing cohesion of lime-based mortars, consequently resulting in higher mortar strength and hardness. A conductivity test was performed in the present study (Figure 9), and the faster conductivity decreasing rate of Ca(OH)2+ egg white solution within 48 h compared with that of Ca(OH)2+ water solution could confirm the interactions between egg white protein and calcium hydroxide. Additionally, it can be noted in DTG and DSC curves (Figure 8) that specimens containing egg white (~396–422°C) generally have lower decomposition temperatures than those without (~417–433°C), which might be accounted for by interactions/reactions between Ca(OH)2 and the functional groups of proteins (Chandra and Flodin 1987).