Mechanical Properties of a Soy Protein Isolate–Grafted–Acrylate (SGA) Copolymer Used for Wood Coatings

Abstract

Changing demands have led to rapidly growing interest in the modification of waterborne wood coatings. To improve the performance of a polyacrylate wood coating, especially the strength, hardness, and abrasion resistance of the film, a soy protein isolate–grafted–acrylate (SGA) copolymer was prepared in an aqueous solution with ammonium persulfate (APS) as an initiator and sodium pyrosulfite (SPS) as an unfolding agent for the soybean protein isolate (SPI). The emulsion was characterized using transmission electron microscopy, Fourier-transform infrared spectroscopy (FTIR), and a particle size analyzer. Furthermore, the mechanical properties of the film, including the tensile strength, elastic modulus, elongation at break, and pencil hardness, were measured. The results showed that the glass transition temperature of the polyacrylic resin decreased to 35 °C after the SPI grafting. The elastic modulus of the film increased from 0.317 to 46.949 MPa, and the elongation at break decreased from 453.133% to 187.125% as the addition of SPI varied from 0 to 4 g, respectively. The pencil hardness of the wood coating increased from HB to 3H. This paper proposes a feasible route for the utilization of SPI for wood coatings.

Proteins as Promising Biobased Building Blocks for Preparing Functional Hybrid Protein/Synthetic Polymer Nanoparticles

“…67,72,84 In this scenario, highly compatibilized hybrid materials showed superior properties than the simple constituents' addition, demonstrating a synergetic contribution of both components due to the intimate contact between phases. Some of these synergetic improvements observed in the applications of protein-based hybrid NPs were partial biodegradability, 66,67,72,84,124,132 thermal stability, 67 film formation with low requirement of formulation agents (better NPs coalescence), 2 4 , 1 3 1 solvent resistance, 2 4 water resistance, 72,82,102,103,125 and mechanical strength 103,125,126,153 among others.…”

“…Recently, the synthesis of acrylic/SPI hybrid latexes by emulsion copolymerization of acrylic monomers (MMA, BA, and 2-(methacryloyloxy)ethyl acetoacetate), was reported in order to produce waterborne wood coatings. 153 Latex with variable content of SPI (PC = 1.7−11.4%) and with theoretical solid content between 27 and 29% was produced. Soy protein was previously treated by heating in NaOH solution, followed by the addition of sodium metabisulfite to break the secondary and quaternary structures of the protein.…”

“…The main synthesis route for obtaining these protein/synthetic polymer latexes involves the emulsion polymerization in the absence of emulsifier, ,,,, which paves the way for its industrial implementation without significant technological upgrades. The efforts made have allowed the achievement of producing high solids hybrid latexes with elevated protein content ,,,, and compatibility, , highly desirable for an efficient exploitation of this sustainable resource. These features were in most cases the result of a prepolymerization stage of protein modification, which pursues introducing extra active sites onto the protein backbone to promote its grafting with the synthetic polymer , or to modify its hydrophilic–hydrophobic balance. ,, In this scenario, highly compatibilized hybrid materials showed superior properties than the simple constituents’ addition, demonstrating a synergetic contribution of both components due to the intimate contact between phases.…”

“…Recently, the synthesis of acrylic/SPI hybrid latexes by emulsion copolymerization of acrylic monomers (MMA, BA, and 2-(methacryloyloxy)­ethyl acetoacetate), was reported in order to produce waterborne wood coatings . Latex with variable content of SPI (PC = 1.7–11.4%) and with theoretical solid content between 27 and 29% was produced.…”

Reactive Compatibilization of Poly(Butylene Succinate)/Soy Protein Isolate Bio-Composites By Peroxide And Diacrylate Via Melt Blending

“…It is necessary to improve the compatibility of PBS and SPI by modification and compatibilization. [29,30] The reactive blending is a simple, effective and low-cost method to modulate interfacial interactions by in-situ chemical reaction, such as crosslinking and grafting, and thus enhances the properties of immiscible blends. [31] The reactive processing methods had been adopted in many studies, such as PBS/waxy starch [32], PBAT/thermoplastic starch [33], PWP/PBS [28], NTP/PBS [22], TSM/PCL/PBS [24] and SPC/Eastar Bio Copolyester (EPE) [34] composites.…”