Adhesives And Plastics Based On Soy Protein Products

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Industries are conscious about environmental pollution and have adopted eco-friendly nature of production. Therefore, they have turned to renewable natural resources such as soybean to use them as raw materials for their products. Such industries mainly manufacture polymeric products such as plastics and adhesives. These soy-based products are environmentally friendly and help minimize pollution. The article gives details on how soy protein is utilized in manufacturing the products.

The main use of the soy grown in the world is oil extraction and protein. However, most of it goes to waste after being utilized for human consumption and oil; thus, the need to exploit new industrial uses of the wasted soy protein. This innovation has paved way for soy-based adhesives, plastics, coatings, and films, which have been utilized for automobiles, agricultural and marine equipment, and civil engineering. The construction industry has also ventured into soy-based panel products in order to overcome the problem of wood shortage. In addition, the plywood industry is also following suit by adopting soy-based adhesives because of the limited petroleum resources.

The soybean proteins necessary for manufacturing the products such as adhesives include soy protein isolate, soy flour, and protein concentrate either in the form of cake, flakes, meal or chips. Soy proteins’ adhesive performance is determined by the particle size, pH, viscosity, protein structure and nature of the surface. The proteins are normally modified in order to manufacture adhesives that are safe for the workers, highly water-resistant, and effective in lumber finger-jointing. Soybean modification is executed via various methods such as using alkalis and salt. Sodium hydroxide is the alkali used in denaturing and cleaving the proteins to manufacture more water resistant and stronger adhesives than the unmodified ones. Salts such as sodium sulfate and sodium chloride are also used in the modification. This treatment increases the pH and reduces the viscosity; thus, enhancing solubility of the adhesives. Cross linking is also another essential method in improving water resistance, consistency, and working life of the adhesives. Cross linking agents such as sulfur compounds and formaldehyde donors are useful in this process. The emulsifying properties, solubility and hydrophobicity of the products are also improved through modification with enzymes such as papain. High performance adhesives can be obtained by mixing soy-based adhesives with synthetic ones or with other protein adhesives. Blends with phenol-resorcinol formaldehyde, casein, blood, and phenol formaldehyde have yielded glues with unparalleled properties.

Soy-based plastics have also become popular in industries since they are used to manufacture commodities such as toys, bags and spoons. The plastics are biodegradable; thus, easily converted to carbon dioxide and water in both marine and soil environments. Moreover, they have improved qualities such as increased tensile strength, ductility, elongation, and water resistance. In addition, the soy plastics are non-toxic unlike the petroleum-based plastics.

Besides being used as human food and oil extraction, soybean protein has numerous industrial applications. It is essential in manufacturing wood adhesives and other bonding agents, building materials, insulating foams, and plastic films. For example, a new soy-based product called Environ has been produced for interior purposes such as on table tops, or in lamps. It resembles granite in structure and has properties of wood. Soy protein is preferred because it has excellent adhesion properties, safe for use in packaging materials, and easily disposed after use. It is also eco-friendly and legislative because most industries opted to use it after the media raised the alarm on environmental pollution by non-renewable products.

Bibliography

Kumar, Rakesh, Choudhary, Veena, Mishra, Saroj, Varma, I.K. , and Mattiason, Bo. “Adhesives and Plastics Based on Soy Protein Products.” Industrial Crops and Products 16, (2002): 155–172.