Bio-based Blends of Wheat Gluten and Maleated Natural Rubber: Morphology, Mechanical Properties and Water Absorption

AbstractWheat gluten (WG) is a complex protein derived from wheat. WG-based plastics are potentially used as substitutes for conventional petroleum-based plastics. However, the WG plastics are brittle and have high moisture absorption after being processed. In order to reduce stiffness and increase water resistance of the WG plastics, in this work, maleated natural rubber (NRMA) was blended with the WG. Grafting MA on the natural rubber (NR) is able to increase polarity of the NR, thereby increasing compatibility between the WG and NR. The NRMA was prepared by grafting maleic anhydride (MA) on natural rubber (NR) in molten state in an internal mixer at 120°C with no initiator for grafting reaction. Under the grafting condition used in this work, it was found that the grafted MA content on the NR is about 1.78% determined by alkaline titration. Sulfur as a curing agent in the rubber phase was used to prepare WG/NRMA blends with various weight ratios (100/0, 90/10, 80/20, 70/30, 60/40 and 50/50). Mechanical properties, impact strength, water absorption and morphologies of the molded WG/NRMA blends compared with WG/NR blends were investigated. Incorporation of the NRMA into WG improved flexibility and water absorption resistance of the polymer blends with respect to the neat WG. Moreover, the WG/NRMA blends provided higher impact strength and mechanical properties, especially modulus and tensile strength than those of WG/NR, indicating more compatibility between the WG and NRMA comparing to NR, resulting in an improvement of mechanical properties in the WG/NRMA blends

Green composites based on wheat gluten matrix and posidonia oceanica waste fibers as reinforcements

[EN] In this work, green composites from renewable resources were manufactured and characterized. A fibrous material derived from Posidonia oceanica wastes with high cellulose content (close to 90 wt% of the total organic component) was used as reinforcing material. The polymeric matrix to bind the fibers was a protein (wheat gluten) type material. Composites were made by hot-press molding by varying the gluten content on composites in the 10¿40 wt% range. Mechanical properties were evaluated by standardized flexural tests. Thermo-mechanical behavior of composites was evaluated with dynamic mechanical analysis (torsion DMA) and determination of heat deflection temperature. Morphology of samples was studied by scanning electronic microscopy and the water uptake in terms of the water submerged time was evaluated to determine the maximum water uptake of the fibers in the composites. Composites with 10¿40 wt% gluten show interesting mechanical performance, similar or even higher to many commodity and technical plastics, such as polypropylene. Water resistance of these composites increases with the amount of gluten. Therefore, the sensitiveness to the water of the composites can be tailored with the amount of gluten in their formulation.The authors would like to acknowledge the Wallenberg and Lars-Erik Thunholms Foundation for the economical support through the concession of a Postdoctoral Fellowship in Forest related. Authors would also like to thank Marcos and Elena for helping in collecting P. oceanica balls.Ferrero Penadés, B.; Boronat Vitoria, T.; Moriana Torró, R.; Fenollar Gimeno, OÁ.; Balart Gimeno, RA. (2013). Green composites based on wheat gluten matrix and posidonia oceanica waste fibers as reinforcements. Polymer Composites. 34(10):1663-1669. doi:10.1002/pc.22567S16631669341

Application of Wheat Gluten in Polymer Composites and Composite Particleboard

Wheat gluten (WG) is a complex protein from wheat and has been investigated for potential use in non-food applications, such as WG-based plastics, composites and a binder. In this research, WG was used to prepare: (1) particulate-filled WG composites, (2) natural fiber-filled WG composites, and (3) coconut materials composite particleboard using WG as a binder. ^ In the particulate-filled WG composites, functionalized silica and alumina with various functionalities (e.g. thiol, epoxide, aldehyde, and isocyanate groups) were used as fillers. Two mixing procedures, two-step mixing and in-situ mixing, were used for preparation of the composites and the effect of particle dispersion on the properties of filled WG composites has been studied. More homogeneity of filler particles was observed in the in-situ blended composites, which led to better mechanical properties than those observed in the two-step blended composites. ^ In the natural fiber-filled WG composites, the coconut fiber was used as a filler. Interfacial adhesion between the fiber and WG is crucial for mechanical properties of the composites. Two different chemical surface treatments of the fiber, alkaline treatment and silane treatment, were used to enhance the WG-fiber adhesion. It was found that the WG composite reinforced with the alkaline-followed by silane-treated coconut fiber (ASCCF) significantly improved the mechanical properties. ^ Formaldehyde-free particleboard based on coconut pith (CCP) with three binders, wheat gluten (WG), commercial polyisocyanate (RUBINATE ®1780; RN), and commercial polyurethane (PU), were prepared. Alkali-followed by silane-treated coconut fiber (ASCCF) at 10 wt% fiber was used to reinforce the particleboards. Modulus of elasticity (MOE), modulus of rupture (MOR), tensile strength parallel to surface (TS), water absorption (WA%), thickness swelling (TSW%), and thermal stability of the particleboards were investigated. It was found that the particleboards bound with binders have higher mechanical properties than the binderless particleboard. Among these binders, RN provided superior mechanical and thermal properties, as well as increased water resistance.

Application of Wheat Gluten in Polymer Composites and Composite Particleboard

Wheat gluten (WG) is a complex protein from wheat and has been investigated for potential use in non-food applications, such as WG-based plastics, composites and a binder. In this research, WG was used to prepare: (1) particulate-filled WG composites, (2) natural fiber-filled WG composites, and (3) coconut materials composite particleboard using WG as a binder. ^ In the particulate-filled WG composites, functionalized silica and alumina with various functionalities (e.g. thiol, epoxide, aldehyde, and isocyanate groups) were used as fillers. Two mixing procedures, two-step mixing and in-situ mixing, were used for preparation of the composites and the effect of particle dispersion on the properties of filled WG composites has been studied. More homogeneity of filler particles was observed in the in-situ blended composites, which led to better mechanical properties than those observed in the two-step blended composites. ^ In the natural fiber-filled WG composites, the coconut fiber was used as a filler. Interfacial adhesion between the fiber and WG is crucial for mechanical properties of the composites. Two different chemical surface treatments of the fiber, alkaline treatment and silane treatment, were used to enhance the WG-fiber adhesion. It was found that the WG composite reinforced with the alkaline-followed by silane-treated coconut fiber (ASCCF) significantly improved the mechanical properties. ^ Formaldehyde-free particleboard based on coconut pith (CCP) with three binders, wheat gluten (WG), commercial polyisocyanate (RUBINATE ®1780; RN), and commercial polyurethane (PU), were prepared. Alkali-followed by silane-treated coconut fiber (ASCCF) at 10 wt% fiber was used to reinforce the particleboards. Modulus of elasticity (MOE), modulus of rupture (MOR), tensile strength parallel to surface (TS), water absorption (WA%), thickness swelling (TSW%), and thermal stability of the particleboards were investigated. It was found that the particleboards bound with binders have higher mechanical properties than the binderless particleboard. Among these binders, RN provided superior mechanical and thermal properties, as well as increased water resistance.