EFFECT OF GRAPHENE-BASED FILLERS ON THE PROPERTIES OF SUNFLOWER-BASED POLYURETHANE

Polyurethane market majorly depends on synthetic materials which are noxious. This stimulated an idea to replace petrochemical resources with renewable resources for polyurethane production. Keeping this in mind, this research focused on the use of sunflower oil for the preparation of polyol and its use in polyurethane composition. The reaction mechanism of epoxidation and ring-opening was approached for the conversion of sunflower oil to polyol. During the conversion of sunflower oil, unsaturated groups of sunflower oil were converted into hydroxyl groups of polyol. Sunflower oil-based polyol was successfully blended with methylene diphenyl diisocyanate (MDI) to form urethane bonds. Confirmative tests such as fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), viscosity, and hydroxyl number analysis were performed. Very small amounts of graphene-based fillers such as graphene nanoplatelets (GNPs), graphene nanoribbon (GNR), graphene oxide (GO), and reduced graphene oxide (rGO) were separately dispersed into polyol by ultrasonication method to prepare polyurethane composites to enhance thermal and mechanical strength of the polyurethane. Structure of graphene-based fillers was confirmed by X-ray diffraction study. Film specimens from polyurethane composites were prepared for mechanical tests such as Shore D hardness, tensile and flexural. In the study of tensile strength, the highest tensile strength was recorded 34.9 MPa for polyurethane/graphene nanoplatelet films. For thermal stability analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) tests were conducted. Almost all polyurethane composite samples were thermally stable up to 280 oC. The change in thermal stability upon adding graphene-based fillers was analyzed by comparing residual percentages. The surface morphology of the films was studied by water contact angle (WCA), and atomic force microscopy (AFM). The highest WCA was measured at 104.22 for with 0.05 wt.% rGO filler. Hence, this research studied the effect of a very small quantity of graphene-based fillers on the sunflower oil-based polyurethane film

Toward Utilization of Agricultural Wastes: Development of a Novel Keratin Reinforced Soybean Meal-based Adhesive

The development of low-cost bio-based formaldehyde-free adhesives has aroused widespread interest in the wood adhesive industry. In this study, a series of aldehyde-free adhesives were prepared from soybean meal (SM) and chicken feather (CF), which were both largely produced from agricultural wastes. Incorporation of 10 wt % of keratin and calcium phosphate oligomer (CPO) significantly reinforced the performance of the fabricated adhesive material (namely, SMK10-CPO10). The dry and wet bonding strength of SMK10-CPO10 improved to 3.01 and 1.46 MPa, which was 1.75 and 2.15 times that of the adhesive made with SM alone (1.72 and 0.68 MPa), respectively. Meanwhile, the viscosity of the adhesive decreased from 40.77 (SM alone) to 22.32 Pa·s (SMK10-CPO10), which apparently improved the fluidity and wettability of the protein-based adhesive. This work not only put forward a novel method to prepare the green high-performance bio-based adhesive but also opened up a new way for the utilization of waste resources and a new strategy for the design and synthesis of advanced structural and functional materials

Graphene in Bio-derived Polyurethane for Improved Mechanical Properties

Polyurethane based polymers have a wide range of application due to their versatility. And to mention a few, they can be manipulated into foams in car seats, medical devices and lubricants. Until recently, polyols, which play a vital role in the properties of polyurethane were petroleum based. However, due to their fast depletion and the earnest need to protect the environment, researchers are more intrigued about using green and costefficient alternatives. Scientists have found bio-based polyols from sources like vegetable oils and limonene to produce polyurethanes with high quality properties hence, the gradual expansion in that research area. In this work, sunflower oil is converted into a polyol using an epoxidation reaction followed by ring opening with methanol. The polyol is further used in the synthesis of a polyurethane composite in an easy one step reaction with isocyanate. To improve the mechanical properties of the bio-based polyurethane composite, graphene was introduced in increasing percent concentrations. The dispersion of the graphene as well as the effects of the polyol was studied. In addition, TGA, and elasticity among the many others were used to test the effects of graphene on the properties of the materials. It was observed that the elastic modulus and tensile strength increased to over 450 MPa and 47 MPa respectively. TGA results also showed a high thermal stability of our synthesized materials. This experiment established a fast and facile method for the production of the biobased polyurethane composites that had improved mechanical properties with the addition of graphene