Composites made from a soybean oil biopolyurethane and cellulose nanocrystals

Hybrid Films from Blends of Castor Oil and Polycaprolactone Waterborne Polyurethanes

Waterborne polyurethanes (WBPUs) with relatively high biobased content (up to 43.7%) were synthesized, aiming at their use as coatings for metals and woods. The study was performed on self-standing films obtained from anionic polyurethane water dispersions (PUDs). The initially targeted PUD was prepared from castor oil (CO), while tartaric acid (TA), a byproduct of wine production, was utilized as the internal anionic emulsifier. Although the films were cohesive and transparent, they were fragile, and thus blending the CO-TA PUD with other WBPUs was the chosen strategy to obtain films with improved handling characteristics. Two different WBPUs based on polycaprolactone diol (PCL), a biodegradable macrodiol, were prepared with dimethylolpropionic acid (DMPA) and tartaric acid (TA) as synthetic and biobased internal emulsifiers, respectively. The use of blends with PCL-TA and PCL-DMPA allowed for tailoring the moduli of the samples and also varying their transparency and haze. The characterization of the neat and hybrid films was performed by colorimetry, FTIR-ATR, XRD, DMA, TGA, solubility and swelling in toluene, and water contact angle. In general, the addition of PCL-based films increases haze; reduces the storage modulus, G’, which at room temperature can vary in the range of 100 to 350 MPa; and reduces thermal degradation at high temperatures. The results are related to the high gel content of the CO-TA film (93.5 wt.%), which contributes to the cohesion of the blend films and to the crystallization of the PCL segments in the samples. The highest crystallinity values corresponded to the neat PCL-based films (32.3% and 26.9%, for PCL-DMPA and PCL-TA, respectively). The strategy of mixing dispersions is simpler than preparing a new synthesis for each new requirement and opens possibilities for new alternatives in the future.

Ternary Nanocomposite System Composing of Graphene Nanoplatelet, Cellulose Nanofiber and Jatropha Oil Based Waterborne Polyurethane: Characterizations, Mechanical, Thermal Properties and Conductivity

This work aims to evaluate the performance of graphene nanoplatelet (GNP) as conductive filler with the presence of 0.5 wt.% cellulose nanofiber (CNF) on the physical, mechanical, conductivity and thermal properties of jatropha oil based waterborne polyurethane. Polyurethane was made from crude jatropha oil using an epoxidation and ring-opening process. 0.5, 1.0, 1.5, 2.0 wt.% GNP and 0.5 wt.% CNF were incorporated using casting method to enhance film performance. Mechanical properties were studied following standard method as stated in ASTM D638-03 Type V. Thermal stability of the nanocomposite system was studied using thermal gravimetric analysis (TGA). Filler interaction and chemical crosslinking was monitored using Fourier-transform infrared spectroscopy (FTIR) and film morphology were observed with field emission scanning electron microscopy (FESEM). Water uptake analysis, water contact angle and conductivity tests are also carried out. The results showed that when the GNP was incorporated at fixed CNF content, it was found to enhance the nanocomposite film, its mechanical, thermal and water behavior properties as supported by morphology and water uptake. Nanocomposite film with 0.5 wt.% GNP shows the highest improvement in term of tensile strength, Young’s modulus, thermal degradation and water behavior. As the GNP loading increases, water uptake of the nanocomposite film was found relatively small (<1%). Contact angle test also indicates that the film is hydrophobic with addition of GNP. The conductivity properties of the nanocomposite film were not enhanced due to electrostatic repulsion force between GNP sheet and hard segment of WBPU. Overall, with addition of GNP, mechanical and thermal properties was greatly enhanced. However, conductivity value was not enhanced as expected due to electrostatic repulsion force. Therefore, ternary nanocomposite system is a suitable candidate for coating application.

Effect of Cellulose Nanofibrils on the Properties of Jatropha Oil-Based Waterborne Polyurethane Nanocomposite Film

The objective of this work was to study the influence of cellulose nanofibrils (CNF) on the physical, mechanical, and thermal properties of Jatropha oil-based waterborne polyurethane (WBPU) nanocomposite films. The polyol to produce polyurethane was synthesized from crude Jatropha oil through epoxidation and ring-opening method. The chain extender, 1,6-hexanediol, was used to improve film elasticity by 0.1, 0.25, and 0.5 wt.% of CNF loading was incorporated to enhance film performance. Mechanical performance was studied using a universal test machine as specified in ASTM D638-03 Type V and was achieved by 0.18 MPa at 0.5 wt.% of CNF. Thermal gravimetric analysis (TGA) was performed to measure the temperature of degradation and the chemical crosslinking and film morphology were studied using Fourier-transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The results showed that when the CNF was incorporated, it was found to enhance the nanocomposite film, in particular its mechanical and thermal properties supported by morphology. Nanocomposite film with 0.5 wt.% of CNF showed the highest improvement in terms of tensile strength, Young’s modulus, and thermal degradation. Although the contact angle decreases as the CNF content increases, the effect on the water absorption of the film was found to be relatively small (<3.5%). The difference between the neat WPBU and the highest CNF loading film was not more than 1%, even after 5 days of being immersed in water.