Browsing by Author "Stark, Nicole"

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Nano Boron Oxide and Zinc Oxide Doped Lignin Containing Cellulose Nanocrystals Improve the Thermal, Mechanical and Flammability Properties of High-Density Poly(ethylene)
(MDPI, 2023-12) Bajwa, Dilpreet S.; Holt, Greg; Stark, Nicole; Bajwa, Sreekala G.; Chanda, Saptaparni; Quadir, Mohiuddin
The widely used high-density polyethylene (HDPE) polymer has inadequate mechanical and thermal properties for structural applications. To overcome this challenge, nano zinc oxide (ZnO) and nano boron oxide (B2O3) doped lignin-containing cellulose nanocrystals (L-CNC) were blended in the polymer matrix. The working hypothesis is that lignin will prevent CNC aggregation, and metal oxides will reduce the flammability of polymers by modifying their degradation pathways. This research prepared and incorporated safe, effective, and eco-friendly hybrid systems of nano ZnO/L-CNC and nano B2O3/L-CNC into the HDPE matrix to improve their physio-mechanical and fire-retardant properties. The composites were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, thermo-gravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, horizontal burning test, and microcalorimetry test. The results demonstrated a substantial increase in mechanical properties and a reduction in flammability. The scanning electron microscope (SEM) images showed some agglomeration and irregular distribution of the inorganic oxides.
Silane compatibilzation to improve the dispersion, thermal and mechancial properties of cellulose nanocrystals in poly (ethylene oxide)
(Informa UK Limited, 2021-01) Chanda, Saptaparni; Bajwa, Dilpreet S.; Holt, Greg A.; Stark, Nicole; Bajwa, Sreekala G.; Quadir, Mohiuddin
Cellulose nanocrystal (CNC) has potential to be used as a reinforcement in polymeric nanocomposites because of their inherent biodegradability, universal accessibility, and superior mechanical properties. The most crucial challenge faced in the nanocomposite production is dispersing the nanoparticles effectively in the polymer matrix, so that the exceptional mechanical properties of the nanoparticles can be transferred to the macroscale properties to the bulk nanocomposites. In this research, a safe, effective and ecofriendly modification was used to functionalize the surface hydroxyl groups of CNC via silane treatment. These modified CNCs were used as reinforcements to prepare poly (ethylene oxide) (PEO)/CNC nanocomposites. The composites were prepared using solvent casting method. The composite properties were evaluated using Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Thermo-Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Dynamic Mechanical Analysis (DMA). The SEM micrographs demonstrated that the composites incorporated with silane treated CNCs showed improvement in the dispersion behavior of the nanoparticles in the matrix. Oxidative combustion of the composites containing silane treated CNCs promoted char formation and enhanced thermal stability. The composites containing (1:1) silane treated CNCs exhibited the better crystallization ability, highest storage modulus, and lowest tan δ value compared to the other silane treated systems indicating improved dispersion of CNC. The polysiloxane network provided an efficient surface covering of the CNC molecules, imparting reduced polar surface characteristics and enhancing the overall mechanical properties of the composites.