Polymethylmethacrylate/cellulose nanocomposites were prepared by in situ polymerization and ex situ dispersion techniques with 10 wt% loading of cellulose nanoparticles. Cellulose nanoparticles were prepared from jute fibers by acid hydrolysis. The suspension polymerization of methylmethacrylate was carried out in presence of cellulose nanoparticles, which were dispersed in water medium and in situ polymethylmethacrylate/cellulose nanocomposite granules were formed. These granules were dissolved in chloroform, sonicated and films were prepared by solution casting method (IPC). Polymethylmethacrylate granules were prepared by similar suspension polymerization process and made into films by solution casting method. Another set of polymethylmethacrylate/cellulose nanocomposite films were prepared by dispersing nanocellulose powder (10 wt%) in polymethylmethacrylate solution and casting into films (EPC). The unreinforced polymethylmethacrylate and polymethylmethacrylate extracted from IPC films were subjected to size exclusion chromatography and nuclear magnetic resonance study. The average molecular weights of neat polymethylmethacrylate and polymethylmethacrylate from IPC were quite close, but the ‘dispersity’ was slightly higher in IPC than that in neat polymethylmethacrylate. Fourier transform infrared spectroscopy revealed some shifts in EPC. X-ray diffraction study showed a similar nature of X-ray diffraction curves in all the samples. Transmission electron microscopy of IPC and EPC showed a better dispersion of fillers and formation of a network structure in IPC, whereas in EPC, the fillers were agglomerated. Surface morphology of the films was examined by field emission scanning electron microscopy and atomic force microscopy. IPC exhibited a much smoother surface compared to that of EPC indicating a more homogeneous dispersion of fillers. IPC showed a higher modulus of elasticity compared to PMMA and EPC. Differential scanning calorimetry showed a shift of glass transition temperature to a higher one (125°C) in IPC compared to that of polymethylmethacrylate (118°C). Thermogravimetric analysis was done to study the thermal degradation behavior of the composites.
Polyurethane foams are widely used for insulation applications due to their high insulation properties as compared to conventional materials such as extruded polystyrene foam and mineral wool. In this study, soy-based polyurethane foams were prepared using five different surfactants while keeping other components such as soy-based polyol, diisocyanate, catalyst, and blowing agent (water) constant. Prepared samples were tested for mechanical and thermal properties to evaluate the effect of different surfactants used in varying quantities. The morphology of the foam samples was observed using a scanning electron microscope. Seventeen fold reduction in the cell size was observed with an increase in the amount of surfactant from 0.5 to 5.0 g. Samples with higher amounts of surfactant also exhibited a higher number of closed cells. Better thermal insulation was observed for samples with 2.0 and 5.0 g of surfactant as compared to samples with 0.5 g of surfactant. A similar trend was observed in the mechanical strength, moisture absorbance, and density of the fabricated foam samples.
Traumatic brain injury (TBI) is a serious public health concern for which sensitive and objective diagnostic methods remain lacking. While advances in neuroimaging have improved diagnostic capabilities, the complementary use of molecular biomarkers can provide clinicians with additional insight into the nature and severity of TBI. In this study, a panel of eight metabolites involved in distinct pathophysiological processes related to concussion was quantified using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Specifically, the newly developed method can simultaneously determine urinary concentrations of glutamic acid, homovanillic acid, 5-hydroxyindoleacetic acid, methionine sulfoxide, lactic acid, pyruvic acid, N-acetylaspartic acid, and F2α-isoprostane without intensive sample preparation or preconcentration. The method was systematically validated to assess sensitivity (method detection limits: 1–20 μg/L), accuracy (81–124% spike recoveries in urine), and reproducibility (relative standard deviation: 4–12%). The method was ultimately applied to a small cohort of urine specimens obtained from healthy college student volunteers. The method presented here provides a new technique to facilitate future work aiming to assess the clinical efficacy of these putative biomarkers for noninvasive assessment of TBI.
Environmental concerns continue to pose the challenge to replace petroleum‐based products with renewable ones completely or at least partially while maintaining comparable properties. Herein, rigid polyurethane (PU) foams were prepared using soy‐based polyol for structural and thermal insulation applications. Cell size, density, thermal resistivity, and compression force deflection (CFD) values were evaluated and compared with that of petroleum‐based PU foam Baydur 683. The roles of different additives, that is, catalyst, blowing agent, surfactants, and different functionalities of polyol on the properties of fabricated foam were also investigated. For this study, dibutyltin dilaurate was employed as catalyst and water as environment friendly blowing agent. Their competitive effect on density and cell size of the PU foams were evaluated. Five different silicone‐based surfactants were employed to study the effect of surface tension on cell size of foam. It was also found that 5 g of surfactant per 100 g of polyol produced a foam with minimum surface tension and highest thermal resistivity (R value: 26.11 m2·K/W). However, CFD values were compromised for higher surfactant loading. Additionally, blending of 5 g of higher functionality soy‐based polyol improved the CFD values to 328.19 kPa, which was comparable to that of petroleum‐based foam Baydur 683.
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