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The objective of this research was to evaluate the properties of the chemically retted kenaf bast fiber impregnated with the inorganic nanoparticles. High quality kenaf bast fibers were obtained from a chemical retting process. An in situ inorganic nanoparticle impregnation (INI) process was used to introduce the CaCO3 nanoparticles into the retted kenaf bast fibers. It was found that some of the lignin-based components in the retted fibers were further removed during the INI treatment. From the characterization results, the inorganic nanoparticles CaCO3, with different shapes and sizes, appeared at the surface of the impregnated fiber after treatment. Heterogeneous CaCO3 nanoparticle distribution was observed on the INI treated fibers. The CaCO3 contents were different at different locations along the impregnated fiber. The presence of CaCO3 inorganic nanoparticles at the fiber surface increased the root mean square (RMS) surface roughness by 5.8% and decreased the hydrophilic nature of the retted fibers, evidenced by a 59.4% decrease in adhesion force between the fiber and hydrophilic AFM tip. In addition, the impregnation of CaCO3 dramatically increased the Young’s modulus of the fiber by 344%.

In this research, three different types of biocomposites were made from kenaf fiber/soy protein, kenaf fiber/DS 3530, and kenaf fiber/soy protein/DS 3530. Fourier transform infrared spectra of the biocomposites showed that there were chemical reactions among the kenaf fiber, soy flour, and BASF Acrodur resin. The hot-pressing time had a significant effect on the flexural properties and density of both the kenaf fiber/soy flour composites and kenaf fiber/BASF Acrodur resin composites. However, the effect was opposite for the composites from 10 to 20 min of hot pressing. As the hot-pressing time increased, the flexural properties and density increased for the kenaf fiber/soy flour composites and decreased for the other two composites with BASF Acrodur resin. BASF Acro- dur resin reduced the hot-pressing time of the biocomposites. With 28 wt % BASF Acrodur resin (on the basis of 100% solid con- tent) as a binder and with the biocomposites hot-pressed for 10 min, the swelling thickness and water absorption of the composites were reduced by 55 and 64%, and the flexural strength and modulus were improved by 72 and 188%, respectively. More simultaneous failures of the fiber and adhesive were observed at the fracture surface of the kenaf fiber/soy flour/BASF Acrodur resin composite. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 000: 000-000, 2012

Soybean meal flour, polyethylene glycol (PEG), sodium hydroxide (NaOH), and a melamine-urea-formaldehyde (MUF) resin were used to formulate soybean meal/MUF resin adhesive. Effects of the adhesive components on the water resistance and formaldehyde emission were measured on three-ply plywood. The viscosity and solid content of the different adhesive formulations were measured. The functional groups of the cured adhesives were evaluated. The results showed that the wet shear strength of plywood bonded by soybean meal/NaOH adhesive increased by 33% to 0.61 MPa after adding NaOH into the adhesive formulation. Addition of PEG reduced the viscosity of the soybean meal/NaOH/PEG adhesive by 91% to 34,489 cP. By using the MUF resin, the solid content of the soybean meal/MUF resin adhesive was improved to 39.2%, the viscosity of the adhesive was further reduced by 37% to 21,727 cP, and the wet shear strength of plywood bonded by the adhesive was increased to 0.95 MPa, which met the interior plywood requirements (≥0.7 MPa). The formaldehyde emission of plywood bonded by the soybean meal/MUF resin adhesive was obtained at 0.28 mg/L, which met the strictest requirement of the China National Standard (≤0.5 mg/L). FTIR showed using the MUF resin formed more CH2 group in the cured adhesive. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The objective of this study was to improve the wet shear strength and reduce the formaldehyde emissions for the soybean meal/melamine urea-formaldehyde (MUF) adhesive–bonded plywood by optimizing the hot pressing parameters in plywood manufacturing. An L(44) experimental design was used. A dynamic mechanical analyzer (DMA) was used to study the curing process of the adhesive during hot pressing. The DMA results showed that the storage modulus (E′) first decreased to a minimum at 72.9°C and then increased as the temperature increased to a maximum at 157.2°C. At temperatures higher than 157.2°C, the storage modulus decreased as the temperature increased. The hot press temperature had a significant effect on both the wet shear strength and the formaldehyde emissions from 120°C to 150°C, while no significant effect was found by varying the hot press time from 50 to 80 s/mm and changing the pressure from 0.8 to 1.2 MPa. The adhesive spread rate had a significant effect on the formaldehyde emissions. No signifi...

Polyurethane foam was fabricated from polymeric diphenylmethane diisocyanate (pMDI) and soy-based polyol. Nanoclay Cloisite 30B was incorporated into the foam systems to improve their thermal stabilities and mechanical properties. Neat polyurethane was used as a control. Soy-based polyurethane foams with 0.5–3 parts per hundred of polyols by weight (php) of nanoclay were prepared. The distribution of nanoclay in the composites was analyzed by X-ray diffraction (XRD), and the morphology of the composites was analyzed through scanning electron microscopy (SEM). The thermal properties were evaluated through dynamic mechanical thermal analysis (DMTA). Compression and three-point bending tests were conducted on the composites. The densities of nanoclay soy-based polyurethane foams were higher than that of the neat soy-based polyurethane foam. At a loading of 0.5 php nanoclay, the compressive, flexural strength, and modulus of the soy-based polyurethane foam were increased by 98%, 26%, 22%, and 65%, respectively, as compared to those of the neat soy-based polyurethane foam. The storage modulus of the soy-based polyurethane foam was improved by the incorporation of nanoclay. The glass transition temperature of the foam was increased as the nanoclay loading was increased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

A series of poly(methyl methacrylate) (PMMA) blends with rigid ladderlike polyphenylsilsesquioxane (PPSQ) were prepared at weight ratios of 100/0, 95/5, 90/10, 85/15, and 80/20 by solution casting and then hot-pressing. Their rheological properties have been studied under both dynamic shear and uniaxial elongation conditions. Their rheological properties depend on the compositions. The storage modulus, G′, loss modulus, G″, and dynamic shear viscosity, η*, of the PMMA/PPSQ 95/5 blend were slightly lower than those of pure PMMA. However, the values of G′, G″, and η* for the other PMMA/PPSQ blends are higher than those of PMMA. The G′ values increase with an increase in PPSQ content from 5% through 15% PPSQ at low frequencies and then drop as the PPSQ content increases to 20%. Uniaxial elongational viscosity (ηE) data demonstrate that PMMA/PPSQ blends exhibit slightly weaker (5% PPSQ) and much weaker (10% PPSQ) strain-hardening than PMMA. In contrast, the PMMA/PPSQ 85/15 blend shows strain-softening. Neither strain-hardening nor strain-softening was observed in the 80/20 blend. The special rheological properties for the 95/5 blend is probably due to a decrease in PMMA entanglements brought by the specific PMMA–PPSQ interactions. Rheological properties of PMMA/PPSQ blends with higher PPSQ content (≥10%) are mainly affected by formation of hard PPSQ particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 352–359, 2007

The cold-start behavior and the effect of sub-zero temperatures on fuel cell performance were studied using a 25-cm 2 proton exchange membrane fuel cell (PEMFC). The fuel cell system was housed in an environmental chamber that allowed the system to be subjected to temperatures ranging from sub-freezing to those encountered during normal operation. Fuel cell cold-start was investigated under a wide range of operating conditions. The cold-start measurements showed that the cell was capable of starting operation at −5 °C without irreversible performance loss when the cell was initially dry. The fuel cell was also able to operate at low environmental temperatures, down to −15 °C. However, irreversible performance losses were found if the cell cathode temperature fell below −5 °C during operation. Freezing of the water generated by fuel cell operation damaged fuel cell internal components. Several low temperature failure cases were investigated in PEM fuel cells that underwent sub-zero start and operation from −20 °C. Cell components were removed from the fuel cells and analyzed with scanning electron microscopy (SEM). Significant damage to the membrane electrode assembly (MEA) and backing layer was observed in these components after operation below −5 °C. Catalyst layer delamination from both the membrane and the gas diffusion layer (GDL) was observed, as were cracks in the membrane, leading to hydrogen crossover. The membrane surface became rough and cracked and pinhole formation was observed in the membrane after operation at sub-zero temperatures. Some minor damage was observed to the backing layer coating Teflon and binder structure due to ice formation during operation.

The structure and properties of organic–inorganic hybrid nanocomposites prepared from a resole phenolic resin and a POSS mixture containing >95 wt% trisilanolphenyl POSS was investigated by POM (polarized optical microscopy), SEM, TEM, WAXD, FT-IR, DSC, and TGA techniques. Composites with 1.0–10.4 wt% of POSS were prepared by dissolving the POSS and the phenolic resin into THF, followed by solvent removal and curing. Both nano- and micro-sized POSS filler aggregates and particles were shown to be heterogeneously dispersed in the cured matrix by POM, TEM, SEM, and X-EDS. POSS was found everywhere, including in both dispersed phase domains and in the matrix. The nanocomposite morphology appears to form by a multi-step POSS aggregation during the process of phase separation. Both the matrix and dispersed ‘particulate’ phase domains are mixtures of phenolic resin and POSS. POSS micro-crystals act as the core of the dispersed phase. The bigger dispersed domains consist of smaller particles or aggregates of POSS molecules that exhibit some order but regions of matrix resin are interspersed. A WAXD peak at 2θ∼7.3° indicates crystalline order in the POSS aggregates. This characteristic peak's intensity increases with an increase in POSS loading, suggesting that more POSS molecules have aggregated or crystallized. FT-IR spectra confirm that hydrogen bonding exists between the phenolic resin and POSS Si–OH groups. This increases their mutual compatibility, but H-bonding does not prevent POSS aggregation and phase separation during curing. TGA measurements in air confirmed the temperature for 5% mass loss in increases with increase of POSS loading and at T>550° the thermal stability increases more sharply with POSS loading. The nanocomposite glass transition temperatures (Tg) are only slightly be affected by the POSS filler.

Cyanate ester (PT-15, Lonza Corp.) composites containing the blended polyhedral oligomeric silsesquioxane (POSS), TriSilanolPhenyl-POSS (C42H38O12Si7), were prepared containing PT-15/POSS 99/1, 97/3, 95/5, 90/10, and 85/15 w/w ratios. The composites were characterized by FT-TR, X-ray diffraction (XRD), small-angle neutron scattering (SANS), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (X-EDS), transmission electron microscopy (TEM), dynamic mechanical thermal analysis (DMTA), and three-point bending flexural tests. TriSilanolPhenyl-POSS was throughly dispersed into uncured liquid PT-15 resin. After curing, XRD, SANS, and X-EDS measurements were consistent with partial molecular dispersion of a portion of the POSS units in the continuous matrix phase while the remainder forms POSS aggregates. Larger aggregates are formed at higher loadings. SANS, SEM, and TEM show that POSS-enriched nanoparticles are present in the PT-15/POSS composites. The storage bending moduli, E‘, and the g...