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Papers by Brian Grady

World Academy of Science, Engineering and Technology, International Journal of Chemical and Molecular Engineering, Feb 27, 2014

Poly (trimethylene terephthalate) (PTT) is a linear aromatic polyester with good strength and sti... more Poly (trimethylene terephthalate) (PTT) is a linear aromatic polyester with good strength and stiffness, good surface appearance, low shrinkage and war page, and good dimensional stability. However, it has low impact strength which is a problem in automotive application. Thus, modification of PTT with the other polymer or polymer blending is a one way to develop a new material with excellence properties. In this study, PTT/High Density Polyethylene (HDPE) blends and PTT/Linear Low Density Polyethylene (LLDPE) blends with and without compatibilizers base on maleic anhydride grafted HDPE (MAH-g-HDPE) and ethylene-methacrylic acid neutralized sodium metal (Na-EMAA) were prepared by a twin-screw extruder. The blended samples with different ratios of polymers and compatibilizers were characterized on mechanical and rheological properties. Moreover, the phase morphology and dispersion size were studied by using SEM to give better understanding of the compatibility of the blends.

Journal of Applied Polymer Science, May 6, 2003

The effect of the composition on the morphologies and properties of uncompatibilized and compatib... more The effect of the composition on the morphologies and properties of uncompatibilized and compatibilized blends of nylon 6 and low‐density polyethylene were studied over a wide range of weight fractions. The uncompatibilized blends had substantially reduced mechanical properties after mixing, and this was almost certainly due to poor interfacial adhesion between the two polymers. The addition of a zinc‐neutralized poly(ethylene‐co‐methacrylic acid) ionomer (Surlyn® 9020) as a compatibilizer improved the mechanical properties in comparison with those of the material blended without the compatibilizer. The clearest evidence of this improvement came from dynamic mechanical studies; for selected blends with high polyethylene contents, the drop in the modulus corresponding to the transition of a solid to a melt occurred at higher temperatures with the added compatibilizer. This improvement in the properties was accompanied by a reduction in the dispersed‐phase size due to the interaction between the ionic part of the ionomer and the amide groups of nylon 6, especially when nylon 6 was the dispersed phase of the blend. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 620–629, 2003

Polymer Bulletin, Jul 18, 2012

Blends of polyamide-6 (PA-6) and high-density polyethylene (HDPE) with blend ratios of 80/20 (wt/... more Blends of polyamide-6 (PA-6) and high-density polyethylene (HDPE) with blend ratios of 80/20 (wt/wt) and 20/80 (wt/wt) were studied using zinc-neutralized maleic anhydride (MAH) grafted HDPE as compatibilizers. MAH groups were hydrolyzed and neutralized with different amounts of zinc acetate dihydrate in a twin-screw extruder to produce different levels of zinc-neutralization (0, 14, 41, 69, and 95 %) at one and ten parts per hundred of resin of compatibilizer. Melt neutralization of MAH was confirmed by X-ray fluorescence, FT–IR, and rheological properties. SEM micrographs showed a large reduction in the dispersed phase size in the compatibilized blends. Tensile measurements showed improvement of tensile strength for all compatibilized blends; moreover, the elongation at break of compatibilized blends at 10 phr of compatibilizer was improved. Blending increased the crystallization temperature for the PA-6, and the addition of compatibilizer reduced the crystallization temperature slightly. A significant increase in melt viscosity of the compatibilizer was found with zinc addition and adding compatibilizer increased the viscosity of the blends. However, the addition of zinc to the compatibilizer did not change the viscosity in the PA-6-rich blends and actually led to a decrease in viscosity in the HDPE-rich blends.

European Polymer Journal, Nov 1, 2004

An ethylene–methacrylic acid copolymer partially neutralized with sodium (Na-EMAA) was successful... more An ethylene–methacrylic acid copolymer partially neutralized with sodium (Na-EMAA) was successfully used to compatibilize Nylon 6 (Ny6) and low-density polyethylene (LDPE) blends. The phase morphology and thermal behavior of these blends were investigated over a range of compositions using a variety of analytical techniques. The addition of small amounts (0.5 phr) of Na-EMAA improved the compatibility of Ny6/LDPE blends as

European Polymer Journal, Apr 1, 2004

Efforts have been made to develop fluorine-free mould fluxes for the continuous casting of steel ... more Efforts have been made to develop fluorine-free mould fluxes for the continuous casting of steel process. In this work the crystallization behaviour of fluorine-free mould slags based on the CaO-Al 2 O 3-B 2 O 3 system was investigated by differential scanning calorimeter (DSC) and scanning electron microscopy equipped with energy dispersive spectroscopy(SEM-EDS). The crystallization kinetics for Ca 3 Al 2 O 6 primary crystals was analysed by combining modified Avrami analysis with Friedman isoconversional method. Avrami parameter n is close to 4 for samples with the ratios w(CaO)/w(Al 2 O 3) = 1 and w(CaO)/w(Al 2 O 3) = 1.2, indicating a crystallization mechanism of continuous bulk nucleation and 3D crystal growth. The Avrami parameter n for samples with w(CaO)/w(Al 2 O 3) = 0.9 is close to 3, indicating instantaneous bulk nucleation and 3D crystal growth. The crystallization rate constant is the highest and half crystallization time is the lowest for the samples with w(CaO)/w(Al 2 O 3) = 0.9, indicating the fastest crystallization. In the initial stage, effective activation energies were mainly determined by the undercooling values. In the final stage, kinetic barrier for crystallization could have some influence on crystallization; for the investigated mould fluxes crystallization in the final stage is retarded by increasing w(CaO)/w(Al 2 O 3) ratio. Thus crystallization mechanisms were elucidated and effective activation energy of crystallization for the first crystal which precipitates from melt was determined.

Polymer Bulletin, Jun 3, 2008

... τactual = ) (2 nR L PR + Δ = ) /(2nRL P + Δ (3) where n is a multiplication factor according ... more ... τactual = ) (2 nR L PR + Δ = ) /(2nRL P + Δ (3) where n is a multiplication factor according to theBagley correction; and the actual shear rate γactual is defined as actual . ... Sci. 60:1736 5. Sinthavathavorn W, Nithanakul M , Magaraphan R, Grady BP (2007) J. Appl.Polym. Sci. ...

Journal of Applied Polymer Science, 2003

The effect of methyl acrylate content in ethylene-methyl acrylate-acrylic acid (E-MA-AA) terpolym... more The effect of methyl acrylate content in ethylene-methyl acrylate-acrylic acid (E-MA-AA) terpolymers and acrylic acid content in ethylene-acrylic acid (E-AA) copolymers was investigated in blends of these two materials. The E-MA-AA terpolymer with 8 mol % methyl acrylate was not miscible with any E-AA material no matter what the AA content, whereas the terpolymer with only about 2 mol % methyl acrylate was miscible, at least to some extent, with the E-AA copolymer at high acrylic acid contents. Evidence supporting this conclusion derived from gloss, differential scanning calorimetry testing, and dynamic mechanical measurements. For the E-AA polymer material with the highest acid content, there was a synergistic effect for some properties at low added amounts of E-MA-AA copolymer; the tensile strength and hardness were 10% higher than values for the E-AA copolymer, even though the E-AA copolymer was much stiffer.

Polymer Bulletin, Mar 14, 2009

... Plast Polym 41:39–43 4. Bagley EB (1961) The separation of elastic and viscous effects in pol... more ... Plast Polym 41:39–43 4. Bagley EB (1961) The separation of elastic and viscous effects in polymer flow. ... Sinthavathavorn W, Nithitanakul M, Magaraphan R, Grady BP (2008) Blends of polyamide 6 with low-density polyethylene compatibilized with ethylenemethacrylic acid ...

Public reporting burden for the collection of information is estimated to average 1 hour per resp... more Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

Journal of Applied Polymer Science, 2006

A high-density polyethylene with grafted maleic anhydride units has been investigated as a compat... more A high-density polyethylene with grafted maleic anhydride units has been investigated as a compatibilizer for high-density polyethylene with polyamide 6. The material acts as an effective compatibilizer, causing a marked reduction in dispersed phase size as well as an increase in tensile strength and toughness. Compatibilizer also affects the glass-transition temperature, crystallization kinetics, and amount of crystalline material for certain blend compositions. The addition of zinc cations, which are effective in increasing ethylene-acid copolymer compatibilizer performance in low-density polyethylene/polyamide blends, has little, if any, effect on compatibilizer performance in these high-density polyethylene/polyamide blends.

Colloid and Polymer Science, 2017

Poly(D,L-lactide-co-glycolide) (PLGA) with encapsulated hydrophobic magnetite (Fe3O4) nanoparticl... more Poly(D,L-lactide-co-glycolide) (PLGA) with encapsulated hydrophobic magnetite (Fe3O4) nanoparticles or hydroxyapatite (HAp) nanoparticles were prepared by the w/o/w emulsion technique. The weight ratios of nanoparticles (Fe3O4 or HAp) to PLGA and polymer molecular weight were varied in the oil phase and the properties of the composite nanoparticles were studied. The final weight percent of nanoparticles in the spherical PLGA particles varied from ~ 5 to 60 wt%. Hydrodynamic diameters of the composite nanoparticles as measured by dynamic light scattering (DLS) were found to decrease with decreasing polymer molecular weight and were independent of nanoparticle loading. Particle sizes measured from TEM were smaller by almost a factor of two vs. those obtained from DLS. The zeta potentials of the particles were about − 23 mV, independent of polymer molecular weight and nanoparticle loading within statistical significance. In vitro cytotoxicity tests show a high level of cytocompatibility suggesting satisfactory biocompatibility for biomedical applications.

$Research paper thumbnail of Pseudosolid, shear-thinning gel formation in binary dispersions of metal oxide nanoparticles at low volume fractions$

Langmuir : the ACS journal of surfaces and colloids, Jan 16, 2014

Hydroxyl groups on the surface of metal oxide nanoparticles (nps) can be protonated or deprotonat... more Hydroxyl groups on the surface of metal oxide nanoparticles (nps) can be protonated or deprotonated depending on solution pH, changing both the magnitude and sign of the nps' surface charge. Binary mixtures of fumed metal oxide nps, dispersed in water at a solution pH where one species is positively charged and the other is negatively charged, form pseudosolid gels at volume fractions as low as 1.5 vol %. This work maps out regions of gel formation for binary mixtures of silica and alumina nps, silica and titania nps, and alumina and titania nps. The microscopic structure of these gels is investigated using transmission electron microscopy (TEM), small-angle x-ray scattering (SAXS), acoustic spectroscopy, and light microscopy.

Otology & Neurotology, 2013

Hypothesis-Magnetically susceptible PLGA nanoparticles will effectively target the round window m... more Hypothesis-Magnetically susceptible PLGA nanoparticles will effectively target the round window membrane (RWM) for delivery of dexamethasone-acetate (Dex-Ac) to the scala tympani. Background-Targeted delivery of therapeutics to specific tissues can be accomplished using different targeting mechanisms. One technology includes iron oxide nanoparticles, susceptible to external magnetic fields. If a nanocomposite composed of biocompatible polymer (PLGA), magnetite, and Dex-Ac can be pulled into and across the mammalian RWM, drug delivery can be enhanced. Method-In vitro targeting and release kinetics of PLGA-magnetite-Dex-Ac nanoparticles first were measured using a RWM model. Next, these optimized nanocomposites were targeted to the RWM by filling the niche in anesthetized guinea pigs. A permanent magnet was placed opposite the RWM for 1 hour. Cochlear soft tissues, perilymph, and RWM were harvested after euthanasia and steroid levels were measured using HPLC. Results-Membrane transport, in vitro, proved optimal targeting using a lower particle magnetite concentration (1 versus 5 or 10 mg/ml). In vivo targeted PLGA-magnetite-Dex-Ac particles had an average size of 482.8 ± 158 nm (DLS) and an average zeta potential −19.9 ± 3.3 mV. In 1 hour, there was significantly increased cochlear targeted delivery of Dex or Dex-Ac, compared with diffusion alone. Conclusion-Superparamagnetic PLGA-magnetite-Dex-Ac nanoparticles under an external magnetic field (0.26 mT) for 1 hour significantly increased Dex-Ac delivery to the inner ear. The RWM was not completely permeated and also became loaded with nanocomposites, indicating that delivery to the cochlea would continue for weeks by PLGA degradation and passive diffusion.

Journal of Nanoparticle Research, 2010

3,5-Bis(2-fluorobenzylidene)-4-piperidone (EF24) is an anti-proliferative diphenyldifluoroketone ... more 3,5-Bis(2-fluorobenzylidene)-4-piperidone (EF24) is an anti-proliferative diphenyldifluoroketone analog of curcumin with more potent activity. The authors describe a liposome preparation of EF24 using a "drug-in-CD-in liposome" approach. An aqueous solution of EF24 and hydroxypropyl-β-cyclodextrin (HPβCD) inclusion complex (IC) was used to prepare EF24 liposomes. The liposome size was reduced by a combination of multiple freeze-thaw cycles. Coencapsulation of glutathione inside the liposomes conferred them with the capability of labeling with imageable radionuclide Tc-99m. Phase solubility analysis of EF24-HPβCD mixture provided k 1:1 value of 9.9 M −1. The enhanced aqueous solubility of EF24 (from 1.64 to 13.8 mg/mL) due to the presence of HPβCD helped in the liposome preparation. About 19% of the EF24 IC was encapsulated inside the liposomes (320.5 ± 2.6 nm) by dehydration-rehydration technique. With extrusion technique, the size of 177 ± 6.5 nm was obtained without any effect on encapsulation efficiency. The EF24-liposomes were evaluated for anti-proliferative activity in lung adenocarcinoma H441 and prostate cancer PC-3 cells. The EF24-liposomes demonstrated antiproliferative activity superior to that of plain EF24 at 10 μM dose. When injected in rats, the Tc-99m-labeled EF24-liposomes cleared from blood with an α-t 1/2 of 21.4 min and β-t 1/2 of 397 min. Tissue radioactivity counting upon necropsy showed that the majority of clearance was due to the uptake in liver and spleen. The results suggest that using "drug-in-CD-in liposome" approach is a feasible strategy to formulate an effective parenteral preparation of EF24. In vitro

Langmuir, 2019

Rheological properties of the solution of an extended surfactant, a sodium alkoxy sulfate (C 8-(P... more Rheological properties of the solution of an extended surfactant, a sodium alkoxy sulfate (C 8-(PO) 4-(EO) 1-SO Na), are investigated as a function of the presence of various paraffinic oils over a range of salt conditions in the Winsor III microemulsion region, at oil fractions where the microemulsion is "oil-starved". The addition of as small as 3 vol% alkane to 2 wt% surfactant solutions at salt concentrations where the oil-water interfacial tension is minimized induces a sudden shift in rheological behavior. The solution viscosity increases by 5 orders of magnitude, with solid-like behaviors (G′ > G′′) being observed in the entire frequency region investigated (0.01-100 rad/s). Commonly, in the cases where wormlike micelles are present in the solution, alkanes are believed to be solubilized in the core of micelles, leading to a radial growth of the cylindrical part of the wormlike micelle, resulting in a drop of end-cap energy (E C) and micelle length, and a reduction in viscosity. In this study, however, the addition of oil causes the formation of wormlike micelles. The viscosity of solubilized-oil samples does however decrease with an increase of incorporated oil volume. We hypothesize that this "abnormal oleo-responsive" viscoelastic behavior is related to a spacer of intermediate hydrophilicity, i.e., polypropylene oxide (PO) segment of the alkoxy sulfate, being inserted between the hydrophobic tail and hydrophilic head (the ethoxylated sulfate segment) of the extended surfactant. The addition of a small amount oil likely extends the PO moiety and increases the tail length of the surfactant in the aggregates as well as reducing the head group size, driving the formation of wormlike micelles from a solution that initially had a viscosity consistent with the absence of such structures.

Journal of Colloid and Interface Science, 2020

Hypothesis Confinement causes a change in the amount of surfactant adsorbed and adsorption morpho... more Hypothesis Confinement causes a change in the amount of surfactant adsorbed and adsorption morphology. Experiments Two cationic surfactants, tetradecyltrimethylammonium bromide (TTAB) and cetylpyridinium chloride (CPC) were adsorbed at the silica-water interface. Atomic force microscopy (AFM) force curves were measured on 50 nm and 80 nm wide trenches. Force curves were also measured on silica pillars, and the results were quantified based on distance from the edge. Findings Trenches: Adsorbed surfactants films in 50 nm and 80 nm trenches showed the same breakthrough values. However, compared to unconfined values, TTAB in trenches had decreased breakthrough and adhesion forces while CPC in trenches had increased breakthrough and adhesion forces, indicating that surfactant identity varies the confinement effect. Pillars: Near the edge, few surfactants adsorb, and those that do stretch in the direction normal to the surface. While the experimental data agree qualitatively with previous coarse-grained molecular dynamic simulations, the length scales at which the phenomena are detected differ by ~ half-order of magnitude. Specifically, experimental data show measurable effects on adsorbed surfactant morphology at a distance from the edge 10-20 times the length of a surfactant molecule after accounting for the ~8 nm size of the probe.

Journal of Surfactants and Detergents, 2019

The effects of temperature and surface roughness on the mass and viscoelasticity of an adsorbed s... more The effects of temperature and surface roughness on the mass and viscoelasticity of an adsorbed surfactant layer were monitored using the quartz crystal microbalance with dissipation monitoring (QCM-D). Adsorption isotherms at 30, 40, 50 and 60C and at two different roughnesses on gold were measured for cetyltrimethylammonium bromide (CTAB). All isotherms displayed an increase in mass and dissipation as surfactant concentration was increased to its critical micelle concentration (CMC). Above the CMC adsorption reached a peak followed by a slight decrease to a plateau at the equilibrium adsorption value. As the temperature was increased the adsorbed mass above the CMC decreased. The adsorbed mass decreased further by increasing substrate roughness, while the dissipation remained unchanged within experimental uncertainty. Dynamic adsorption experiments were also conducted at various temperatures for select concentrations above and below the CMC, providing evidence of the importance of different adsorption mechanisms as a function of both surfactant concentration and surface roughness.

Nanoscale, Jan 31, 2017

The effect of simultaneous alignment of polyethylene (PE) lamellae and graphene nanoplatelets (Gn... more The effect of simultaneous alignment of polyethylene (PE) lamellae and graphene nanoplatelets (GnP) on the thermal conductivity (k) of PE-GnP composites is investigated. Measurements reveal a large increase of 1100% in k of the aligned PE-GnP composite using 10 wt% GnPs relative to unoriented pure PE. The rate of increase of k with applied strain for the pure PE-GnP composite with 10 wt% GnP is found to be almost a factor of two higher than the pure PE sample, pointing to the beneficial effect of GnP alignment on k enhancement. Aligned GnPs are further found to be 3 times as effective in enhancing k as in the randomly oriented configuration. Enhancement in k is correlated with the alignment of PE lamellae and GnPs through wide-angle X-ray scattering and polarized Raman spectroscopy. At the maximum applied strain of 400% and using 10 wt% GnPs, a composite k of 5.9 W mK(-1) is achieved. These results demonstrate the great potential of simultaneous alignment effects in achieving high k...

Industrial & Engineering Chemistry Research, 2015

Recent interest in the use of nanoparticles in emulsion stabilization has driven increased effort... more Recent interest in the use of nanoparticles in emulsion stabilization has driven increased efforts to understand how the characteristics of the particles influence emulsion properties. While it is clear that contact angle and wettability must play significant roles in determining the type of emulsion formed, it is not straightforward to measure the contact angle of a nanoparticle. In this paper we compare multiple techniques for characterizing the water-air contact angle of silica nanoparticles while systematically varying the hydrophobicity of the nanoparticles using silanization. We then compare the performance of the particles in decane/water emulsions. While the heat of immersion measured by microcalorimetry is found to provide the best method for discriminating between the wettability of the particles, the fraction of surface covered by the silane groups was observed to affect the structure of the emulsion more profoundly than the differences in the contact angles of the particles. Furthermore, we find that the phase of initial dispersion is extremely influential in determining the resulting emultion type and droplet size.

Journal of Surfactants and Detergents, 2002