Robert A. Sailer

Moisture-curing alkoxysilane-functionalized isocyanurate coatings

An amilnosilane functionalzed isocyanurate of 1,6-hexamethylene diisocyanate (HDI isocyanurate) was used to formulate coatings. The coatings were formulated using a mixture of the silane-functionalized isocyanurate and the unfunctionalized HDI isocyanurate. The general coating properties and tensile properties were evaluated as a function of alkoxysilane modified isocyanurate. In addition, the thermo-machanical and rheological properties of the films were also investigated. The moisture-curing process was investigated using FT-IR and NMR. The results indicates that alkoxysilane-functionalized isocyanurate dramatically enhances the adhesion and increases the crosslink density.

Cobalt ferrite nanoparticles: Achieving the superparamagnetic limit by chemical reduction

An unanticipated superparamagnetic response has been observed in cobalt ferrite materials after thermal treatment under inert atmosphere. Cobalt ferrite particles were prepared via normal micelle precipitation that typically yields CoxFe3−xO4 nanoparticles (x=0.6−1.0). While samples thermally treated under oxygen show majority spinel phase formation, annealing in nitrogen gas yields materials consisting of Co-Fe alloy, FeS, and CoFe2O4 spinel. After thermal treatment, thermomagnetic studies reveal composition-insensitive, but highly treatment-sensitive, saturation magnetization, coercivity, blocking temperature, and Verwey transition temperature dependence. Extremely high saturation magnetization (159 emu/g) with low coercivity (31 Oe) was observed for one of the treated compositions, which drastically deviates from prototypical cobalt ferrite with large magnetocrystalline anisotropy. We attribute such unique magnetic response to Co-Fe alloy coexisting with FeS and CoFe2O4 spinel where the diameter of the...

Linseed and sunflower oil alkyd ceramers

Abstract New inorganic/organic hybrid coatings were prepared, using linseed and sunflower oil based alkyds with sol–gel precursors. Three sol–gel precursors, titanium (IV) i -propoxide (TIP), titanium di- i -propoxide, diacetylacetonate (TIA), and zirconium (IV) n -propoxide (ZRP), were used in this study. The goal of this study was to investigate the affects of the type of alkyd on the overall properties of the alkyd ceramer coating. Various coatings properties such as hardness, impact resistance, adhesion, tensile properties and flexibility were evaluated as a function of alkyd type and sol–gel precursor content. Thermal and mechanical properties were also investigated as a function of sol–gel precursor and alkyd type. Alkyd ceramers high in linolenic acid content produced harder, tougher films while maintaining the same degree of flexibility as the high linoleic acid alkyds. At low sol–gel precursor content, the tensile properties of both the sunflower and linseed oil based alkyd ceramers initially decreased. As the sol–gel content was increased, the tensile properties increased as a function of sol–gel content.

Oxidizing alkyd ceramers

New inorganic/organic hybrid coatings known as ceramers were prepared using an oxidizing alkyd. Three sol-gel precursors, titanium(IV)-i-propoxide (TIP), titanium diisopropoxide bis(acetylacetonate) (TIA), and zirconium(IV)-n-propoxide (ZRP) were evaluated as a function of weight percent. The goal of this study was to formulate ceramer coatings which could be cured on a commercially viable time schedule. Overall, coating properties were found to be dependent on the type and amount of sol-gel precursor. The sol-gel precursor was also found to interact with the drier used to cure the alkyd.

Atmospheric-pressure plasma-enhanced chemical vapor deposition of a-SiCN:H films: role of precursors on the film growth and properties.

Atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD) using Surfx Atomflow(TM) 250D APPJ was utilized to synthesize amorphous silicon carbonitride coatings using tetramethyldisilizane (TMDZ) and hexamethyldisilizane (HMDZ) as the single source precursors. The effect of precursor chemistry and substrate temperature (T(s)) on the properties of a-SiCN:H films were evaluated, while nitrogen was used as the reactive gas. Surface morphology of the films was evaluated using atomic force microscopy (AFM); chemical properties were determined using Fourier transform infrared spectroscopy (FTIR); thickness and optical properties were determined using spectroscopic ellipsometry and mechanical properties were determined using nanoindentation. In general, films deposited at substrate temperature (T(s)) < 200 °C contained organic moieties, while the films deposited at T(s) > 200 °C depicted strong Si-N and Si-CN absorption. Refractive indices (n) of the thin films showed values between 1.5 and 2.0, depending on the deposition parameters. Mechanical properties of the films determined using nanoindentation revealed that these films have hardness between 0.5 GPa and 15 GPa, depending on the T(s) value. AFM evaluation of the films showed high roughness (R(a)) values of 2-3 nm for the films grown at low T(s) (<250 °C) while the films grown at T(s) ≥ 300 °C exhibited atomically smooth surface with R(a) of ~0.5 nm. Based on the gas-phase (plasma) chemistry, precursor chemistry and the other experimental observations, a possible growth model that prevails in the AP-PECVD of a-SiCN:H thin films is proposed.

Fracture toughness of inorganic-organic hybrid coatings

The concepts of fracture toughness and the energy release rate at fracture for thin polymeric films are introduced. Fracture toughness and energy release rate data for ceramer films based on a linseed oil alkyd, a sunflower oil alkyd, and a commercial alkyd with titanium diisopropoxide bis(acetylacetonate), titanium(IV) isopropoxide, and zirconium(IV) propoxide are presented and compared to previously reported tensile data. Differences between the fracture data and the tensile data demonstrate the usefulness of fracture toughness testing. The energy release rate at fracture may be the one property to maximize in order to optimize all of the other coating properties. It may therefore be a great aid in the optimization of coating formulations. Data from dynamic mechanical thermal analysis indicate that there may be a correlation between fracture properties and secondary relaxation processes in the films.

Investigation of cobalt drier retardation

Abstract The retardation of cobalt driers was investigated using a commercial alkyd. The onset of curing and crosslink density of the alkyd was used to evaluate four cobalt complexes, Co(acac)2, Co(acac)3, Co(OH)2, and Co(NH3)6Cl3. The catalytic activity of these complexes were compared to cobalt naphthenate. Differential scanning calorimetry and dynamic mechanical thermal analysis data were used to determine acceleration or retardation of the autoxidation drying mechanism. The Co(acac)2 accelerates the process in comparison to Cobalt(II) naphthenate, whereas the three other complexes seem to retard the process.

Viscoelastic properties of alkyd ceramers

The viscoelastic behavior of three alkyd ceramers was studied using dynamic mechanical thermal analysis (DMTA). A commercial product was compared to model alkyds. The model alkyds were prepared from phthalic anhydride, glycerol, and linseed or sunflower seed oil. Three sol–gel precursors, titanium tetra-i-propoxide, titanium di-i-propoxide diacetylacetonate, and zirconium tera-n-propoxide were investigated. The alkyd ceramers were evaluated as a function of both alkyd type and a sol–gel precursor content. The viscoelastic data showed that both E′ and Tg were affected by sol–gel precursor content. Both the crosslink density and Tg demonstrated a minimum at low sol–gel precursor contents. After this minimum, both the crosslink density and the Tg increased substantially.

An investigation of the viability of UHF RFID for subsurface soil sensors

A study was performed to assess the viability of using ultra-high frequency (UHF) radio frequency identification (RFID) to communicate with subsurface sensors. The results showed that, when the reader operated near the FCC limit, read ranges for the sensorwere greater than a half meter for soil moisture levels of 15% by weight or less. Moisture levels at 15% or greater resulted in significant attenuation or complete loss of signal. Tags also had desireable read ranges for depths up to 15 cm.

Thin films by metal-organic precursor plasma spray

While most plasma spray routes to coatings utilize solids as the precursor feedstock, metal-organic precursor plasma spray (MOPPS) is an area that the authors have investigated recently as a novel route to thin film materials. Very thin films are possible via MOPPS and the technology offers the possibility of forming graded structures by metering the liquid feed. The current work employs metal-organic compounds that are liquids at standard temperature-pressure conditions. In addition, these complexes contain chemical functionality that allows straightforward thermolytic transformation to targeted phases of interest. Toward that end, aluminum 3,5-heptanedionate (Al(hd)3), triethylsilane (HSi(C2H5)3 or HSiEt3), and titanium tetrakisdiethylamide (Ti(N(C2H5)2)4 or Ti(NEt2)4) were employed as precursors to aluminum oxide, silicon carbide, and titanium nitride, respectively. In all instances, the liquids contain metal-heteroatom bonds envisioned to provide atomic concentrations of the appropriate reagents at th...