Thermodynamics of the Sublimation and of the Vaporization of ε-Caprolactam

Zaitsau, Dzmitry H.; Paulechka, Yauheni U.; Kabo, Gennady J.; Kolpikau, Aleh N.; Emel′yanenko, Vladimir N.; Heintz, Andreas; Verevkin, Sergey P.

doi:10.1021/je050277k

Cited by 25 publications

(22 citation statements)

References 20 publications

(40 reference statements)

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“…PA6 in general has an ∼1 wt % monomer in the final polymer and has a vapor pressure of ∼0.07 Torr at 60 °C and increases to ∼1.4 Torr at 100 °C. 30 At exposure temperatures below 100 °C, the outgassing of the caprolactam from the PA6 is minimal in comparison to H 2 O outgassing. At higher temperatures where the caprolactam outgassing is substantial, the effects on the materials growth may be dependent on the reaction affinity for TMA with the PA6 or the caprolactam.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Other unbound materials in the polymer, such as PA6 monomer (caprolactam, (CH 2 ) 5 C(O)NH), may also effect the hybrid formation. PA6 in general has an ∼1 wt % monomer in the final polymer and has a vapor pressure of ∼0.07 Torr at 60 °C and increases to ∼1.4 Torr at 100 °C . At exposure temperatures below 100 °C, the outgassing of the caprolactam from the PA6 is minimal in comparison to H 2 O outgassing.…”

Section: Resultsmentioning

confidence: 99%

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Temperature and Exposure Dependence of Hybrid Organic–Inorganic Layer Formation by Sequential Vapor Infiltration into Polymer Fibers

et al. 2012

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The characteristic processing behavior for growth of a conformal nanoscale hybrid organic-inorganic modification to polyamide 6 (PA6) by sequential vapor infiltration (SVI) is demonstrated. The SVI process is a materials growth technique by which exposure of organometallic vapors to a polymeric material promotes the formation of a hybrid organic-inorganic modification at the near surface region of the polymer. This work investigates the SVI exposure temperature and cycling times of sequential exposures of trimethylaluminum (TMA) on PA6 fiber mats. The result of TMA exposure is the preferential subsurface organic-inorganic growth by diffusion into the polymer and reaction with the carbonyl in PA6. Mass gain, infrared spectroscopy, and transmission electron microscopy analysis indicate enhanced materials growth and uniformity at lower processing temperatures. The inverse relationship between mass gain and exposure temperature is explained by the formation of a hybrid layer that prevents the diffusion of TMA into the polymer to react with the PA6 upon subsequent exposure cycles. As few as 10 SVI exposure cycles are observed to saturate the growth, yielding a modified thickness of ∼75 nm and mass increase of ∼14 wt %. Removal of the inherent PA6 moisture content reduces the mass gain by ∼4 wt % at low temperature exposures. The ability to understand the characteristic growth process is critical for the development of the hybrid materials fabrication and modification techniques.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Temperature and Exposure Dependence of Hybrid Organic–Inorganic Layer Formation by Sequential Vapor Infiltration into Polymer Fibers

et al. 2012

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“…Outgassing of the H 2 O and/or caprolactam during the TMA exposure may result in material growth that pushes NPs away from the polymer surface during growth. At 60 °C operating temperature, the vapor pressure of caprolactam is ∼0.07 Torr, 46 whereas the vapor pressure of H 2 O is ∼150 Torr. Therefore, the H 2 O is more likely to outgas from the PA-6 more than the caprolactam during processing, resulting in the preferential CVD growth of Al 2 O 3 near the surface.…”

Section: Resultsmentioning

confidence: 99%

Thermal Stability of Gold Nanoparticles Embedded within Metal Oxide Frameworks Fabricated by Hybrid Modifications onto Sacrificial Textile Templates

et al. 2015

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The stability and spatial separation of nanoparticles (NP's) is essential for employing their advantageous nanoscale properties. This work demonstrates the entrapment of gold NP's embedded in a porous inorganic matrix. Initially, gold NP's are decorated on fibrous nylon-6, which is used as an inexpensive sacrificial template. This is followed by inorganic modification using a novel single exposure cycle vapor phase technique resulting in distributed NP's embedded within a hybrid organic-inorganic matrix. The processing is extended to the synthesis of porous nanoflakes after calcination of the modified nylon-6 yielding a porous metal oxide framework surrounding the disconnected NP's with a surface area of 250 m(2)/g. A unique feature of this work is the use of a transmission electron microscope (TEM) equipped with an in situ annealing sample holder. The apparatus affords the opportunity to explore the underlying nanoscopic stability of NP's embedded in these frameworks in a single step. TEM analysis indicates thermal stability up to 670 °C and agglomeration characteristics thereafter. The vapor phase processes developed in this work will facilitate new complex NP/oxide materials useful for catalytic platforms.

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“…The vapor pressures were calculated using the following equation 3 : where p sat is the equilibrium vapor pressure of the substance; S samp is the geometric surface of the sample; S orif is the area of the effusion orifice; k is the transmission probability coefficient through the effusion orifice; α is the condensation coefficient; p * is the vapor pressure in the cell calculated as Δ m is the mass loss of the sample during the exposure time τ; T is the temperature of the heat carrier in the thermostat; and M is the molar mass of the substance (assumption that the vapor of ketol tends to be monomolecular has been made according to arguments given in the discussion below). The k coefficient was determined according to Wahlbeck's theory 3 as described in refs and . An effective diameter of ketol molecule σ = 7.214·10 -10 m was calculated from a van der Waals volume assuming the molecule to be spherical.…”

Section: Methodsmentioning

confidence: 99%

Thermodynamics of 2-(1‘-Hydroxycyclohexyl)cyclohexanone: Vaporization, Sublimation, and the Ideal Gas State Thermodynamic Properties

et al. 2006

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The thermodynamics of one of the byproducts of caprolactam production, 2-(1′-hydroxycyclohexyl)cyclohexanone (ketol), have been studied in this work. Saturated vapor pressure for liquid and crystalline ketol was measured by the Knudsen method in the temperature ranges from (308.2 to 330.4) K and from (289.6 to 300.8) K, respectively. Additionally, the saturated vapor pressures over ketol in the undercooled state and in the liquid were measured by the transpiration method in the temperature range from (287.9 to 303.0) K and from (308.0 to 351.5) K, respectively. The enthalpy of vaporization and the enthalpy of sublimation of ketol at the average temperatures studied were obtained indirectly from the temperature dependence of the vapor pressure measured by the Knudsen method as well as by the transpiration method. Furthermore, the standard molar enthalpy of sublimation was measured directly at 303.1 K using calorimetry. The entropy of ketol in the vapor state at (320.8 and 298.2) K was derived. The thermodynamic properties for 2-(1′-hydroxycyclohexyl)cyclohexanone in the ideal gas state were calculated from statistical mechanic calculations in the broad temperature range from (50 to 1000) K. The gaseous thermodynamic equilibrium constant K°(at 332.1 K) for cyclohexanone auto-condensation (side reaction of the caprolactam production) leading to 2-(1′-hydroxycyclohexyl)cyclohexanone was assessed.

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Thermodynamics of the Sublimation and of the Vaporization of ε-Caprolactam

Cited by 25 publications

References 20 publications

Temperature and Exposure Dependence of Hybrid Organic–Inorganic Layer Formation by Sequential Vapor Infiltration into Polymer Fibers

Temperature and Exposure Dependence of Hybrid Organic–Inorganic Layer Formation by Sequential Vapor Infiltration into Polymer Fibers

Thermal Stability of Gold Nanoparticles Embedded within Metal Oxide Frameworks Fabricated by Hybrid Modifications onto Sacrificial Textile Templates

Thermodynamics of 2-(1‘-Hydroxycyclohexyl)cyclohexanone: Vaporization, Sublimation, and the Ideal Gas State Thermodynamic Properties

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