“…The results reported by Aihara 13 agree well with the those of the present investigation for temperatures below 300 K; however, at higher temperatures the deviations of those results from the presently obtained ones increase up to 15 %. 3 Deviation of the experimental vapor pressure data for liquid caprolactam from the values predicted by eq 7: +, transpiration method data; ◇, data from ref ; □, data from ref ; open triangle pointing right, data from ref . The data from refs −17 are not presented because of their enormous deviation from the most reliable results. 4 Conformers of ε-caprolactam.…”
Section: Resultsmentioning
confidence: 99%
“…Deviation of the experimental vapor pressure data for liquid caprolactam from the values predicted by eq 7: +, transpiration method data; ◇, data from ref ; □, data from ref ; open triangle pointing right, data from ref . The data from refs −17 are not presented because of their enormous deviation from the most reliable results.…”
Section: Resultsmentioning
confidence: 99%
“…The vapor pressures of crystalline caprolactam were determined earlier by Aihara 13 and the vapor pressures of the liquid phase were determined by several authors [14][15][16][17][18][19] (Figure 3). The results reported by Aihara 13 agree well with the those of the present investigation for temperatures below 300 K; however, at higher temperatures the deviations of those results from the presently obtained ones increase up to 15 %.…”
The vapor pressure for crystalline -caprolactam (CAS Registry No. 105602) was measured by the Knudsen method in the temperature range (293 to 338) K with a modified effusion cell with enlarged sublimation surface and by the transpiration method between T ) (302 and 339) K. The latter method was also used to measure the vapor pressures of the liquid phase between T ) (345 and 373) K. The thermodynamic parameters of sublimation and of vaporization and the standard entropy of caprolactam in the ideal gas state were estimated from the obtained data. Calculations of the thermodynamic properties of caprolactam in the ideal gas state were carried out based on the molecular data and the results obtained by DFT (B3LYP/6-311G*) quantum-mechanical calculations. The experimental and calculated values of the entropy of gaseous caprolactam agree with each other within 0.2 % at 298 K.
“…The results reported by Aihara 13 agree well with the those of the present investigation for temperatures below 300 K; however, at higher temperatures the deviations of those results from the presently obtained ones increase up to 15 %. 3 Deviation of the experimental vapor pressure data for liquid caprolactam from the values predicted by eq 7: +, transpiration method data; ◇, data from ref ; □, data from ref ; open triangle pointing right, data from ref . The data from refs −17 are not presented because of their enormous deviation from the most reliable results. 4 Conformers of ε-caprolactam.…”
Section: Resultsmentioning
confidence: 99%
“…Deviation of the experimental vapor pressure data for liquid caprolactam from the values predicted by eq 7: +, transpiration method data; ◇, data from ref ; □, data from ref ; open triangle pointing right, data from ref . The data from refs −17 are not presented because of their enormous deviation from the most reliable results.…”
Section: Resultsmentioning
confidence: 99%
“…The vapor pressures of crystalline caprolactam were determined earlier by Aihara 13 and the vapor pressures of the liquid phase were determined by several authors [14][15][16][17][18][19] (Figure 3). The results reported by Aihara 13 agree well with the those of the present investigation for temperatures below 300 K; however, at higher temperatures the deviations of those results from the presently obtained ones increase up to 15 %.…”
The vapor pressure for crystalline -caprolactam (CAS Registry No. 105602) was measured by the Knudsen method in the temperature range (293 to 338) K with a modified effusion cell with enlarged sublimation surface and by the transpiration method between T ) (302 and 339) K. The latter method was also used to measure the vapor pressures of the liquid phase between T ) (345 and 373) K. The thermodynamic parameters of sublimation and of vaporization and the standard entropy of caprolactam in the ideal gas state were estimated from the obtained data. Calculations of the thermodynamic properties of caprolactam in the ideal gas state were carried out based on the molecular data and the results obtained by DFT (B3LYP/6-311G*) quantum-mechanical calculations. The experimental and calculated values of the entropy of gaseous caprolactam agree with each other within 0.2 % at 298 K.
Nylon-6 is a commonly produced plastic that has found a wide range of applications in carpets, textiles, electronics, and automotive parts. Chemical depolymerization to form the nylon-6 monomer caprolactam (CL) has been practiced to recover oligomers and postindustrial nylon-6 waste. There is a growing interest in developing and improving processes for closed-loop recycling of postconsumer nylon-6 waste. This work presents a comprehensive assessment of the three primary types of nylon-6 depolymerization processes: liquid-phase hydrolysis, steam stripping, and solvent-free depolymerization. This study is unique in providing a thorough assessment of both the academic literature and industrial patents. We develop depolymerization kinetic models and suggest further experimental measurements for determining reaction mechanisms and discuss industrial practice of crude CL purification methodologies and waste management strategies. We develop for the first time detailed Aspen Plus simulation models incorporating thermodynamic and kinetic modeling, impurity separation, product purification, and waste minimization to provide the quantitative foundation for sustainable design of all three types of depolymerization processes. We identify where there are uncertainties in design and modeling and where gaps in data currently exist. Finally, we implement heat integration and process intensification to reduce utility demand and CO 2 emission, enhance the sustainable design, and provide quantitative comparison of depolymerization process options in terms of energy demands and CO 2 emission, among others.
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