Papers by Keyword: Caprolactam

Abstract: Process speed in pultrusion is significantly influenced by the exothermic reactions of the matrix materials used. The main reaction zone (gel zone) is a key indicator to describe and interpret the reaction behavior in pultrusion. It can be easily observed by elevated temperatures in the die, particularly for highly exothermic thermoset matrices like vinyl ester, epoxy, and polyurethane. However, this effect is not as pronounced in reactive thermoplastics. The exothermic reactions contribute to a reduction in power consumption of the heating plates within the different heating zones, each with its individual temperature. Analyzing the power consumption of the individual heating zones across different process parameter settings allows to determine the position of the gel zone. This information is foundational for pultrusion process optimization, as it allows for more efficient utilization of the die length, ultimately increasing the pull speeds and enabling higher production rates. In this study, a comparative analysis of the power consumption across the heating zones was performed. To validate the findings obtained from the power measurements, thermocouples were drawn through the die at the same process parameters to accurately measure the temperature evolution within the pultruded profile throughout the die length.

Abstract: Two core-shell structure poly methyl methacrylate-caprolactam (PMMA-CPL) and poly methyl methacrylate-caprolactam-sericin (PMMA-CPL-SS) nanoparticles were synthesized by emulsion polymerization. A latex blending process was performed on preparation of natural rubber (NR) blends, NR/PMMA-CPL and NR/PMMA-CPL-SS. Transmission electron microscopy (TEM) images showed that PMMA-CPL and PMMA-CPL-SS nanoparticles covering on the surface of NR particles homogeneously. SEM, AFM, ATR-FTIR and DSC were used to compare the difference between NR/PMMA-CPL-SS and NR/PMMA-CPL. The results showed that addition of SS improved the smoothness and reduced the amount of incompatible particles on the surface of NR/PMMA-CPL-SS film. Due to the introduction of CPL and SS, the number of escaping particles on the surface of NR was decreased during film forming process and the Tg of NR shifted to a higher temperature. The results indicated that the interfacial adhesion and compatibility of PMMA and NR were improved. Mechanical testing showed that PMMA-CPL nanoparticles could improve the mechanical property of NR. When the content of PMMA-CPL-SS was 10%, the tensile strength of NR/PMMA-CPL-SS film was increased by 19.6% compared to NR/PMMA-CPL. Moreover, the NR/PMMA-CPL-SS film exhibited a higher hydrophilic property after modification with PMMA-CPL-SS nanoparticles.

Abstract: This paper describes tensile properties, and morphology analysis of different composition of RHDPE and EVA blends were studied. The main goals are to describe the effect of Caprolactam as compatibilizer used to improve the compatibility between RHDPE and EVA. The RHDPE/EVA blends were prepared at 160°C and the rotor speed of 50rpm in an internal mixer. The tensile strength for RHDPE/EVA blends increased, while adding Caprolactam by 6phr in the blend formulation significantly improved the tensile properties. The SEM micrograph show a better interfacial adhesion between RHDPE and EVA phases for RHDEP/EVA/Caprolactam blends than RHDPE/EVA blends.

Abstract: Three rare earth complexes of (Eu (C₆H₁₁NO)₈, La_0.6Eu_0.4(C₆H₁₁NO)₆ , Tb_0.5Eu_0.5(C₆H₁₁NO)₆(H₂O)) were synthesized by solid-state method. The as-prepared complexes were characterized by elemental analysis, thermogravimetry-differential thermogravimetry-differential scanning calorimetry (TG-DTG-DSC), infrared (IR) spectra and fluorescence spectra. The results showed that complexed were prepared by the rare earth ions directly bonded to oxygen atoms of caprolactam ligand and emitted a characteristic fluorescence of the Eu^{3 +}or Tb³⁺ ions.

Abstract: Through the polymerization and grafting reaction of bisphenol A dianhydride and bisphenol A diamine, the polyimide activator (PI activator) of acyl caprolactam end capping is obtained and then the anionic in-situ polymerization modified nylon 6 resin is obtained. Viscosity analysis shows that PI consumption is higher than 0.1 (of monomer mass), the reaction temperature is higher than 160°C, the viscosity rises rapidly in a short time and the rapid polymerization molding can be realized; when PI consumption is higher than 0.15 (of monomer mass), the water absorption of matrix resin will be lower than 1.4%; compared with the nylon resin, its water absorption is significantly lowered and its mechanical property is improved greatly; microscopic analysis shows that PI molecules fail to enter the crystalline phase of the nylon 6 and form lamellar crystals in the nylon matrix, which plays a role of enhancement and obstruction; differential thermal analysis shows that PI reduces the melting enthalpy and melting point temperature of nylon 6 resin, which indicates that PI reduces the crystallization capacity of nylon 6.

Abstract: The effects of mole ratio of formaldehyde and melamine (F/M), solution pH, reaction temperature and time on the foaming melamine-formaldehyde resin (MF resin) with caprolactam as modifier were investigated by orthogonal experiment design where the solid content and the viscosity of the resin, the density and the size uniformity of the foam resin were used as performance evaluation parameters. The results had shown that the optimal conditions for preparing the foaming MF resin were F/M= 3.25, pH=8.0, T=90°C, t=45min. The MF resin prepared under the optimal conditions could be foamed well and its storage time was prolonged to 16 days. The structure and thermal properties of MF resin under the optimal conditions were investigated.

Abstract: Kinetic parameters are calculated based on the reactive temperature rise curve measured by adiabatic approach at the temperature of 145 to 160 °C with the catalytic system of NaOH and acyl caprolactam End-capped butadiene-acrylonitrile rubber (CHTBN) or styrene-butadiene rubber (CHTBS). The reaction order is first order, the activation energy is between 72.91−73.16 kJ∙mol⁻¹ and the pre-exponential factor is between 3.22×10¹¹− 3.38×10¹¹ mol¹⁻ⁿ∙s⁻¹ in the system of CHTBN/NaOH. While in CHTBS/NaOH, the reaction order is between 1.23-1.34, the activation energy is between 85.55－86.88 kJ∙mol⁻¹ and the pre-exponential factor is between 4.52×10¹¹−5.0 9×10¹¹ mol¹⁻ⁿ∙s⁻¹. The adiabatic reaction kinetic model of caprolactam anion was constructed based on the existing research findings, by which the polymerizing reaction is simulated. The coincidence between the simulation results and the experimental data revealed that the model is reasonable and correct.

Abstract: Kinetic parameters were calculated based on the catalytic reaction systems of sodium caprolactam salt、N-75 biuret and at the temperature of 145 to 160 °C. The reaction order was approximately first order. The activation energy was between 73.2−77.1 kJ∙mol⁻¹ and the pre-exponential factor was between 2.9×10¹¹−3.6×10¹¹ mol¹⁻ⁿ∙s⁻¹. The calculated reaction heat of 134.5−137.3 J∙g⁻¹ was in consonance with the literature value of 138.6 J∙g⁻¹. The adiabatic reaction kinetic model of caprolactam anion was constructed based on the existing research findings. The coincidence between the simulation results and the experimental data revealed that the model was reasonable and correct.

Abstract: The effect of caprolactam as a coupling agent on the tensile properties, swelling behavior and morphology analysis of recycled high density polyethylene/ natural rubber/ chicken feather fiber (R-HDPE/ NR/ CFF) composites was studied. The R-HDPE/NR/CFF composites with and without caprolactam were prepared using Brabender Plasticorder at 160°C and rotor speed of 50 rpm. The results indicated that R-HDPE/NR/CFF with caprolactam showed higher value of tensile strength but lower elongation at break and mass swell percentage than R-HDPE/NR/CFF composites. SEM morphology showed that the addition of caprolactam improved the fiber matrix-interfacial adhesion and good dispersion of the fiber in the R-HDPE/NR blends.

Abstract: Caprolactam recovery from waste water is an important and challenging problem in industry. In comparison with extraction columns widely applied in the recovery of caprolactam, annular centrifugal contactor is featured by compact structure, convenient maintenance, and high throughput and efficiency with low energy consumption, etc., which have a wide application in industry. The effects of flow ratio, radius of heavy phase weir and the rotational speeds on entrainment, separation capacity and mass transfer efficiency were studied with annular centrifugal contactors for caprolactam recovery. The results show that the caprolactam with 99.99% purity, the maximum separation capacity of 109L and the highest mass transfer efficiency of 99.8% were obtained.