Synergistic Flame Retardant Effect between Ionic Liquid Functionalized Imogolite Nanotubes and Ammonium Polyphosphate in Epoxy Resin.

Ionic liquid functionalized imogolite nanotubes (INTs-PF6-ILs) were introduced into the epoxy resin (EP)/ammonium polyphosphate (APP) system to investigate the flame retardant performance and thermal properties using the limiting oxygen index (LOI) test, the UL-94 test, and the cone calorimeter test (CCT). The results suggested that a synergistic effect exists between INTs-PF6-ILs and APP on the char formation and anti-dripping behavior of EP composites. For the EP/APP, an UL-94 V-1 rating was obtained for the loading of 4 wt% APP. However, the composites containing 3.7 wt% APP and 0.3 wt% INTs-PF6-ILs could pass the UL-94 V-0 rating without dripping behavior. In addition, compared with the EP/APP composite, the fire performance index (FPI) value and fire spread index (FSI) value of EP/APP/INTs-PF6-ILs composites were remarkably reduced by 11.4% and 21.1%, respectively. Moreover, the char formed by EP/APP composites was intumescent, but of poor quality. In contrast, the char for EP/APP/INTs-PF6-ILs was strong and compact. Therefore, it can resist the erosion due to heat and gas formation and protect the inside of the matrix. This was the main reason for the good flame retardant property of EP/APP/INTs-PF6-ILs composites.

Synergistic Flame Retardant Effect between Ionic Liquid-Functionalized Imogolite Nanotubes and Ammonium Polyphosphate in Unsaturated Polyester Resin.

Imogolite nanotubes (INTs) were synthesized from tetraethoxysilane, aluminum nitrate nonahydrate, and ammonia solution by the method of Arancibia-Miranda, and their dispersion was modified by 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) to obtain ionic liquid (IL)-functionalized INTs (INTs-PF6-ILs). Then, the flame retardant INTs-PF6-ILs was complexed with ammonium polyphosphate (APP) and applied to unsaturated polyester resin (UPR). The limiting oxygen index value and the UL-94 level of the UPR/APP/INTs-PF6-ILs composites reached 28 and V-0, respectively. The residual carbon of the composites in thermogravimetric analysis increased by 19.47%, compared with that of pure UPR. The cone calorimeter test result showed that the peak of heat release rate and total heat rate values of the UPR/APP/INTs-PF6-ILs composites were lowered by 41 and 34% than those of the pure UPR, respectively. The effect of heat combustion and the maximum mass loss rate of UPR/APP/INTs-PF6-ILs composites were also greatly decreased. There were no holes or folds observed on the surface of the UPR/APP/INTs-PF6-ILs composites' residual carbon in scanning electron microscopy images. The intact residual carbon could have effectively insulated the heat and oxygen to improve the flame retardant performance.

Remediation of diesel-contaminated soil by alkoxyethanol aqueous two-phase system.

The increasing diesel pollution accidents pose a serious threat to the ecological environment and human health. Remediation of diesel-contaminated soil (DCS) has attracted widespread attention during the past few decades. This work proposed an approach for the remediation of DCS by alkoxyethanol aqueous two-phase extraction (ATPE), which was an application of this small molecule aqueous two-phase system (ATPS). In addition, the influence of temperature, stirring speed, stirring time, and solid-liquid ratio on the removal of diesel was explored respectively. The removal efficiency of diesel could reach more than 97.18% in 18 min. Meanwhile, ATPS had high reusability, and the removal efficiency remained above 85.17% in the reuse process. Alkoxyethanol ATPE could effectively remove diesel hydrocarbons with different carbon chain lengths and the remediation process hardly caused residual organic solvents on the soil surface according to the analysis of gas chromatography-mass spectrometry (GC-MS) and Fourier transforms infrared (FT-IR), which could be regarded as the distinct advantage compared to the traditional surfactant washing method and organic solvent extraction method. The study of soil physicochemical properties and wheat germination proved that the soil structure and properties changed little after ATPE remediation. And finally, the mechanism of alkoxyethanol ATPE was intensively discussed according to the remediation characteristic. This work provided an efficient method for the remediation of DCS and widened the application fields of alkoxyethanol ATPS as well.

Flame Retardancy and Thermal Behavior of an Unsaturated Polyester Modified with Kaolinite-Urea Intercalation Complexes.

Organic modified kaolinite-urea intercalation complex (KUIC) was prepared using dimethyl sulfoxide (DMSO) as the precursor of kaolinite intercalation. Its structure was characterized by Fourier transform infrared (FTIR) and X-ray diffraction (XRD). Subsequently, as a synergistic agent, KUIC was combined with flame retardant ammonium polyphosphate (APP) to improve the flame retardant and smoke suppression performance of unsaturated polyester (UP) resin. A cone calorimeter (CONE) was used to study its flame retardancy and smoke suppression, and a scanning electron microscope (SEM) and thermogravimetry (TG) were used to study the micro morphology of the char and flame retardant mechanism. The results show that 12 phr of APP and 3 phr of KUIC were doped into UP to obtain a 28.0% limiting oxygen index (LOI) value. Compared with UP, the heat release rate and smoke production of UP/APP/KUIC composites were greatly decreased. Meanwhile, KUIC indeed enhanced the mechanical properties of UP.

Effect of combined spinal-epidural analgesia in labor on frequency of emergency cesarean delivery among nulliparous Chinese women.

OBJECTIVE: To determine whether combined spinal-epidural analgesia (CSEA) during labor increases the frequency of emergency cesarean delivery among Chinese nulliparous women. METHODS: In a retrospective study, the medical records of nulliparous women with a singleton fetus in cephalic presentation who delivered at term at Tongling Maternity Hospital, China, between January 2012 and December 2014 were reviewed. Information about CSEA, mode of delivery, labor duration, oxytocin augmentation, and neonatal outcome was obtained. Logistic regression was used to examine independent associations between CSEA and emergency cesarean after controlling for confounding variables. RESULTS: Among 3456 women included, 1786 (51.7%) received CSEA and 1670 (48.3%) received no labor analgesia. Emergency cesarean was more frequent among CSEA users (219/1786 [12.3%]) than non-users (119/1670 [7.1%]; P<0.001). Among the maternal-fetal variables included in multivariate regression, maternal age, maternal height, cervical dilatation at admission, birth weight, and CSEA use were significantly associated with emergency cesarean. After adjustment, women with CSEA maintained a slightly increased risk for cesarean (adjusted odds ratio 1.54, 95% confidence interval 1.20-2.00). CONCLUSION: Among Chinese nulliparous women, use of CSEA for labor pain was associated with an increased risk of emergency cesarean delivery; moreover, this effect was maintained after adjustment for other potential obstetric risk factors.