Melt-dripping is always a big chanllenge in flame retardant finishing of synthetic fabrics. In this work, vinyltrimethoxysilane（VTMS） was introduced onto the polyamide66（PA66） surface by microwave grafting to impr...Melt-dripping is always a big chanllenge in flame retardant finishing of synthetic fabrics. In this work, vinyltrimethoxysilane（VTMS） was introduced onto the polyamide66（PA66） surface by microwave grafting to improve the fire performance. The chemical structure of the grafted fabric was characterized by attenuated total reflection Fourier transformation infrared spectroscopy（ATR-FTIR） and X-ray photoelectron spectroscopy（XPS）. The thermal stability analysis and flammability evaluation of the grafted samples by thermogravimetric analysis（TGA）, cone calorimetry, vertical burning tests and limiting oxygen index（LOI） demonstrate that the presence of grafting chains significantly reduces the dripping tendency and decreases the heat release rate of polyamide66（PA66） fabric. The surface morphology observed by scanning electron microscope（SEM） indicates that VTMS can not only promote the formation of protective layers, which prevent the substrate from further thermal degradation, but also promote the char formation ofPA66 substrate during combustion.展开更多
Liquid crystalline polymer-polyamide 66 (LCP/PA66) blends were compounded by using a Brabender mixing followed by compression moulding. The LCP employed was a semi-flexible liquid crystalline copolyesteramide based o...Liquid crystalline polymer-polyamide 66 (LCP/PA66) blends were compounded by using a Brabender mixing followed by compression moulding. The LCP employed was a semi-flexible liquid crystalline copolyesteramide based on 30% (molar fraction ) of p-amino benzoic acid (ABA ) and 70% (molar fraction) of poly (ethylene terephthalate) (PET). The LCP/PA66 blends were investigated in terms of the thermal and dynamic mechanical properties. It was found that PA66 and LCP components of the blends are miscible in the molten state, but are partially miscible in the solid state. The inclusion of the semi-flexible LCP into PA66 retards the crystallization rate of PA66. Furthermore, the melting temperature and the degree of crystallinity of PA66 are reduced considerably due to the LCP addition.展开更多
Two master-batches,polyamide 66 (PA66)/organo-montmorillonite (OMMT) and polyamide 6 (PA6)/OMMT, prepared by melt compounding with methyl methacrylate (MMA) as co-intercalation agent,have been used to prepare nearly e...Two master-batches,polyamide 66 (PA66)/organo-montmorillonite (OMMT) and polyamide 6 (PA6)/OMMT, prepared by melt compounding with methyl methacrylate (MMA) as co-intercalation agent,have been used to prepare nearly exfoliated PA661montmorillonite (MMT) nanocomposites.The resulting nanocomposites are compared in view of their morphology and properties.Nano-scale dispersion of OMMT is realized in both types of nanocomposites,as revealed by XRD,TEM and Molau tests.PA66/MMT nanocomposites having superior mecha...展开更多
The montmorillonites (MMTs), layered, smectite-type silicates, were premodified by two different methods prior to the polymer melt intercalation. In one case MMTs were modified with cetyltrimethylammonium bromide (CTA...The montmorillonites (MMTs), layered, smectite-type silicates, were premodified by two different methods prior to the polymer melt intercalation. In one case MMTs were modified with cetyltrimethylammonium bromide (CTAB), and termed as organomontmorillonites (OMMTs); in the other case MMTs were modified by nylon, and the products were called modified montmorillonites (MMMTs). The effects of CTAB and nylon on the MMTs were investigated by using TG and WAXD. The results show that interlayer spacings of CTAB and nylon modified MMTs are larger than that of sodium MMTs. Then, polyamide 66 (PA 66)/MMT nanocomposites were obtained through the method of melt intercalation of polymers. The nanocomposites were characterized by WAXD, TEM and Molau experiments. The results indicate that the MMTs disperse homogeneously in the PA 66 matrix. The mechanical properties of nanocomposites, such as tensile properties and flexural properties, were also measured and show a tendency to increase with increase of MMT content and reach the maximum values at 5phr MMT content. The heat distortion temperature (HDT) of the nanocomposites (7 phr) is about 32 K higher than that of pure PA 66.展开更多
The effect of heating treatment on the trap level distribution in polyamide 66 film electret is studied by thermally stimulated depolarization current （TSDC） technique. For annealed polyamide 66, there are three tra...The effect of heating treatment on the trap level distribution in polyamide 66 film electret is studied by thermally stimulated depolarization current （TSDC） technique. For annealed polyamide 66, there are three trap levels that respectively originate from space charge trapped in amorphous phase, interphase and crystalline phase. There is one peak that originates from space charge trapped in amorphous phase for quenched one. Using multi-point method to fit the experimental curves, the detrapping current peaks can be separated and the trap depth is obtained. The shallower trap levels trapped in amorphous phase and interphase are obviously close to the deeper trap level trapped in crystalline phase for annealed polyamide 66 as the polarization temperature increases, while the trap level distribution remains unaffected by polarization temperature for quenched one.展开更多
基金Supported by the National Natural Science Foundation of China（Nos.21374004, 21674008）.
文摘Melt-dripping is always a big chanllenge in flame retardant finishing of synthetic fabrics. In this work, vinyltrimethoxysilane（VTMS） was introduced onto the polyamide66（PA66） surface by microwave grafting to improve the fire performance. The chemical structure of the grafted fabric was characterized by attenuated total reflection Fourier transformation infrared spectroscopy（ATR-FTIR） and X-ray photoelectron spectroscopy（XPS）. The thermal stability analysis and flammability evaluation of the grafted samples by thermogravimetric analysis（TGA）, cone calorimetry, vertical burning tests and limiting oxygen index（LOI） demonstrate that the presence of grafting chains significantly reduces the dripping tendency and decreases the heat release rate of polyamide66（PA66） fabric. The surface morphology observed by scanning electron microscope（SEM） indicates that VTMS can not only promote the formation of protective layers, which prevent the substrate from further thermal degradation, but also promote the char formation ofPA66 substrate during combustion.
基金Supported by the National Natural Science Foundation of China.
文摘Liquid crystalline polymer-polyamide 66 (LCP/PA66) blends were compounded by using a Brabender mixing followed by compression moulding. The LCP employed was a semi-flexible liquid crystalline copolyesteramide based on 30% (molar fraction ) of p-amino benzoic acid (ABA ) and 70% (molar fraction) of poly (ethylene terephthalate) (PET). The LCP/PA66 blends were investigated in terms of the thermal and dynamic mechanical properties. It was found that PA66 and LCP components of the blends are miscible in the molten state, but are partially miscible in the solid state. The inclusion of the semi-flexible LCP into PA66 retards the crystallization rate of PA66. Furthermore, the melting temperature and the degree of crystallinity of PA66 are reduced considerably due to the LCP addition.
文摘Two master-batches,polyamide 66 (PA66)/organo-montmorillonite (OMMT) and polyamide 6 (PA6)/OMMT, prepared by melt compounding with methyl methacrylate (MMA) as co-intercalation agent,have been used to prepare nearly exfoliated PA661montmorillonite (MMT) nanocomposites.The resulting nanocomposites are compared in view of their morphology and properties.Nano-scale dispersion of OMMT is realized in both types of nanocomposites,as revealed by XRD,TEM and Molau tests.PA66/MMT nanocomposites having superior mecha...
基金This project was supported by the Science Funds for Henan Province's Prominent Youth and the Science Funds for Henan Province's Creative Persons.
文摘The montmorillonites (MMTs), layered, smectite-type silicates, were premodified by two different methods prior to the polymer melt intercalation. In one case MMTs were modified with cetyltrimethylammonium bromide (CTAB), and termed as organomontmorillonites (OMMTs); in the other case MMTs were modified by nylon, and the products were called modified montmorillonites (MMMTs). The effects of CTAB and nylon on the MMTs were investigated by using TG and WAXD. The results show that interlayer spacings of CTAB and nylon modified MMTs are larger than that of sodium MMTs. Then, polyamide 66 (PA 66)/MMT nanocomposites were obtained through the method of melt intercalation of polymers. The nanocomposites were characterized by WAXD, TEM and Molau experiments. The results indicate that the MMTs disperse homogeneously in the PA 66 matrix. The mechanical properties of nanocomposites, such as tensile properties and flexural properties, were also measured and show a tendency to increase with increase of MMT content and reach the maximum values at 5phr MMT content. The heat distortion temperature (HDT) of the nanocomposites (7 phr) is about 32 K higher than that of pure PA 66.
基金Project supported by the National Natural Science Foundation of China(Grant No.20974108)the Natural Science Foundation of Anhui Province,China(Grant No.1308085QB40)the Fundamental Research Funds for the Central Universities of Ministry of Education of China(Grant Nos.2013HGQC0016 and 2011HGBZ1323)
文摘The effect of heating treatment on the trap level distribution in polyamide 66 film electret is studied by thermally stimulated depolarization current （TSDC） technique. For annealed polyamide 66, there are three trap levels that respectively originate from space charge trapped in amorphous phase, interphase and crystalline phase. There is one peak that originates from space charge trapped in amorphous phase for quenched one. Using multi-point method to fit the experimental curves, the detrapping current peaks can be separated and the trap depth is obtained. The shallower trap levels trapped in amorphous phase and interphase are obviously close to the deeper trap level trapped in crystalline phase for annealed polyamide 66 as the polarization temperature increases, while the trap level distribution remains unaffected by polarization temperature for quenched one.
