Variable temperature X ray diffraction(XRD) was used to investigate the crystalline transition of Nylon 1012. The results show that Nylon 1012 undergoes a crystalline relaxation between the glass transition temperatur...Variable temperature X ray diffraction(XRD) was used to investigate the crystalline transition of Nylon 1012. The results show that Nylon 1012 undergoes a crystalline relaxation between the glass transition temperature and the melting point. We thus demonstrate, for the first time, the presence of the Brill transition in Nylon 1012, a phenomena that has been extensively studied in Nylon 66. It is found that the Brill transition temperature is about 120 ℃ and we have also showed that the Brill transition of Nylon 1012 is reversible when cooling the high temperature pseudohexagonal structure to room temperature. [WT5HZ]展开更多
A new kind of nano-crysta cellulose (NCC) prepared from natural cotton fiber has been obtained by the method ofacid hydrolysis. Compared to most other nanophase materials that derive from inorganic materials, our prod...A new kind of nano-crysta cellulose (NCC) prepared from natural cotton fiber has been obtained by the method ofacid hydrolysis. Compared to most other nanophase materials that derive from inorganic materials, our products are preparedfrom natural cotton fibers. The products are of spherical shape with mixed crystal forms of cellulose I and II. The preparationconditions determine the properties of the products. Prior treatment is a critical procedure. The properties of the products arealso strongly affected by such conditions as the kinds of acids used, the ratio of the acid mixture, the acid concentration, theultrasonic agitation time and hydrolysis temperature. The number average molecular weight of NCC is determined by gelpermeation chromatography (GPC). The particle size and shape were determined by transmission electron microscopy(TEM). X-ray diffraction was used to detect the crystallinity and average crystallite size of the panicle.展开更多
文摘Variable temperature X ray diffraction(XRD) was used to investigate the crystalline transition of Nylon 1012. The results show that Nylon 1012 undergoes a crystalline relaxation between the glass transition temperature and the melting point. We thus demonstrate, for the first time, the presence of the Brill transition in Nylon 1012, a phenomena that has been extensively studied in Nylon 66. It is found that the Brill transition temperature is about 120 ℃ and we have also showed that the Brill transition of Nylon 1012 is reversible when cooling the high temperature pseudohexagonal structure to room temperature. [WT5HZ]
基金This work was supported by the Special Funds for Major State Basic Research Projects (95-12 and G1999064800).
文摘A new kind of nano-crysta cellulose (NCC) prepared from natural cotton fiber has been obtained by the method ofacid hydrolysis. Compared to most other nanophase materials that derive from inorganic materials, our products are preparedfrom natural cotton fibers. The products are of spherical shape with mixed crystal forms of cellulose I and II. The preparationconditions determine the properties of the products. Prior treatment is a critical procedure. The properties of the products arealso strongly affected by such conditions as the kinds of acids used, the ratio of the acid mixture, the acid concentration, theultrasonic agitation time and hydrolysis temperature. The number average molecular weight of NCC is determined by gelpermeation chromatography (GPC). The particle size and shape were determined by transmission electron microscopy(TEM). X-ray diffraction was used to detect the crystallinity and average crystallite size of the panicle.
