Papers by Keyword: Crystallinity

Abstract: Regenerated cellulose fiber is the most widely-used and most variety of cellulose fiber. Five categories and ten kinds of fibers such as lyocell fiber, viscose fiber, modal fiber, bamboo pulp fiber, and sheng-bast fiber were chosen as the research object. The sectional shape, crystallinity and degree of polymerization of fibers were tested and analysis, to explore the nature of the reasons for the formation of fiber performance difference, and to verify through experiments.

Abstract: The preparation of ZSM-5 templates in the absence of organics is an area of high technological impact. These are responsible for the enhancement of the final products (zeolites). Therefore, the preparation of zeolites in the absence of template allows a compromise covering the low cost and environment. This study aimed to investigate the influence of synthesis time in the preparation of ZSM-5. This zeolite was prepared by hydrothermal synthesis, using as co-template (C₂H₅OH) and addition of seeds. The times of synthesis used were 3 to 5 days. The solids were characterized by XRD, BET and Spectroscopy in the infrared region. Through the results obtained with XRD, it was observed that all samples showed characteristic peaks of MFI structure of the group at intervals of 2θ = 7-9° and 23-25°, showing no presence of secondary phases. BET surface area showed a corresponding literature. The infrared showed bands characteristic of ZSM-5.

Abstract: As to demonstrate the effect of treatment temperature on hemp fibre, this article recorded and compared the change of supramolecular structure and properties of hemp fibre under different processing temperature (150°C and -30°C). The result shows: the change of processing temperature can affect the crystallinity of hemp fibre, with the rise of treatment time, the crystallinity of fiber increases at high temperature and is contrary at low temperature. Meantime, the degree of thermodynamic change is higher at low processing temperature than that of high temperature. Furthermore, with the rise of treatment time, the moisture regain of fibre fluctuates under high temperature and rises under low temperature.

Abstract: Cellulase named as Celluclast 1.5L was used to deal with bleached softwood pulp. By analyzing the changes of water retention value and crystallinity of fiber after enzymatic treatment, studied the influence of cellulase to aggregation structure of bleached softwood pulp. The results show that with the increasing of the enzyme dosage, the proportion of long-fiber decreases and the content of fines increases. Water retention value of pulp first decreases and then increases. The fiber crystal does not change with the enzymatic treatment, but with the increasing of the enzyme dosage, the crystallinity of fiber first increases and then decreases. It indicates that the cellulase would act on the crystalline region of fiber in the higher enzyme dosage.

Abstract: PVA nanofibers are generally required to be modified because of its poor stability in water. The water stability of PVA nanofibers was improved by heat treatment in this paper. The DSC test results showed that the crystallinity of heat-treated PVA nanofibers at 150°C for 10 min reached the maximum which increased by 12% compared with PVA nanofibers. From the SEM images it was observed that the heat-treated fibers didn’t dissolve in water but showed certain degree of agglutination and swelling. PVA nanofibers were taken as the inner layer of the sandwich structure purification material prepared with the hot pressing technology. The filtering experiments showed that the filtration properties were better when the area density of PVA nanofibers was 2.5 g/m2.

Abstract: By adopting a facile solution combustion synthesis (SCS) method, pure well-crystallized (Ba,Sr)MgAl₁₀O₁₇:Mn green phosphors were successfully prepared. The crystallinity, particle size, morphology, and luminescent properties were characterized by XRD, FE-SEM and spectrofluorometer respectively. The results indicated that the obtained phosphors have spherical morphology, good crystallinity, and strong green emission. The emission spectra of obtained nanophosphor on 147nm excitation consist of a wide band with the peak at 518nm, which corresponds to the transition from the 3d⁵(⁴T_1g) excited state to the 3d⁵(⁶A_1g) ground state of Mn2+. The synthesized phosphors can be efficiently excited at VUV light and have potential application in Plasma Display Panels (PDPs), 3D displays and mercury-free fluorescent lamps

Abstract: In this article, based on nucleation and growth mechanism of films, different process conditions of rapid thermal annealing (RTA) had been investigated to attain different orientation and the crystallinity of PZT film. At first, the PZT films had been fabricated by magnetron sputtering on Si/SiO2/Ti/Pt substrates, then crystallized by different stepped rapid thermal annealing process. X-ray diffraction (XRD) was used to analyze the crystal structures of the films and scanning electron microscope (SEM) was used to analyze the surface morphology of the films. As a conclusion about the research is that it is good for controlling the crystallographic orientation and enhancing the crystallinity of PZT film by different stepped rapid thermal annealing process

Abstract: With the thermal gravity analysis and relative breaking strength test, both crystallization variability and the important temperature is determined in heating process of hemp fibers. Meanwhile, the critical time and temperature is got which have a effect on relative breaking strength of hemp fibres and the hemp fabric appearance. Those data about thermal stability is helpful for hemp manufacturing and processing.

Abstract: A novel nucleating agent for polyoxymethylene (POM) was successfully prepared. The effect of nucleating agent on POM was characterized by using mechanical properties testing machine and differential scanning calorimetry (DSC). The results demonstrate that the addition of nucleating agent can improve the crystallization growth rate and mechanical properties of POM, and the nucleating agent maybe have potential application in POM field.

Abstract: In order to test whether the crystallinity and orientation of ramie fibers have changed after they are treated by the lattice distortion modification processing technology, this paper does some experiments on it. Firstly, process ramie fibers by the lattice distortion modification processing equipment. Then use X-ray diffraction method to determine the crystallinity and orientation of pristine and modified ramie fibers. Finally analyse the effect of lattice distortion modification processing on the lattice structure of ramie fiber. The experimental results show that the lattice structure of ramie fiber has changed after modification processing, with crystallinity, grain size decreasing obviously and orientation slight descent, which make ramie fibers appear softer and more puffy from macrocosmic perspective.