| With the non renewable oil resources shortage, people get to know more the present petroleum based materials environmental hazards, research on the preparation of composite materials has become a global focus, instead of the fastest growing non renewable materials renewable resources become the plant fiber composites. However, renewable plant fiber used for the preparation of composite material has many limitations, such as the strong moisture absorption, poor thermal stability and easy to burn, and the poor thermal stability which are the limiting factors to limit the domain application of plant fiber composite material. Thermal stability study on the characteristics of pulp fibers and the use of composite flame retardant synergistic effect to improve the thermal stability of pulp fiber play an important theoretical and practical significance.This paper applied aluminum hydroxide and ten bromo two benzene ethane as flame retardant, to improve the heat resistance properties of pulp fibers, and study on the physical and chemical properties under the heating conditions of the pulp fiber, and discuss the improvement of pulp fiber thermal degradation mechanism, using softwood pulp as raw material for flame retardant paper and non flame retardant paper pulp. Study further on the mechanism of flame retardant paper retention performance, which is modified with cationic starch, chitosan, cationic polyacrylamide, and fiber decay mechanism is also further discussed.The study found that glucose and xylose are the main sugar pulp fiber group selection, including glucose and xylan contents which were 71.23% and 21.91%, and total sugar was 93.14%; cellulose pulp fibers in the number average molecular weight of Mn were 3.58 × 105; the weight average molecular weight of Mw was 2.32 × 106; mass average molecular weight of Mw was 5.53 × 106; Through the XRD analysis it showed that the crystallization of pulp fiber samples of degree was 65.34%. The changes performance of pulp fiber crystallinity is mainly due to pulp fiber thermal decay, and this provides basis theory for study on microstructure changes of pulp fiber. By thermogravimetric analysis and pyrolysis kinetics model of thermal decay properties of pulp fiber, found in different heating rate, pyrolysis kinetics of pulp is a first-order reaction. The main pyrolysis temperature is the same temperature range as the heating rate increased and shifted to a higher temperature decomposition temperature, with the increase of heating rate, the activation energy (E) and frequency factor (A) also showed an increasing trend. Make the activation energy and frequency factor comparison, activation energy is impacted much more due to temperature increase greatly, and fiber thermal decay degeneration decreases with the increase of heating rate, these findings provide a theoretical basis for the changes of pulp fiber thermal decay properties.Through the study on the physical properties of pulp fibers after heat treatment, the pulp fiber heat treatment led to the pattern of whiteness, tensile strength, breaking resistance and resistance to reduce the degree of physical indicators in different degree, and the water retention value and reduce the beating degree. Through the specific surface area analyzer and atomic force microscopy (AFM) analysis of pulp fibers, it showed that heat treatment make the pulp fiber surface become dense, the specific surface area decreased, at the 280 degrees in the treatment of 5minutes, the specific surface area was 0.362 square meters/g, and the untreated pulp fiber surface area decreased 10.21%, which showed that heat treatment caused a horny fiber, resulting in low reaction properties of pulp fibers.The study found that, the heat treatment on the fibers may result in the different level reduction of whiteness, tensile strength, bursting strength and folding properties, also found that the heat treatment could make the more dense on the fiber surface, on the other hand the water retention value and beating degree was reduced, through chemical analysis it is found out that there was a reduction of the content of carboxyl and an increased lactone content, also the decreased reaction properties of pulp fibers, after heat treatment the fiber had obvious cornification, which leads to the thermal decay of pulp fibers.Based on the environmental protection evaluation, to suppress the thermal decay effect, inhibition of smoke production and investment cost comparison selection principle, it was made the choice of using aluminum hydroxide and ten bromo two benzene ethane as a pulp fiber thermal decay inhibitors. Through the study on thermal degradation of these two, we found that the synergistic flame retardant effect was very good. Study separately on aluminum hydroxide with ten bromo two benzene ethane both alone and compound as a flame retardant inhibition of pulp fiber thermal decay. The proportion of choosing the flame retardant aluminium hydroxide and ten bromo two ethyl benzene was 3:1, this composite flame retardant had two main degradation temperature range of Ⅰ (205 to 310 DEGC) and the main degradation temperature range of Ⅱ (315 to 421 DEGC), adding amount of oven dry pulp fiber 70%, at this time the tensile index was 82.5 Nm/g, oxygen index reached 27, being the hard burning flame retardant grade.Study effects of different cationic auxiliary agents on retention of flame retardant and strength of paper properties. It is showed that when adding the amount of cationic starch 0.2%, chitosan 0.3%, cationic polyacrylamide 0.4%, it could reach good retention effect. Through the electron microscopic analysis of retention characteristics, it discussed the flame retardant retention due to both mechanical entrapment and colloid adsorption dual mechanism. The retention rates were 47.2%,50.4%,60.2%, because the pattern of ash increase which has some negative effects on the binding force, the corresponding pattern of tensile index decreased by 38.5%,35.4%,28.6%. The addition of 0.4% cationic polyacrylamide can achieve better retention and strength retention effect. The study found that with the increase of retention agent dosage, the oxygen index becomes larger, the beating degree decline showed a downward trend. Flame retardant retention characteristics of the electron microscope analysis showed that the flame retardant which has a dual role in adsorption is completed under mechanical force of interception and colloid.Observing the microstructure after the heat treatment of non flame retardant and flame retardant samples at 300 DEG C, it found that the fiber network structure was more compact without adding flame retardant, three-dimensional mesh structure levels decreased, the surface tends to be more smooth, the gap is smaller between the structure of micro fiber. Adding flame retardant pulp fiber, obviously it can be clearly seen the retained fiber weaving structure, on the surface of pulp fibers it can be also seen the coating structure formed of flame retardant pyrolysis, the coating material can be very good isolation of pulp fiber from thermal decay in the environment, thus it leads to suppress the thermal decay effect of fiber. Through the analysis of fiber morphology and crystallinity of the addition of flame retardant pulp fiber after heat treatment, the ratio of length to width of curl index and kink index compared with non flame retardant samples was improved to a certain extent, and the crystallinity of the fiber was relatively small, it showed that flame retardant inhibit the thermal decay of the fibers. |
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