Preparation Of Cotton Stalk Bark Fibers (CSBF) By Steam Explosion Pretreatment And CSBF/PBS Composites

Cotton stalk is a kind of biomass energy with high source and high yield. But the use of cotton stalk is still very narrow, mainly due to its limited processing technology and the cost. Cotton stalk bark is a layer of bast fibers attached to the cotton stalk,accounting for 26% of the weight of cotton stalk. Cotton stalk bark is mainly composed of cellulose, hemicellulose,lignin and some pectin, wax fat composition.This paper mainly studiedthe separationof cotton stalk barkand preparation of cotton stalk bark fibers using steam explosion combined with ultrasonic wave and microwave assisted treatment(SUMAT), extractingthe cellulose and other active ingredients from cotton stalk, the preparation of cotton stalk bark fibers, and then using the prepared cotton stalk fibers mixed with polybutylene succinate(PBS) to prepare composites materials.First of all, this paper studied the steam-explosion method to pretreat cotton stalk bark. It mainly studied the effect of steam explosion pressure(0.8MPa, 1.0MPa,1.2MPa, 1.4MPa, 1.6MPa) and flash explosion time(60s, 120, 180 s, 240 s, 360s) on properties(Composition, surface morphology, mechanical properties) of cotton stalk bark fibers. The results show that the steam explosion can effectively isolate the compact structure of the cotton stalk bark, so that it can get the initial separation, at the same time can remove part of the non-cellulose substances of the cotton stalk bark.However, both of over high or over low conditions have some drawbacks. When The steam pressure is too low, the cotton stalk bark can't get the effective isolation. If the steam pressure is too high, the fiber properties of the cotton stalk bark fibers is poor,while the fiber length is short and the strength is weak. The optimal steam explosion process: steam pressure of 1.2MPa; steam explosion time of 3min. At this time, the obtained cotton stalk bark fibers had content of hemicellulose of 8.8%, length of 66.2mm, a fineness 48 of dtex, a breaking strength of 2.4 cN / dtex and a yield of 48%.Secondly, the cotton stalk bark fibers post-treated by SUMAT. In this paper, a new type of enhanced processing method, SUMAT, was used to assist tetramethylammonium hydroxide(TMAOH) to post-treat fibers after steam explosion.The pre-treated cotton stalk fibers were post-treated for the purpose of obtaining better performance of cotton stalk bark fibers. The effects of ultrasonic/microwave power, time, temperature and organic alkali concentration on the strength and aspectratio of cotton stalk bark fiber were studied in this chapter. The results showed that the total amount of waxy, pectin and water soluble material decreased from 21% to6%, hemicellulose content decreased from 21.8% to 15.2%, the obtained fiber fineness was 59 dtex, aspect ratio 957, tensile strength 2.15 cN/dtex. The total amount of waxy, pectin and water soluble material decreased to 1.4%, and the hemicellulose content was reduced to 9.2%. The aspect ratio of cotton stalk bark fibers was improved to 1169, Fineness of 34 dtex, tensile strength of 2.85 cN/dtex after SUMAT.The content of lignin in cotton stalk had no obvious change before and after pretreatment. Compared with the existing methods, this paper mainly removes the hydrophilic hemicellulose, pectin, water-soluble substances, while retaining the hydrophobic lignin and high aspect ratio, high breaking strength of cotton stalk bark fibers.Finally, the prepared cotton stalk bark fibers were carded by carding machine and then reinforced polybutylene succinate(PBS) to prepare composite materials. The effects of hot pressing conditions on the mechanical properties of the composites and the degradation properties of the composites were studied. The results showed that the addition of cotton stalk bark fiber to the PBS matrix could improve the mechanical and thermal properties of the composites to a certain extent. The results showed that there are serious cracks on the surface and cotton-like hollow inside of the composite material, at the same time the quality is reduced after degradation experiment. The single factor test of temperature, time, pressure and fiber mass fraction of hot-pressing process was carried out to determine the optimum conditions of the hot-pressing process: pressure of 2MPa, temperature of 140 ?, time of 20 min and fiber mass fraction of 40%.Steam explosion is an effective method in isolation of cotton lignin cellulose material which can make cotton stalk get an initial separation to obtain cotton stalk bark fibers. SUMAT can refine the obtained cotton stalk fibers and improve the properties. Prepared composites were biodegradable and can be potentially applied in architecture, automotive industry and so on.