Study On The Identification Methods Of Bamboo Fibers

Bamboo fibers, which are renewable, biodegradable, low-priced and abundant as a kind of cellulosic fiber, are favored by more and more people because of the good physical and chemical properties nowadays. However, the effective identification of natural bamboo fibers and bamboo viscose fibers, natural bamboo fibers and bast fibers (eg:ramie), bamboo viscose fibers and conventional viscose fibers has become a problem due to their similar morphological structure or physical and chemical properties, and there has no unified standard about the identification methods of bamboo fibers so far. Therefore, the phenomenon of ramie and viscose fibers being pretended to bamboo fibers occurred frequently in the market, and the identification of bamboo fibers has turned into a barrier for the promoting of new products now.At present, some conventional inspection methods on the identification of bamboo fibers have been researched while with deficiency in applicability and effectiveness. In this paper, natural bamboo fibers and bamboo viscose fibers which produced by the main domestic manufacturers are collected widely, and the comprehensive research is carried out using conventional inspection methods at first, then, the near infrared test method is proposed on the basis of it and achieves the identification of natural bamboo fibers, bamboo viscose fibers, ramie, flax and viscose fibers finally. The specific contents are as follows:Firstly, the macro morphological characteristics of the fibers are obtained through handle-visual method. The results show that:natural bamboo fibers are short in length and uneven, felt thick and tough without curls but with dim luster; ramie is long in length, felt thick and tough without curls; bamboo viscose fibers and viscose fibers are similar with the length of about38mm, they are finer than the two former and more soft and smooth with natural curls and good luster.Secondly, the microstructure features of the fibers are researched by the comparative analysis of optical microscopy pictures and scanning electron microscopy (SEM) pictures. The results indicate that:the cross-section and longitudinal direction structure characteristics of natural bamboo fibers and bamboo viscose fibers are obviously different, the cross-section of natural bamboo fibers is irregular ellipse or kidney-shaped with lumen internal while that of bamboo viscose fibers is irregularly jagged without lumen, the longitudinal direction of natural bamboo fibers is not smooth with crosswise lines while that of bamboo viscose fibers is smooth with many long lengthways grooves, which contribute a lot to the identification of the two fibers; however, ramie and viscose fibers have almost the same morphological characteristics with natural bamboo fibers and bamboo viscose fibers respectively, so they can not be identified effectively by these two methods. Thirdly, the physical and chemical properties of the fibers are studied by the comprehensive testing and analysis of combustion, dissolution, Fourier infrared spectra, X-ray diffraction and thermogravimetric analysis/FTIR spectra. The results prove that:the burning characteristics of natural bamboo fibers and bamboo viscose fibers are only slightly different on the color of remains, which contribute little to the identification of the fibers; but their dissolution features in40%sulfuric acid,37%hydrochloric acid and formic acid-zinc reagent with different temperature are obviously different, the shape of FTIR spectra at around1105cm" and the shape and position of XRD peaks are not the same, the thermostability of natural bamboo fibers is better than that of bamboo viscose fibers, therefore, the identification of these two fibers can be realized through these four methods. The burning characteristics of natural bamboo fibers and ramie are totally the same, their shape, intensity and position of FTIR peaks are generally consistent, so they can not be identified by these two methods; however, their dissolving performance in40%sulfuric acid,37%hydrochloric acid and formic acid-zinc reagent with different temperature are somewhat different which can help to achieve the preliminary identification of the fibers; their shape and position of XRD peaks are similar, the thermostability of naturan bamboo fibers is much better than that of ramie, therefore, these two methods can achieve the identification of the two fibers. Bamboo viscose fibers and viscose fibers are both regenerated cellulosic fibers with similar structure and properties, their burning characteristics and dissolution features are totally the same, the FTIR spectra and XRD spectra are generally consistent, and their thermostability are almost the same, therefore, bamboo viscose fibers and viscose fibers can not be identified by the five conventional inspection methods.At last, the applicability and effectiveness of near infrared spectra modeling method on the identification of natural bamboo fibers, bamboo viscose fibers, ramie, flax and viscose fibers are investigated. Fiber samples which are various and representative are collected to build modeling sample set and correction sample set, and the spectra of the fibers are scanned under the same conditions, then the grouped and comprehensive discrimination models of the fibers are build by means of Ward’s algorithm and Hierarchical Cluster Analysis after the first derivative and vector normalization pretreatment, verify the accuracy of the models finally. The results show that:the accuracy of both the near infrared spectra grouped models and comprehensive model is high, not only the grouped models can achieve the effective identification of the kinds of fibers, but also the comprehensive model can realize the identification of all the five fibers using only one model, it is more effective than the grouped models, in a word, these two kinds of discrimination models both can identify the fibers simply, rapidly, accurately and nondestructively.