Research On The Rapid Identification Method Of Plant Dyed And Chemically Dyed Cotton Fabrics

Nowadays,along with the development of social productivity and the improvement of people’s living standard,the significance of textiles has expanded from warmth to health and environmental protection,etc.Plant dyes are favored and respected by people for their excellent environmental compatibility,and are widely used in the preparation of a variety of high value-added textiles.Due to the slow progress of industrialization of plant dyeing,its industrial production technology,product standards and identification methods are still in development,especially there is no feasible identification method of plant dyeing products,which has a great obstacle to the promotion of plant dyeing industry.The identification of the two fabrics is currently still a problem,while there was no complete and unified standard in this area.To build a simple and rapid plant identification method for the development and application of plant dyes has important theoretical and practical significance.In this study,cotton fabrics dyed with plant dyes(madder turmeric and indigo)and chemical dyes(direct dyeing red 224,direct dyeing 12,direct dyeing blue 71)were taken as the research objects,decoloring technology and near-infrared spectrum technology were combined to obtain a fast,efficient and non-destructive identification method for plant dyeing and chemical dyeing cotton fabrics.The main contents and results are as follows:1、The bleached cotton fabrics were dyed with red,yellow and blue plant dyes and chemical dyes.The effects of dyeing condition such as dyes concentration and time of dyeing on the cotton fabric dyeing were analyzed,and the K/S value were tested,to ensure the diversity and independence of the samples,which provided raw materials for the rapid identification of the plant and chemical dyed cotton fabric.The results showed that:80 pieces of plant and chemical dyed red,yellow and blue cotton fabrics were prepared in this experiment,and there were some differences in dyeing depth and dyeing uniformity,which provided sufficient sample space for subsequent identification studies.The optimal dye concentration of chemical dyeing and plant dyeing red,yellow and blue cotton fabrics were2.5%,3%,2.5%,6%,7%,6%,and the dyeing time was 45min and 60min,respectively.The corresponding K/S values of dyed cotton fabrics were 7.473,15.681,15.383 and 5.785,6.780,19.555,respectively.2、In this paper,chemical decolorization method was used to distinguish cotton fabrics dyed by plants from that dyed by chemicals.The decolorization effects of several different decolorizing reagents such as hydrogen peroxide,glacial acetic acid and sodium chlorite on red,yellow and blue cotton fabrics dyed by plant dyes and chemical dyes was discussed.The results showed that the solution of sodium chlorite and glacial acetic acid could decolorize the cotton fabrics dyed with plant dyes,but not for chemical dyestuffs.However,this method has a destructive effect on cotton fabrics,and it requires too much equipment and operation to realize the rapid and non-destructive identification of plant and chemical dyed cotton fabrics.3、Near infrared technology combined with the supervised clustering method--soft independent modeling of class analogy(SIMCA)was applied to identify cotton fabrics dyed with plant and chemical dyes.The original spectra were preprocessed with standard normalization correction,and the pre-processed data was modeled.The model was optimized by selecting the spectral analysis range,and the model recognition effect was reflected by the model recognition rate and rejection rate.The results showed that the correct recognition rate and internal rejection rate of the samples of the calibration set were 100%in the SIMCA model of the spectrum within the range of 7500-4000cm~-11 wave number,and the correct recognition rate of the prediction set was 99%.The model can realize the fast and nondestructive identification of plant and chemical dyed cotton fabrics.4、Near infrared technology combined with two kinds of pattern recognition methods including partial least squares(PLS)regression and principal component regression(PCR)were applied to identify cotton fabrics dyed with plant and chemical dyes.After the pretreatment of Savitzky-Golay first derivative,the calibration model was constructed.The PLS model showed that the number of principal components(PCs)and the correlation coefficient(R~2)were 8 and 0.9978;and the results of PCR were PC=10,R~2=0.9937.The RMSEP of the two models was 0.1366 and 0.1459,respectively.Both of the methods were satisfactory for the predicted results,and the six different types of samples have 100%recognition rate under the two modeling methods in the prediction set.The overall results indicated that NIR could be used for rapid and nondestructive identification of plant dyed cotton fabrics and chemical dyed cotton fabrics.