Study On Raman Detection Technology For Mulberry Silk And Development Of Standard Samples

Mulberry silk has good moisture absorption and breathability,which is soft,elastic and glossy,earning it the reputation of"fiber queen".It has good wearing performance with its smooth,breathable,comfortable,and antibacterial charactertistic.It can also be made into high-quality products such as silk quilts.Due to the excellent performance,low production volume,and high processing costs of mulberry silk,its price has always been high.However,the price of tussah silk is much lower than that of mulberry silk.Many unscrupulous merchants often use tussah silk to impersonate mulberry silk and deceive consumers.Therefore,the identification method of mulberry silk has always been a hot topic of concern in the textile industry.Traditional methods for identifying mulberry silk have problems such as long cycles,low efficiency,strong subjectivity and sample destruction.There is an urgent need for fast,efficient,and accurate non-destructive identification techniques for mulberry silk.Raman spectroscopy technology possesses the characteristics of not being interfered by water molecules,non-destructive,fast,pollution-free,requiring less sample quantity and no pre-treatment.The use of Raman spectroscopy technology to identify mulberry silk will become a new development direction.In order to reduce the dependence on human experience and skills in identifying mulberry silk and improve the accuracy and efficiency of laboratory testing,in this study,I investigate the macroscopic,microscopic,and physicochemical properties of mulberry silk,tussah silk,and their fabrics.The feasibility of using confocal Raman spectroscopy technology to identify mulberry silk is explored,and a fast and accurate non-destructive testing method for mulberry silk is ultimately established.Stable samples with typical characteristic structures used for non-destructive testing and corresponding standard sample Raman spectra libraries are developed and established.The specific conclusions of the study are as follows:（1）Mulberry and tussah silk are very similar in macroscopic morphology and combustion performance,making it difficult to distinguish them using tactile vision and combustion methods.Identification can be achieved through the differences in the microstructure of mulberry and tussah silk under optical microscopy and scanning electron microscopy.Identification also can be achieved through the differences in the solubility of mulberry and tussah silk in calcium chloride ethanol solution using chemical dissolution methods.Non destructive identification of mulberry and tussah silk can be achieved through ATR-FTIR technology.The mulberry silk has two characteristic absorption peaks attributed to Ala-Gly-Ala at 997cm^-1and 973 cm^-1,while the tussah silk has a characteristic absorption peak attributed to Ala-Ala-Ala at 964cm^-1.However,these characteristic absorption peaks are very weak on the spectrum,and it is difficult to use them to quickly and accurately identify silk species.There are certain differences in the mechanical properties of mulberry silk from different regions,with an average linear density ranging from 21 dtex to 31 dtex,a breaking strength of 3.25 c N/dtex to 4.10 c N/dtex,and an elongation at break of 18.9%to 25.6%.However,there is no significant difference in the morphological structure and molecular structure of mulberry silk from different regions.（2）The Raman spectra of mulberry silk from different regions were studied using the confocal Raman spectroscopy.The characteristic peaks were located near 1084.5cm^-1,1229.2cm^-1,1265.4 cm^-1,1451.2 cm^-1,and 1666.3cm^-1,with deviations within 2 cm^-1.The main differences in Raman spectra between mulberry silk and tussah silk are at the position of the main peak of the amide III band(1229cm^-1and 1240cm^-1respectively),the position of the sensitive peak ofβ-sheet(1084cm^-1and 1094cm^-1respectively)and the unique Ala characteristic peak of tussah silk at 905 cm^-1,which can be used to distinguish mulberry and tussah silk.The Raman spectral characteristics and patterns of white mulberry silk fabrics and mulberry silk fibers are consistent.The type of fabric does not affect the Raman testing results,while the color and impurities of the fabric are the main factors affecting the Raman testing results.（3）Based on the common types and technological processes of mulberry silk fabrics in the market,two homogeneous,stable,and typical fabrics were produced and ultimately selected as the standard samples for non-destructive testing of mulberry silk fabrics.A corresponding Raman spectrum library was established.The Raman spectra are measured using a microscopic imaging Raman spectrometer at an excitation wavelength of 532nm,there are 5 characteristic peaks clearly visible(1084cm^-1,1229cm^-1,1264 cm^-1,1449 cm^-1,1664 cm^-1),with a characteristic peak deviation within 1cm^-1.Uniformity testing and external sample testing are conducted on the standard samples,and it is found that the uniformity of the standard samples RM-WF and RM-KF is good within a 99.9%confidence interval.By using the standard samples of mulberry silk fabrics and their Raman spectra library for Raman testing,mulberry silk fabrics can be accurately identified.