Study On The Structure And Properties Of The Silk From Male Silkworms

Researchers have a great interest in the study of silk,and have been working to improve the properties of silk.In the process of research,it was found that male silkworm had a series of advantages compared with female silkworm,such as stronger resistance,stronger constitution,faster growth rate in the fourth and fifth instar,less mulberry eating,etc.These characteristics can improve the economic benefit of silk industry to some extent.Male silk,as a new kind of silk,is an ideal material for reeling high-grade raw silk,which has the characteristics of length,better clarity,high grade of raw silk and good elasticity,compared with the common silk reeled by male and female cocoons in the market.At present,there are two ways to obtain pure male silk,one is to identify male and female silkworms by gender characteristics,and then breed them separately for reeling silk,the other is to breed special male silkworm varieties,such as using the sex linkage equilibrium lethal system to make the female silkworm eggs die in the embryonic stage,while the male eggs can hatch normally.Due to the lack of systematic and in-depth research on the structure and properties of male silk,and the lack of sufficient understanding on the differences between male silk and female silk,it is impossible to match the corresponding production technology according to the characteristics of male silk in the subsequent processing process,so that the performance advantages of male silk and its products cannot be played.The male silk and its products on the market cannot be effectively identified,which is not conducive to the development and application of male silk.Therefore,the systematic and in-depth study on the structure and properties of male silk,and the comparison with female silk,and the analysis of their differences,can provide more theoretical support for the development of male silk,is the urgent matter of the development and application of male silk.In this study,the cocoon quality difference between male and female silkworm cocoons was compared and analyzed using ordinary white silkworm cocoons as raw material.The morphology and secondary structure of male and female silk were analyzed by scanning electron microscopy,transmission electron microscopy,Fourier transform infrared spectroscopy and X-ray diffraction.In addition,the moisture absorption and desorption properties,thermal properties,mechanical properties and dyeing properties of acid and reactive dyes of male and female silk were studied.The composition of male silk and female silk was analyzed.The results are as follows.The cocoon quality of male and female cocoons was investigated.The cocoon shape and pupa weight of male cocoons were smaller than that of female cocoons.The cocoon length and cocoon width of female cocoons were about 5.40% and 7.24% higher than that of male cocoons,respectively.The total cocoon weight of female cocoons was about 25.50% higher than that of male cocoons,but the cocoon layer ratio of male cocoons was about 19.53% higher than that of female cocoons.The sericin content in each cocoon layer of male cocoons was less than that of female cocoons.The results of scanning electron microscopy showed that the cross sections of both male and female silk were approximately triangular,but the cross sections of male silk were significantly smaller than that of female silk.The longitudinal surface of the two kinds of silk was smooth,and the fineness of the male silk was less than that of the female silk.The average diameter of the female silk was about 12.34(12.34±0.98)?m,and the average diameter of the male silk was about(11.01±0.15)?m.Under transmission electron microscope,both male silk and female silk had lattice structure,and obvious lattice fringes of male silk could be observed.Infrared spectroscopy and X-ray diffraction analysis showed that the basic structure of the two kinds of silk is the same.Both kinds of silk contain ?-sheet,?-helix/random coil and ?-turn structure.The ?-sheet content in each cocoon layer of male cocoon was higher than that of female silk,with an average height of about 24.09%.The crystallinity of each cocoon layer of male cocoon was higher than that of female cocoon,with an average height of about 6.35%.The results of thermal analysis showed that the thermal decomposition temperature of male silk was higher,and the residual mass after decomposition was greater than that of female silk.The results of mechanical properties showed that the average breaking strength of male silk was about 6.87% higher,the average initial modulus was about 6.24% higher,and the average elongation at break was about 5.83% lower than that of female silk under dry condition.Under wet condition,the average breaking strength of male silk was 4.55% higher than that of female silk,the average initial modulus was 3.10% higher,and the average elongation at break was 6.67%lower than that of female silk.In acid dyeing,male silk did not show obvious superior properties compared with female silk.The dyeing rate of male silk was higher and the apparent depth of silk specimen after dyeing was deeper.The results of liquid chromatography and gas chromatography analysis of male silk and female silk showed that the components of the two kinds of silk were basically the same,but the relative contents of the components were obviously different...