Advanced Materials Research Vols. 175-176

Abstract: In this paper, the cellulose whisker/silk fibroin (CW/SF) aqueous solution with different composition was obtained by a dialysis against polyethylene glycol (PEG) solution at room temperature. The rheological behavior of CW/SF solution was investigated and the reinforced CW/SF hybrid fibres were prepared by a dry-wet spinning method. The results showed that the spinnability was better for the CW/SF solution according to the calculation of flowing characteristic index. The cellulose whiskers were dispersed homogeneously in the silk matrix. Moreover, it could be found that the tensile strength and Young’s modulus of the hybrid fibers were improved with the increase of cellulose whisker content, which reached the maximum when the cellulose whisker content was 5 wt%. Compared with the pure silk fiber, the tensile strength and Young’s modulus of the CW/SF hybrid fibers containing 5 wt% CWs were increased from 135.78±12.73 MPa and 5.74±0.43 GPa to 438.68±22.63 MPa and 17.36±2.04 GPa, respectively.

Abstract: A hydrophobic bombyx silk achieved by sol coating is characterized. The agent was firstly prepared by Dodecafluoroheptyl-propyl-trimethoxylsilane（DFS）hydrolysis, then through a sol–gel process, it coated and gelled on the fiber surface with lower surface free energy using bombyx silk fabrics as a substrate. The results of the wide-angle X-ray diffraction measurements (WAXD), TGA and DTG indicated that the thermal stability of the modified fiber was improved with the sol introduction. Scanning electron microscopic analysis (SEM) showed the morphology of the fibers in detail. The results indicated that the treated textiles had excellent water repellent property and water contact angle (CA) increased to 120.2 o.

Abstract: The textured yarn was respectively prepared with pure silk, silk/polyester POY composite filament, silk/polyester FDY composite filament by the self-made processing device. The effects of heat shrinkage of polyester fibers on the structure and properties of the textured filaments were investigated. The results revealed that silk/POY composite filament contained higher heat shrinkage. Synthetic fibers produced crimps with larger amplitude and smaller bandwidth, and the textured filaments presented a larger yarn count, resulting in the notable crimped deformation.

Abstract: The denier of raw silk is enlarged by selected high denier cocoon silk and combined silk filament. The silk impregnating agent was mixed with hot water in order to enhance the softness of silk when reeling silk. After reeling, the silk and polyester partially oriented yarn（POY）were combined and textured by mechanical force and heat, and the silk multifilament with physic mechanical and geometric distortion was produced. Several silk multifilaments were fed together into the yarn carrier of coarse V-bed flat machine and grey cloth was knitted. The silk knitting fabrics with coarse style were produced through refining and drying. Such fabric, which bulkiness, elasticity and drapability are excellent, is suitable for kinds of knitting outer wear.

Abstract: In order to obtain a water soluble and reactive chitosan derivative, quaternary ammonium salt groups and acrylamidomethyl groups were introduced to chitosan by two steps. The chitosan derivative, reactive quaternary ammonium salt of chitosan, was then applied to Antheraea pernyi (A. pernyi) silk by padding and curing method. FT-IR, XRD and SEM were used to characterize the structure of A. pernyi silk before and after treatment. The peak in FT-IR spectra at 1480 cm-1 and 1650 cm-1 revealed the crosslinking reactions of A. pernyi silk fibroin and reactive quaternized chitosan. The XRD results indicated the crystallinity of the treated silk fiber increase a little in comparison with the untreated ones. SEM images clearly showed the reactive quaternary ammonium salt of chitosan attached on the surface of the treated A. pernyi silk fiber, while the surface of the untreated sample was relatively smooth. The thermal stability of the treated silk fiber was enhanced compared to the untreated one by DSC analysis. It was also found that the antibacterial activity of the treated A. pernyi silk fabric against E. coli was more than 99%.

Abstract: Researchers have paid much attention to small-scale natural fibers among the biological materials to seek innovative methods in order to create new high performance materials. Recently, spider dragline silk fibers are being studied because of their unique combination of high strength to weight ratio and high extensibility, which leads to a tough and lightweight fiber. Biomimetic fibers based on spider silk have been a focus of research for the past decade. However, there are still many unanswered questions about the mechanisms by which silk achieves its unique mechanical properties, as well as challenges in mechanical testing of electrospinning silk nanofibers which are often hindered by both small diameters and limited material availability. A method to characterize local mechanical behavior in small diameter nanofibers was developed to both improve understanding of structure-property in natural fibers and provide a method for comparing mechanical behavior in natural and electrospinning fibers.

Abstract: The ancient silk fabrics are important signs of the development of textile technology. Based on the micro-sampling, this paper discusses the application of micro-damaged testing methods in the analysis of ancient silk materials, which includes the Energy Dispersive X-ray Spectroscopy (EDS) and infrared spectrum (FTIR). By testing the ancient silk, the elementary compositions and the contents of the materials can be obtained by EDS, which provides evidence for the inference of their applications and storage environment. The composition and structure of the materials can be obtained by FTIR, which serves as the basis of the study on the degradation status.

Abstract: The natural bamboo fiber is a new kind of textile material. It is made from bamboo plant in physical ways. We studied the basic microstructure of natural bamboo fiber with the scanning electron microscope. The features of fiber length, the linear density and mechanical property were also analyzed. The degrees of crystallization and orientation were tested by diffractometer as well. The results showed that there were a lot of recesses and strips in the longitudinal direction, while the cross-section of the fiber was the shape of polygon with lumen in it. The length distribution arranged from 1.5mm to 215mm, the linear density was about 5.8dtex. The crystallization degree of the natural bamboo fiber was similar to the ramie fiber. In standard state, the breaking strength of the bamboo fiber was 6.71 cN/dtex, and the breaking elongation was about 3.48%, so the natural bamboo fiber was a kind of fiber with high strength and low extension. In hygrometric state, the tenacity and the elongation were both become larger.

Abstract: Mechanical properties have close relation with microstructure. Based on orientation of the molecule chain in fiber, they show a rapid increase in tensile properties. Nevertheless, block materials mainly gain rise of mechanical properties by blend or composite, it is hardly proposed on the self-reinforced materials by optimizing the microstructure. In this paper, a strengthening of PP was gained by uniaxial compression through small deformation of spherulite. A series of measurements were applied, including tensile test, polarizing optical microscope (POM) and differential scanning calorimeter (DSC). The results show that the tensile properties of polypropylene (PP) have a rapid rise. POM suggestes that the spherulite has deformed into ellipsoid even belt along the orientation of sample of PP, which plays an important role in self-reinforcing of PP. And the initial melt point displayed by DSC slightly decreases because of the partial ruptures of crystal phase.

Abstract: In this paper, the polyester fiber surfaces were modified with the combined method of causticization and low-temperature plasma. The effect of Alkali pre-treatment on plasma treatment was studied to investigate the influence of the combined treatment on the properties of the polyester fibers. Through changing the process parameters, such as the temperature of causticization and the plasma treatment duration, the changes of weight loss, mechanical properties, wetting properties and dyeing properties of the polyester fibers after the causticization-plasma treatment were analyzed. In addition, the change of the surface morphology and chemical composition of the polyester fibers after the treatment was investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) analysis respectively. The results showed that the wetting and dyeing properties of the polyester fibers were improved in a higher degree after causticization-plasma treatment than the causticization and plasma treatment independently. Meanwhile, the wetting and dyeing properties were improved more significantly with the increase of the causticization temperature in the causticization-plasma treatment. It was concluded that the pretreatment of the causticization before the low temperature plasma treatment can accelerate the etching and oxidization towards the polyester surface during the plasma treatment.