Mei Niu

Molecular structure and properties of wool fiber surface-grafted with nano-antibacterial materials

Wool fiber was modified by ultraviolet irradiation (UV) and functionalized by grafting antibacterial agent. The structure and properties of antibacterial wool fiber were discussed in detail. The secondary structure changes and crystal structure were analyzed based on Fourier Transformation Raman Spectrometry (FTR) and X-ray diffraction (XRD). The results show that the disordered degree of UV-treated sample was increased and the antibacterial sample became more oriented. Compared with parent wool fiber, the antibacterial wool fiber was improved in mechanical property. The force, tensile strength and elongation were increased by 18%, 16%, and 7%, respectively. Also, the anti-shrinkage performance was increased because of the decrease in the directional frictional effect (DFE).

Preparation of SiO2/PPS Fiber and Study of its Heat-Resistant Properties

Through the addition of nano-silicon dioxide in the pure polyphenylene sulfide, the masterbatches were obtained, then using melt spinning technology to prepare SiO2/PPS fiber. The structure and heat-resistant properties of samples were characterized by transmission election microscopy (TEM), infrared spectrum (IR), differential scanning calorimeter (DSC) and other measurements. The experiment results indicate that the mechanical and heat resistance properties of PPS fiber were improved after adding the content of 1%wt nano-silicon dioxide. When the fiber was heated at 230°C for 24 hours, the breaking strength and elongation increased by 2.412cN/dtex and 11.90% compared to the pure PPS fiber. Moreover, the working temperature raised by 50°C.

Structures and flammability properties of polyethylene terephthalate(PET) fibers containing encapsulated carbon materials

Abstract In this paper, carbon nanotubes (CNTs) and carbon microspheres (CMSs) have been microencapsulated to obtain microencapsulated carbon nanotubes (MCNTs) and microencapsulated carbon microspheres (MCMSs). Moreover, a series of PET fibers with CNTs/CMSs or MCNTs/MCMSs were prepared by melt spinning. Morphologic structures, mechanical, thermal, and flame retardant properties of MCNTs/MCMSs /PET fibers have been studied by TEM, SEM, electronic tension meter, DSC, TG, limiting oxygen index (LOI), and vertical flammability instruments. The results show that the tensile strength of MCNTs/MCMSs/PET fibers are increased because of better dispersion and compatibility of MCNTs/MCMSs in PET and enhanced orientation degrees of fibers, compared with CNTs/CMSs/PET fibers. Moreover, the highest values of mechanical properties are observed with 0.4 wt% content. Meanwhile, the MCNTs/MCMSs/PET fibers have good thermal stabilities and their fabrics have higher LOI value of 25.3%, reaching B1 class of China standard GB 17591-2006. Overall, this method endowed the MCNTs/MCMSs/PET fibers with the good mechanical and flame-retardant properties.

Study on the Preparation, Structure and Performances of Antibacterial PET Masterbatch

The antibacterial PET (polyethylene terephthalate) masterbatch was extruded from twin screw extruder, using silver and zinc-loading Nano-SiO2 antibacterial agent (SLSZ) as the functional material. The content of SLSZ and extruding techniques were investigated. The dispersion and compatibility of antibacterial agent in antibacterial PET masterbatch were further characterized using Scanning Electron Microscopy and Transmission Electron Microscopy. The antibacterial performances and adsorption process of the antibacterial PET masterbatch against Escherichia coli (E. coli) were tested using alive-bacteria-counting method. The experimental results indicate that when the content of SLSZ was 30 wt. %, the antibacterial agent with an average diameter of 150nm showed excellent dispersion and compatibility in antibacterial PET masterbatch, and had excellent antibacterial performances. The adsorption process of antibacterial PET masterbatch against E. coli was controlled by Coulomb force between them. As the amount of the antibacterial PET masterbatch increased, the adsorbing rate and capacity were increased.

Preparation and Properties of Antibacterial Functional PET Fibers with Ag-Loading MWNTs

With Ag-loading MWNTs antibacterial agent as functional material, the antibacterial functional PET fibers were prepared by melt blending spinning-draft one-step method. The crystallinity and the orientation of specimens were characterized by differential scanning calorimetry, polarization microscope and sound velocimeter. Moreover, the mechanical properties and antibacterial properties were measured. The results showed that the antibacterial PET fibers had good spinnability when the content of Ag-loading MWNTs less than 1.0 % (wt); compared with pure PET fibers, the degree of crystallinity, the degree of orientation and the fracture strength were improved, but the elongation was decreased; the antibacterial PET fibers exhibited excellent antibacterial properties against E.coli by the method of flask shaking.

Study on the Dyeing Behavior of Wool Fiber Treated with Nano-SiO2/Ag Antibacterial Agent

Wool fiber was firstly pretreated by nano-SiO2/Ag antibacterial agent, and then dyed with an acid dyes at low temperature by ultrasonic dyeing. Many factors had an important influence on the dye ability and the antibacterial behavior during the dyeing process of antibacterial wool fiber. The experimental results indicate that the dye-takeup rates of antibacterial wool fiber were enhanced with the increase of the concentration of nano-SiO2/Ag, the dyeing temperature, the dyeing time and the ultrasonic frequency (less than 60Hz). However, the antibacterial ratios of wool fiber were declined in the impact of these factors other than the concentration of antibacterial agent.

Enhancing the flame retardant of polyethylene terephthalate (PET) fiber via incorporation of multi-walled carbon nanotubes based phosphorylated chitosan

Abstract Phosphorylated chitosan (PCS) were first deposited on the multi-walled carbon nanotubes (MWNTs) surface via chemical modification to obtain functionalized MWNTs-based PCS (PCS-MWNTs). Then, a series of PET fibers with MWNTs or PCS-MWNTs were prepared via melt spinning. The microstructure and molecular structure of PCS-MWNTs were characterized by field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy. The morphological structures, mechanical, thermal, and flame-retardant properties of the PET fibers containing MWNTs or PCS-MWNTs were analyzed by FESEM, therogravimetry, differential scanning calorimetry, cone and electronic tension meter method. The results showed that MWNTs were coated with PCS. Compared to PET fiber, when the content of PCS-MWNTs was 0.9 wt.%, the PCS-MWNTs/PET fibers exhibited an efficient flame-retardant capacity, with the lower heat release rate and total release rate values of 81.03 kW/m2 and 39.05 MJ/m2, respectively, decreasing by 130.06 kW/m2 and 11.87 MJ/m2. The thermal stability of PCS-MWNTs/PET fibers strengthened, and the char residue increased from 7.21 to 13.52%. Compared to MWNTs/PET fiber, the crystallization property and tensile strength of PCS-MWNTs/PET fiber improved, because of the good dispersion and strong interface binding force with the PET fiber. Overall, the PCS layer endowed the MWNTs with good dispersion and flame-retardant characteristics.

Preparation of microencapsulated carbon microspheres coated by magnesium hydroxide/polyethylene terephthalate flame–retardant functional fibers and its flame retardant properties

Abstract In order to improve the compatibility between the flame retardants of carbon microspheres coated by magnesium hydroxide (MH@CMSs) and the PET matrix and improve the spinnability of the masterbatch, MH@CMSs have been microencapsulated by PET to obtain microencapsulated carbon microspheres coated by magnesium hydroxide flame retardants – MMH@CMSs.Morphologies and structures of MMH@CMSs have been studied by scanning electron microscope (SEM), transmission electron microscopy (TEM), and FTIR, which showed that an organic shell layer of PET as capsule wall was coated on the surface of MH@CMSs. A series of MMH@CMSs/PET fibers with different MMH@CMSs contents were successfully prepared through the melt-spinning method. The morphology and structure of MMH@CMSs/PET fibers were characterized by SEM and FTIR. The flame retardancy of MMH@CMSs/PET fibers was determined via limiting oxygen index (LOI) test and cone calorimeter. Results showed that the MMH@CMSs/PET fibers possessed optimum flame retardancy when the MMH@CMSs content is 0.6 wt.%, at which the LOI reached a maximum of 25.8, and the pk-HRR, total heat release, and total smoke release were reduced by 27.4, 20, and 13.6%, compared with pure PET fibers, respectively. Moreover, the flame-retardant mechanism was studied by thermogravimetric analysis, thermogravimetric analysis-infrared spectrometry, and the SEM of the residue char, which disclosed that MMH@CMSs enhanced the thermal stability of PET fibers, and promoted PET fibers to form a dense and continuous protective char layer that effectively blocked heat transfer and combustible gas release.

Synthesis of a novel microcapsule flame retardant and flame-retardant property of its composites with poly (ethylene terephthalate)

A novel halogen-free microcapsule flame retardant, carbon microspheres coated with magnesium hydroxide microcapsule and polyethylene terephthalate (PET) (MMH@CMSs) were synthesized. Then, the prepared MMH@CMSs were introduced into PET resin to prepare MH@CMSs/PET composites. The morphology and structure of MMH@CMSs were characterized by SEM, TEM and FTIR, which showed that an organic shell layer of PET as capsule wall was coated on the surface of MH@CMSs. The prepared MMH@CMSs/PET reached the LOI of 27.4 with only 1wt.% MMH@CMSs, and UL94 test results showed that MMH@CMSs/PET reached UL94 V-0 rating when the dosage of MMH@CMSs was over 1.5wt.%. Tensile properties results showed that the microcapsule treatment of MH@CMSs significantly improved the mechanical properties of the composite, and the tensile strength of 1wt.% MMH@CMSs/PET increased by 83.9% compared with 1wt.% MH@CMSs/PET. The flame retardant mechanism was studied by cone calorimeter measurement, TGA, TGA-FTIR, SEM and FTIR. The results disclosed that MMH@CMSs enhanced the thermal stability of PET in air, and promoted PET to form a dense and continuous protective char layer that effectively blocked heat transfer and combustible gas release.

Functionalized multiwalled carbon nanotubes by loading phosphorylated chitosan: Preparation, characterization, and flame-retardant applications of polyethylene terephthalate

Novel flame-retardant phosphorylated chitosan-multiwalled carbon nanotubes (PCS-MWCNTs) were obtained by the loading of PCS on the surface of MWCNTs by a chemical deposition cross-linking method. A series of polyethylene terephthalate (PET) composites were prepared by melt compounding with MWCNTs or PCS-MWCNTs to investigate the flame-retardant properties. Field-emission scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared (FTIR) spectrometry were employed to characterize the morphology, chemical structure, and functionalization effect of MWCNTs. The coating degree and thermal stability of PCS-MWCNTs were investigated by thermogravimetric analysis (TGA). Thermal decomposition products after TGA and flame-retardant properties of PET composites were characterized by FTIR and CONE measurements, respectively. The results indicated that PCS is loaded on the MWCNT surface. Modified PCS-MWCNTs exhibited better dispersion and efficient flame retardancy. TGA data indicated that PCS-MWCNTs can enhance the onset temperature of PET and increase the amount of the char residues. The char residue with 1 wt% PCS-MWCNTs/PET increased from 12.62% (pure PET) to 15.46%. The analysis of the decomposition products and morphology of the char residue indicated that PCS-MWCNTs not only retain the effect of alternating couplet carbon (C) and physical barrier by MWCNTs, but also form P–C compounds, improving the flame retardancy of PET. CONE tests demonstrated that the PCS-MWCNTs lead to the efficient decrease in the flammability parameters, such as the heat release rate (HRR), total release heat rate (THR), total smoke production (TSP), mean mass loss rate (MMLR), and the total combustion time. The peak HRR value decreased from 513.22 kW m−2 to 341 kW m−2. The THR, TSP, and MMLR values decreased by 20.38 MJ m−2, 1.1 m2, and 1.32 g s−1, respectively. The total combustion time decreased by 98 s, from 388 s to 290 s, indicating that PCS-MWCNTs extinguish fire.