Zaisheng Cai

Synthesis of polypropylene carbonate polyol-based waterborne polyurethane modified with polysiloxane and its film properties

Waterborne polyurethane (WPU) prepolymer was synthesized using polypropylene carbonate polyol as the soft segment, dimethylolpropionic acid as a hydrophilic chain extender and isophorone diisocyanate. The prepolymer was modified with aminoethyl aminopropyl dimethicon (AEAPS) to prepare a series of WPU emulsions and films. The structures and the films properties of the WPUs were characterized by Fourier transform infrared spectrometry, gel permeation chromatography, atomic force microscopy, X-ray diffraction, thermogravimetric analysis, dynamic thermomechanical analysis, X-ray photoelectron spectroscopy, water contact angles and water absorption. It was found that pure polypropylene carbonate WPU had a wide molecular weight distribution and its microphase separation was not apparent between its hard and soft segments. The WPU also had a high glass transition temperature (24.5 °C) and its film had a high damping property (tan δ>0.40) from 12 °C to 42 °C. Modification with polysiloxane had enlarged the molecular weight, narrowed the molecular weight distribution and resulted in the microphase separation between the hard and soft segments of WPUs, and this amplified the damping temperature of the WPU films. Along with the increasing utilization of polysiloxane the thermolysis, water resistance and water contact angles of WPU films were improved while the orientation of their structure regularity declined.

Study on chemical modification and dyeing properties of jute fiber

Glycidyl trimethyl ammonium chloride (Glytac) was used as a modifier for surface modification of jute fiber. Modifying effect factors such as Glytac concentration, sodium hydroxide concentration, temperature, and time were optimized as follows: Glytac concentration, 60 g/L; sodium hydroxide concentration, 20 g/L; temperature, 60°C; and treatment time, 60 min. After the Glytac treatment, the zeta potential value on the fiber surface increased over a pH range of 3.5–9.5. Compared to the raw jute fibers, the modified jute fibers could be dyed with reactive dye using a small amount of salt and alkali and had higher K/S values under the same dye concentration range of 0.5–8.0% (o.w.f.). Furthermore, the dyed Glytac-treated jute fibers had higher exhaustion, fixation, and total fixation and better washing fastness and dry rubbing fastness than those of raw jute fibers.

Studies on the remedial effect of transglutaminase on protease anti‐felting treated wool

Oxidative protease treatment can improve anti‐felting of wool and also result in its loss of strength. In this study, one kind of microbial transglutaminase (MTG) was applied in the wet process of wool fabrics. The results indicated that transglutaminase could remediate wool damage following hydrogen peroxide and protease anti‐felting finishing, resulting in an increase in wool fabric strength and a decrease in alkali solubility. In addition, the evidence was provided that some cross‐linking through transglutaminase had occurred in the wool protein. The SEM showed that the scale structure became smoother after MTG treating. Analyzing of the thermal behavior revealed that the thermal stability of the MTG‐treated wool was enhanced. UV‐spectrum analysis suggested a decrease in protein extracted from the intercellular cements of the treated wool with MTG.

Synthesis of blocking polyether silicone oil and silicone blocking waterborne polyurethane and application to cashmere knitted fabric finishing

Blocking polyether silicone oil is prepared through a reaction between amino-terminated polyether and epoxide-terminated polyether silicones. A fabric finishing agent made with cationic waterborne polyurethane modified by silicone oil is prepared by using polytetramethylene glycol as the soft segment, N-methyl diethanolamine as the hydrophilic unit, and tailor-made blocking polyether silicone oil as a chain extender for modification purposes. The finishing agent and the blocking polyether silicone oil are jointly used to treat cashmere knitted fabric. It is found that resistance to pilling of the treated cashmere knitted fabric is improved from a scale of 2–3 to 4 and its washing shrinkage rate is reduced from 11.2% to 3.3%. The treated cashmere knitted fabric has good hydrophilic ability, high water vapor and air permeabilities, and a soft handle. Moreover, the color of the fabric remains almost unchanged after finishing and the durability of the finishing properties is excellent.

Dyeing of male silk fibers with reactive dyes

A study of the dyeing behavior of male silk fibers (obtained from silk cocoons spun by male worms) was undertaken. Normal silk (composed of filaments made by male and female worms) was also dyed for comparison purposes. Physical and chemical characteristics of silk which may affect dyeing behavior were also investigated using scanning electron microscope (SEM) and Fourier transform infrared (FT‐IR) spectroscopy. From the results obtained in this research work, it can be concluded that male silk fibers tend to be finer than the normal silk fibers. The male silk fibers’ dye uptake was tested and found to be lower than that of normal silk. Adjustment of exhaustion salt and dyeing temperature to higher levels had significant improvement on dye uptake and K/S value for male silk.