The Research On Modification And Dyeing Performance Of Kapok Fiber

Kapok fiber, as a nature non cotton fiber, has the structure of hollow thin wall,features of health caring, warm keeping and weight lessening. However, applications of the Kapok fiber was, for a long time, restricted to cotton filling(ex: filling up in quilt, pillow, and cotton stuffed coat), to heat-insulated materials, sound-absorbed materials and floating materials producing etc. Applications in clothing and apparel were rarely reported, thus the Kapok fiber could be considered as the only natural cellulose fiber which has not been widely used in clothing and apparel industry. A worse spinnability and a low dyeing rate could account for this situation. In recent years, the problem of the spinnability has been effectively solved, while the dyeing problem is still not attacked. Research on the Kapok fiber dyeing properties is almost a blank world-widely.In this paper, a fiber surface modification with rare earthand, positive ion modifier,hyperbranched polymers and plasma surface treatment technology have been applied onto the Kapok fiber and how they improve dyeing ability of reactive dyes on Kapok fiber has been studied. The main studies stated as below:1. Effects of the rare earth modification on the kapok fiber and the dyeing property of reactive dyes :The improvements of the rare earth modification made to the dyeing ability were studied by varying the rare earth raw material, specifying the rare earth processing method and compounding the rare earth mordant. The result shows that, 1.the lanthanum has the best mordant effect than the cerium and the neodymium in a rare earth mordant process of reactive dyes NOVACRON RED FN-R; 2. It is more reasonable to adopt the one bath dyeing process; 3. 1:1 was a suitable ratio for the Lanthanum chloride and citric acid mordant with citric acid being complexant; 4.the dyeing rate and the fixation of NOVACRON RED FN-R on the kapok fiber increase from 38% to 70% and 29%to 68%, respectively after a mordant dyeing(0.8 owf mordant, 1%dyes, Na Cl 10~20g/L, bath ratio 1:50,alkaline agent 10g/L was added 30 min after dyeing at 60 oC, fixing color for60min); 5. soaping fastness increases from level 4 to level 4~5; 6. dyeing value K/S is unchanged.2. Effects of the positive ion modifier on the kapok fiber the dyeing property of reactive dyes :A self-made positive ion modifier was applied to the Kapok fiber. An Infrared spectrum and a small angle X-Ray diffraction were used to feature the molecule structure of the kapok fiber before and after modification. Result shows that:positive ion modifying process: 10%(o.w.f) modifier; p H value of modified solution: 10~12; modified solution temperature: 75?; modification time: 45 min.Dyeing with a reactive dyes NOVACRON RED FN-R after modification: dyes0.5~1.0%(o. w. f.);temperature 40?;Na Cl 20g/L; after dyeing for 30 min, 10g/L Na2CO3 was added to fix color for 90 min. Dyeing rate can reach above 90% on the kapok fiber.In a modified kapok fiber infrared spectrum, the absorption peak reduced or even disappeared in the region of 1510~1245cm-1which belongs to a C-O stretching vibration( C-Ost) and an-OH inner surface bend, or an inner surface shear vibration(O-H?. It indicates that the long chain aliphatic hydrocarbons-(CH 2) 11-CH 3 in the modifier was grafted onto the kapok fiber molecule, which restricted the O-H inner surface bend or shear vibration. A calculation of the grain size and the relative crystallinity before and after modification was carried based on Segal empirical method. The micro-structure of the kapok fiber after modification was hardly changed according to the calculation. The granularity and potential analysis showed that the Zeta electric potential in the water solution of modified kapok fiber increased with the growth of positive ion modifier density.3. The synthesis of hyperbranched polymers and it's application in the dyeing of kapok fiber with reactive dyes:Couple-Monomer methodology was applied to synthesize the water-soluble polymer terminal amino hyperbranched polymers(HBP-NH2), where methacrylate and diethylenetriamine as raw materials, methanol as solvent. The synthesized HBP-NH2 was then combined with the self-made positive ion modifier, to form the quaternary ammonium hyperbranched polymers(HBP-HDC). UV spectrophotometer, Infrared spectrophotometer, NMR spectrometer and ubbelohde viscometer were used to feature the synthesized product. Results are listed as below: infrared and UV spectroscopy analysis confirmed the success of synthesize of HBP-NH2; NMR spectrum analysis confirmed that positive ion modifier has been successfully grafted onto HBP-NH2,which formed quaternary ammonium salted hyperbranched polymers HBP-HDC;HBP-NH2, as well as HBP-HDC has a favorable UV absorption property at245 nm and 195 nm wavelength; HBP-NH2 and HBP-HDC have a high solubility in some strong solvents such as water and ethanol, while in acetone and chloroform, the solubility is relatively low; the intrinsic viscosity [?] of HBP-NH2 is 4.313ml/g.After a HBP-NH2 modification, the dyeing rate of reactive dyes NOVACRON RED FN-R onto the kapok fiber reaches around 75%. Increase in fixation and K/S value has also been observed.In order to improve the fastness of HBP-NH2 onto kapok fiber, semi-oxide modification was carried. A new absorbing peak at 1729 cm-1which belongs to the C=O stretch vibration in aldehyde was observed in infrared spectrum analysis.The emergence of aldehyde indicates the success of semi-oxide modification. The dyeing rate of reactive dyes NOVACRON RED FN-R On the HBP-NH2 modified semi-oxide kapok fiber, the reactive dyes NOVACRON RED FN-R has a dyeing rate of 85%, a color fixation of 65%, K/S value of 6 and a wash fastness level of4.After a further HBP-HDC modification, reactive dyeing rate could reach as high as 100% and color fixation could go up to 77%. Increase in K/S value and washing fastness have also been observed.4. Effects of plasma treatment on the kapok fiber dyeing property and a study of hydrophobic reason of the kapok fiber:On the plasma(air plasma) treated kapok fiber, the reactive dyes NOVACRON RED FN-R has a dyeing rate of 84%, a color fixation of 65%, a washing fastness level of 4~5 and a K/S value of 6.3. While a 80% dyeing rate, 62% color fixation,4~5 level washing fastness and 6.7 K/S value can be achieved on the kapok fiber which were treated under oxygen plasma. And 76% dyeing rate, 57% color fixation, 4 level washing fastness and 5.4 K/S value can be achieved on the kapok fiber which were treated under nitrogen plasmaThe kapok fiber structure before and after plasma treatment were observed though a SEM. The results showed that there are etchings appearing on the surface of plasma treated kapok fiber. The etching degree was related to the type of plasma.In air excited, oxygen excited or nitrogen excited plasma, a large amount of etchings are generated and some of them were deep etching. Also, dynamic contact angle observation showed that the contact angle decreased from 119.19° to94.6°. Furthermore, the XPS was used to test the changing of element content on the kapok fiber surface The result showed that the content of C-C group on the fiber surface was decreased after being processed in air, oxygen and nitrogen plasma, while the content of C-O group was increased. Even the C=O group was observed in some samples. This result implied that the kapok fiber became more hydrophilic because the hydrophobic groups such as C-C group decreased, as the hydrophilic group such as C-O and C=O increased. The-OH group on fiber surface was increased by 50% and 80% after being processed in oxygen plasma and air plasma, respectively. But for nitrogen plasma treated fiber, the-OH group deceased by 53%. And for both case, the-C=O increased and the-O-C=O group deceased. This result confirmed the conclusion that the plasma treated kapok fiber became more hydrophilic in oxygen plasma and air plasma. Because the content of-OH group which is known as a highly hydrophilic group, was dramatically increased on the plasma treated kapok fiber.5. The analysis of the poor dyeing performance of kapok fiberBesides with low cellulose content, the dyeing property of the kapok fiber is related to its form feature and surface element contents. That the extremely smooth outer the kapok fiber has, and the relatively high content of hydrophobic groups(-C-C,-C=O, and-C-C=O) on the fiber surface, cause the low dyeing rates.Because the dyes cannot be easily spread onto its' surface and thus the fiber cannot get immersed into the dyes. For summary, the bad dyeing property is related to low cellulose content, the hydrophobic and lipophilic feature of the kapok fiber, which makes it hard for dyes to be spread and further moist the kapok fiber.