Modification of Cellulosic Fibres with Synthesized Functional Chitosan Derivatives for Ecofriendly Textile Products

Abstract

Cellulosic fibres, especially jute and cotton, are the most abundant agriculturalrenewable raw materials. They have the qualities of stiffness, low elasticity,susceptibility toward sunlight and microbial attacks etc. which are hindrances on use of those fibres. Chitinous wastes from different sources and fish processing industries always pollute the environment in different ways. A huge amount of prawn shell wastes is deposited as sea food waste in different areas of fish processing industries which have virtually no demand for its use. These indigenous, cheap and available chitinous wastes can easily be used to produce valuable chitosan (Ch) and its functional derivatives, especially N-octyl chitosan (NOCh), carboxymethyl chitosan (CMCh), carboxymethyl chitosan-grafted-acrylic acid (CMCh-g-AA), N-(2-hydroxy) propyl-3- trimethyl ammonium chitosan chloride (HTAChC) and N-methylolacrylamide-N-(2- hydroxy) propyl-3-trimethyl ammonium chitosan chloride (NMA-HTAChC), which are commercially important and will ultimately reduce pollution problems. The purpose of this research was to develop soluble chitosan and water soluble modifiers, based on that chitosan, which have excellent textile modification properties. These new products can substitute for toxic textile chemical modifiers. In addition, cellulosic fibres like jute and cotton can enhance their effectiveness for intensified textile use through ecofriendly modification. In addition, the dyeability of unmodified and modified jute and cotton fibres, including their tensile strength, moisture absorbance, swelling capacity, chemical resistance, dye-ability and colour fastness properties were investigated. Chitosan was prepared from chitin, which was obtained from prawn shell waste by a series of chemical processes involving demineralization, deproteinization,decolouration, and deacetylation. Chitosan (Ch) and its said derivatives were successfully prepared by deacetylation of chitin, reductive amination of chitosan, carboxymethylation of chitosan, graft copolymerization of CMCh, quarternization of chitosan and acrylamidomethylation of HTAChC, respectively, at ambient condition, which were also optimized. The optimized condition for deacetylation is 50% alkalinesolution, solid to liquor ration 1:50 (w/v), at 800C for 4h, in presence of ethanol withreflux system. Lower yield and substitution to higher yield and substituted products were obtained from single step to multistep reactions. Chitosan and its synthesized derivatives were characterized with their physicochemical properties, degree of deacetylation (DDA), solubility, viscosity, molecular weight, nitrogen content, degree of substitution (DS) and degree of quarternization (DQ) were investigated. The obtained DDA of prepared chitosan was 85% and DS of prepared NOCh and CMCh in different steps of reaction ranges from 0.008 to 0.051 and 0.54 to 1.44 and DS was determined by titrimetric analysis. The moisture absorbency, ash content and molecular weight of prepared chitosan, NOCh, CMCh, CMCh-g-AA, HTAChC and NMA-HTAChC were 9.79%, 8.17%, 13.76%, 6.83%, 18.43%, 17.71% and 1.34%, 0.75%, 14.87%, 8.39%, 0.84%, 0.79%, respectively and 1,39,958.73 Da for chitosan, 1,62,181 Da for NOCh, 2,06,179 Da for CMCh, 3,10,270 Da for CMCh-g-AA. The synthesized chitosan, NOCh, CMCh, CMCh-g-AA, HTAChC and NMA-HTAChC are characterized by Fourier Transform Infrared Spectroscopy (FTIR) which showed prominent peaks at 1659 cm-1 for (-CO) at 1600 cm-1 for (–NH2) groups of chitosan, at 1516 cm-1 for corresponding to C-H stretching into methyl groups of NOCh, at 1384 cm-1 for symmetrical -COO− group and near at 1741 cm-1 for −COOH group of CMCh and at 1319 cm-1 for poly (AA) of CMCh-g-AA, at 1480 cm-1 for C-H bending of trimethylammonium group of HTAChC and at 1670 cm-1 for C=O stretching and 1545 cm-1 for N–H bending of NMA-HTAChC which confirms the synthesized derivatives. The structure of chitosan, NOCh, CMCh, CMCh-g-AA, HTAChC and NMA-HTAChC were investigated by FTIR and 1H NMR. Jute and cotton fibres were modified with prepared chitosan and its functional derivatives. Optimized modification conditions for jute and cotton with chitosan, NOCh, CMCh, CMCh-g-AA, HTAChC and NMA-HTAChC where modifier concentration 20% on the basis of weight of fibre, 5% K2S2O8, 5% FeSO4 based on the weight of monomer, solid liquor ration of 1:50 temperature 550C and time for 60 min. Grafting of chitosan, NOCh, CMCh, CMCh-g-AA, HTAChC and NMA-HTAChC on cellulosic fibre surfaces were confirmed by graft yield percent for jute 6.79%, 6.12%,12.06%, 9.39%, 10.69% and 14.74% and for cotton 11.78%, 10.75%, 16.77%, 12.06%, 14.56% and 18.86% respectively. FTIR at 1600 cm-1 for the NH2 group, at 1516 cm-1 for C-H stretching, at 1740 cm-1 for –COOH group, at 1319 cm-1 for poly (AA), at 1480 cm-1 for C=O stretching and 1545 cm-1 for N–H bending respectively due to incorporation of said modifier on cellulosic fibres. The surface of fibres was investigated by Scanning Electron Microscopy (SEM) and modified fibres surface was smoother than unmodified fibres. X-ray diffraction pattern showed moderate crystallinity and the order is as follows: chitosan modified > NOCh modified > CMCh modified > CMCh-g-AA modified > HTAChC modified > and NMA-HTAChC modified cellulosic jute and cotton. The thermal behavior of modified fibres was also investigated by TGA, DTA and DTG analysis. On the basis of initial decomposition temperature (Ti) thermal stability of those jute and cotton fibres follows the order, chitosan modified > CMCh modified > unmodified > NOCh modified > HTAChC modified > CMCh-g-AA modified, NMA- HTAChC modified and chitosan modified > unmodified > HTAChC modified > NOCh modified > NMA- HTAChC modified > CMCh modified > CMCh-g-AA modified respectively. It was observed that textile modifying properties of NMA-HTAChC is comperatively better than that of other functional chitosan derivatives due to higher fibre affinity of NMA-HTAChC. It was also observed that over all modification showed improved chemical resistance to acid and alkali, moisture absorbency, tensile strength, moderate thermal stability and reduced swelling resistance in different solvent, compared to unmodified jute and cotton fibres. The modified fibres were dyed with reactive dyes (Reactive Orange 14 and Reactive Brown 10) and direct dyes (Direct Orange 31 and Direct Yellow 29). Dyeing of modified and unmodified jute and cotton fibres revealed that dye exhaustions were increased up to 10% due to modification through sorption of prepared chitosan and its functional derivatives causes the increment of reactive sites of the fibres which also enhanced the sunlight, wash, alkali and acid fastness of the dyed fibres. Chitosan and its functional derivatives are safe, biocompatible and ecofriendly substances for human use so those are valuable as textile materials for textile and garment finishing.