Acrylamide Grafting on Banana Fibres for Increased Water Absorbency and Retention

Acrylamide Grafting on Banana fibres Final Year B.Tech Project by Ketki Chavan ( B.Tech – F.T.P.T.) (2014) Banana fibres • Obtained from Pseudo-stem of fully grown banana plants, usually extracted after harvesting of fruits and uprooting of the grown plant. • Chemical Composition: – Cellulose: 63 to 65% – Hemicellulose: 20 to 22% – Lignin: 12 to 16% (chemical composition varies with the variety of the plant and geographical conditions where the plant was grown) Characteristics of Banana fibres • Lignocellulosic fibre • Strong fibre, high tensile modulus, low elongation at break • Average fineness 2400Nm • Light weight • Good spinnability • Strong moisture absorbing ability; absorbs as well as releases moisture very fast. • Eco-friendly fibre. Acrylamide Monomer • IUPAC name: Pro-2-enamide • Chemical formula: C3H5NO • Structure: CH2=CH-C=O NH2 • White odourless crystalline solid • Water, ether, ethanol and chloroform soluble • Carcinogenic if inhaled • Used for Polymer preparation or as Cross-linking agent. Polyacrylamide is not carcinogenic. Introduction to Grafting of cellulosic fibres A graft copolymer consists of a polymeric backbone with covalently linked polymeric side chains. In principle, both the backbone and side chains could be homopolymers or copolymers. Grafting can be carried out in such a way that the properties of the side chains can be added to those of the substrate polymer without changing the latter. But with other types of grafting, the crystalline nature of the cellulose, for example, can be largely destroyed. This releases the natural absorbency of cellulose as well as adding that of the hydrophic side chains leading to very high water absorbency. This can be accomplished by a decrystallization procedure after grafting or, in the case of the hydrolyzed grafted products, by the process itself. Methods for synthesis of Graft Copolymers 2 methods: 1. Side chain polymer A could be linked directed by a suitable chemical reaction to the backbone polymer B 2. Backbone polymer B could have active sites such as free radicals or ions formed upon it. These can then be used to polymerize a suitable monomer to produce the side chains of polymer A. • The first method is difficult except in solution and perhaps the most successful has been by treating "living" polymers to a suitably reactive backbone. A good example is the polystyrene- polyvinyl pyridine system where both polymers have been used as backbones and side chains • Advantages of this approach: – Simple Synthetic method – Fewer problems of homopolymer formation – Length and number of side chains could be controlled – Superior properties, including absorbency, because of the higher degrees of substitution and shorter side chains • Disadvantages of this approach: – difficulty of inducing polymer reactions Types of grafting The second general method is much more successful and a large number of techniques have been developed. Essentially, these are free radical processes. Techniques: • Chain Transfer Method • Direct Oxidation • Initiators for Polysaccharide • Polysaccharide derivatives as Co-monomers • Direct Radiation Chain Transfer Method • In this method radicals are created on the polysaccharide backbone including cellulose and starch by use of the reactions: R can be the growing chain of polymers formed by polymerization with a radical initiator in the presence of the polysaccharide, or by the primary radical from the initiator itself. The efficiency of this type of grafting reaction is also greatly improved by increasing the ratio of polysaccharide to monomers such as by using a simple swollen system or with the correct choice of swelling agents. Direct Oxidation • A number of oxidizing agents have been found to interact with polysaccharides to form macroradicals which, with monomer, form graft copolymers. The most successful and best studied of these is ceric ion. Briefly the reaction is as follows: • In fact the reaction is much more complicated and the oxidation- reaction is often preceded by complexing of the ceric ion by the polysaccharides. • Other oxidizing agents studied include pentavalent vanadium, manganese(III) and manganese(IV) ions. [...]... out in atmospheric conditions & not in inert N2 atmosphere • Variation in Parameters: (MLR used 1:50) PARAMATER VALUES Initiator Concentration (% wt/vol) 0.1, 0.2, 0.4 Monomer Concentration (% wt/vol) 1,2,3 Temperature of Grafting (°C) 30,70,100 Time for Grafting (hrs) 0.5,1,1.5,2,2.5,3 Plan to optimize Initiator & monomer concentration, temperature of grafting and Time Duration OF GRAFTING Treatments... add -on were analysed [refer results and discussions] Good values of % weight add -on were observed between temperatures 70 and 100°C when the monomer concentration was 2 and 3% wt/vol and initiator concentration was above 0.2% wt/vol Optimising temperature and monomer concentration: 28 29 30 31 32 33 34 Treatment Initiator 35 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 2 2 2 2 3 3 3 3 70 80 90 100 70 80 90 100 Conc... Calculation of % Weight Add -on: • The fibres after bleaching and before grafting are dried in an oven at 105°C for 30 mins and then weighed This weight is abbreviated as Wb • The fibres obtained after Hydrolysis and Precipitation are also dried at 105°C for 30 mins and then weighed This weight is abbreviated as Wg Now, % Weight Add -on = [ ( Wg - Wb ) / Wb ] x 100 Testing procedure 2 Calculation of Water Absorbency: ... Conc (%wt/vol) Monomer Conc (%wt/vol) Temp (°C) • Again the samples with max % weigth add -on were treated to be the optimum and so by maintaining these conditions the following plan was used for optimization of Time Duration for Grafting: Treatment 36 37 38 39 40 41 Initiator 0.2 0.2 0.2 0.2 0.2 0.2 3 3 3 3 3 3 70 70 70 70 70 70 0.5 1 1.5 2 2.5 3 Concentration (% wt/vol) Monomer Concentration (% wt/vol)... Cellulose Grafting for Enhanced Water Absorbency The grafting techniques for cellulose superabsorbency are broadly classified under 2 types: • Saponifiable grafts to cellulose • Direct grafting of acrylic and methacrylic acids to cellulose • Saponifiable grafts to cellulose: In this approach monomers such as acrylonitrile, acrylamide, and various acrylate and methacrylate esters and their mixtures... prepared and all of them were Hydrolyzed and Precipitated • Procedure for Hydrolysis: Hydrolysis treatment of the grafted fibres is carried out using an 8% (wt/vol) NaOH solution at 70°C for 2 hours in atmospheric conditions • Procedure for Precipitation: Precipitation is done in Absolute Alcohol after completion of the Hydrolysis treatment Use of safety goggles and gloves is a must during precipitation... saponification to sodium polyacrylate or methacrylate Non-saponifiable co-monomers are sometimes also used • Direct grafting of acrylic and methacrylic acids: A direct method is initiation by high energy radiation Since these monomers homopolymerize rapidly with radiation, the pre-irradiation method is the most convenient In principle, however, direct irradiation of cellulose in the presence of monomer... proper face masks, Safety Goggles and Hand Gloves is a must during the Precipitation process as Alcohol is involved in the process and a continuous exposure to the precipitating medium may cause severe headache and watering of eyes along with yellowing of hands Results & Discussions Temp, Monomer & Initiator Conc Optimization Sample No / Weight Add -on Water Absorbency Treatment No (%) (gm/gm of grafted... concentration (% wt/vol) Monomer concentration (% wt/vol) Temperature (°C) 30 Treatment 16 17 18 19 20 21 22 23 24 25 26 27 Initiator 0.1 0.2 0.4 0.1 0.2 0.4 0.1 0.2 0.4 0.1 0.2 0.4 3 3 3 1 1 1 2 2 2 3 3 3 70 70 70 100 100 100 100 100 100 100 100 100 concentration (% wt/vol) Monomer concentration (% wt/vol) Temperature (°C) In all experiments, time duration was kept constant at 2 hours The conditions... polysaccharide and adding the monomer, plus any swelling agent needed, subsequently This method is very valuable for monomers such as acrylic acid which polymerize rapidly with radiation Cellulose Grafting for Enhanced Water Absorbency Cellulose is the key raw material for most commercial absorbent products Because of the constant demand to increase the absorbency of these products, there has been a concomitant . introduction of a combination of ionic and non-ionic monomer grafting approach, focusing on meeting the requirements of disposable absorbent products. Cellulose Grafting for Enhanced Water Absorbency The. there has been a concomitant demand for improvement in absorbency of natural and regenerated cellulose fibres. The absorbency of cellulose fibres has been improved by modification of their chemical. radiation. Cellulose Grafting for Enhanced Water Absorbency Cellulose is the key raw material for most commercial absorbent products. Because of the constant demand to increase the absorbency