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Synthesis of low molecular weight (on) phosphorus polyacrylic acid

2015-07-03 23:34:57

        With the extensive application of polyacrylic acid, polyacrylic acid molecular weight in different areas have different needs, phosphorus, controllable molecular synthesis has become a basic indicator of polyacrylic acid. Taking water as solvent, acrylic monomers, ammonium persulfate as the initiator synthetic phosphorus polyacrylic acid, gel chromatography of synthetic phosphorus polyacrylic acid molecular weight monitored and investigated monomer concentration, initiator concentration, Effect of chain transfer agents, reaction temperature and the molecular weight modifier selection and other factors on phosphorus polyacrylic acid molecular weight, molecular weight synthetic phosphorus to arrive at more favorable terms of polyacrylic acid.

        Phosphorus polyacrylic acid (PAA) is an environmentally friendly functional polymer materials, versatile, biodegradable and environmental pollution. Different molecular weight products have different properties and uses, especially in 1000-8000 weight average molecular weight of PAA, the main act DISPERSOR can be used in industrial water treatment scale inhibitor and dispersant (sodium polyacrylate paas) , paper, printing and dyeing, petrochemical, detergent additives, and other fields.
        PAA using conventional industrial production of sodium hypophosphite as chain transfer, resulting in products containing phosphorus, heavy use causing water eutrophication, leading to water pollution. Phosphorus process to use isopropanol as chain transfer agent, the main problems is higher than the residual monomer product, and the product needs to remove any residual alcohol by distillation, in some cases will affect the use. In this paper, water solvent method, using the new chain transfer agent to regulate the molecular weight synthetic AYA PAA, and to explore the effects of various factors on the PAA molecular weight.
        First, the experimental section
        1, reagents and equipment
        Acrylic acid; ammonium persulfate; chain transfer agent AYA; molecular weight modifier CC; molecular weight modifier CF; constant temperature circulating water bath; current pump; 20L glass reactor; gel chromatography PL-GPC50
        2. Synthesis step
        Join in 20L glass reactor equipped with a stirrer, a reflux condenser, a thermometer, a circulating water bath is sure to come in deionized water, stirring constantly heated to a certain temperature, adding an appropriate amount of chain transfer agent and molecular weight regulator, start acrylic acid solution was added dropwise, a solution of the chain transfer agent and initiator solution, dropwise with constant acceleration pump control, the acrylic acid solution in 2h, after the chain transfer agent solution and initiator solution addition was complete, incubation period to give a colorless to pale yellow transparent PAA solution.
        3 Analysis and Testing
        3.1 molecular weight determination
        PAA measured by the British company's PL gel chromatography PL-GPC50 weight average molecular weight
        3.2 monomer conversion
        Determination of the amount of residual monomers using Br2-KI microtiter method. Specific methods: After completion of the polymerization reaction sampling, weighed 0.2g (accurate to 0.0001g) sample into 250mL iodine bottle, add 50mL distilled water, set 45 ℃ water bath heated to dissolve completely, precision by adding 20mL0. 1mol / L bromine solution and 5mL1: 1 hydrochloric acid solution, Shake, Mesa, dark place at room temperature for 15min, adding starch indicator and continue the titration until the blue color disappears is the end, my colleagues blank test.
        Acrylic monomer conversion rate is calculated as follows:

        Where: V0: blank sample consumption of sodium thiosulfate standard solution volume (mL)
                    V: consumption of sodium thiosulfate standard titration of the sample solution volume (mL)
                    c: concentration of standard solution of sodium thiosulfate (mol / L)
                   m: mass of sample (g);
                   P: Sample Solid content (%)

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