Enchancing the Chemical and Mechanical Properties of Unsaturated Polyster Resin

Abstract

Recent research in medical field has reviled that phthalates are carcinogenic. Phthalates are derivatives of phthalic acid, are produced by reacting phthalic anhydride with appropriate alcohols. Phthalates have been termed as metabolic disruptors. Longer exposure of many years to these metabolic disruptors can deregulate the complex metabolic pathways in a subtle manner. Resulting in the damage to the vital organs like liver and kidneys. The unsaturated polyester resins (UPRs) used in the manufacturing of products which come in contact with human foods or useables should be phthalate free. In August 2008 a legislation was enacted in USA under Consumer Product Safety Improvement Act, public law 110-314. Under this law, it became unlawful for any person to manufacture or sale, distribute or import in USA any children toys or child care article that contains 0.1% of Di ethyl hexyl phthalate ( DEHP) , Di butyl phthalate( DBP) or Benzyl butyl phthlate (BBP). A similar restriction was imposed in Europe in 2009. In view of above we worked to develop phthalate free resins. We had to eliminate the sources of phthalates i.e. phthalic acid and its anhydrides also the solvents like Di butyl phthalate having phthalate molecules .This deteriorates the mechanical properties, to overcome this problem step by step reduction of phthalic anhydride was done through a series of recipes. The reaction time, temperature and raw materials were monitored to achieve the required branching of the molecular structure leading to improved mechanical properties of the product. The UPR developed through this experimentation is free of phthalates and exhibits tensile strength in the range of 61 MPA or higher. For development of phthate free resins with acceptable mechanical properties, we used an experimental set up comprising a glass reactor, equipped with a mechanical anchor type stirrer, heating system having a range from 0-400 0c, covered with a glass lid with five holes, to accommodate, thermocouple, thermometer, condenser, inlet for chemicals. The chemicals used include , phthalic anhydride, maleic anhydride, adipic acid, fumaric acid, di ethylene glycol, mono ethylene glycol, neo pentyle glycol, styrene monomer, potassium hydroxide, hydroquinone, waxes, methyl ethyl ketone per oxide, cobalt octoate, methyl ethyl ketone . a Taking into account the properties of the different raw materials and their stichiometeric requirements to carry out the polymerization reaction properly we established different recipes and produced several batches of UPR. These resins were then used as a matrix to produce GRP sheets, chopped strand matt of 450 gms/m2 was used as reinforcement medium, for surface strength we used tissue mat of 50 gms/m2. Sheets were laminated in a glass mould, thickness being 3mm and size 1 ft 2 . From above GRP sheets, we arranged sample strips of 127*25.4*2.5 mm3 in accordance with the requirements of ASTM D3039, to measure tensile strength on UTM TIRA 2810.Similarly sample strips having dimensions 101.6*13*2.5 mm3 in accordance with the requirements of ASTM D3479 were developed to determine the flexural strength. Our recipe number 6 and 7, having no phthalates as raw materials reached the maximum tensile strength of 62 N/mm2. and flexural strength of 100 N/mm2 these mechanical strengths are good enough to produce a variety of GRP products with phthalates free status. An application titled “PHTHALATE FREE UNSATURATED POLYESTER RESIN”, has been submitted to intellectual Property Organization (IPO) Pakistan for grant of patent rights (Application No. 543/2014 dated 24.07.2014).