Polymer Science and Technology Division, Research Institute of Petroleum Industry (RIPI), Tehran, Iran
The incorporation of several anti-rodent masterbatches into polyethylene (PE) granules used for gas pipes and the effects of the masterbatches on the physical properties of the pipes were studied. Four commercial anti-rodent masterbatches from different international companies including, Clariant, Alchemix, PolyOne, and Newgen were used in this research. Each of the masterbatch was primarily dry-blended with PE granules by a laboratory-scale tumbling mixer. The concentration of anti-rodent masterbatches used in the PE blends was fixed according to the recipe recommended by the producers as 1, 2.5, 3, and 4 phr for the masterbatches of Clarian, Alchemix, PolyOne, and Newgen respectively. PE granules and masterbatch blends were separately fed into the hopper of a pipe extruder and a length of a hundred and fifty meters of the pipe with the outside diameter (O.D.) of 25 millimeters was continuously produced for each anti-rodent-added PE compound. Two groups of experiments were planned for this investigation; laboratory experiments including impact resistance, tensile elongation, environmental stress cracking (ESCR), melt flow rate (MFR), and differential scanning calorimetry (DSC) were carried out on the control (anti-rodent free) and anti-rodent-added PE100 test samples prepared in the laboratory. Also, a group of factory tests such as burst, hydrostatic (100, 165, and 1000 hr), slow crack growth (SCG), and oxygen induction time (OIT) were performed on the control and anti-rodent-added pipe samples.
 "A powerful aversive rodent repellent of Repela”, Aversion Technologies website: www.aversiontech.com/index.html.
 ASTM D2513, “Standard Specification for Thermoplastic Gas Pressure Pipe, Tubing and Fittings”, American Society for Testing and Materials, West Conshohocken, PA.
 ASTM D638, “Standard Test Method for Tensile Properties of Plastics”, American Society for testing and Materials, West Conshohocken, PA.
 ASTM D1599, “Standard Test Method for Short-Term Hydraulic Failure Pressure of Plastic Pipe, Tubing and Fittings”, American Society for Testing and Materials, West Conshohocken, PA.
 ASTM F1473, “Standard Test Method for Notch Tensile Test to Measure the Resistance to Slow Crack Growth of Polyethylene Pipes and Resins”, American Society for Testing and Materials, West Conshohocken, PA.
 U. Anderson, “Which Factors Control the Lifetime of Plastic Pipes and How the Lifetime can be predicted”.2001,Proceedings of Plastics Pipes XI, IOM Communications, London, 3-6 September.