The standard “ASTM D4603-18 Standard Test Method for Determination of Inherent Viscosity of Poly(ethylene terephthalate) (PET) by Glass Capillary Viscometer” published by the American Society for Testing and Materials (ASTM) describes a test method for determining the intrinsic viscosity of poly(ethylene terephthalate) (PET) dissolved in a 60/40 phenol/1,1,2,2 tetrachloroethane solution at a concentration of 0,50 percent by means of a glass capillary viscometer. Highly crystalline forms of PET that are insoluble in this solvent mixture require a different procedure. The intrinsic viscosity values obtained by this test method can be compared with the values obtained using a differential viscometer described in the standard “D5225-22 Standard Test Method for Measurement of Solution Viscosity of Polymers by Differential Viscometer”.
For the purposes of this standard, the inherent viscosity (logarithmic viscosity number) is defined by the equation given in the standard. The inherent viscosity is determined by measuring the flow time of a solution of known polymer concentration and the flow time of the pure solvent in a capillary viscometer at a constant temperature. The inherent viscosity value is calculated from the flow time values. The inherent viscosity is related to the composition and molecular weight of a polyester resin. It must be controlled to ensure that the processability and final properties of the resin remain within the desired range.
The equipment used in these tests includes:
The solvent used in this procedure is a mixture of 60 percent phenol by weight and 40 percent 1,1,2,2-tetrachloroethane by weight. Both compounds and mixtures are toxic and require care in their use. Material safety data sheets available from suppliers of these compounds should be consulted to assess the hazards they pose. In addition to using a fume hood for adequate ventilation when handling these materials, protection against skin contact is also important.
Material safety data sheets for methylene chloride, acetone and chromic acid solution used to clean test equipment must be obtained from suppliers. Material safety data sheets should be consulted before using the materials.
If the PET sample contains 0,5 percent or more of inert material, such as titanium dioxide or fiberglass, the amount of inert material should be accurately determined by a procedure appropriate to the type of inert material present. If the sample is suspected of being wet (above the moisture level resulting from exposure to ambient humidity conditions), the sample is dried in an oven at 65 degrees plus/minus 5 degrees for a recommended minimum of 2 hours or until a constant weight of plus/minus 0,1 percent is reached. The moisture from the ambient humidity should be 0,30 percent by weight and is negligible in this procedure. A suitable method is used to determine the moisture content.
Polyethylene terephthalate or poly(ethylene terephthalate) (abbreviated PET) is the most common thermoplastic polymer resin of the polyester family and is used in fibers for clothing, liquid and food containers, and thermoforming for manufacturing, and with fiberglass for engineering resins. This plastic is commonly used to package food and beverages, especially carbonated soft drinks, juices, and water bottles. Its raw materials are ethylene glycol and terephthalic acid. These are produced to form a polymer chain and then form PET resin pellets, which can be heated to a molten liquid. This allows the plastic to be extruded or molded into practically any shape.
PET can also be stretched into a thin sheet to create PET film, which is used in video, photography, and packaging applications. Its high strength, transparency, and variety of colors make it a popular packaging material for health, beauty, and cleaning products. PET is also recognized by global health authorities as safe for food, beverage, personal care, pharmaceutical, and medical applications.
Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services are also provided to businesses in accordance with the standard "ASTM D4603-18 Standard test method for determining the natural viscosity of poly(ethylene terephthalate) (PET) with glass capillary viscometer".
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