Thermal properties melt flow index

Melt flow index (g/10 min) 150°C, 2160 g Thermal properties ASTM D1238 3 3 3... 

Oilfields in the North Sea provide some of the harshest environments for polymers, coupled with a requirement for reliability. Many environmental tests have therefore been performed to demonstrate the fitness-for-purpose of the materials and the products before they are put into service. Of recent examples [33-35], a complete test rig has been set up to test 250-300 mm diameter pipes, made of steel with a polypropylene jacket for thermal insulation and corrosion protection, with a design temperature of 140 °C, internal pressures of up to 50 MPa (500 bar) and a water depth of 350 m (external pressure 3.5 MPa or 35 bar). In the test rig the oil filled pipes are maintained at 140 °C in constantly renewed sea water at a pressure of 30 bar. Tests last for 3 years and after 2 years there have been no significant changes in melt flow index or mechanical properties. A separate programme was established for the selection of materials for the internal sheath of pipelines, whose purpose is to contain the oil and protect the main steel armour windings. Environmental ageing was performed first (immersion in oil, sea water and acid) and followed by mechanical tests as well as specialised tests (rapid gas decompression, methane permeability) related to the application. Creep was measured separately. 

Another thermal property which is of great industrial importance is the melt viscosity, characterized, e.g., by the melt flow index, MFI, or the melt flow rate, MFR (see Sect. 2.3.4.6). The melt viscosity is first of all influenced by the molecular weight according to ... 

All the ordinary extrusion and molding equipment and techniques can be used to process PVDF into different shapes ranging from pipes, fitting, parts, solid rods and sheets, to thin films. Longevity of equipment can be extended using special alloys on the surface that is in contact with molten PVDF, but usually it is not necessary. PVDF based polymers are available commercially in a wide range of melt flow index and with additives to enhance processing or end use properties. However, both homopolymers and copolymers may be shaped from the molten state without extrusion aids or thermal stabilizers. 

This property is measured by a melt flow index extrusion plastomer, which measures the weight of polymer extruded through a standard orifice in 10 minutes (see Table 16.1). Alternatively, a multi-functional extrusion plastomer that measures melt flow rate resistance to thermal degradation is available. 

For instance, in Ex. 1, the starting monomer mixture contained 55 mole% of TFE and 45-mole% Et. The reaction mixture was heated up to 65°C while the pressure reached 2.8 MPa. After two hours the autoclave was cooled and the contents were removed. The copolymer (139 g) was washed with boiling water, filtered, and dried, and its properties were measured (Table 5.53). Melting point deereased with an inerease in TFE content while melt flow index inereased. Tensile strength of the copolymer deereased, indieating a reduction of the molecular weight at higher TFE eon-tent. Thermal stability was evaluated by the repeated... 

Features Tough engineering resin with high abrasion resist, and stability in harsh thermal, chem., and UV environments readily melt processable Properties Sp.gr. 1.78 melt flow 3-7 g/10 min m.p. 141-145 C ref. index 1.41 tens. str. 3500-6000 psi (break) tens, elong. 10-20% (yield), 400-500% (break) Izod impact 12-18 ft Ib/in. notch Shore hardness D65-70 water absorp. 0.03% distort, temp. 40-50 C (1.8 MPa) sp. heat 1.26-1.42 y/kg K flamm. V-0. 

The performance of an extruder is determined as much by the characteristics of the feedstock as it is by the machine. Feedstock properties that affect the extrusion process inciude buik properties, meit flow properties, and thermal properties. Important buik flow properties are the buik density, compressibility, particle size, particle shape, external and internal coefficient of friction, and agglomeration tendency. Important melt flow properties are the shear and eiongational viscosity as a function of strain rate and temperature. The commonly used melt indexer provides only limited information on the meit viscosity. Important thermal properties include the specific heat, the glass transition temperature, the crystalline melting point, the latent heat of fusion, the thermal conductivity, the density, the degradation temperature, and the induction time as a function of temperature. 

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