Continuous service temperature

Mech nic lProperties. Extensive Hsts of the physical properties of FEP copolymers are given in References 58—63. Mechanical properties are shown in Table 3. Most of the important properties of FEP are similar to those of PTFE the main difference is the lower continuous service temperature of 204°C of FEP compared to that of 260°C of PTFE. The flexibiUty at low temperatures and the low coefficients of friction and stabiUty at high temperatures are relatively independent of fabrication conditions. Unlike PTFE, FEP resins do not exhibit a marked change in volume at room temperature, because they do not have a first-order transition at 19°C. They ate usehil above —267°C and are highly flexible above —79°C (64). 

A VDF unit also follows FIFP m the structurally much more complex terpo-lymers [30] Dipolymers contain 60 wt % VDF (66% F) and terpolymers contain 33-50 wt % VDF (66-69 5% F) and generally less than 28 wt % TFE Molecular weights range from 1 5 x 10 to 10 Their respective continuous service temperature ranges are -18 to 210 °C and -12 to 230 °C Dipolymer vulcanizates retam over 50% of their tensile strength for more than 1 year at 200 °C or for 2 months at 260 C... 

Thin-walled (approximately 0.010-0.040 in., or 0.25-1.0 mm) tubing is usually selected by continuous service temperature, which may range from 90°C (194°F) for some PVC tubing up to 250°C (482°F) for tubing made from PTFE. The main use of thin shrink tubing is in electrical and electronic applications. 

ODA). These polymers are characterized by excellent high temperature properties with Tgs typically above 270 °C and continuous service temperatures of about 230 °C. The PAIs utilized here for blending studies were prepared by a simple solution polymerization route, i.e., by reacting trimellitic anhydride acid chloride and 6FDA and diamine monomer (ODA and MDA) in an appropriate solvent (e.g., DM Ac). 

Mechanical properties of FEP are in general similar to those of PTFE with the exception of the continuous service temperature, 204°C (400°F) as compared with that of PTFE (260°C or 500°F). Unlike PTFE, FEP does not exhibit a marked volume change at room temperature because it is lacking the first-order transition at 19°C. FEP resins are useful above -267°C ( 1490F) and are highly flexible above -79°C (-110°F).42... 

Perfluoroelastomers, such as Kalrez (copolymer of TEE and PMVE), can maintain their thermal stability to temperatures as high as 300°C (572°F) or even higher, with a maximum continuous service temperature of 315°C (599°F). Moreover, instead of hardening, the elastomer becomes more elastic with aging.13... 

Fluorocarbon elastomers, such as copolymers of VDF and HFP, typically have a maximum continuous service temperature of 215°C (419°F). Some metal oxides may cause dehydrofluorination at a temperature of 150°C (302°F) or even lower.16 Copolymers of VDF and CTFE (e.g., Kel-F ) have a maximum long-term service temperature of 200°C (392°F). Fluorocarbon elastomers based on copolymers of VDF/HPFP (hydropentafluoropropylene) and on terpolymers of VDF/HPFP/TFE have lower thermal stability than copolymers of VDF/HFP because they have a lower fluorine content than the latter.17 A detailed study of thermal stability of fluoroelastomers was performed by Cox et al.18... 

When exposed to low doses of ionizing radiation (either gamma or electron beam), ETFE becomes cross-linked. Cross-linking improves its high-temperature properties, such as cut-through by a hot soldering iron, and increases the continuous service temperature from 150°C (302°F) to 200°C (392°F).29... 

In Table 15.3 are shown the chemical structures and Tg and of some representative thermoplastic polymers for use at high temperature (3,9). These matrices have high continuous service temperatures (120-200° C) even under wet environmental conditions. Advantages of thermoplastic over thermoset matrices are their shorter fabrication cycle (generally controlled environment storage is not required) and the possibility to be reprocessed and reconsolidated after manufacture. Poly(ether ether ketone) is a strong contender with epoxy resins for use as a matrix in composite prepregs with carbon fibers to be utilized in structural aircraft components. 

Polyester and Vinyl Ester Mortars These two mortars, of which there are many types, are suitable for a pH range of about 0-11 and a continuous service temperature of 225°-230°F. The two related resins, which complement the epoxy resins, resist dilute and concentrated acids and weak alkalies. Their resistance to acid bleaches such as chlorine dioxide and to oxidizing acids such as nitric and chromic is superior to that of other resinous mortars, and they are excellent in acetic acid and related esters. However, polyester and vinyl ester mortars are the poorest resin mortars in other organic chemical exposures including solvents in general. Such mortars are widely used in paper mills and are suitable with acid brick or ceramic tile in the lower temperature zones of mildly acidic utility FGD systems. 

Thermoplastic Type Designation Max. Continuous Service Temperature Comments... 

Industrial usage includes a variety of tank, vessel, and piping insulation. The PIR foams are often preferred, because of their higher continuous service temperature (150 C). Cut and preshaped slabstock is used for many industrial plant piping applications. The foam spraying of tanks and pipelines is getting considerable attention in the Middle East and African markets. 

The glass reinforcement content is relatively low, at 20 wt%, but stiffness and impact strength are high (with a modulus about 50% higher than glass reinforced TS polyester and 3-4 times higher than RTFs). Heat distortion temperature is 300°C at 1.8 MPa and continuous service temperature is 170-190°C. Molding conditions are similar to those for TS polyester SMC. The recommended mold temperature is about 145°C and pressure is 5-8 MPa. 

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