Tham khảo tài liệu 'handbook of materials for product design part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Plastics TABLE Thermal Physical and Mechanical Properties of Parylenes38 Parylene N Parylene C Typical thermal properties Melting temperature C Linear coefficient of expansion mm mm C Thermal conductivity 10 4 cal s cm2 C cm 405 3 280 Typical physical and mechanical properties Tensile strength lb 6 500 10 000 Yield strength lb 6 100 8 000 Elongation to break 30 200 Yield elongation Density g cm3 Coefficient of friction Static Dynamic Water absorption 24 h in in Index of refraction nD 23 C Data recorded following appropriate ASTM method. TABLE Film-Barrier Properties of Parylenes38 Polymer Gas permeability cm3-mil 100 in2 24 h-atm 23 C Moisture-vapor transmission g-mil 100 in2 24 h 37 C 90 RH N2 O2 CO2 H2 S SO2 Cl2 Parylene N 214 795 1 890 74 Parylene C 13 11 Epoxies 4 5-10 8 Silicones 50 000 300 000 Urethanes 80 200 3 000 Data recorded following appropriate ASTM method. fabrication by conventional melt-processing techniques. Typical properties are given in Ref. 40. Thermal properties. Polyaryl sulfone is characterized by a very high heat-deflection temperature 535 F at 264 lb in2 which is approximately 150 F higher than many other commercially available thermoplastics as shown in Fig. . This is a consequence of its high glass- Chapter 4 temperatures for some engineering thermoplastics at 264 lb in2. transition temperature 550 F rather than the effect of filler reinforcement or a crystalline melting point. At 500 F it maintains a tensile strength in excess of 4000 lb in2 and a flexural modulus of 250 000 lb in2. The resistance to oxidative degradation is indicated by the ability of polyaryl sulfone to retain its tensile strength after 2000-h exposure to 500 F air-oven aging. Chemical resistance. Polyaryl sulfone has good resistance to a wide variety of chemicals including acids bases and common .