Even the same type of nylon will exhibit significantly different linear expansion behavior if the nylon’s thermal history differs. Figure 40 shows post-heat-treatment linear expansion in each type of nylon. Compared to metallic materials, nylon’s thermal properties feature low thermal conductivity and a large linear expansion coefficient. However, for applications requiring continuous use under load, temperatures should not normally exceed 100☌ for nylon 66, or 70☌ for nylon 6 and nylon 610. The melting point of nylon 66 is 255☌, nylon 6 is 225☌ and nylon 610 is 220☌. Dimensional change resulting from water absorptionįigure 40: Linear expansion of each type of nylonĬompared to other general-purpose thermoplastic resins, nylon has a very high melting point.
#Does nylon absorb water full#
Therefore, the time required to reach full equilibrium water absorption would be 330 × 2.5 = 825 hours and 4,110 × 2.5 = 10,275 hours, respectively. Similarly, find the time required to reach 80% of equilibrium water absorption in the atmosphere at 20☌, 60%RH. Use formula (c) to find the time required to reach 80% of equilibrium water absorption in CM1017 (60mmφ×3mm disc, ω = 733) immersed in 20☌ water. The time required to reach full equilibrium water absorption is approximately 2.5 times the time required to reach 80% of equilibrium water absorption. Please note that this formula can only be used to calculate the time required to reach up to 80% of equilibrium water absorption. = water-absorption rate (%) after a given time t andĬs = equilibrium water absorption (%) under the applicable environmental conditions. Use formula (b) to find the time it takes for an injection-molded product to reach a certain water-absorption rate when immersed in 20☌ water: Table 4: Calculated examples of diffusion constants for CM1017 (nylon 6) Table 4 shows the diffusion constant D for a number of nylon molded products based on the range where a linear relationship exists.
Relative to actual measurements, the relationship between and forms a straight line until it equals approximately 0.8. S = the surface area (m2) of the molded product. V = the volume (m 3) of the molded product and Using these assumptions, the change over time in concentration C can be expressed as:Īverage concentration (t) based on arbitrary measurements at arbitrary times can be expressed as:Ĭs = equilibrium water absorption under the respective conditions C(x,t) represents the water present in a place located distance x from the object surface at time t. Next we will use a diffusion equation to find the change over time in water absorption of nylon molded products.įor simplification, the water-absorption direction in a semi-infinite object shall be one-dimensional.
Table 3: Examples of water-absorption constant values m and n
Figure 37: Water-absorption curve of CM1017.Figure 36: Water-absorption curve of CM1017 (nylon 6).Figure 35: Change in water absorption per surface area.Table 3 shows the values for m and n for a 60mmφ×3mm disc and a 12.7×6.35×127mm square bar. The values m and n are constants determined by the type of nylon, shape of the formed product and the molding conditions (crystallinity). As you can see, the relationship between water absorption y (%) and time t can be represented by the following formula. Figure 35 illustrates that phenomenon.įigures 36 and 37 show the water-absorption curve of nylon 6 in 100☌ water and in atmospheric air, respectively. (The water-absorption rates shown in Table 36 represent values based on immersion in water and therefore differ from atmospheric equilibrium water absorption.) Figure 34 shows the change over time of water-absorption rates for each type of nylon.Įven using the same type of nylon, water-absorption speed will vary depending on the shape of the formed product. Water absorption will result in dimensional change.Īssuming ordinary atmospheric conditions (23☌/60%RH), the equilibrium water absorption is 3.5% for nylon 6, 2.5% for nylon 66, and 1.5% for nylon 610. Water absorption rateĪt the molecular level, nylon contains hydrophilic amide groups. AMILAN™ Nylon Resin Technical Information｜Properties｜Physical properties Ⅰ.
0 kommentar(er)
