Tensile Property Measurements

Mechanical Tensile Properties, measured according to ASTM D638 on 3-mil thick cured films of the conformal coating, are modulus of 1750 psi, tensile of 2000 psi, and elongation-at-failure of 285%. 

The tensile properties measured on the unaged and heat-aged elastomer materials made from HER and butanediol are given in Table 8.16. 

Table 2 lists typical tensile properties measured on selected thin (0.5-1.0 mm or 0.02-0.04 in.) sheet materials. The following properties, usually obtained from a tensile test, are used in specifications. 

An increase in the high temperature (200 °C) tensile properties of the ethylene-tetrafluoroethylene copolymer, ETFE, after irradiation in nitrogen at room temperature followed by heat treatment at 162 °C in nitrogen for 20 min indicates some crosslinking [118]. On the other hand, irradiatimi carried out in air showed very little cross-linking [119]. ETFE behaves in some ways similar to poly-vinyUdene fluoride (PVDFO in that there is competition between crosslinking and scissimi. Some of the tensile properties, measured at 200 °C, of irradiated ETFE are shown in Table 52.14 [119]. 

TABLE 52.14. Tensile properties measured at 200 °C, of irradiated ETFE. ... 

The tensile properties measured at six different gauge lengths are given on Figure 5.8. The markers indicate the mean values and the vertical bars indicate the maximum and minimum measured for each batch. The trend of the mechanical properties shows a decrease with the increasing gauge length. This tendency is similar to the results foimd on fiber bundles [44-47]. 

Table 14.3 shows the comparison of the measured average tensile properties of WG-treated and reported alkali-treated fibers. It is clear that the tensile properties measured differ from the reported values because of different fiber sources, alkali solutions, and testing conditions were used. 

Test specimens for tensile property measurements (Instron tester) were prepared by either casting from dilute solution or molding at 150 C, 12,000 psi for 5 minutes in an hydraulic press and annealing at a rate of l C/minute. The cast film samples were stored in a vacuum oven at 60°C for 3 days prior to testing,... 

Test specimens (dumbells 71mm long, 8mm wide at clamp and 2mm wide at neck) for tensile property measurements (Instron Universal Testing Instrument Model 1130 load cell, 5kg full scale strain rate of 5cm/min.) were prepared by solvent casting from dilute (<10%) solutions in benzene on mercury the films were then dried to constant weight in a vacuum oven. The films were cured by placing them in a Pasadena Press at 2500 psi at 160°C for varying time periods. 

Although oven temperatures between 282-357°C have been sueeessfully tried for rotomolding ECTFE, the recommended range is 288-315°C.1 1 At temperatures above 321°C, small bubbles are formed that are difficult to eliminate from the part. Cycle time has to be determined experimentally. The best approaeh is to begin with a short eyele and inerease it until the optimal cyele has been determined. Speeific gravity and tensile property measurements ean eontrol the quality of the part. Table 9.10 gives examples of cycles for a few different part designs. 

Copolymers of PBS and butylene adipate, PBSA, have been largely used to prepare bionanocomposites [338-343]. Ray and Bousmina [338] prepared PBSA/layered silicate nanocomposites by melt extrusion of PBSA and commercially available OMMT. They showed that increasing the level of interactions (miscibihty) between the organic modifier and PBSA matrix, increased the tendency of the sihcate layers to delaminate and distribute nicely within the PBSA matrix. Thermal analysis revealed that the extent of crystallinity of PBSA matrix was directly related to the extent of exfoliation of silicate layers in the nanocomposites and DMA and tensile property measurements showed concurrent improvement in mechanical properties when compared to the neat PBSA and the extent of improvement is directly related to the extent of delamination of silicate layers in the PBSA matrix. DMA also revealed remarkable increase in flexural storage modulus when compared with that of neat PBSA. Tensile properties were also improved with nanoclay addition [339], therefore in agreement with other studies reported in the literature for similar systems [344-347]. 

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