Poly tensile stress-strain curves

Figure 35-12. Tensile stress-strain curves for poly(styrene), PS, and high-impact poly(styrene), HIPS, at 20 C. The arrows indicate the onset of a whitish coloration. (After C. B. Bucknall.)...

The mechanical properties of a craze were first investigated by Kambour who measured the stress-strain curves of crazes in polycarbonate (Lexan, M = 35000) which had first been grown across the whole cross-section of the specimen in a liquid environment and subsequently dried. Figure 25 gives examples of the stress-strain curves of the craze determined after the 1st and 5th tensile loading cycle and in comparison the tensile behavior of the normal polymer. The craze becomes more and more elastic in character with increasing load cycles and its behavior has been characterized as similar to that of an opencell polymer foam. When completely elastic behavior is observed the apparent craze modulus is 25 % that of the normal poly-... 

All tensile measurements were performed by the authors with microtomed ribbons of 0.1 mm thickness at ambient temperature. In Fig. 10 typical stress-strain curves for all three poly(ether ester) materials are plotted. All samples were extruded at a common undercooling of 60 °C. The initial tensile modulus increased from 14 MPa for material A to 62 MPa and 208 MPa for B and C, respectively. 

The stress-strain curves of tire chitin nanofiber-g-poly(LA-co-CL) films under tensile mode exhibited the larger fracture strain values (4.3-6.2%) than those of the original pre-treated film. Furthermore, the fracture stress values relatively tended to increase with increasing the amounts and the LA/CL composition ratios of the grafted polyesters, whereas the fracture strain values decreased in this order. These data suggested that the mechanical properties of the chitin nanofiber-g-poly(LA-co-CL) films were strongly affected by the amounts and the LA/CL composition ratios of the grafted polyesters. In comparison with the aforementioned chitin nanofiber PVA blend films (Kadokawa et al., 2011), the present ehi-tin nanofiber-g-poly (LA-co-CL) films showed much better mechanical properties. 

Figure 3.3. Tensile properties of PP (MFI = 6.7 g/10 min) based nanocomposites as a fmic-tion of Si02 content (a) tensile strength (b) Young s modulus (c) elongation to break and (d) area under stress-strain curve [3]. (Si02-g-PMMA means poly(methyl methacrylate) grafted nano-Si02)...

Plastics with stress-strain curves of the type in Figure 18.1a are rigid and brittle. The former term refers to the high initial modulus. The latter refers to the area under the stress-strain curve, which represents the energy per unit volume required to cause failure. These materials usually fail by catastrophic crack propagation at strains in the order of 2%. Since hardness correlates well with tensile modulus, which is another valuable property of this type of plastic. Examples of this class are polystyrene, poly(methyl methacrylate), and most thermosets. 

Uniaxial tensile tests of poly (ethylene terephthalate) (PET)/montmorillonite(MMT) nanocomposites were preformed over a temperature range of 85°C-105°C and stretch rate of 7.5mm/s-12.5mm/s. The stress-strain curves consisted of three regions the hnear visoelasticity, the rubbery plateau and the strain hardening. The effects of temperature and stretch rate on stress-strain behavior were discussed. The results of differential scanning calorimetry (DSC) measurements indicated that the stretch lead the increase of the crystallinity degree of specimens. The wide angle X-ray diffraction (WAXD) measurements revealed that the more perfect crystal structures were obtained with the increase of temperature and oriented along the stretch direction. 

Fig. 8.7. Stress-extension curves measured for a sample of PE (M = 3.6 -10 ) at the indicated Hencky strain rates. Constant strain rates were realized by a registration of the strain at the location of a developing neck and a continuous readjustment of the applied tensile force, using an electronically controlled feedback circle. The broken line gives the cT22 (A)-curve measured for a poly(ethylene-co-vinylacetate)(27% vac-units, (j)c = 0.30). No strain rate dependence is observed for this rubbery material [85]...

Figure 5. Tensile behaviour to point of ftacture for 85% kraft lignin-based thermoplastic blends with poly(vinyl acetate) in presence of diethyleneglycol dibenzoate (1.6%) and indene (0.8%). Stress-strain a-e curves determined for material test pieces at strain rate of 4.5 x 10" sec" graphical data from reference 1.

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