PVC Mechanical Properties

PVC's mechanical properties are quite different to those of HDPE: 

• The uniaxial stress-strain curve does not display a yield point (a point of instability). It is a "predictable" curve of decreasing slope with no discontinuities up to a break of over 300%.The multiaxial stress-strain curve displays a lower break stress than HDPE but a much higher break strain.

• Much of PVC's deformation (up to the break strain) is recoverable. In HDPE strain in excess of about 12% (the yield point) is not recoverable.

• PVC will conform to geometrical profiles much more readily than HDPE. HDPE has a higher puncture stress but a lower puncture strain than PVC.

Being different, each will perform better in different environments. Neither is the best under all circumstances.

Useful strain in HDPE is 10%.

Useful strain in PVC is 300%.

HDPE yield point is a point of instability. 

Figure 4.) Multiaxial Stress vs. Strain For Five Geomembrane Materials PVC has excellent ductility - ability to conform to subgrade. 

PUNCTURE TESTING 

HDPE has high resistance to puncturing but with little deformation. PVC will deform significantly before puncturing.

HYDROSTATIC TESTING: PRESSURE TO FAILURE            

PVC conforms to subgrade better than HDPE. HDPE has higher apparent strength but PVC conforms better and maintains an impermeable barrier.

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