Most monofilament tennis strings are polyester, a blend of polyester, or PEEK.

As you know, we believe there is no wrong string, just wrong applications.  The graph will show the comparative stiffness of three (3) materials.  The string is pulled at a rate of 1mm per second.  The resultant spreadsheet for this particular test is about 5300 rows long.

With our spreadsheet, we have access to every mm of data.  Maybe sometime we can post some of the individual data points.

Blast is polyester, V-Star is a unique blend of material (I do not know what it is), and MonogutZX is PEEK (polyetheretherketone).

The graph shows the cycle from 0 to 50 pounds three (3) times, then to failure (UTS).  The quicker (shorter distance) the string reaches the 50-pound mark, the stiffer it is.  MonoGut ZX did not fail in the 180mm excursion.  You can see, in this case, the stiffer string fails at a higher force but shorter excursion.

Stiffer strings deliver less power and have a higher shock value.  The midrange stiffness shows exactly what would be expected, and the softest string also indicates expected results.