Polypropylene (PP) clay nanocomposites have recently advanced significantly. A detailed study of pure PP and PP nanocomposites, their structure, and characterization will be of significance in all sectors of commercial applications after the trend diminishes. In this work we characterise and contrast the thermomechanical properties of a typical Zeigler-Natta catalysed PP, with a high crystallinity PP, a metallocene catalysed PP, block and random PP ethylene copolymers, two PP–butene copolymers and poly(butene) (PB). The PPs all have the same crystal structure but varying crystallinity and melting temperatures. Thermomechanical (TM) tensile properties measured include isothermal stress–strain (designated dynamic force TM, sf-TM); the modulus was found to vary with crystallinity as determined by structural regularity. Properties measured under a constant or static force (sf-TM) are creep and recovery that were modelled using the four-element viscoelastic relationships for creep, and a stretched exponential function, the Kohlrausch–Williams–Watts (KWW) function for the recovery. Creep analysis provided parameters for elastic, viscoelastic and viscous behaviour. Recovery analysis provided corresponding elastic and viscous elements, while KWW portrayed delayed relaxations dependent upon cooperative molecular motions. Dynamic mechanical analysis, more correctly called modulated force TM, or mf-TM, under current recommended terminology, was performed using a synthetic frequency mode that enable five frequencies to be applied as a composite waveform and the individual frequency data was extracted using Fourier analysis, over the temperature range of interest. Storage moduli, loss moduli and damping factor were used to compare and contrast the group of PPs.