Toughening mechanisms in commercial thermoplastic polyolefin blends

Abstract

Impact fracture mechanisms in a variety of commercially available and experimental thermoplastic polyolefin (TPO) blends were studied using the doublenotch four-point-bend Charpy impact test, followed by microscopy observations. It was shown that the failure mechanisms and the sizes of the subcritically formed crack-tip damage zone before fracture were quite different among the TPO systems investigated. The room temperature Izod impact strengths of the TPOs investigated were found to correlate qualitatively well with the sizes of the damage zone. At room temperature the main fracture mechanisms observed in TPOs include matrix crazing, particle-matrix debonding, rubber particle internal cavitation, and shear banding. At low temperature (Ϫ40°C), the operative fracture mechanisms in TPOs are limited only to crazing, particle cavitation, and debonding. A strategy for improving impact strength without sacrificing scratch/mar resistance of TPOs is discussed.

Biaxial yielding of polypropylene/elastomeric polyolefin blends: Effect of elastomer content and thermal annealing

“…7, micrographs of PPH and PP/10POE after removal of elastomeric particles are compared. The results obtained are in agreement with others in literature pointing out that the presence of rubber particles in a PP matrix normally does not affect its crystalline morphology [36,44,46,47]. ii.…”

Scratch behavior and material property relationship in polymers

“…Furthermore, rubber particle cavitation and debonding are likely to take place in rubber-modified TPO systems and increase scratch visibility. 23 Therefore, significant work is still needed to improve the scratch resistance of TPOs to reduce scratch visibility. The recent work of Wei et al showed that the rigid-rigid polymer toughening concept 24 can improve the scratch resistance of TPOs.…”

Effect of Processing Parameters on the Mechanical Properties of Injection Molded Thermoplastic Polyolefin (TPO) Cellular Foams

“…Rubber toughened PP is called TPO. [12,13] The automotive industry has been increasingly using TPO alloys in exterior and interior applications, such as bumper fascias, claddings, and wire insulation, because of their excellent weatherability, low density, and low cost. [10,12,14] However, TPO foams have not been utilized because the technologies for foaming TPO materials using batch or injection foaming processes have not been developed yet.…”