ISSN:
0032-3888
Schlagwort(e):
Chemistry
;
Chemical Engineering
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
,
Physik
Notizen:
The fracture mode of poly(vinyl chloride)/methyl methacrylate/butadiene/styrene (PVC/MBS) polymer blends can change from ductile to brittle in accordance with the changes in shape of the test specimen or test conditions. Therefore, the mechanisms of impact energy absorption and the main cause of stress whitening are complicated. The following results on PVC/MBS blends were obtained by carrying out fracture experiments at different test speeds and temperatures: (1)The ductile/brittle fracture mode of the PVC and PVC/MBS blends can be explained by σ (the craze initiation stress)/σy (the shear yield initiation stress), which depends on the strain rates and temperature.(2)The fracture behavior of the PVC/MBS blends can be classified into the following types from the standpoints of fracture mode and whitening degree: Fracture I: ductile fracture without whitening;Fracture II: ductile fracture with whitening; andFracture III: brittle fracture without whitening.(3)The following concepts can be estimated from the measurements of yield stress, specific gravity and SEM, TEM and visual observations. In Fracture I, shear yield occurs mainly. In Fracture II, both shear yield and crazing occur. In Fracture III, deformation of the rubber and local crazing occur.(4)The main cause of stress whitening in PVC/MBS blends is light scattering by cavities in the rubber particles.(5)In Fracture II, at first, crazes with cavities in the rubber particles occur. Then, shear yield occurs. Finally, crazes are healed by the heat, and only the cavities in the rubber remain.
Zusätzliches Material:
19 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pen.760340810
