Polyamide-rubber blends: micrscopic studies of the deformation zone

The morphology of injection moulded samples of polyamide—polybutadiene blends (85.15) with an average particle size of 0.3 μm was studied. The samples were fractured in a notched tensile test at crosshead speeds of 10−4 and 1 ms −1 and the structure of the deformation zone was studied using various techniques: polarized light microscopy, scanning electron microscopy, transmission electron microscopy on stained cut samples and carbon replicas, and selected area electron diffraction transmission electron microscopy. The deformation zone of samples tested at 10−4 ms−1 was found to consist of two layers. Far from the fracture surface a layer was observed with more or less round cavities and with cavities in the rubber particles, while near the fracture surface a layer with strongly deformed cavities (length/diameter ratio of 5–10) could be seen. In the samples tested at 1 ms−1 the deformation zone was found to have three layers. In addition to the two previous layers an extra layer next to the fracture plane was found. This layer was 2–3 μm thick with round rubber particles and no orientation of the matrix material. This indicates that, at the high deformation speed of the test, relaxation in the melt took place, suggesting that the material around the crack tip was molten during fracture.\u

Polyamide-rubber blends: micrscopic studies of the deformation zone

The morphology of injection moulded samples of polyamide—polybutadiene blends (85.15) with an average particle size of 0.3 μm was studied. The samples were fractured in a notched tensile test at crosshead speeds of 10−4 and 1 ms −1 and the structure of the deformation zone was studied using various techniques: polarized light microscopy, scanning electron microscopy, transmission electron microscopy on stained cut samples and carbon replicas, and selected area electron diffraction transmission electron microscopy. The deformation zone of samples tested at 10−4 ms−1 was found to consist of two layers. Far from the fracture surface a layer was observed with more or less round cavities and with cavities in the rubber particles, while near the fracture surface a layer with strongly deformed cavities (length/diameter ratio of 5–10) could be seen. In the samples tested at 1 ms−1 the deformation zone was found to have three layers. In addition to the two previous layers an extra layer next to the fracture plane was found. This layer was 2–3 μm thick with round rubber particles and no orientation of the matrix material. This indicates that, at the high deformation speed of the test, relaxation in the melt took place, suggesting that the material around the crack tip was molten during fracture

Ruthenium tetraoxide staining of polybutylene terephthalaat (PBT) and polyisobutylene-b-PBT block copolymers

A ruthenium tetroxide (RuO4) staining method has been evaluated for segmented polyisobutylene-b-polybutylene terephthalate (PIB-b-PBT). Solution cast films and melt pressed samples have been studied. For comparison PBT has also been studied. PBT and PIB-b-PBT could be stained with RuO4 at room temperature. The observed structures on the PBT and PIB-b-PBT films were spherulitic with lamellae. In some regions in the PIB-b-PBT films large scale phase separation was observed. In the melt pressed PIB-b-PBT samples the spherulitic and lamellar structures were less well developed. The PBT segments appeared to have crystallized out in bundles and the PIB phase was present as microspheres with diameters of 3-6 nm