Which way do fibrils disappear?

Polyethylene–Silica Nanocomposites with the Structure of Semi‐Interpenetrating Networks

“…Composites consisting of a HDPE matrix and different amounts of SiO 2 were obtained in this work. For this purpose, a porous structure was initially formed in the polymer via its uniaxial deformation in an adsorption‐active medium by the intercrystalline (delocalized) crazing mechanism . During this process, the separation of the stacks of lamellae and the formation of a system of oriented and isolated fibrils with the nanoscopic level of dispersity in the interlamellar region gave rise to the appearance of a system of interpenetrating slit‐like pores 10–20 nm wide and 30–130 nm long depending on the tensile strain of HDPE throughout the polymer volume.…”

“…The through pores, which have been formed in the polymer–inorganic skeleton as a result of the partial migration and redistribution of HDPE, contain H 3 PO 4 as a liquid component. It should be noted that pores have different sizes, because they, apparently, have been formed via the melting of both thin fibrils with diameters of about 10 nm and larger undeformed parts of the polymer (lamella, stack of lamellae, etc.). Since orthophosphoric acid has a high level of proton conductivity, it might be expected that the obtained three‐component composite materials would have a higher conductivity than that of the initial polymeric matrix and silica.…”

“…During tension, the bulk porosity of the polymer film was measured at certain tensile strains. For this purpose, the routine procedure described previously and based on measuring the change in the geometric dimensions of a polymer sample was used. Then, the deformed films were fixed along their perimeters in a special clamping device to prevent them from longitudinal shrinkage and blown through with compressed air at room temperature for 30 min to remove n ‐heptane from the polymer bulk.…”

“…One of the alternative methods for obtaining composites (including nanocomposites) with a high level of the mutual dispersity of the components is the environmental crazing, which is a type of inelastic deformation of glassy and semicrystalline polymers . Mechanical stress applied to a polymer in the presence of an adsorption‐active medium (AAM) leads to the self‐dispersion of the polymer in the zones of local deformation (crazes) into oriented fibrils 5–20 nm in diameter, which are spatially separated by nanosized cavities; as a result, developed porosity (as high as 60 vol%) is created . At the same time, a component dissolved in the AAM is incorporated into the fibrillar‐porous structure of crazes being formed .…”

Surface modification of poly(tetrafluoroethylene) and poly(ethylene terephthalate) films via environmental crazing

“…Environmental crazing is known to be a specific mode of plastic deformation of polymers upon their tensile drawing in the presence of physically active liquid environments (PALEs), which are able to exert either a plasticizing or an adsorptionally active action on polymers. As was shown in references environmental crazing of semicrystalline polymers (so‐called intercrystallite crazing) is achieved by the separation of crystalline lamellae and the formation of a fibrillar‐porous structure with nanoscale pore dimensions within the interlamellar amorphous regions. Since environmental crazing leads to the dispersion of a polymer material down to nanoscale level and to the development of a high surface area (above 100 m 2 g −1 ), the resultant fibrillar‐porous structure appears to be thermodynamically unstable, and the polymer sample experiences strain recovery upon unloading .…”