Scanning electron microscopy polymer blends

Scanning electron microscopy (SEM) involves scanning an electron beam (5-lOnm) across a surface and then detecting the scattered electrons. Literature abounds, with work focussing on the use of SEM in the fracture and failure of epoxy resins and other thermoset polymers. Also work on multiphase thermosets (thermoset-thermoplastic blends, thermoset nanocomposites, interpenetrating network (IPN) polymers) is abundant. 

Use of high-resolution scanning electron microscopy (SEM) allowed the uncovering of a further substructure in these polymer-fullerene blends, besides some larger fullerene clusters (see Fig. 24) MDMO-PPV nanospheres representing a coiled polymer conformation were detected together with some solvent-dependent amount of PCBM fullerenes [55,60-62,137]. 

The scanning electron microscopy (SEM) revealed that both ternary and binary blends have a phase morphology typical of blend composites with active interphase interaction between polymer components. At equal concentrations of g-PO in blends, the ternary systems look more homogeneous than binary ones. It may be presumed. 

Scanning electron microscopy (SEM) data for carbon-black compounds and conductive polymer blends [72c], supported by recent transmission electron microscopy (TEM) evaluations [79,80] (shown in Figure 11.39) were made, they also contradict the assumption of a statistical distribution. We find complete dispersion below the critical volume concentration (I) and a sudden stiucture formation ( branched flocculate chains ) at the critical volume concentration. This structural feature remains at higher concentrations. 

Scanning electron microscopy (SEM) can offer a good depth of held, good resolution, and easy specimen preparation. It can be used for immiscible polymer blends, where the phases are sufficiently large and can be easily debonded. Information on surface topography, size, and distribution of the dispersed phase and interfacial interaction between phases can be elucidated with this technique. Elemental analysis on the blend components can also be obtained if the SEM equipment includes an energy dispersion X-ray spectrometer (EDX). 

Bio-based and recycled polymers often have short-lifecycles compared to oil-based virgin resins. We studied bio-based (PAX) and recycled (PA6) polyamide (PA) blends [LOU 13]. Scanning electron microscopy (Figure 12.4) shows that the formulations are composed of 75% PA6 and 25% PAX by mass (denoted PA6/PAX (25/75)) and PAX nodules appear in the PA6 matrix. To refine the morphology and improve PA6/PAX interfaces, we conducted reactive compatibilization to couple the... 

The polymers, whose characteristics are summarized in Table 1, were melt mixed in a Brabender-like apparatus at 200 C and at two residence times 6 min, at 2 r.p.m. and further 10 min. at 32 r.p.m. The blend compositions are listed in Table 2. After premixing, cylindrical specimens were obtained directly by extrusion using a melting-elastic miniextruder (CSI max mixing extruder mod. CS-194), Thermal and tensile mechanical tests were performed on these specimens by an Instron Machine (mod. 1122) at room temperature and at cross-head speed of 10 mm/min. Also made were morphological studies by optical microscopy of sections microtomed from tensile samples and scanning electron microscopy of fractured surfaces of samples broken at liquid nitrogen temperature. Further details on the experimental procedures and on the techniques used are reported elsewhere . 

Suarez, J. C. M., Mano, E. B., Characterization of degradation on gamma-irradiated recycled polyethylene blends by scanning electron microscopy. Polymer Degradation and Stability 2001,72,217-221. 

Compatibility is a concept depending on the scale of a particular experiment. Thus, a polymer blend can be judged compatible when tested for mechanical properties or incompatible as revealed by structural determinations such as glass transition temperature (Tg), scanning electron microscopy (SEM), etc. 

Miscibility is one essential concept in polymer science, since blended systems are commonly used to address multiple property optimizations as typical for many applications. Several methods can be used to determine the miscibility of two- and more component systems. Morphological investigations of blend systems can easily been done with microscopic methods. Several electron microscopic techniques are used, that is, scanning electron microscopy (SEM), TEM, AFM, and scanning tunneling microscopy (STM). Inhomogeneities are typically... 

Scanning electron microscopy (SEM) is one of the very useful microscopic methods for the morphological and structural analysis of materials. Larena et al. classified nanopolymers into three groups (1) self-assembled nanostructures (lamellar, lamellar-within-spherical, lamellar-within-cylinder, lamellar-within-lamellar, cylinder within-lamellar, spherical-within-lamellar, and colloidal particles with block copolymers), (2) non-self-assembled nanostructures (dendrimers, hyperbranched polymers, polymer brushes, nanofibers, nanotubes, nanoparticles, nanospheres, nanocapsules, porous materials, and nano-objects), and (3) number of nanoscale dimensions [uD 1 nD (thin films), 2 nD (nanofibers, nanotubes, nanostructures on polymeric surfaces), and 3 nD (nanospheres, nanocapsules, dendrimers, hyperbranched polymers, self-assembled structures, porous materials, nano-objects)] [153]. Most of the polymer blends are immiscible, thermodynamically incompatible, and exhibit multiphase structures depending on the composition and viscosity ratio. They have two types of phase morphology sea-island structure (one phase are dispersed in the matrix in the form of isolated droplets, rods, or platelets) and co-continuous structure (usually formed in dual blends). 

The aforementioned theoretical approach was used for the first time to foam polymers at a nanoscale in 2004 and further developed by Yokoyama et al. [83] and Li et al. [84,88]. Since then it has been widely used in amorphous polymers (which allows diffusion of the CO2 molecules between the polymer chains because of their amorphous organization), but also in semicrystalline polymers blended with a C02-philic component. Characterization of the initial nanostructuration was performed by classical methodologies [eg, atomic force microscopy (AFM), transmission electron microscopy (TEM), or scanning electron microscopy (SEM)], sometimes combining with etching procedures (further details can be found in the cited woiks). 

Figure 9.21 Scanning electron microscopy image of the foamed PS-b-PFDA blend. Reprinted from J.A.R. Ruiz, E. Cloutet, M. Dumon, Investigation of the nanocellular foaming of polystyrene in supercritical CO2 by adding a C02-philic perfluorinated block copolymer, Journal of Applied Polymer Science, 126 (1) (2012) 38-45 with permission from John Wiley and Sons.

TC Yu. Impact modification of polypropylenes. Proceedings of Society of Plastics Engineers Annual Technical Conference, San Francisco, 1994, pp 2439-2445. GM Brown, JH Butler. New method for the characterization of domain morphology of polymer blends using ruthenium tetroxide staining and low voltage scanning electron microscopy (LVSEM). Polymer 38 3937-3945, 1997. 

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