Microhardness Studies of the Interphase Boundary in Rubber‐Softened Glassy Polymer Blends Prepared with/without Compatibilizer

Abstract

The interphase boundary of incompatible polymer blends such as poly(methyl methacrylate) (PMMA)/natural rubber (NR) and polystyrene (PS)/NR, and of compatible blends such as PMMA/NR/epoxidized NR (ENR) and PS/NR/styrene -butadienestyrene (SBS) block copolymer, where ENR and SBS were used as compatibilizers, was studied by means of microindentation hardness (H) and microscopy. Cast films of neat PMMA and PS, and blended films of PMMA/NR, PS/NR, PMMA/NR/ ENR, and PS/NR/SBS were prepared by the solution method using a common solvent (toluene). Hardness values of 178 and 173 MPa were obtained on the surfaces of the neat PMMA and PS, respectively. After the inclusion of soft phases, the binary (incompatible) and the ternary (compatible) blend surfaces show markedly lower H-values. Scanning electron and optical microscopy reveal a clear difference at the phase boundary of the surface of compatible (smooth boundary) and incompatible (sharp boundary) blends. The compatibilized blends were characterized by using microhardness measurements, as having the thinnest phase boundary (30 mm), while incompatible blends were shown to present a boundary of about 60 mm.The hardness values indicate that the compatibilizer is smoothly distributed across the interface between the two blend components. Results highlight that the microindentation technique, in combination with microscopic observations, is a sensitive tool for studying the breadth and quality of the interphase boundary in non-or compatibilized polymer blends and other inhomogeneous materials.

Thermal Conductive and Mechanical Properties of Polymeric Composites Based on Solution-Exfoliated Boron Nitride and Graphene Nanosheets: A Morphology-Promoted Synergistic Effect

“…Figure a,b displayed Young’s modulus ( E ) and microhardness ( H ) of the composites by nanoindentation technique which is a widely used method to the characterize the mechanical behavior of materials at small scales . The results (Figure ) showed that E and H of neat PS were 0.14 and 4.32 GPa, respectively, which were roughly consistent with the reported value 0.17 GPa , and 2–5 GPa . The values significantly increased with the loading of fillers.…”

Radiation induced crosslinking effect on semi - interpenetrating polymer networks of poly(vinyl alcohol)

“…The structural and morphological features obtained for un-irradiated specimens of semi-IPNs using Fourier Transform Infrared Spectroscopy (FTIR), Environmental Scanning Electron Microscopy (ESEM) and X Ray Diffraction (XRD) helps in understanding the overall effect of irradiation on the microhardness. The Vickers microhardness testing method is found to be versatile in revealing the structural, morphological and plasticization aspects in polymers [27].…”

Morphology and mechanical properties of polypropylene/polystyrene blends compatibilized with styrene–butadiene block copolymers

“…On the contrary, it has been shown that the microhardness values of uncompatibilized PP/liquid crystalline polymer blends are close to the additive ones, while for compatibilized blends, a strong positive deviation from additivity has been established [39]. Concerning the glassy polymer blends, it has been demonstrated that after the inclusion of soft styrene–butadiene–styrene block copolymer in PS/natural rubber blends, the microhardness values markedly decrease [40]. The changes of the microhardness of poly (methyl methacrylate)/natural rubber blends are correlated with the variation of the glass transition temperature [41].…”