Polymer blend

About: Polymer blend is a research topic. Over the lifetime, 18474 publications have been published within this topic receiving 437183 citations. The topic is also known as: polymer mixture & Polymerblend 或者 Polyblend.

Fibers from Polymer Blends

Abstract: Publisher Summary This chapter provides an overview on the fibers from polymer blends. In fiber technology, two or more polymers may be incorporated into a product to obtain combinations of individual material characteristics or new ones by either of two routes, both of which are known as blending. The first is the older and well-developed concept of fiber–fiber blending in which conventional synthetic or natural fibers are mixed and are referred to as fiber blends. Fiber blending can be done in different ways. This chapter discusses an approach in which the polymer–polymer blends comprise the individual filaments that is known as the blend fibers. It is limited to synthetic fibers as the polymer blending occurs prior to fiber formation rather than in later steps of textile processing. The chapter also discusses the classification of blend fibers by phase morphology. The chapter further highlights the new products that lead to solving problems faced while using the old blend fiber. One polymer simply serves as a convenient fiber additive that has advantages over other potential additives because its high molecular weight makes it less prone to loss by evaporation or leaching and thereby more permanent. The chapter also discusses the improved hot–wet mechanical properties, flame retardance, and dyeability among other improved properties.

Rheological behavior of polymer blends

Abstract: Steady and oscillatory shearing flow properties of compatible and incompatible polymer blend systems were measured, using a cone-and-plate rheometer. The compatible blend systems investigated are blends of two low-density polyethylenes (LDPE) having different values of molecular weight and blends of poly(methyl methacrylate) (PMMA) with poly(vinylidene fluoride) (PVDF). The incompatible blend system investigated is a blend of poly(methyl methacrylate) (PMMA) with polystyrene (PS). It was found that (1) plots of first normal stress difference (τ11 – τ22) vs. shear stress (τ12) and plots of storage modulus (G′) vs. loss modulus (G″) for the LDPE blends become independent of temperature and blend composition; (2) plots of τ11 – τ22 vs. τ12, and G′ vs. G″ for the PMMA/PVDF blends become independent of temperature but dependent upon blend composition. It was found further that, for the incompatible PMMA/PS blends, the dependence of τ11 – τ22 on blend composition, when plotted against τ12, is different from the dependence of G′ on blend composition, when plotted against G″. However, in both compatible and incompatible blend systems, plots of τ11 – τ22 vs. τ12 and plots of G′ versus G″ are independent of temperature. The seemingly complicated composition-dependent rheological behavior of the incompatible blend system is explained with the aid of photomicrographs describing the state of dispersion.

Nanoparticle-assisted high photoconductive gain in composites of polymer and fullerene

Abstract: Polymer-inorganic nanocrystal composites offer an attractive means to combine the merits of organic and inorganic materials into novel electronic and photonic systems. However, many applications of these composites are limited by the solubility and distribution of the nanocrystals in the polymer matrices. Here we show that blending CdTe nanoparticles into a polymer-fullerene matrix followed by solvent annealing can achieve high photoconductive gain under low applied voltages. The surface capping ligand renders the nanoparticles highly soluble in the polymer blend, thereby enabling high CdTe loadings. An external quantum efficiency as high as approximately 8,000% at 350 nm was achieved at -4.5 V. Hole-dominant devices coupled with atomic force microscopy images show a higher concentration of nanoparticles near the cathode-polymer interface. The nanoparticles and trapped electrons assist hole injection into the polymer under reverse bias, contributing to efficiency values in excess of 100%.