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.

Miscibility and Hydrogen Bonding in Blends of Poly(ethylene oxide) and Kraft Lignin

Abstract: Polymer blending is a convenient method to develop products with desirable properties. Through specific intermolecular interactions favorable polymer blending can occur, and composite materials with desirable properties can be produced. In this study we have prepared poly(ethylene oxide)−lignin blends using thermal mixing. Miscible blends were observed over the entire blend ratio. A melting point depression, comparable to results obtained from phenoxy/PEO blends, and a negative deviation of Tg from the weight-average values was observed. The effect of the binary interaction parameter, χ, on Tg was analyzed. Satisfactory prediction of the Tg−composition curve was obtained, in which specific intermolecular interactions exist. FT-IR analyses revealed a strong hydrogen bond between the aromatic hydroxyl proton and the ether oxygen in PEO.

Flow-induced mixing, demixing, and phase transitions in polymeric fluids

Abstract: In polymer solutions or blends, flow can strongly influence the degree of mixing of the components. In a shearing flow, droplets in a dispersion can be broken down to sizes comparable to the dimensions of the polymer molecules themselves, thereby inducing molecular-scale mixing. Demixing can also occur when the two components of the mixture differ greatly in viscoelastic properties. Shear or extensional flow can induce polymer migration in nonhomogeneous flows or in flows with curved streamlines, and can render turbid solutions or blends that are otherwise transparent. Flow can also induce polymer gelation, and can induce ordering transitions in liquid crystals or block copolymers. Here, we review these phenomena, discuss proposed mechanisms, and assess the degree to which recent theories can account for the observations. Because the phenomena are complex, multiple experimental probes and theoretical methods are required to study them. Successful theories must incorporate polymer/polymer or polymer/solvent thermodynamics, critical phenomena, and phase transitions, as well as polymer theology and the kinetics of diffusion or crystallization. The experimental techniques used to study these phenomena are equally wide ranging, and include turbidity measurements, light, x-ray, and neutron scattering, fluorescence quenching, microscopy, and theology.

Ethylene polymer blend and polymerization process for preparation thereof

Abstract: A high density ethylene polymer blend having improved impact strength and environmental stress crack resistance comprises a high molecular weight, non-elastomeric ethylene/propylene copolymer having a crystallinity of at least 5 percent and an intermediate molecular weight, high density ethylene polymer. The improved ethylene polymer blend is provided by a dual zone, low pressure, Ziegler solution polymerization process wherein (1) ethylene and propylene are copolymerized at a low pressure and solution temperatures in presence of a titanium-containing catalyst in an auxiliary polymerization zone, (2) ethylene is polymerized in a primary polymerization zone at low pressure and solution temperature in the presence of a titanium-containing catalyst and (3) the resulting solutions of the reaction products of both zones are combined to form an essentially homogeneous mixture.

Miscibility and phase structure of binary blends of polylactide and poly(methyl methacrylate)

Abstract: Blends of amorphous poly(DL-lactide) (DL-PLA) and crystalline poly(L-lactide) (PLLA) with poly(methyl methacrylate) (PMMA) were prepared by both solution/precipitation and solution-casting film methods. The miscibility, crystallization behavior, and component interaction of these blends were examined by differential scanning calorimetry. Only one glass-transition temperature (Tg) was found in the DL-PLA/PMMA solution/precipitation blends, indicating miscibility in this system. Two isolated Tg's appeared in the DL-PLA/PMMA solution-casting film blends, suggesting two segregated phases in the blend system, but evidence showed that two components were partially miscible. In the PLLA/PMMA blend, the crystallization of PLLA was greatly restricted by amorphous PMMA. Once the thermal history of the blend was destroyed, PLLA and PMMA were miscible. The Tg composition relationship for both DL-PLA/PMMA and PLLA/PMMA miscible systems obeyed the Gordon–Taylor equation. Experiment results indicated that there is no more favorable trend of DL-PLA to form miscible blends with PMMA than PLLA when PLLA is in the amorphous state. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 23–30, 2003

A study on polymer blending microrheology: Part IV. The influence of coalescence on blend morphology origination

Abstract: The influence of shear induced coalescence on the origination of morphologies in polymer blending processes is investigated both theoretically and experimentally. In the theoretical part a route is proposed to estimate the fraction of collisions between disperse phase domains in simple shear flow that result in an actual coalescence. It was shown that under polymer blending conditions this “coalescence probability” is only substantial if the polymer/polymer interfaces exhibit a high degree of mobility. In the experimental part, the phenomenon of gravity induced droplet/planar interface coalescence is utilized to show the high degree of mobility of molten polymer interfaces. Seoul experiments on the relation between domain size and disperse phase concentration in polymer blends prepared on a single screw extruder were carried out. For extremely low concentration (<½ %) the domain size could be predicted satisfactorily by means of Taylor's classical criterion for Newtonian liquids, while at higher concentration coalescence increased the average domain size manifold.