In the present work, ethylene-propylene block copolymer (EP90) and ethylene-propylene random copolymer (EPR) were separated from a PP/EPR in-reactor alloy. The EP90 and EPR were then blended with neat isotactic polypr...
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In the present work, ethylene-propylene block copolymer (EP90) and ethylene-propylene random copolymer (EPR) were separated from a PP/EPR in-reactor alloy. The EP90 and EPR were then blended with neat isotactic polypropylene (PP) at various proportions to obtain ternary blends. The isothermal crystallization kinetics and morphology of the ternary blends were studied and were compared with those of PP/EP90 binary blend. It is observed that the Avrami exponent increases with crystallization temperature for all the blends, but the PP/EP90/EPR ternary blends compared to the PP/EP90 binary blend exhibit larger Avrami exponents. The crystallization rate decreases as the crystallization temperature increases, as it is indicated by the increase of crystallization half-time. At the same crystallization temperature, the PP/EP90 binary blend exhibits the slowest crystallization rate. The data of crystallization kinetics were also analyzed with Hoffman-Lauritzen crystallization regime theory. It is found that all the blends crystallize in regime III. The increase in the content of EPR in the ternary blends is followed by increases in secondary nucleation constant, the free energy of the chain folding surface, and the chain folding work. The blends were etched with xylene at room temperature and at 80C to remove EPR and EP90, respectively, and their morphology was studied with scanning electronic microscopy (SEM). The SEM results reveal that the block component EP90 is partially miscible with both PP and EPR, leading to increase in both domain number and domain size. Since both EPR and EP90 retard crystallization of PP in the PP/EPR and PP/EP90 binary blends, we speculate that the miscibility of EPR and EP90 can weaken the interference of EP90 on crystallization of neat PP.
The interactions between surfactants and vesicles formed by double-tail amphiphiles are investigated by the dissipative particle dynamics. As the surfactant concentration is increased, vesicle solubilization can be ge...
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Nd:YAG laser treatment was used in order to increase surface cell adhesion aspects of polycarbonate (PC) films prepared via melt process. The treatment was carried out under different wavelengths and beam diameters. A...
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An on-chip electrochemical melting curve analysis based on immobilization-free electrochemical DNA detection is reported. This method makes use of the neutral backbone of a ferrocene labeled peptide nucleic acid (PNA)...
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Most existing iterative learning control (ILC) algorithms work in direct pattern;while indirect ILC is an open problem. In this paper, model predictive control (MPC) is chosen as the local controller for processes and...
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In this research, thermo- and pH-responsive chitosan-based porous nanoparticles were prepared by the temperature-dependent self assembly method. The chitosan-graft-poly(N-isopropylacrylamide) (CS-PNIPAAm) copolymer so...
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In this research, poly(methyl methacrylate)-6-poly(butyl acrylate) (PMMA-b-PBA) block copolymers were prepared by 1,1-diphenylethene (DPE) controlled radical polymerization in homogeneous and miniemulsion systems. Fir...
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A unique approach to toughening thermosets has been identified by introducing small amounts of amphiphilic block copolymer. The result is a good viscosity-Tg-toughness balance. In this paper, the fracture behavior of ...
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ISBN:
(纸本)9781617383663
A unique approach to toughening thermosets has been identified by introducing small amounts of amphiphilic block copolymer. The result is a good viscosity-Tg-toughness balance. In this paper, the fracture behavior of these modified epoxies, was carefully studied in an attempt to understand the toughening mechanisms that exist. The findings suggest that cavitation in even these nano-sized spherical micelles is the primary mechanism of toughening. These findings were also found to be a strong function of the crosslink density of the host network with higher levels of plastic deformation at the crack tip being observed in the low crosslink density systems. Glass fiber reinforced composites made with epoxies modified with these toughening agents were found to have improved fatigue resistance.
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