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Habibpour S.,Amirkabir University of Technology | Habibpour S.,Loghman Fundamental Technological Research Group | Yazdani-Ahmadabadi H.,Amirkabir University of Technology
Polymer Testing | Year: 2016

Herein, a toughed dynamically-quaternary photopolymeric material was designed through photopolymerization and the polymeric nanoparticle incorporation process. In order for availability of such reinforced system, a low content of poly (styrene-co-acrylonitrile) (SAN) nanoparticle was incorporated into an acrylate-based photopolymerization-induced dynamically-binary photopolymeric network. The dynamic transformation from a binary form to a quaternary form with addition of only 1 wt% of the SAN nanoparticles was demonstrated through the dynamic mechanical results. Relaxation characteristics of all four dynamic characteristic domains including microgel particle, the soft matrix, that of the SAN nanoparticle, and interfacial loose layer were studied. The relaxation characteristic length (ξ(Tg)) of the microgel particle, the soft matrix, the SAN nanoparticle, and the interfacial loose layer were estimated to be 2.24 nm, 2.55 nm, 2.2 nm, and 2.66 nm, respectively. The dynamic fragility index (m) of the SAN and the microgel particle were computed to be 133 and 16, respectively. © 2016 Elsevier Ltd. All rights reserved. Source


Azadimanesh F.,Amirkabir University of Technology | Azadimanesh F.,Loghman Fundamental Technological Research Group | Mohammadi N.,Amirkabir University of Technology | Mohammadi N.,Loghman Fundamental Technological Research Group
Carbohydrate Polymers | Year: 2015

Cellulose triacetate (CTA) plasticization with 25wt% glycerin (GLY), triethyl citrate (TEC) or dioctyl phthalate (DOP) enhanced its crystalline content as much as 55%, while only 10% crystalline content increase noticed using poly (ethylene glycol) (PEG). In addition, GLY and PEG did not cause any sensible T g depression regarding CTA, whereas DOP and TEC decreased it as much as 46°C and 16°C, respectively. Furthermore, the work of fracture (WoF) of CTA was deteriorated by PEG, did not change using GLY and magnified as much as 6.5 and 15 times by TEC and DOP, respectively. The elastic modulus (EM) of the plasticized CTAs, however, were 1.07, 1.06, 0.42 and 0.3GPa using GLY, PEG, TEC and DOP, respectively. Finally, the normalized WoF and EM of the plasticized CTAs by their T g depression (δT g ) and crystalline content (X c ) showed a universal correlation with a plasticizer index containing its molar volume, concentration and polymer/plasticizer Painter-Coleman interaction parameter. © 2015. Source


Ghasemirad S.,Amirkabir University of Technology | Ghasemirad S.,Loghman Fundamental Technological Research Group | Mohammadi N.,Amirkabir University of Technology | Mohammadi N.,Loghman Fundamental Technological Research Group
RSC Advances | Year: 2015

The tear strength of a model methyl methacrylate-butyl acrylate copolymer containing 30 wt% methyl methacrylate (MBC30) and its adhesion strength to poly(ethylene terephthalate) were determined to be 10.2 and 0.26 kN m-1, respectively. The addition of 5 wt% mono-size, 180 nm in diameter, soft nanoparticles of poly(styrene-co-acrylonitrile) with 30 wt% acrylonitrile (SAN70) through latex blending, followed by drying, amplified the adhesion strength while reducing the tear strength. Mild and harsh annealing of the nanocomposite led to partial and full deterioration of work of failure per unit volume (WoF), resulting in augmented adhesion and tear strengths followed by their severe decline, respectively. The G0(1 + Pdbl) model-based partitioning of interfacial and bulk fracture energies of the annealed nanocomposites into intrinsic energy × viscoelastic dissipation led to minimum active layer thicknesses of 0.46 and 33.5 nm across the crack plane, respectively. They implied extension of three consecutive C-C bonds or 70% of the matrix entanglement-to-entanglement strand contour length, respectively, corresponding to maximum WoF. © The Royal Society of Chemistry 2015. Source


Ghasemirad S.,Amirkabir University of Technology | Ghasemirad S.,Loghman Fundamental Technological Research Group | Mohammadi N.,Amirkabir University of Technology | Mohammadi N.,Loghman Fundamental Technological Research Group
Colloid and Polymer Science | Year: 2015

Temperature-induced nonlinearity of an upper critical solution temperature (UCST) copolymer blend and its nanocomposites containing 5 wt% mono-size soft nanoparticles (SNPs) were investigated. Mechanical and thermal energies contribution into the nonlinearity of UCST copolymer blend was 8.9 × 103 Jm−3 and 2.2 × 103 Jmol−1, respectively. Addition of SNP did not change the system thermal-based nonlinearity, while altered its mechanical contribution at constant heating and solicitation conditions. It diminished to 0.4 × 103 Jm−3 in the nanocomposite containing nano-size dispersion of aged SNPs. Micron-size agglomeration of the fresh SNPs in the nanocomposite; however, enhanced the required mechanical energy for nonlinearity to 4.1 × 103 Jm−3. Short-time annealing of the nanocomposite with micron-size agglomerates reduced its mechanical energy part to 2.8 × 103 Jm−3, while annealing extension maximized it at 9.3 × 103 Jm−3. Heating rate increase amplified the thermal contribution into the nonlinearity at constant or reduced mechanical contribution. Finally, room-temperature annealing magnified the temperature-induced nonlinearity of the UCST copolymer blend at minimum mechanical contribution. © 2014, Springer-Verlag Berlin Heidelberg. Source

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