The Experts below are selected from a list of 2646 Experts worldwide ranked by ideXlab platform

Fabrice Leroux - One of the best experts on this subject based on the ideXlab platform.

  • Chain Extender effect of 3 4 hydroxyphenyl propionic acid layered double hydroxide in pbs bionanocomposites
    European Polymer Journal, 2017
    Co-Authors: Grazia Totaro, Laura Sisti, Annamaria Celli, Haroutioun Askanian, Mohammed Hennous, Vincent Verney, Fabrice Leroux
    Abstract:

    Abstract 3-(4-Hydroxyphenyl)propionic acid (HPPA), a biobased hydroxy acid, has been used as organic modifier in layered double hydroxides (LDHs) based on ZnAl and MgAl cations. PBS bionanocomposites have been prepared via in situ polymerization (with both types of clays) and melt blending (just with ZnAl-HPPA) obtaining completely green materials, potentially fully biodegradable. The filler loading is included within the range 1–10 wt%. The materials have been studied in terms of morphological, thermal and viscoelastic properties, resulting to have high thermal stability and huge mechanical reinforcement thanks to an excellent filler/polymer interfacial interaction highlighted by rheology experiments. HPPA, hosted by LDH, has a great Chain Extender effect toward the matrix. In particular, the melt blended samples, even if WAXD analysis evidence the formation of intercalated structures, show a tunable Chain Extender effect proportional to the composition and no gel-like structure has been produced. Moreover, LDHs, besides being bio and food compatibles, decrease the gas and solvents permeability of matrix and are potentially antibacterial and antioxidant; therefore such hybrid system is multifunctional and could be exploited in a wide range of applications.

John M Torkelson - One of the best experts on this subject based on the ideXlab platform.

  • tuning the properties of segmented polyhydroxyurethanes via Chain Extender structure
    Journal of Applied Polymer Science, 2017
    Co-Authors: Goliath Beniah, William H Heath, Junho Jeon, John M Torkelson
    Abstract:

    The influence of Chain Extender structure on the properties of segmented polyhydroxyurethane (PHU) was investigated with four diamine molecules: 1,4-diaminobutane, isophorone diamine, methylene bis(cyclohexyl amine), and bis(aminomethyl) norbornane. These nonisocyanate polyurethanes were synthesized with polytetramethylene oxide-based soft segment and divinyl benzene dicyclocarbonate (DVBDCC) as hard segment. They were characterized with small-angle X-ray scattering (SAXS), dynamic mechanical analysis (DMA), and tensile testing. All PHUs possess nanophase-separated morphology with interdomain spacings of 12 to 16 nm via SAXS. DMA shows that the nanophase separation is accompanied with broad interphases having a wide range of local compositions. These PHUs exhibit tan δ ≥ 0.30 over broad temperature ranges, indicating their potential as effective damping materials. The flow temperature (Tflow), the temperature range with tan δ ≥ 0.30, and the tensile properties of these PHUs are strongly affected by the molecular structure of the Chain Extender used in synthesis. At 50 wt % hard-segment content, values of Tflow, tensile strength, and elongation-at-break can be tuned via Chain Extender from 57 to 105 °C, 1.6 to 22.4 MPa, and 70 to 500%, respectively. Notably, PHU at 50 wt % hard-segment content, synthesized with norbornane-based Chain Extender exhibits the best thermal and mechanical properties with Tflow of 105 °C, tensile strength of 22.4 MPa, elongation-at-break of 500%, and tan δ ≥ 0.30 over 74 °C in breadth. By varying hard-segment content between 30 and 50 wt %, norbornane-based PHUs afford broad tunability in tensile strength from 0.5 to 22.4 MPa with tan δ ≥ 0.30 spanning temperature range as large as 85 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44942.

  • Non-Isocyanate Polyurethane Thermoplastic Elastomer: Amide-Based Chain Extender Yields Enhanced Nanophase Separation and Properties in Polyhydroxyurethane
    Macromolecules, 2017
    Co-Authors: Goliath Beniah, William H Heath, David J. Fortman, William R. Dichtel, John M Torkelson
    Abstract:

    Non-isocyanate polyurethane (NIPU) was synthesized via cyclic carbonate aminolysis using poly(ethylene oxide) (PEO)- and poly(tetramethylene oxide) (PTMO)-based soft segments, divinylbenzene dicyclocarbonate as hard segment, and diamine–diamide (DDA) Chain Extender. Characterization of the resulting segmented polyhydroxyurethanes (PHUs) reveals that the use of amide-based DDA Chain Extender leads to unprecedented improvements in nanophase separation and thermal and mechanical properties over segmented PHUs without DDA Chain Extender. With PEO-based soft segments, previously known to yield only phase-mixed PHUs, use of DDA Chain Extender yields nanophase-separated PHUs above a certain hard-segment content, as characterized by small-angle X-ray scattering. With PTMO-based soft segments, previously known to yield nanophase-separated PHUs with broad interphase, use of DDA Chain Extender produces nanophase-separated PHUs with sharp domain interphase, leading to wide, relatively temperature-independent rubbery ...

  • Non-Isocyanate Polyurethane Thermoplastic Elastomer: Amide-Based Chain Extender Yields Enhanced Nanophase Separation and Properties in Polyhydroxyurethane
    2017
    Co-Authors: Goliath Beniah, William H Heath, David J. Fortman, William R. Dichtel, John M Torkelson
    Abstract:

    Non-isocyanate polyurethane (NIPU) was synthesized via cyclic carbonate aminolysis using poly­(ethylene oxide) (PEO)- and poly­(tetramethylene oxide) (PTMO)-based soft segments, divinylbenzene dicyclocarbonate as hard segment, and diamine–diamide (DDA) Chain Extender. Characterization of the resulting segmented polyhydroxyurethanes (PHUs) reveals that the use of amide-based DDA Chain Extender leads to unprecedented improvements in nanophase separation and thermal and mechanical properties over segmented PHUs without DDA Chain Extender. With PEO-based soft segments, previously known to yield only phase-mixed PHUs, use of DDA Chain Extender yields nanophase-separated PHUs above a certain hard-segment content, as characterized by small-angle X-ray scattering. With PTMO-based soft segments, previously known to yield nanophase-separated PHUs with broad interphase, use of DDA Chain Extender produces nanophase-separated PHUs with sharp domain interphase, leading to wide, relatively temperature-independent rubbery plateau regions and much improved thermal properties with flow temperature as high as 200 °C. The PTMO-based PHUs with 19–34 wt % hard-segment content exhibit tunable mechanical properties with Young’s modulus ranging from 6.6 to 43.2 MPa and tensile strength from 2.4 to 6.7 MPa, with ∼300% elongation at break. Cyclic tensile testing shows that these PHUs exhibit elastomeric recovery with attributes very similar to conventional, isocyanate-based thermoplastic polyurethane elastomers

Grazia Totaro - One of the best experts on this subject based on the ideXlab platform.

  • Chain Extender effect of 3 4 hydroxyphenyl propionic acid layered double hydroxide in pbs bionanocomposites
    European Polymer Journal, 2017
    Co-Authors: Grazia Totaro, Laura Sisti, Annamaria Celli, Haroutioun Askanian, Mohammed Hennous, Vincent Verney, Fabrice Leroux
    Abstract:

    Abstract 3-(4-Hydroxyphenyl)propionic acid (HPPA), a biobased hydroxy acid, has been used as organic modifier in layered double hydroxides (LDHs) based on ZnAl and MgAl cations. PBS bionanocomposites have been prepared via in situ polymerization (with both types of clays) and melt blending (just with ZnAl-HPPA) obtaining completely green materials, potentially fully biodegradable. The filler loading is included within the range 1–10 wt%. The materials have been studied in terms of morphological, thermal and viscoelastic properties, resulting to have high thermal stability and huge mechanical reinforcement thanks to an excellent filler/polymer interfacial interaction highlighted by rheology experiments. HPPA, hosted by LDH, has a great Chain Extender effect toward the matrix. In particular, the melt blended samples, even if WAXD analysis evidence the formation of intercalated structures, show a tunable Chain Extender effect proportional to the composition and no gel-like structure has been produced. Moreover, LDHs, besides being bio and food compatibles, decrease the gas and solvents permeability of matrix and are potentially antibacterial and antioxidant; therefore such hybrid system is multifunctional and could be exploited in a wide range of applications.

Joaquin Martinez Urreaga - One of the best experts on this subject based on the ideXlab platform.

  • mechanical recycling of poly lactic acid evaluation of a Chain Extender and a peroxide as additives for upgrading the recycled plastic
    Journal of Cleaner Production, 2019
    Co-Authors: Freddys R Beltran, Celia Infante, Ma Ulagares De La Orden, Joaquin Martinez Urreaga
    Abstract:

    Abstract Mechanical recycling of poly(lactic acid) (PLA) could improve the social, economic and environmental impacts of the use of this bioplastic. However, the degradation of the polymer during its service life and during mechanical reprocessing reduces the performance of the recycled material, so it would be of great interest to develop cost-effective methods to improve the properties of this material. In this work, the effects of two additives, a Chain Extender and an organic peroxide, on the structure and properties of mechanically recycled PLA have been investigated. Two PLA residues, a simulated post-consumer one and a severely degraded material, have been considered. The study of the mechanisms of action has revealed that the two additives react with the PLA residues giving rise to cross-linking, branching and Chain extension reactions, but also to degradation processes, thus explaining that the overall effect of the additives depends on the amount used and the previous degradation of the polymer. Significant improvements in viscosity, thermal stability and microhardness have been obtained, indicating that the use of these additives could be suitable for improving the recyclability of PLA and reducing the consumption of raw materials.

Goliath Beniah - One of the best experts on this subject based on the ideXlab platform.

  • tuning the properties of segmented polyhydroxyurethanes via Chain Extender structure
    Journal of Applied Polymer Science, 2017
    Co-Authors: Goliath Beniah, William H Heath, Junho Jeon, John M Torkelson
    Abstract:

    The influence of Chain Extender structure on the properties of segmented polyhydroxyurethane (PHU) was investigated with four diamine molecules: 1,4-diaminobutane, isophorone diamine, methylene bis(cyclohexyl amine), and bis(aminomethyl) norbornane. These nonisocyanate polyurethanes were synthesized with polytetramethylene oxide-based soft segment and divinyl benzene dicyclocarbonate (DVBDCC) as hard segment. They were characterized with small-angle X-ray scattering (SAXS), dynamic mechanical analysis (DMA), and tensile testing. All PHUs possess nanophase-separated morphology with interdomain spacings of 12 to 16 nm via SAXS. DMA shows that the nanophase separation is accompanied with broad interphases having a wide range of local compositions. These PHUs exhibit tan δ ≥ 0.30 over broad temperature ranges, indicating their potential as effective damping materials. The flow temperature (Tflow), the temperature range with tan δ ≥ 0.30, and the tensile properties of these PHUs are strongly affected by the molecular structure of the Chain Extender used in synthesis. At 50 wt % hard-segment content, values of Tflow, tensile strength, and elongation-at-break can be tuned via Chain Extender from 57 to 105 °C, 1.6 to 22.4 MPa, and 70 to 500%, respectively. Notably, PHU at 50 wt % hard-segment content, synthesized with norbornane-based Chain Extender exhibits the best thermal and mechanical properties with Tflow of 105 °C, tensile strength of 22.4 MPa, elongation-at-break of 500%, and tan δ ≥ 0.30 over 74 °C in breadth. By varying hard-segment content between 30 and 50 wt %, norbornane-based PHUs afford broad tunability in tensile strength from 0.5 to 22.4 MPa with tan δ ≥ 0.30 spanning temperature range as large as 85 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44942.

  • Non-Isocyanate Polyurethane Thermoplastic Elastomer: Amide-Based Chain Extender Yields Enhanced Nanophase Separation and Properties in Polyhydroxyurethane
    Macromolecules, 2017
    Co-Authors: Goliath Beniah, William H Heath, David J. Fortman, William R. Dichtel, John M Torkelson
    Abstract:

    Non-isocyanate polyurethane (NIPU) was synthesized via cyclic carbonate aminolysis using poly(ethylene oxide) (PEO)- and poly(tetramethylene oxide) (PTMO)-based soft segments, divinylbenzene dicyclocarbonate as hard segment, and diamine–diamide (DDA) Chain Extender. Characterization of the resulting segmented polyhydroxyurethanes (PHUs) reveals that the use of amide-based DDA Chain Extender leads to unprecedented improvements in nanophase separation and thermal and mechanical properties over segmented PHUs without DDA Chain Extender. With PEO-based soft segments, previously known to yield only phase-mixed PHUs, use of DDA Chain Extender yields nanophase-separated PHUs above a certain hard-segment content, as characterized by small-angle X-ray scattering. With PTMO-based soft segments, previously known to yield nanophase-separated PHUs with broad interphase, use of DDA Chain Extender produces nanophase-separated PHUs with sharp domain interphase, leading to wide, relatively temperature-independent rubbery ...

  • Non-Isocyanate Polyurethane Thermoplastic Elastomer: Amide-Based Chain Extender Yields Enhanced Nanophase Separation and Properties in Polyhydroxyurethane
    2017
    Co-Authors: Goliath Beniah, William H Heath, David J. Fortman, William R. Dichtel, John M Torkelson
    Abstract:

    Non-isocyanate polyurethane (NIPU) was synthesized via cyclic carbonate aminolysis using poly­(ethylene oxide) (PEO)- and poly­(tetramethylene oxide) (PTMO)-based soft segments, divinylbenzene dicyclocarbonate as hard segment, and diamine–diamide (DDA) Chain Extender. Characterization of the resulting segmented polyhydroxyurethanes (PHUs) reveals that the use of amide-based DDA Chain Extender leads to unprecedented improvements in nanophase separation and thermal and mechanical properties over segmented PHUs without DDA Chain Extender. With PEO-based soft segments, previously known to yield only phase-mixed PHUs, use of DDA Chain Extender yields nanophase-separated PHUs above a certain hard-segment content, as characterized by small-angle X-ray scattering. With PTMO-based soft segments, previously known to yield nanophase-separated PHUs with broad interphase, use of DDA Chain Extender produces nanophase-separated PHUs with sharp domain interphase, leading to wide, relatively temperature-independent rubbery plateau regions and much improved thermal properties with flow temperature as high as 200 °C. The PTMO-based PHUs with 19–34 wt % hard-segment content exhibit tunable mechanical properties with Young’s modulus ranging from 6.6 to 43.2 MPa and tensile strength from 2.4 to 6.7 MPa, with ∼300% elongation at break. Cyclic tensile testing shows that these PHUs exhibit elastomeric recovery with attributes very similar to conventional, isocyanate-based thermoplastic polyurethane elastomers