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John M Torkelson - One of the best experts on this subject based on the ideXlab platform.
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dispersion and property enhancements in polyolefin soy flour biocomposites prepared via melt extrusion followed by solid state shear pulverization
Macromolecular Materials and Engineering, 2015Co-Authors: Krishnan A Iyer, John M TorkelsonAbstract:Biocomposites of low-density polyethylene (LDPE) and polypropylene (PP) with 5–40 wt% soy flour (SF) are produced by two-step single-screw extrusion (SSE) followed by solid-state shear pulverization (SSSP). The SSE-SSSP approach overcomes limitations with melt mixing, e.g poor SF dispersion and degradation, and limitations with single-step SSSP. Microscopy shows that SF is well dispersed in SSE-SSSP composites but agglomerated and degraded in melt-mixed composites. The SSE-SSSP composites exhibit major improvements in Young's modulus relative to Neat Polymer, including 74 and 43% increases in 80/20 wt% LDPE/SF and 95/5 wt% PP/SF composites, respectively. Relative to Neat Polymer, SSE-SSSP composites exhibit the largest improvements in Young's modulus and best tensile strengths reported for polyolefin/SF composites. Crystallization and viscosity are only slightly affected by SF in the composites. At 20% and higher mass loss, char can result in greater thermo-oxidative stability of 80/20 wt% polyolefin/SF composites relative to Neat Polymer.
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sustainable green hybrids of polyolefins and lignin yield major improvements in mechanical properties when prepared via solid state shear pulverization
ACS Sustainable Chemistry & Engineering, 2015Co-Authors: Krishnan A Iyer, John M TorkelsonAbstract:Lignin, a byproduct of paper and pulp industries, is a sustainable, inexpensive biomaterial with potential as composite filler. Past research on polyolefin/lignin composites made by melt processing has led to modest increases in Young’s modulus and drastic reductions in tensile strength and elongation at break relative to Neat Polymer. Here, green hybrids of low density polyethylene (LDPE) and polypropylene (PP) with 5–30 wt % lignin are made by solid-state shear pulverization (SSSP). Microscopy shows that SSSP leads to superior lignin dispersion and suppressed degradation when compared to melt-mixed composites reported in the literature. Composites made by SSSP exhibit major improvements in Young’s modulus (81% and 62% increases for 30 wt % lignin in LDPE and PP, respectively, relative to Neat Polymer), tensile strength equal to or better than that of Neat LDPE and near that of Neat PP, and much better strain at break than reported in the literature for polyolefin/lignin composites. The SSSP-produced hyb...
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Sustainable Green Hybrids of Polyolefins and Lignin Yield Major Improvements in Mechanical Properties When Prepared via Solid-State Shear Pulverization
ACS Sustainable Chemistry & Engineering, 2015Co-Authors: Krishnan A Iyer, John M TorkelsonAbstract:Lignin, a byproduct of paper and pulp industries, is a sustainable, inexpensive biomaterial with potential as composite filler. Past research on polyolefin/lignin composites made by melt processing has led to modest increases in Young’s modulus and drastic reductions in tensile strength and elongation at break relative to Neat Polymer. Here, green hybrids of low density polyethylene (LDPE) and polypropylene (PP) with 5–30 wt % lignin are made by solid-state shear pulverization (SSSP). Microscopy shows that SSSP leads to superior lignin dispersion and suppressed degradation when compared to melt-mixed composites reported in the literature. Composites made by SSSP exhibit major improvements in Young’s modulus (81% and 62% increases for 30 wt % lignin in LDPE and PP, respectively, relative to Neat Polymer), tensile strength equal to or better than that of Neat LDPE and near that of Neat PP, and much better strain at break than reported in the literature for polyolefin/lignin composites. The SSSP-produced hyb...
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Dispersion and Property Enhancements in Polyolefin/Soy Flour Biocomposites Prepared via Melt Extrusion Followed by Solid-State Shear Pulverization
Macromolecular Materials and Engineering, 2015Co-Authors: Krishnan A Iyer, John M TorkelsonAbstract:Biocomposites of low-density polyethylene (LDPE) and polypropylene (PP) with 5–40 wt% soy flour (SF) are produced by two-step single-screw extrusion (SSE) followed by solid-state shear pulverization (SSSP). The SSE-SSSP approach overcomes limitations with melt mixing, e.g poor SF dispersion and degradation, and limitations with single-step SSSP. Microscopy shows that SF is well dispersed in SSE-SSSP composites but agglomerated and degraded in melt-mixed composites. The SSE-SSSP composites exhibit major improvements in Young's modulus relative to Neat Polymer, including 74 and 43% increases in 80/20 wt% LDPE/SF and 95/5 wt% PP/SF composites, respectively. Relative to Neat Polymer, SSE-SSSP composites exhibit the largest improvements in Young's modulus and best tensile strengths reported for polyolefin/SF composites. Crystallization and viscosity are only slightly affected by SF in the composites. At 20% and higher mass loss, char can result in greater thermo-oxidative stability of 80/20 wt% polyolefin/SF composites relative to Neat Polymer.
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cellulose nanocrystal polyolefin biocomposites prepared by solid state shear pulverization superior dispersion leading to synergistic property enhancements
Polymer, 2015Co-Authors: Krishnan A Iyer, Gregory T Schueneman, John M TorkelsonAbstract:Abstract Cellulose nanocrystals (CNCs), a class of renewable bionanomaterials with excellent mechanical properties, have gained major interest as filler for Polymers. However, challenges associated with effective CNC dispersion have hindered the production of composites with desired property enhancements. Here, composites of polypropylene (PP) and low density polyethylene (LDPE) with 5–10 wt% unmodified CNC are produced for the first time via a solventless process. In particular, we employ solid-state shear pulverization (SSSP). Optical and electron microscopy reveals excellent CNC dispersion with strongly suppressed degradation relative to composites made by melt mixing. Effective dispersion leads to major increases in Young's modulus, including a 69% increase in 90/10 wt% LDPE/CNC composites relative to Neat LDPE, the highest modulus enhancement ever reported for polyolefin/CNC composites. The composites also exhibit superior creep performance with modest increment in yield strength compared to Neat Polymer. The LDPE/CNC composites retain elongation at break values that are equal to that of Neat Polymer while a decrease is observed with PP/CNC composites. The CNC thermal degradation temperature in air is close to that of PP melt processing conditions. We hypothesize that during melt-processing CNCs undergo preferential thermo-oxidative degradation in LDPE and simultaneous degradation in PP. Thus, CNC incorporation results in impaired thermal stability in LDPE and, especially, PP. Care must be taken in selecting the post-SSSP melt processing temperature and residence time in order to suppress degradation. Taking that into account, this study has produced polyolefin/CNC composites with superior dispersion and property enhancements and shown that CNC is an attractive filler for green Polymer biocomposites.
Krishnan A Iyer - One of the best experts on this subject based on the ideXlab platform.
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dispersion and property enhancements in polyolefin soy flour biocomposites prepared via melt extrusion followed by solid state shear pulverization
Macromolecular Materials and Engineering, 2015Co-Authors: Krishnan A Iyer, John M TorkelsonAbstract:Biocomposites of low-density polyethylene (LDPE) and polypropylene (PP) with 5–40 wt% soy flour (SF) are produced by two-step single-screw extrusion (SSE) followed by solid-state shear pulverization (SSSP). The SSE-SSSP approach overcomes limitations with melt mixing, e.g poor SF dispersion and degradation, and limitations with single-step SSSP. Microscopy shows that SF is well dispersed in SSE-SSSP composites but agglomerated and degraded in melt-mixed composites. The SSE-SSSP composites exhibit major improvements in Young's modulus relative to Neat Polymer, including 74 and 43% increases in 80/20 wt% LDPE/SF and 95/5 wt% PP/SF composites, respectively. Relative to Neat Polymer, SSE-SSSP composites exhibit the largest improvements in Young's modulus and best tensile strengths reported for polyolefin/SF composites. Crystallization and viscosity are only slightly affected by SF in the composites. At 20% and higher mass loss, char can result in greater thermo-oxidative stability of 80/20 wt% polyolefin/SF composites relative to Neat Polymer.
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sustainable green hybrids of polyolefins and lignin yield major improvements in mechanical properties when prepared via solid state shear pulverization
ACS Sustainable Chemistry & Engineering, 2015Co-Authors: Krishnan A Iyer, John M TorkelsonAbstract:Lignin, a byproduct of paper and pulp industries, is a sustainable, inexpensive biomaterial with potential as composite filler. Past research on polyolefin/lignin composites made by melt processing has led to modest increases in Young’s modulus and drastic reductions in tensile strength and elongation at break relative to Neat Polymer. Here, green hybrids of low density polyethylene (LDPE) and polypropylene (PP) with 5–30 wt % lignin are made by solid-state shear pulverization (SSSP). Microscopy shows that SSSP leads to superior lignin dispersion and suppressed degradation when compared to melt-mixed composites reported in the literature. Composites made by SSSP exhibit major improvements in Young’s modulus (81% and 62% increases for 30 wt % lignin in LDPE and PP, respectively, relative to Neat Polymer), tensile strength equal to or better than that of Neat LDPE and near that of Neat PP, and much better strain at break than reported in the literature for polyolefin/lignin composites. The SSSP-produced hyb...
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Sustainable Green Hybrids of Polyolefins and Lignin Yield Major Improvements in Mechanical Properties When Prepared via Solid-State Shear Pulverization
ACS Sustainable Chemistry & Engineering, 2015Co-Authors: Krishnan A Iyer, John M TorkelsonAbstract:Lignin, a byproduct of paper and pulp industries, is a sustainable, inexpensive biomaterial with potential as composite filler. Past research on polyolefin/lignin composites made by melt processing has led to modest increases in Young’s modulus and drastic reductions in tensile strength and elongation at break relative to Neat Polymer. Here, green hybrids of low density polyethylene (LDPE) and polypropylene (PP) with 5–30 wt % lignin are made by solid-state shear pulverization (SSSP). Microscopy shows that SSSP leads to superior lignin dispersion and suppressed degradation when compared to melt-mixed composites reported in the literature. Composites made by SSSP exhibit major improvements in Young’s modulus (81% and 62% increases for 30 wt % lignin in LDPE and PP, respectively, relative to Neat Polymer), tensile strength equal to or better than that of Neat LDPE and near that of Neat PP, and much better strain at break than reported in the literature for polyolefin/lignin composites. The SSSP-produced hyb...
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Dispersion and Property Enhancements in Polyolefin/Soy Flour Biocomposites Prepared via Melt Extrusion Followed by Solid-State Shear Pulverization
Macromolecular Materials and Engineering, 2015Co-Authors: Krishnan A Iyer, John M TorkelsonAbstract:Biocomposites of low-density polyethylene (LDPE) and polypropylene (PP) with 5–40 wt% soy flour (SF) are produced by two-step single-screw extrusion (SSE) followed by solid-state shear pulverization (SSSP). The SSE-SSSP approach overcomes limitations with melt mixing, e.g poor SF dispersion and degradation, and limitations with single-step SSSP. Microscopy shows that SF is well dispersed in SSE-SSSP composites but agglomerated and degraded in melt-mixed composites. The SSE-SSSP composites exhibit major improvements in Young's modulus relative to Neat Polymer, including 74 and 43% increases in 80/20 wt% LDPE/SF and 95/5 wt% PP/SF composites, respectively. Relative to Neat Polymer, SSE-SSSP composites exhibit the largest improvements in Young's modulus and best tensile strengths reported for polyolefin/SF composites. Crystallization and viscosity are only slightly affected by SF in the composites. At 20% and higher mass loss, char can result in greater thermo-oxidative stability of 80/20 wt% polyolefin/SF composites relative to Neat Polymer.
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cellulose nanocrystal polyolefin biocomposites prepared by solid state shear pulverization superior dispersion leading to synergistic property enhancements
Polymer, 2015Co-Authors: Krishnan A Iyer, Gregory T Schueneman, John M TorkelsonAbstract:Abstract Cellulose nanocrystals (CNCs), a class of renewable bionanomaterials with excellent mechanical properties, have gained major interest as filler for Polymers. However, challenges associated with effective CNC dispersion have hindered the production of composites with desired property enhancements. Here, composites of polypropylene (PP) and low density polyethylene (LDPE) with 5–10 wt% unmodified CNC are produced for the first time via a solventless process. In particular, we employ solid-state shear pulverization (SSSP). Optical and electron microscopy reveals excellent CNC dispersion with strongly suppressed degradation relative to composites made by melt mixing. Effective dispersion leads to major increases in Young's modulus, including a 69% increase in 90/10 wt% LDPE/CNC composites relative to Neat LDPE, the highest modulus enhancement ever reported for polyolefin/CNC composites. The composites also exhibit superior creep performance with modest increment in yield strength compared to Neat Polymer. The LDPE/CNC composites retain elongation at break values that are equal to that of Neat Polymer while a decrease is observed with PP/CNC composites. The CNC thermal degradation temperature in air is close to that of PP melt processing conditions. We hypothesize that during melt-processing CNCs undergo preferential thermo-oxidative degradation in LDPE and simultaneous degradation in PP. Thus, CNC incorporation results in impaired thermal stability in LDPE and, especially, PP. Care must be taken in selecting the post-SSSP melt processing temperature and residence time in order to suppress degradation. Taking that into account, this study has produced polyolefin/CNC composites with superior dispersion and property enhancements and shown that CNC is an attractive filler for green Polymer biocomposites.
William J. Koros - One of the best experts on this subject based on the ideXlab platform.
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gas transport property performance of hybrid carbon molecular sieve Polymer materials
Industrial & Engineering Chemistry Research, 2010Co-Authors: Mita Das, John D. Perry, William J. KorosAbstract:High-performance hybrid materials using carbon molecular sieve materials and 6FDA−6FpDA were produced. A detailed analysis of the effects of casting processes and the annealing temperature is reported. Two existing major obstacles, sieve agglomeration and residual stress, were addressed in this work, and subsequently a new membrane formation technique was developed to produce high-performing membranes. The successfully improved interfacial region of the hybrid membranes allows the sieves to increase the selectivity of the membranes above the Neat Polymer properties. Furthermore, an additional performance enhancement was seen with increased sieve loading in the hybrid membranes, leading to an actual performance above the upper bound for pure Polymer membranes. The membranes were also tested under a mixed-gas environment, which further demonstrated promising results.
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mixed matrix hollow fiber membranes made with modified hssz 13 zeolite in polyetherimide Polymer matrix for gas separation
Journal of Membrane Science, 2007Co-Authors: Shabbir Husain, William J. KorosAbstract:Abstract Organic–inorganic hybrid (mixed matrix) asymmetric hollow fiber membranes were spun via a dry jet-wet quench procedure using surface modified inorganic small pore size zeolite incorporated in an Ultem ® 1000 polyetherimide matrix. The zeolites were modified via two separate techniques and termed as (1) Ultem ® “sized” and (2) Grignard treated. The first technique failed to achieve successful mixed matrix performance, but the second approach gave very attractive results. The Ultem ® “sized” zeolites were prepared by treating the zeolites with a silane coupling agent to allow Ultem ® Polymer chains to be grafted to the surface. Poor adhesion was observed between the bulk Polymer and most of the zeolite particles in the final membrane using Ultem ® “sized” particles. The post-treated fibers did not display enhanced selectivity over Neat Polymer with pure gas nitrogen, oxygen, helium, methane and carbon dioxide testing or mixed gas carbon dioxide and methane gas pair. The absence of the mixed matrix effect is hypothesized to be due to the nucleation of hydrophilic solvent and non-solvent around the Ultem ® “sized” zeolite particles during phase separation in the quench bath forming a so called sieve-in-a-cage defect. Although such defects have been reported in dense mixed matrix films, they have not yet been investigated in hollow fibers format which are formed via a phase separation process and thus remain prone to the effects of the non-solvent quenching media. To test the nucleation hypothesis, fibers incorporating 10.3 vol% (with respect to Polymer) of zeolites modified with a Grignard reagent were spun. These fibers, after post-treatment, showed significant selectivity enhancement of 10% for O 2 /N 2 , 29% for He/N 2 , 17% for CO 2 /CH 4 pure gases and 25% for mixed gas CO 2 /CH 4 pairs over Neat Polymer results. The selectivity properties in these fibers are similar to or exceed the Maxwell model predictions for these hybrid materials.
A Aniskevich - One of the best experts on this subject based on the ideXlab platform.
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water transport in epoxy mwcnt composites
European Polymer Journal, 2013Co-Authors: Olesja Starkova, Samuel T Buschhorn, E Mannov, Karl Schulte, A AniskevichAbstract:Moisture and water uptake of epoxy/multi-wall carbon nanotube (MWCNT) composites was studied in a wide range of atmosphere relative humidity and temperatures. Addition of up to 1 wt.% of MWCNTs into the Neat epoxy resulted to the twofold decrease of the diffusivity, while the levels of moisture/water uptake remained unchanged. The positive effect on the reduction of the diffusion coefficient diminishes with the increase of temperature. Differences in the water transport properties and plasticization ability of the Neat Polymer and its nanocomposites are explained by the free volume considerations and the Polymer–water interactions, which are verified by the results of thermomechanical analysis. Water uptake by the nanocomposites resulted to a lower decrease of the storage modulus than that of the Neat epoxy.
Gregory T Schueneman - One of the best experts on this subject based on the ideXlab platform.
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cellulose nanocrystal polyolefin biocomposites prepared by solid state shear pulverization superior dispersion leading to synergistic property enhancements
Polymer, 2015Co-Authors: Krishnan A Iyer, Gregory T Schueneman, John M TorkelsonAbstract:Abstract Cellulose nanocrystals (CNCs), a class of renewable bionanomaterials with excellent mechanical properties, have gained major interest as filler for Polymers. However, challenges associated with effective CNC dispersion have hindered the production of composites with desired property enhancements. Here, composites of polypropylene (PP) and low density polyethylene (LDPE) with 5–10 wt% unmodified CNC are produced for the first time via a solventless process. In particular, we employ solid-state shear pulverization (SSSP). Optical and electron microscopy reveals excellent CNC dispersion with strongly suppressed degradation relative to composites made by melt mixing. Effective dispersion leads to major increases in Young's modulus, including a 69% increase in 90/10 wt% LDPE/CNC composites relative to Neat LDPE, the highest modulus enhancement ever reported for polyolefin/CNC composites. The composites also exhibit superior creep performance with modest increment in yield strength compared to Neat Polymer. The LDPE/CNC composites retain elongation at break values that are equal to that of Neat Polymer while a decrease is observed with PP/CNC composites. The CNC thermal degradation temperature in air is close to that of PP melt processing conditions. We hypothesize that during melt-processing CNCs undergo preferential thermo-oxidative degradation in LDPE and simultaneous degradation in PP. Thus, CNC incorporation results in impaired thermal stability in LDPE and, especially, PP. Care must be taken in selecting the post-SSSP melt processing temperature and residence time in order to suppress degradation. Taking that into account, this study has produced polyolefin/CNC composites with superior dispersion and property enhancements and shown that CNC is an attractive filler for green Polymer biocomposites.
