Determination of Mechanical and Surface Properties of Semicrystalline Polyhedral Oligomeric Silsesquioxane (POSS) Nanocomposites (original) (raw)
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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. maximize the interactions between the POSS compounds and the polymer by the modification of the organic groups surrounding the inorganic cage. This study examines the ability of POSS to improve the mechanical and surface properties of three semicrystalline polymers, fluorinated ethylene-propylene (FEP), poly(vinylidene fluoride) (PVDF) and isotactic polypropylene (PP). The POSS materials used included methyl 8 T 8 and two FluoroPOSS compounds, fluorodecyl 8 T 8 and fluorooctyl 8 T 8 . The FluoroPOSS compounds have been shown to exhibit remarkable surface characteristics, which have been observed in water contact angle measurements. In a comparative study, five and ten weight percent of methyl 8 T 8 was melt blended into PVDF, FEP and PP and the same weight percent loadings of fluorodecyl 8 T 8 and fluorooctyl 8 T 8 were investigated in PVDF and FEP. The addition of methyl 8 T 8 was found to increase the modulus of FEP and PP, while the incorporation of all three POSS compounds decreased the modulus of PVDF. In addition, the methyl 8 T 8 in PP increased the tensile strength, Izod impact strength and heat deflection temperature. The injection molded FEP blend samples showed indirect evidence of surface migration, as demonstrated in the core/shell morphology observed in pulled tensile bars and disks for surface analysis. Unclassified b. ABSTRACT Unclassified c. THIS PAGE Unclassified A 12 19b. TELEPHONE NUMBER (include area code) (661) 275-5857 Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. 239.18
Express Polymer Letters, 2012
The polyhedral oligomeric silsesquioxane (POSS) additivated polystyrene (PS) based nanocomposites were prepared by melt processing and the structure-properties relationships of the POSS-PS systems were compared to those of the neat PS. In order to investigate the effect of these structural parameters on the final properties of the polymer nanocomposites, five different kinds of POSS samples were used, in particular, POSS with different inorganic cage and with different organic pendent groups. The rheological investigation suggests clearly that the POSS acts as a plasticizer and that the processability of the PS was positively modified. The affinity between the POSS samples and the PS matrix was estimated by the calculated theoretical solubility parameters, considering the Hoy's method and by morphology analysis. Minor difference between the solubility parameter of POSS and the matrix means better compatibility and no aggregation tendency. Furthermore, the POSS loading leads to a decrease of the rigidity, of the glass transition temperature and of the damping factor of the nanocomposite systems. The loading of different POSS molecules with open cage leads to a more pronounced effect on all the investigated properties that the loading of the POSS molecules with closed cage. Moreover, the melt properties are significantly influenced by the type of inorganic framework, by the type of the pendent organic groups and by the interaction between the POSS organic groups and the host matrix, while, the solid state properties appears to be influenced more by the kind of cage.
Polymer, 2009
We synthesized the polyhedral oligomeric silsesquioxane (POSS) derivatives octakis[dimethyl(phenethyl)siloxy]silsesquioxane (OS-POSS), octakis[dimethyl(4-acetoxy phenethyl)siloxy]silsesquioxane (OA-POSS), and octakis[dimethyl(4-hydroxyphenethyl)siloxy] silsesquioxane (OP-POSS) through hydrosilylation with octakis(dimethylsiloxy)silsesquioxane (Q 8 M 8 H). To investigate the influence of these octuply functionalized POSS derivatives in polymer nanocomposites, we blended OP-POSS, OA-POSS, and OP-POSS with the homopolymer poly(ethylene oxide) (PEO) and characterized its resulting intermolecular interactions (e.g., hydroxyl-ether and carbonyl-ethylene oxide) using FTIR spectroscopy. The thermal properties of these blend systems were investigated using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The crystallization kinetics in the miscible binary blends of the crystalline polymer and these inorganic nanoparticles were also determined through DSC and optical microscopy (OM) analyses. Herein, we emphasize the effects of the functional groups on POSS nanocomposites on the crystallization kinetics of PEO. We found that OP-POSS/PEO blend had the highest thermal stability and lowest crystallization rate because its hydrogen bonding interactions (between its hydroxyl and ether units) were stronger than those (between carbonyl and methylene groups) in OA-POSS/PEO.
Acs Symposium Series, 2007
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SN Applied Sciences
The present study investigated the influence of different compatibilizer on the dispersion of polyhedral oligomeric silsesquioxane (POSS). The effect of POSS dispersion in the epoxy resin in terms of mechanical, and thermal properties were reported. The three solvent used to disperse POSS in this work are ethanol, acetone, and toluene. The POSS was initially dispersed in the solvent followed by an addition in the epoxy resin by systematically varying the weight fraction from 0.5 to 8 wt%. Mechanical properties of nanocomposites were characterized in terms of elastic modulus, and fracture toughness. The obtained result illustrates that nanocomposites prepared by polar solvent dispersion such as ethanol showed an increase in values of elastic modulus and fracture toughness value. The increase in the modulus and fracture toughness value is due to the better interaction between POSS and ethanol disperse the POSS uniformly in the epoxy resin while avoiding the agglomeration. However, nanocomposites prepared by nonpolar solvent does not show substantial change in the mechanical properties. Fractured surface morphology was studied using scanning electron microscopy. Differential scanning calorimetry and dynamic mechanical analysis illustrates that with better POSS dispersion value of glass transition temperature (T g ) increased. Fourier transformation infrared spectroscopy showed that POSS completely interacted with the epoxy resin and no phase separation was observed.
Hydrophobic Silsesquioxane Nanoparticles and Nanocomposite Surfaces
ACS Symposium Series, 2007
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Polyhedral Oligomeric Silsesquioxane (POSS)-Containing Polymer Nanocomposites
Hybrid materials with superior structural and functional properties can be obtained by incorporating nanofillers into polymer matrices. Polyhedral oligomeric silsesquioxane (POSS) nanoparticles have attracted much attention recently due to their nanometer size, the ease of which these particles can be incorporated into polymeric materials and the unique capability to reinforce polymers. We review here the state of POSS-containing polymer nanocomposites. We discuss the influence of the incorporation of POSS into polymer matrices via chemical cross-linking or physical blending on the structure of nanocomposites, as affected by surface functional groups, and the POSS concentration.
Chemistry of Materials, 2006
Cyanate ester Lonza Corp.) composites containing the blended polyhedral oligomeric silsesquioxane (POSS), TriSilanolPhenyl-POSS (C 42 H 38 O 12 Si 7 ), were prepared containing PT-15/POSS 99/1, 97/3, 95/5, 90/10, and 85/15 w/w ratios. The composites were characterized by FT-TR, X-ray diffraction (XRD), small-angle neutron scattering (SANS), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (X-EDS), transmission electron microscopy (TEM), dynamic mechanical thermal analysis (DMTA), and three-point bending flexural tests. TriSilanolPhenyl-POSS was throughly dispersed into uncured liquid PT-15 resin. After curing, XRD, SANS, and X-EDS measurements were consistent with partial molecular dispersion of a portion of the POSS units in the continuous matrix phase while the remainder forms POSS aggregates. Larger aggregates are formed at higher loadings. SANS, SEM, and TEM show that POSS-enriched nanoparticles are present in the PT-15/POSS composites. The storage bending moduli, E′, and the glass transition temperatures, T g , of PT-15/POSS 99/1, 97/3, and 95/5 composites are higher than those of the pure PT-15 over the temperature range from 35 to 350°C