TriSilanolPhenyl POSS–polyimide nanocomposites: Structure–properties relationship (original) (raw)
Related papers
Effect of the POSS–Polyimide nanostructure on its mechanical and electrical properties
Composites Science and Technology, 2012
Nanocomposite films consisted of Polyhedral Oligomeric Silsesquioxane (POSS) filler in a Polyimide (PI) matrix were prepared. The effect of the nanocomposites' structure on its mechanical and electrical properties was evaluated with respect to survival in the low Earth orbit (LEO) environment. The POSS-PI structure consists of POSS nano-aggregates formed in the bulk and on the surface. The aggregates' size and distribution are POSS content-dependant. The fracture mechanism during hypervelocity impact at extreme temperature conditions was studied. The hypervelocity impacts of the POSS-PI films result in a brittle fracture, compared to ductile fracture in the case of PI, and in formation of radial cracks. A model based on formation and coalescence of voids around the aggregates, when load is applied, is suggested to explain the effect of the POSS content on the POSS-PI fracture mechanism. The size and density of the POSS aggregates also affect the nanocomposite's volume electrical resistivity. An inverse dependence exists between the POSS aggregates' surface density and the nanocomposites' volume electrical resistivity.
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.
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.
Polymer, 2009
Mixed matrix blends containing polyimide (PI) and polyhedral oligomeric silsesquioxanes (POSS) are studied with atomistic molecular dynamics simulation. To examine the effect of functional group, two types of POSS are considered, either octahydrido silsesquioxane (OHS) or octaaminophenyl silsesquioxane (OAPS). The glass transition temperature of the model PI-OAPS blends increases with the incorporation of OAPS, an observation consistent with recent experiments on these systems. A decrease in glass transition temperature is shown for the model PI-OHS blends. Radial distribution functions for both blends are presented to show how packing between the inorganic (POSS) and organic (PI) species in the mixed matrix varies as a function of POSS loading and POSS functionalization. In addition, we report the mobility of the PI chains and POSS molecules in the material by calculating the mean square displacement. These results provide molecular insight about thermal property enhancements afforded by POSS-based additives.
Polymer, 2002
Vinyl ester (VE) composites containing chemically bonded, multifunctional polyhedral oligomeric silsesquioxane (POSS), POSS-1 ((C 6 H 5 CHCHO) 4 (Si 8 O 12 )(CHyCHC 6 H 5 ) 4 ), nanoparticles were prepared with VE/POSS-1 95/5 and 90/10 w/w ratios. The mole percents of POSS-1 in these two composites are low (,0.5 and ,1%, respectively) due to the high mass of POSS-1 mwt 1305: VE composites of two non-functional POSS-3 (octaisobutyl POSS) and POSS-4 (dodecaphenyl POSS) derivatives were also prepared with 95/5 w/w compositions. Additionally, POSS-1 was also incorporated into styrene copolymers at levels of 5 wt% (0.42 mol%) and 10 wt% (0.88 mol%) of POSS-1. The composites and copolymers were characterized by dynamic mechanical thermal analysis and mechanical testing. The POSS-1 units incorporated into the vinyl ester network were well dispersed. No phase-separation in the VE/POSS-1 90/10 composite could be detected by TEM from low to 8 £ 10 5 magni®cation. In VE composites containing 10 wt% POSS-1, silicon-rich phases were observed ranging in size from a few nm to ,75 nm by electron energy loss spectroscopy (
Functional Polyimide/Polyhedral Oligomeric Silsesquioxane Nanocomposites
Polymers, 2018
The preparation of hybrid nanocomposite materials derived from polyhedral oligomeric silsesquioxane (POSS) nanoparticles and polyimide (PI) has recently attracted much attention from both academia and industry, because such materials can display low water absorption, high thermal stability, good mechanical characteristics, low dielectric constant, flame retardance, chemical resistance, thermo-redox stability, surface hydrophobicity, and excellent electrical properties. Herein, we discussed the various methods that have been used to insert POSS nanoparticles into PI matrices, through covalent chemical bonding and physical blending, as well as the influence of the POSS units on the physical properties of the PIs.
2005
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.
Polyoxymethylene nanocomposites with octakis (dimethylsiloxy, ethyl epoxycyclohexy) octasilsesquioxanes (POSS) were ob-tained during melt blending. The influence of the POSS nanoparticles on the morphology and mechanical properties of polyoxymethylene (POM) nanocomposites properties was investigated. POM/POSS nanocomposites were produced by means of melt mixing of POM with POSS; with a POSS content of 0.5, and 1 wt.%. The uniaxial elongation test of polyoxymethylene has been performed to determine the influence of POSS on the mechanical properties of the new hybrid material. The disper-sion of POSS in the POM nanocomposites was studied by scanning electron microscopy (SEM). According to the mechanical investigation, it was found that the process of polyhedral oligomeric silsesquioxane (POSS) addition leads to an enhancement of both the tensile strength and stiffness, where the most encouraging results were achieved for the POM/POSS nanocomposites with 0.5 wt.% POSS. The SEM studies ...