Effect of Morphology on the Relaxation Processes and Mechanical Properties in Polyimide/Silica Hybrids

Ragosta, G.; Musto, Pellegrino; Abbate, Mario; Russo, Pietro; Scarinzi, Gennaro

doi:10.1002/masy.200750111

Cited by 7 publications

(10 citation statements)

References 26 publications

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“…For a silica concentration of 22.3 wt%, calculated theoretically assuming complete conversion of TEOS and GOTMS to silica [33], the threshold GOTM/TEOS molar ratio is located between 0.06 and 0.08. Figure 4 shows the SEM micrographs of hybrids having 22.3 wt% of silica and GOTMS contents below and above the threshold value [32]. For GOTMS concentrations lower than the limiting value, the hybrids display (Figures 4a and 4b) a particulate morphology like that of Figures 3a, but with smaller particles sizes.…”

Section: Processing and Morphologymentioning

confidence: 95%

“…These interactions delay the onset of phase separation by spinodal decomposition, which results in a higher viscosity of the solution and in a reduction of the rate of particle growth [5,8,32]. It was found that a threshold value of the GOTMS/TEOS molar ratio exists for the formation of co-continuous morphologies [8,32]. This threshold value was found to change with the overall silica content in the hybrid.…”

Section: Processing and Morphologymentioning

confidence: 99%

“…The way through which the coupling agent induces and controls the evolution of the morphology in these hybrid systems was attributed to interactions, possibly by hydrogen bonding, taking place between the epoxy groups of GOTMS and the acid groups of the polyimide precursor. These interactions delay the onset of phase separation by spinodal decomposition, which results in a higher viscosity of the solution and in a reduction of the rate of particle growth [5,8,32]. It was found that a threshold value of the GOTMS/TEOS molar ratio exists for the formation of co-continuous morphologies [8,32].…”

Section: Processing and Morphologymentioning

confidence: 99%

“…Thus, properly formulated PI hybrids with silica domains of nanoscale dimensions could make it possible to extend considerably the maximum temperature at which these systems can be reliably employed. Ragosta and coworkers [32,48] used the Essential Work of Fracture (EWF) method [49][50][51] to assess the fracture toughness of phase separated PI/silica hybrids from ambient temperature to 250°C. ure 14 shows the fracture toughness, expressed in term of the essential work of fracture parameter, w e , versus temperature for a series of particulate PI/silica hybrids and for the pure polyimide.…”

Section: Mechanical and Fracture Propertiesmentioning

confidence: 99%

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Polyimide/silica hybrids via the sol-gel route: High performance materials for the new technological challenges

Ragosta¹,

Musto²

2009

Express Polym. Lett.

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Abstract. The present review article describes in detail the state-of-the-art of organic-inorganic hybrid materials based on polyimide/silica components. The article is divided in three parts. In the first the basic processing route for the preparation of these systems is described, i.e. the sol-gel technique, along with the strategies developed to control the final morphology. In the second part the curing characteristics, the dynamic-mechanical and the mechanical and fracture properties of hybrids with different morphologies are reviewed. Finally, the more technologically relevant applications devised for these high performance materials are discussed. : nanocomposites, hybrid materials, polyimide, silica, sol-gel eXPRESS Polymer Letters Vol.3, No.7 (2009) [413][414][415][416][417][418][419][420][421][422][423][424][425][426][427][428] Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2009.51 or as functional materials [14] such as catalyst supports [15] and microelectronic devices [16]. The sol-gel route represents the preferred way for the synthesis of polyimide based hybrids. The classical sol-gel process consists in a two step hydrolysis-condensation reaction, starting with a metal alkoxides M(OR) 4 , typically tetraethoxisilane Si(OCH 2 CH 3 ) 4 or titanium isopropoxide Ti[OCH(CH 3 ) 2 ] 4 , to produce hydroxyl groups followed by the polycondensation of the hydroxyl groups and residual alkoxy groups to form a three-dimensional network [5,[17][18][19][20][21]. Polyimides are particularly suited for this type of process because they can be obtained from polyamic acid precursors, which are soluble in hygroscopic solvents and can, therefore, tolerate the addition of water necessary to bring about the hydrolysis of the metal alkoxide. Moreover, the outstanding thermal stability of polyimides allows the hybrids to be post-cured at very high temperatures (300-350°C) making it possible the development of a very dense inorganic network without inducing appreciable degradation of the organic phase. Polyimide/silica hybrids made by the sol-gel technique are the subject of this review, in which the approaches used for a close control of their final morphology, the effects of the silica phase on the curing process of polyimide precursors, the dynamic-mechanical and the mechanical and fracture properties that these materials can display, and their possible applications will be presented and discussed. Keywords Processing and morphologyA typical procedure for the preparation of PI/silica hybrids via the sol-gel route, involves the following steps: i) The polyamic acid (PAA) (PI precursor) is formed by a polyaddition reaction of a dianhydride [e.g., pyromellitic anhydride (PMDA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), or 2,2-bis(3,4-dicarboxy-phenyl)-hexafluoropropane dianhydride (6FDA)] with a diamine [e.g., 4,4′-oxydianiline (ODA), or p-phenylen diamine (PPA)] in a common solvent [e.g., dimethylacetamide (DMAc), or N-methyl pyrolidone (NMP)]. The reaction and chemical str...

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Section: Processing and Morphologymentioning

confidence: 95%

Section: Processing and Morphologymentioning

confidence: 99%

Section: Processing and Morphologymentioning

confidence: 99%

Section: Mechanical and Fracture Propertiesmentioning

confidence: 99%

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Polyimide/silica hybrids via the sol-gel route: High performance materials for the new technological challenges

Ragosta¹,

Musto²

2009

Express Polym. Lett.

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“…where A is the pre-exponential factor, R is the gas constant, T is the absolute peak temperature, and E a is the activation energy for the relaxation process [26]. E a represents the relationship between the mechanical loss factor and temperature.…”

Section: Thermomechanical Propertiesmentioning

confidence: 99%

Investigation of thermomechanical properties and matrix–filler interaction on polyimide/graphene oxide composites

Pramoda

Mya

Lin

et al. 2012

Polymer Engineering & Sci

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We report, the preparation of nanocomposites having polyimide (PI) as matrix and graphene oxide (GO) as filler, analyses of matrix–filler interactions, and enhancements in thermomechanical properties of PI/GO as compared with pristine PI. The matrix–filler interactions were analyzed by 1H NMR, X‐ray photoelectron spectroscopy, and density functional theory calculations. The data suggested stronger matrix–filler interactions in PI/GO as compared with PI/G composites. The stronger matrix–filler interactions and homogeneous dispersion of fillers lead to a significant enhancement in mechanical properties in PI/GO nanocomposites. Thus, with just 1 wt% GO content, the modulus of PI/GO composite increased by ∼106% as compared with pristine PI. Finally, thermal expansion coefficients of the nanocomposites are also investigated. A plausible hypothesis has been proposed in the text to explain the observed matrix–filler interactions and the subsequent property enhancements in nanocomposites. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

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Compatibilizing polyimide/silica hybrids by alkoxisilane‐terminated oligoimides: Morphology–Properties relationships

Ragosta

Musto

Abbate

et al. 2011

J of Applied Polymer Sci

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A fluorinated polyimide (PI), synthesized from 4,4 0 -(hexafluoroisopropylidene) diphthalic anhydride and 4,4 0 -diaminodiphenyl ether, was used as matrix for the preparation of PI/silica hybrids. The inorganic phase was obtained in situ by a sol-gel route with tetraethoxysilane as precursor. Both micron-and nano-scale hybrids were obtained depending on the interfacial interaction between the organic and inorganic phases. To promote such interaction a compatibilizing agent was synthesized, in the form of an alkoxisilane-terminated oligoimide. Both the PI and the coupling agent were characterized by FTIR and Raman spectroscopies and by GPC measurements. The effect of the coupling agent on the morphology of the hybrids and on the size of the silica particles was investi-gated by scanning electron microscopy. The viscoelastic, mechanical, and thermal properties of hybrid composites were studied. It was shown that by adding appropriate amounts of the compatibilizer it was possible to control the morphology and to obtain homogeneous nanostructured systems. A general improvement of the mechanical performances and of the thermal stability was demonstrated, together with an increase of T g , which was found more pronounced for the nanocomposites than for the microcomposites.

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Effect of Morphology on the Relaxation Processes and Mechanical Properties in Polyimide/Silica Hybrids

Cited by 7 publications

References 26 publications

Polyimide/silica hybrids via the sol-gel route: High performance materials for the new technological challenges

Polyimide/silica hybrids via the sol-gel route: High performance materials for the new technological challenges

Investigation of thermomechanical properties and matrix–filler interaction on polyimide/graphene oxide composites

Compatibilizing polyimide/silica hybrids by alkoxisilane‐terminated oligoimides: Morphology–Properties relationships

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