Thermal pressure coefficient of a polyhedral oligomeric silsesquioxane (POSS)‐reinforced epoxy resin

Win, Kyaw Zin; Karim, Taskin; Li, Qingxiu; Simon, Sindee L.; McKenna, Gregory B.

doi:10.1002/app.31502

Cited by 6 publications

(5 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This differs from results on a 10 wt % POSS nanoparticle/epoxy system where 10 and 20% reductions in the thermal stress coefficient (as estimated by a P G) and thermal pressure coefficient c at 10 wt % POSS loading were found 4,5 in the glassy state below T g.…”

Section: Discussioncontrasting

confidence: 79%

“…[1][2][3][4] One potential strategy to mitigate thermal residual stresses in fiber-reinforced polymeric materials may be to add nanoparticles to the polymer matrix. 4,5 Although moduli and thermal expansivities normally exhibit a reciprocal relationship, [6][7][8] findings for a 10 wt % polyhedral oligomeric silsesquioxane (POSS)-reinforced epoxy resin show reductions in the thermal pressure coefficient and the thermal stress coefficient (the product of linear thermal expansion coefficient a L and Young's modulus E). 4,5 In addition, model calculations have also reported polymer nanocomposites may have exceptional properties-for example, the incorporation of nanoparticles may reduce the bulk modulus of the neat polymer.…”

Section: Introductionmentioning

confidence: 98%

“…4,5 Although moduli and thermal expansivities normally exhibit a reciprocal relationship, [6][7][8] findings for a 10 wt % polyhedral oligomeric silsesquioxane (POSS)-reinforced epoxy resin show reductions in the thermal pressure coefficient and the thermal stress coefficient (the product of linear thermal expansion coefficient a L and Young's modulus E). 4,5 In addition, model calculations have also reported polymer nanocomposites may have exceptional properties-for example, the incorporation of nanoparticles may reduce the bulk modulus of the neat polymer. Hooper and Schweizer 9 predicted that the bulk modulus of well-dispersed spherical nanoparticle-filled polymer decreases significantly with increasing filler loading using the Polymer Reference Interaction Site Model (PRISM); at 10% filler volume loading, K decreases approximately 10% compared to the neat polymer.…”

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

Pressure‐volume‐temperature and glass transition behavior of silica/polystyrene nanocomposite

Tao

Simon

2015

J Polym Sci B Polym Phys

Self Cite

View full text Add to dashboard Cite

The pressure-volume-temperature (PVT) behavior and glass transition behavior of a 10 wt % silica nanoparticlefilled polystyrene (PS) nanocomposite sample are measured using a custom-built pressurizable dilatometer. The PVT data are fitted to the Tait equation in both liquid and glassy states; the coefficient of thermal expansion a, bulk modulus K, and thermal pressure coefficient c are examined as a function of pressure and compared to the values of neat PS. The glass transition temperature (T g ) is reported as a function of pressure, and the limiting fictive temperature (T f 0 ) from calorimetric measurements is reported as a function of cooling rate. Comparison with data for neat PS indicates that the nanocomposite has a slightly higher T g at elevated pressures, higher bulk moduli at all pressures studied, and its relaxation dynamics are more sensitive to volume. The results for the glassy c values suggest that thermal residual stresses would not be reduced for the nanocomposite sample studied. INTRODUCTION In fiber-reinforced polymer composites, the build-up of residual stresses induced by the mismatch in thermal expansivities between filler and matrix is often inevitable during processing and application. These isotropic thermal residual stresses, which can lead to early failure or suboptimal performance of a material, depend on the thermal pressure coefficient c, which in turn depends on the product of the bulk modulus K (52V(@P/@V) T ) and the isobaric thermal expansion coefficient a p (51/V(@V/@T) P ).

show abstract

Section: Discussioncontrasting

confidence: 79%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

Pressure‐volume‐temperature and glass transition behavior of silica/polystyrene nanocomposite

Tao

Simon

2015

J Polym Sci B Polym Phys

Self Cite

View full text Add to dashboard Cite

show abstract

“…Figure 5 shows calculations of K B normalized to its pure polymer melt analog, K B0 , over a wide range of interface attraction strengths. At higher " pc , where adsorbed layers are well-developed and polymers mediate repulsive interparticle interactions, K B decreases with increasing c , consistent with prior theoretical studies [18,23] as, seemingly, a recent measurement of the thermal pressure coefficient (proportional to K B ) in a polymer nanocomposite [24]. However, for FIG.…”

supporting

confidence: 74%

Multiscale Structure, Interfacial Cohesion, Adsorbed Layers, and Thermodynamics in Dense Polymer-Nanoparticle Mixtures

2011

View full text Add to dashboard Cite

We establish the existence and size of adsorbed polymer layers in miscible dense nanocomposites and their consequences on microstructure and the bulk modulus. Using contrast-matching small-angle neutron scattering to characterize all partial collective structure factors of polymers, particles, and their interface, we demonstrate qualitative failure of the random phase approximation, accuracy of the polymer reference site interaction model theory, ability to deduce the adsorbed polymer layer thickness, and high sensitivity of the nanocomposite bulk modulus to interfacial cohesion. DOI: 10.1103/PhysRevLett.107.225504 PACS numbers: 61.46.Df, 61.05.fg, 61.41.+e Particle aggregation in concentrated polymer solutions, melts, and cross-linked elastomers profoundly alters the mechanical, optical, and electrical properties of nanocomposites [1][2][3][4][5]. Mechanisms of controlling the state of particle aggregation in these complex mixtures remain elusive and poorly understood [6]. Conceptual frameworks for achieving good dispersion generally rely on chemically or physically bound polymer layers [7,8] to induce a repulsive interparticle potential of mean force between nanoparticles [9,10]. Nonetheless, understanding the nature of, and what controls, the structure and properties of these layers remains an outstanding challenge in soft matter of broad importance in polymer science, colloid science, and even biological systems. Obstacles limiting progress include (i) developing experimental tools and physics-based strategies for measuring and controlling the material-specific strength of polymer segments and particle surface attraction, (ii) differentiating polymer segments adsorbed on the nanoparticle surface from bulk polymer in the dense polymer solutions or melts, and (iii) measuring the packing structure of both segments and particles over a wide range of length scales and volume fractions.In this Letter, we present experimental results addressing the above issues using contrast-matching small-angle neutron scattering techniques in conjunction with carefully designed, thermodynamically stable (miscible) concentrated ternary solutions of short-chain polymers (oligomers), nanoparticles, and solvent. Measuring the intensity of scattered neutrons as a function of particle and polymer scattering contrast allows determination of all three partial collective structure factors that quantify spatially resolved segment-segment, particle-particle, and interfacial concentration fluctuations [11]. We employ this experimental knowledge to (i) determine the adsorbed layer thickness, (ii) quantitatively test at an unprecedented level the microscopic polymer reference interaction site model (PRISM) theory [12,13], and (iii) discover strong limitations of the incompressible random phase approximation (IRPA) [14]. How interfacial cohesion can qualitatively modify the effect of particle addition on the nanocomposite bulk modulus is addressed based on the experimentally validated theory.Silica nanoparticles of diameter D ¼ 40 nm are s...

show abstract

“…These were reviewed by Li et al in 2001. Since then, Win et al have shown that addition of 10 wt % POSS reduces the thermal pressure coefficient of an epoxy-diamine thermoset, thereby improving its mechanical properties on thermal cycling, and others have shown that incorporation of small amounts of POSS into epoxy-amine/anhydride mixtures, either as pendant groups or as reactants, improves flame retardency, , elasticity, , dielectric, , physical aging, and related properties. It has been found that in some cases POSS increases the glass–liquid transition temperature of the nanocomposites, − and decreases it for others. ,, Kinetics of polymerization of POSS-containing mixtures has also been studied.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of Polymerization of a Liquid with Nanosize Structural Heterogeneities

Khouri

Johari

2011

J. Phys. Chem. B

View full text Add to dashboard Cite

We report the effects of chemically reacting, nanometer-size structural heterogeneity on a polymerization process. Heterogeneity is introduced by adding 2 nm size molecules of polyhedral oligomeric silsesquioxane with multiepoxide groups (POSS) while maintaining stoichiometry of a polymerizing triamine-diepoxide mixture. Calorimetric studies show that POSS addition first increases the polymerization rate and then decreases it progressively more. In the presence of nanometer-scale structural heterogeneity, diffusion-controlled kinetics begins sooner in time. The enthalpy of polymerization decreases with the amount of POSS heterogeneity according to the mixture rule; the glass-liquid transition endotherm of the partially polymerized state becomes broader, and the enthalpy of post polymerization decreases. The POSS-alone mixture polymerizes relatively slower, and the glass-liquid transition exotherm of the polymerized state is indistinguishably broad. Both are attributed to the distribution of diffusion rates or dispersive kinetics, and the development of dynamic heterogeneity more rapidly for the POSS-only mixture than for others. Increase in the polymerization rate on initial addition of nanometer-size POSS and then decrease on further addition is explained in terms of decoupling of diffusion from viscous flow, that is, when the diffusion rate decreases less rapidly with the polymerization time than the viscosity increases.

show abstract

Thermal pressure coefficient of a polyhedral oligomeric silsesquioxane (POSS)‐reinforced epoxy resin

Cited by 6 publications

References 28 publications

Pressure‐volume‐temperature and glass transition behavior of silica/polystyrene nanocomposite

Pressure‐volume‐temperature and glass transition behavior of silica/polystyrene nanocomposite

Multiscale Structure, Interfacial Cohesion, Adsorbed Layers, and Thermodynamics in Dense Polymer-Nanoparticle Mixtures

Kinetics of Polymerization of a Liquid with Nanosize Structural Heterogeneities

Contact Info

Product

Resources

About