Polymer/layered silicate nanocomposites: a review from preparation to processing

http://staff.ulsu.ru/moliver/ref/polymers/pott11.pdf

Graphene-based polymer nanocomposites

A review on polymer–layered silicate nanocomposites

https://cyberleninka.org/article/n/768408.pdf

Mechanical properties of graphene and graphene-based nanocomposites

Recently, polymer nanocomposites reinforced with lower volume fraction of nanoceramics and carbon nanotubes have attracted steadily growing interest due to their peculiar and fascinating properties as well as their unique applications in commercial sectors. The incorporation of nanoceramics such as layered silicate clays, calcium carbonate or silica nanoparticles arranged on the nanometer scale with a high aspect ratio and/or an extremely large surface area into polymers improves their mechanical performances significantly. The properties of nanocomposites depend greatly on the chemistry of polymer matrices, nature of nanofillers, and the way in which they are prepared. The uniform dispersion of nanofillers in the polymer matrices is a general prerequisite for achieving desired mechanical and physical characteristics. In this review article, current development on the processing, structure, and mechanical properties of polymer nanocomposites reinforced with respective layered silicates, ceramic nanoparticles and carbon nanotubes will be addressed. Particular attention is paid on the structure–property relationship of such novel high-performance polymer nanocomposites.

Structural and mechanical properties of polymer nanocomposites

This article reports the processing and characterization of epoxy resins with near constant molar cross-link density prepared from sequentially reacted amine cross-linking agents. Stoichiometric blends of curing agents with compositions ranging from all polyetheramine to all diaminodiphenylsulfone (DDS) are reacted with an epoxy monomer in a staged curing procedure. The low reactivity of the aromatic amine permits the selective reaction of the aliphatic amine in the first stage. The residual aromatic amine and epoxide functionality are reacted in a second stage at higher temperature. Above approximately 50% DDS content the first stage produces sol glasses which have not reached the gel point. The glass transition temperatures of the partially cured networks decrease monotonically with increasing DDS content. The partially cured networks can be characterized thermally and mechanically above their respective glass transitions without significantly advancing the reaction of the residual DDS and epoxide functionality. The networks formed after the second stage of the cure exhibit thermal and mechanical properties intermediate between those of the two individual amine cured networks, according to composition. The blends do not show any evidence of phase separation across the entire composition range in either the partially cured or fully cured state.

/pdf/characterization-of-double-network-epoxies-with-tunable-37jmhsdwsm.pdf

Characterization of double network epoxies with tunable compositions

Conventional tensile dilatometry techniques are extended to cyclic fatigue applications to study volume changes that occur during controlled-load cyclic fatigue of polyacetal. During fatigue, tn-situ measures of the irreversible and elastic volume change are monitored together with dynamic viscoelastic parameters (E', E, and Tan δ). and changes in the energy densities (strain energy, potential energy, and irreversible work). The results show that the effective irreversible volume of the polyacetal gradually increases over a wide range of applied cyclic stress. However, at high stress levels and/or frequencies (i.e., low-cycle, thermally dominated regime), the effective Poisson's ratio of the polyacetal increases as it softens (evidenced by the dynamic viscoelastic data). Conversely, at lower stress levels, the Poisson's ratio continually decreases coincident with decreases in the loss modulus (E) and the irreversible work density. These results are indicative of entirely different mechanisms governing the low-cycle (high stress level) and high-cycle (low stress) regimes. Also, comparisons between tensile and fatigue dilatometry studies show that the dilational-strain response of samples fatigued at high stress levels are similar to data obtained from monotonic tensile dilatometry. However, the dilation-strain response of samples fatigued at lower stress levels are distinctly different from low-cycle fatigue and tensile dilatometry.

Effective volume changes during fatigue and fracture of polyacetal

Preparation of high performance poly(ethylene terephthalate) fibers: two-stage drawing using high pressure CO2

The drawing behavior of ultrahigh molecular weight polyethylene fibers in supercritical carbon dioxide (scCO 2) is compared to that in air at different tempera- tures. The temperature substantially influences the drawing properties in air, whereas in scCO 2, a constant draw stress and tensile strength are observed. Differential scan- ning calorimetry shows an apparent development of a hexagonal phase along with a significant increase in the crystallinity of air-drawn samples with increasing temper- ature. The existence of this phase is not confirmed by wide-angle X-ray scattering, which instead shows that air-drawn samples crystallize in an internally constrained manner. In contrast, scCO 2 allows crystals to grow without constraints through a possible crystal- crystal transformation, increasing the processing temperature to 110

Alan J. Lesser

Papers

Characterization of double network epoxies with tunable compositions

Effective volume changes during fatigue and fracture of polyacetal

Preparation of high performance poly(ethylene terephthalate) fibers: two-stage drawing using high pressure CO2

Drawing of ultrahigh molecular weight polyethylene fibers in the presence of supercritical carbon dioxide

Multifunctional deoxybenzoin-based epoxies: Synthesis, mechanical properties, and thermal evaluation