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

Mode I and II fracture studies were performed from quasistatic to low velocity impact rates on polymethyl methacrylate (PMMA) and polycarbonate (PC). Mode II tests used an angled double-edge notched specimen loaded in compression. The shear banding response of PMMA is shown to be highly sensitive to rate, with diffuse shear bands forming at low rates and sharp distinct shear bands forming at high rates. As the rate increases, shear deformation becomes more localized to the point where Mode II fracture occurs. PC is much less rate dependent and stable shear band propagation is observed over the range of rates studied with lesser amounts of localization. A new theory is formulated relating orientation in a shear band to intrinsic material properties obtained from true-stress true-strain tests. In a qualitative sense the theory predicts the high rate sensitivity of PMMA. A kinematic limit for orientation within a shear band is also derived based on entanglement network parameters. Mode II fracture in PMMA is shown to occur at this kinematic limit. For the case of PC, the maximum impact rates were not high enough to reach the kinematic limit.

Shear band formation and mode II fracture of polymeric glasses

Hollow cylinders of aromatic-amine cured epoxies, modified with 0%, 10%, and 20% CTBN rubber by weight were tested in stress states ranging from uniaxial compression to biaxial tension. Our results showed that rubber particles decrease the yield strength uniformly over all stress states and suppress brittle fracture in the more demanding stress states. Particle size has no effect on yield strength. Samples were also biaxially loaded and unloaded to varying stress levels to monitor and study their dissipative characteristics. From these tests, a threshold stress was observed where the stiffness of the rubber-modified resin decreases and the deformation becomes increasingly irreversible. By comparing the changes in damage morphology with the change in loading path, we determined that a significant amount of energy is absorbed in the rubber-modified samples prior to macroscopic yield. Additionally, this irreversibility does not appear to be associated with rubber particle cavitation or inelastic void growth.

Yield behavior and energy absorbing characteristics of rubber-modified epoxies subjected to biaxial stress states

The effects of draw conditions were studied for initially amorphous melt-spun poly(ethylene terephthalate) fibers in the presence of subcritical and supercritical (SC) CO2. Both in situ and posttreatment mechanical behavior along with morphological characteristics were investigated. Fibers soaked in subcritical CO2 could be drawn to 30% higher draw ratios (DRs) compared with fibers that were cold-drawn. In situ force response measured with a custom apparatus showed that fibers in subcritical CO2 had no measurable resistance to deformation until strain hardening occurred. In contrast, fibers drawn in SC CO2 displayed a yield response, a significant decrease in ductility, and a significant difference in postyield behavior. Fibers drawn in subcritical CO2 showed slightly lower tensile properties compared with cold-drawn samples whereas fibers treated in SC CO2 had much lower tensile properties because of the limited DR achieved. X-ray diffraction studies indicated that CO2 enhances the development of the crystalline phase compared with cold-drawn samples. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1881–1891, 1999

In situ drawing of high molecular weight poly(ethylene terephthalate) in subcritical and supercritical CO2

High crystalline, porous polyamide 6 by anionic polymerization

Improvements in physical, mechanical, and thermal properties of an epoxy network are made with the use of a unique class of molecules that reinforce the network at the molecular scale. These molecules are commonly referred to as antiplasticizers or fortifiers. In this contribution, two types of fortifiers are incorporated into the model epoxy network. One, dimethyl methylphosphonate, is a simple additive while the other, diethyl phosphoramidate, contains a reactive amine and is cured as part of the network. The two approaches provide some unique differences in the physical and mechanical properties of the networks. Several mechanisms of fortification are discussed and correlated to the observed properties. In addition, it is shown that the fortifiers improve the rheological characteristics of the epoxy resin and act as fire-retardants in the cured network. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4606–4615, 2006

Alan J. Lesser

Papers

Shear band formation and mode II fracture of polymeric glasses

Yield behavior and energy absorbing characteristics of rubber-modified epoxies subjected to biaxial stress states

In situ drawing of high molecular weight poly(ethylene terephthalate) in subcritical and supercritical CO2

High crystalline, porous polyamide 6 by anionic polymerization

Comparing reinforcement strategies for epoxy networks using reactive and non-reactive fortifiers