Misconceptions about filled polymers

Assimilation of Nanoparticles of SiC, ZrC, and WC with Polyaryletherketone for Performance Augmentation of Adhesives

The present paper reports the analyses of results obtained from experiments carried out to explore the challenge of homogeneous, uniform, and deagglomerated dispersion of ultra-heavy nanoparticles (NPs) in the high-performance polyaryletherketone (PAEK) matrix. An equal and fixed amount of (0.5 vol. %) NPs of silicon carbide (SiC), zirconium carbide (ZrC), and tungsten carbide (WC) were dispersed in a PAEK matrix and compression molded to develop three different nanocomposites. Simultaneously, nano-adhesives of the same composition were also developed to join the stainless steel adherends. The composites and adhesives were characterized for their physical, thermal, thermo-mechanical, thermal conductivity (TC), and lap shear strength (LSS) behavior. It was observed that SiC NPs performed significantly better than ZrC and WC NCs in all performance properties (LSS: 154%, TC: 263%, tensile strength: 21%). Thermal conductivity (TC) and tensile properties were validated using various predictive models, such as the rule of mixture parallel model, the Chiew and Glandt model, and the Lewis model. Scanning electron micrographs were used for the morphological analysis of LSS samples to detect macro- and micro-failure. Micrographs showed evidence of micro-striation and plastic deformation as a micromodel, as well as mixed failure, i.e., adhesive-cohesive as a macro-failure mode.

Impact of a nanomixture of carbon black and clay on the mechanical properties of a series of irradiated natural rubber/butyl rubber blend

A series of natural rubber/butyl rubber NR/IIR blend loaded with N660 carbon black (CB) and triethoxy vinyl silane treated clay nanoparticles (TCNPs) were prepared using gamma irradiation in the presence of a polyfunctional monomer, trimethylolpropane triacrylate (TMPTA). The effect of incorporating different contents of N660 CB and five parts per hundred of rubber (phr) of treated clay on the mechanical properties of the prepared nanocomposites has been investigated. The addition of TCNP to CB/rubber composites markedly increase their tensile strength due to the increase of the cross-link density. These results indicated that the TCNP may be enclosed or trapped in the occluded structure of CB. The effect of CB and the TCNP content on the tensile strength (σ), elongation at break (ε b, %), and modulus of elasticity (E, MPa) of natural rubber/butyl rubber NR/IIR blend have been investigated. The incorporation of 5 phr of TCNP into 30 phr CB-loaded NR/IIR composites results in the increased tensile strength value by about 60%. Finally, theoretical models were used to interpret the experimental results.

Experimental and theoretical investigations of the high performance blends of PEEK/PEI

Polyether ether ketone (PEEK) and polyether imide (PEI) blends were made by melt blending using a twin-screw extruder. The blends were characterized by mechanical testing, thermal, rheological and morphological studies. Predictive models were used to explain the tensile modulus and strength properties. The impact strength increases when percentage of the PEI increases in composite. This has been analyzed on the basis of the interphase adhesion. Tensile and flexural strength also increased with increase in the PEI content. Incorporation of PEI increases the glass transition temperature (Tg) and facilitates its processing. Scanning electron microscopy (SEM) was employed to study the phase structure. These experimental findings are in agreement with predictive models based on the rule of mixture and the Nicolais-Narkis model. Multi quadric radial basis function (MQRBF) was applied to study the static and dynamic response of the PEEK/PEI blend plate at uniformly distributed load. The present results were compared with numerical and analytical results.

New method evaluates coupling agents bonding polymer to tooth mineral

Polymerized test specimens consist of a Bis-GMA matrix and a filler of synthetic hydroxyapatite previously coated with the coupling agent under investigation. As the concentration of filler increases for a given coupling agent, the specimen's tensile strength decreases. The more effective the coupling agent, the less pronounced is the decrease. Application of the method is proposed for classifying coupling agents as well as providing a means for assessing the weakening effects of environmental exposure.