P, George SC, Kalarikkal N, Thomas S. Enhanced mechanical and thermal performance of multiwalled carbon nanotubes-filled polypropylene/natural rubber thermoplastic elastomers

This paper reveals the effect of the concentration-dependent migration of MWCNTs among blend components on the static, dynamic, mechanical and thermal properties of MWCNT-filled PP/NR blends.

Incineration of Nanoclay Composites Leads to Byproducts with Reduced Cellular Reactivity

Addition of nanoclays into a polymer matrix leads to nanocomposites with enhanced properties to be used in plastics for food packaging applications. Because of the plastics' high stored energy value, such nanocomposites make good candidates for disposal via municipal solid waste plants. However, upon disposal, increased concerns related to nanocomposites' byproducts potential toxicity arise, especially considering that such byproducts could escape disposal filters to cause inhalation hazards. Herein, we investigated the effects that byproducts of a polymer polylactic acid-based nanocomposite containing a functionalized montmorillonite nanoclay (Cloisite 30B) could pose to human lung epithelial cells, used as a model for inhalation exposure. Analysis showed that the byproducts induced toxic responses, including reductions in cellular viability, changes in cellular morphology, and cytoskeletal alterations, however only at high doses of exposure. The degree of dispersion of nanoclays in the polymer matrix appeared to influence the material characteristics, degradation, and ultimately toxicity. With toxicity of the byproduct occurring at high doses, safety protocols should be considered, along with deleterious effects investigations to thus help aid in safer, yet still effective products and disposal strategies.

Temperature dependent separation of immiscible polymer blend in a melted state

The density and the spectral fingerprint of a compounded blend or composite vary widely depending on the type of the components and their composition. However, the currently used polymer separation techniques, such as density-based and optical sorting systems are not suitable for recovering these materials fully due to the physical-chemical bonding between the components. The application of a novel separation principle creates the opportunity to enrich the blend fractions to neat, homogeneous zones in a melted state by utilising centrifugal force. In this study three different types of plastics: high density polyethylene, polystyrene and polyethylene terephthalate were deeply investigated in order to understand the separability of their blends as a function of rotation time and melt temperature. The results showed that the separation of polymer mixtures and blends depends strongly on the viscosity and bulk density at a given temperature, and the initial particle size also has a significant impact.

Morphological characterization, thermal, and mechanical properties of compatibilized high density polyethylene/polystyrene/organobentonite ternary nanocomposites

Composite materials made from high density polyethylene (HDPE) and polystyrene (PS) were successfully prepared in different HDPE/PS weight ratios, by melt mixing 3 wt% of bentonite clay organically modified with hexadecyl ammonium chloride (organo-modified bentonite, OBT). The structure and morphology of these composites were examined by X-ray diffraction and scanning electron microscopy. Morphological changes between the composite and the constituent materials were observed. The decrease in PS (or HDPE) particle size in HDPE/PS 70/30 (or 30/70) that blend after the OBT addition reflects a clear improvement in the HDPE/PS blend compatibility. The effect of OBT on the thermal and mechanical properties was investigated by differential scanning calorimetry, thermogravimetric analysis, and tensile measurements. The main results show a decrease in the HDPE crystallinity in the composite matrices, which reaches 25% for HDPE/PS/OBT 29/68/3 composite, also an improvement of the thermal stability, as evidenced by the higher T onset values, and finally a reinforcement of the tensile properties as compared to the unfilled blends. Indeed, a significant enhancement of the tensile modulus (~130%) is observed for the 68/29/3 composite matrix as compared to the 70/30 unfilled blend.

Selective Plasma Etching of Polymeric Substrates for Advanced Applications

In today’s nanoworld, there is a strong need to manipulate and process materials on an atom-by-atom scale with new tools such as reactive plasma, which in some states enables high selectivity of interaction between plasma species and materials. These interactions first involve preferential interactions with precise bonds in materials and later cause etching. This typically occurs based on material stability, which leads to preferential etching of one material over other. This process is especially interesting for polymeric substrates with increasing complexity and a “zoo” of bonds, which are used in numerous applications. In this comprehensive summary, we encompass the complete selective etching of polymers and polymer matrix micro-/nanocomposites with plasma and unravel the mechanisms behind the scenes, which ultimately leads to the enhancement of surface properties and device performance.

S, Zachariah AK, V. VK, M. A. S, Bose S, Souza FG, Thomas S. Percolated network formation in biocidal 3D porous PCL/clay nanocomposite scaffolds: effect of organic modifier on interfacial and water sorption properties

The influence of chemical interaction between poly(ε-caprolactone) (PCL) and Cloisite 10A on rheology, water permeability and antibacterial properties were subjected to detailed investigation.