Ákos Kmetty

Water-Assisted Production of Thermoplastic Nanocomposites: A Review

Water-assisted, or more generally liquid-mediated, melt compounding of nanocomposites is basically a combination of solution-assisted and traditional melt mixing methods. It is an emerging technique to overcome several disadvantages of the above two. Water or aqueous liquids with additives, do not work merely as temporary carrier materials of suitable nanofillers. During batchwise and continuous compounding, these liquids are fully or partly evaporated. In the latter case, the residual liquid is working as a plasticizer. This processing technique contributes to a better dispersion of the nanofillers and affects markedly the morphology and properties of the resulting nanocomposites. A survey is given below on the present praxis and possible future developments of water-assisted melt mixing techniques for the production of thermoplastic nanocomposites.

Investigation of the Weldability of the Self-Reinforced Polypropylene Composites

In the present work the weldability of self-reinforced composite was investigated. As reinforcement a fabric, woven from highly stretched split PP yarns, whereas as matrix materials of two kinds of random polypropylene copolymer (with ethylene) were used. The composite sheets were produced by film-stacking method and compression molded with different thickness (1 mm, 2 mm) with different contents at different processing temperatures keeping the holding time and pressure constant. The SRPPC sheets were welded by ultrasonic welding machine with different welding parameters. The welds were qualified by mechanical and microscopic tests. The results showed that the thermoplastic reinforcement has not got melted; therefore the reinforcement was kept the strength-increasing effect.

Production and properties of micro-cellulose reinforced thermoplastic starch

Thermoplastic starch (TPS)/micro-fibrillated cellulose (MFC) composites were prepared from maize starch with different amount of distilled water, glycerol and cellulose reinforcement. The components were homogenized by kneader and twin roll technique. The produced TPS and TPS-based polymer composites were qualified by static and dynamic mechanical tests and their morphology was analysed by microscopic techniques. The results showed that the amount of water and the order of the production steps control the properties of both the TPS and its MFC reinforced version. With increasing content of MFC the stiffness and strength of the TPS matrix increased, as expected. Microscopic inspection revealed that the TPS has a homogenous structure and the MFC is well dispersed therein when suitable preparation conditions were selected.

Preparation and properties of thermoplastic starch/bentonite nanocomposites

Thermoplastic starch (TPS)/bentonite nanocomposites containing up to 7.5 wt.% bentonite were prepared. Maize starch was plasticized with glycerol and water, in presence or absence of bentonite, in a twin-screw extruder. Mechanical, morphological and thermal properties of the TPS/bentonite nanocomposites were determined and discussed. Scanning electron microscopic (SEM) images revealed a good dispersion of bentonite particles with some remaining agglomerates in the range of 0.1 to 1.5 μm. According to the tensile test results the tensile strength and Young’s modulus increased significantly with increasing bentonite content, however, at cost of elongation. Thermogravimetric analysis (TGA) showed that the presence of bentonite exerted little to no effect on the thermal stability of TPS.

Investigating mechanical performance of PLA and CA biodegradable printed circuit boards

The paper presents a set of experiments investigating the mechanical performance of PCBs manufactured from biodegradable, sustainable polymers, compared to conventional materials. Cellulose Acetate (CA), Polylactic Acid (PLA) and Flame-Retardant Class 4 (FR-4) substrates were compared during the experiments. The methods involved dynamic mechanical analysis (DMA), three-point bending tests and UL 94 flammability tests. Preliminary results show that the overall performance of the basic biodegradable, sustainable PCBs are considerably weaker compared to FR4 boards, however further improvements with additives and use in special applications can point to practical purposes of the substrates.