Recycled Polyolefin Blends: Effect of Modified Natural Zeolite on their Properties and Morphology

The purpose of this study is to investigate the effect of treated natural zeolite on the flow behavior, morphology, thermal, and mechanical properties in recycled polyolefin blends. A model polymer blend consisting of 95 wt% polyolefines and 5 wt% polystyrene was studied. Compositions from this recycled blend and dehydrated zeolite in a narrow concentration range (0–5 wt%) were treated with maleic anhydride-grafted polypropylene and initiator dicumyl peroxide. The compositions were characterized by capillary rheometry, wide-angle X-ray scattering, differential scanning calorimetry, scanning electron microscopy, and mechanical tests. The results show a compatibilizing effect of treated zeolite expressed by increase of shear viscosity and improvement of interfacial interactions and impact strength. The results can open wide possibilities for utilization of treated zeolite in recycling of unsorted polymer wastes.The authors are grateful for the financial support from the Bulgarian Ministry of Education and Science (project DTK 2010-02/7) and MINECO (Spain) (project MAT2013- 47972-C2-1-P). WAXS experiments were supported by Dr. Heinrich-Jörg-Stiftung of the University of GrazPeer Reviewe

Conductive composites based on metallocene isotactic poly(propylene): Preparation and properties

The research deals with the preparation and the further comprehensive characterization of metallocene polypropylene-based composite materials by incorporation of carbon black nanoparticles. Composites containing up to 10 wt% of carbon black were prepared by direct melt mixing in a single screw extruder Brabender Extrusiograph type 30/25D with attached static mixer at melt temperature of 200 °C and a screw speed of 30 rpm, according to a two-step process. Some composites were treated with 3 wt% maleic anhydride grafted polypropylene (MAH-PP). The rheological behaviour of the miPP nanocomposites was determined by cone/plate rheological measurements at 180 °C. The composites were characterized by SEM for morphological details and uniaxial stress-strain measurements for determining the mechanical parameters. Electric conductivity of injection molded plates from these composites was investigated. The different miPPs studied are ranked in an ascending order according to their increasing molecular weight concerning the magnitude of their rheological parameters. The maleic anhydride compatibilizer leads to lower viscosity values even at high shear gradients and to better homogenization of the nanofiller in the polymer matrix. The processing conditions, carbon black concentration and viscosity of the virgin polymer have an impact on the final conductivity of the miPP/carbon black composites. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Peer Reviewe

Thermal, mechanical and viscoelastic properties of compatibilized polypropylene/multi-walled carbon nanotube nanocomposites

[EN] Polymer composites containing nanofillers are among the most promising research fields for advanced materials. Carbon nanotubes (CNTs) are considered an ideal inclusion for polymer nanocomposites due to superior electrical, thermal, and mechanical properties which can be explained with the unique atomic structure of the nanotubes. Multi-walled carbon nanotubes (MWCNTs) are used as extremely strong nano-reinforcements for composites to produce a new generation of fiber-reinforced plastics with better application properties. In this experimental study, PP/MWCNT polymer nanocomposites with nanofiller concentrations in the range of 0.05-1 wt% MWCNT and the maleic anhydride amount from 0 to 7.5 wt% were investigated. An experimental study is conducted to examine the influence of MWCNT and compatibilizer contents on the thermal, mechanical, and viscoelastic properties of polypropylene (PP)/MWCNT nanocomposites. Extruded samples are characterized by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and microindentation tests. Standard Berkovich indentation test determined by residual surface impression method based on load-displacement curves was used. DSC results show an increase in the crystallization temperature of maleinated PP with the increase of MWCNT contents proving the nucleation effect of CNTs. DMTA results prove the good modification properties of maleic anhydride in MWCNT/PP nanocomposites at 0.05 wt% nanotubes concentration. Elastic moduli, obtained from both DMTA and microindentation, are compared to investigate the difference between surface and bulk mechanical properties of nanocomposites with increasing nanotubes concentration. Measured values of elastic moduli are within comparable ranges, but the absolute values are different.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work is supported by COST FA0904, FP7-BY NanoERA projects.Borovanska, I.; Kotsilkova, R.; Monleón Pradas, M.; Vallés Lluch, A.; Djoumaliisky, S. (2016). Thermal, mechanical and viscoelastic properties of compatibilized polypropylene/multi-walled carbon nanotube nanocomposites. Journal of Elastomers and Plastics. 48(7):576-599. https://doi.org/10.1177/0095244315613617S57659948