RbstractThis review provides valuable information about the general characteristics, processing conditions and physical properties of carbon nanotube buckypaper (BP) and its polymer composites. Vacuum filtration is the most common technique used for manufacturing BP, since the carbon nanotubes are dispersed in aqueous solution with the aid of surfactant. Previous works have reported that mechanical properties of BP prepared by vacuum filtration technique are relatively weak. On the other hand, the incorporation of polymer materials in those nanostructures revealed a significant improvement in their mechanical behavior, since the impregnation between matrix and BP is optimized. Electrical conductivity of BP/polymer composites can reach values as high as 2000 S/m, which are several orders of magnitude greater than traditional CNT/polymer composites. Also, BP can improve remarkably the thermal stability of polymer matrices, opening new perspectives to use this material in fire retardant applications.

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In this work, dense membranes from aqueous dispersions of poly(urethane‐urea) (PUU) based on poly(propylene glycol) (PPG) and a block copolymer composed of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG), EG‐b‐PG, with 7 wt % of the former were obtained. Nonpolluting formulations were synthesized with proportions of PPG and EG‐b‐PG as 1:0, 1:1, 1:3, and 3:1 in terms of equivalent number ratios. The effect of small and gradual increases in PEG segments was evaluated for the permeability of pure CO2, CH4, and N2, at room temperature. Slight increases in PEG‐based segments in PUU promoted some remarkable properties, which led to a simultaneous increase in CO2 permeability and ideal selectivity for CH4 (300%) and N2 (380%). Infrared spectroscopy showed that the PEG portions induced hydrogen bonds between NH of urethane and ether groups in the PEG portions, which promoted ordering of the flexible segments, confirmed by X‐ray diffractometry and small‐angle X‐ray scattering. Diffractometry techniques also confirmed the absence of crystalline domains, as did dynamic mechanical analysis. The produced membranes showed performance above Robeson's 2008 upper bound and seemed to be a superior polymeric material for CO2/CH4 and CO2/N2 separation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46003.

Benzoxazine resins are a new class of thermosetting phenolic resins that have emerged in recent decades, overcoming the traditional properties of epoxy and phenolic resins applied in the aerospace industry. The incorporation of low mass concentration of carbon nanotube (CNT) in polymer matrices can produce structural materials with superior properties. Thus, this work aims to prepare nanostructured composite benzoxazine resin/CNT and to evaluate the cure kinetic study by differential scanning calorimetry of neat benzoxazine resin and their nanostructured composites produced. Calculations of the activation energy, the reaction order, and kinetic constants are performed by a nonisothermal procedure. In general, it was observed that CNTs act as catalysts for curing the benzoxazine matrix without affecting the initial and final cure temperatures.

Recently, to improve the properties, reduce the amount of polymeric materials, the time of disposal in landfills and the cost of composite parts, the incorporation of vegetal biomass was considered. In this study, composites with 10% and 20% v/v of benzoxazine resins and macadamia nutshell (50#) were made via hand layup with in natura biomass and hydrothermally treated (121°C/45 min in an autoclave). Thermogravimetry indicates that the initial temperature of biomass degradation (209°C) allows it to be used with the resin (oven curing at 190°C). The enthalpies obtained from the DSC indicate that the percentage of cure increased with the biomass. FT‐IR tests indicate that the hydrothermal treatment collapsed part of the lignin and extracted lignocellulosic material. There was no significant modification of the glass transition temperature obtained in DMA and TMA with the introduction of biomass. Optical microscopy showed that the treated reinforcement showed a greater variation in size forming lumps. Based on these results, these composites can be used in the replacement of synthetic composites, contributing to a decrease in the consumption of petroleum derivatives and with this, reducing the disposal in landfills and dumps.