Recent progress in carbon dioxide (CO2) as feedstock for sustainable materials development: Co-polymers and polymer blends

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.polymer.2018.04.078 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/Combustion of fossil fuels and many other industrial activities inevitably produces carbon dioxide (CO2) that is released into the atmosphere and is currently deemed to be among the major contributors to global warming. One of the prominent solutions proposed to mitigate global warming concerns from CO2, capture and storage (CCS), did not attract many CO2 emitting industries as expected, mainly because of economic reasons. On the contrary, environmental pollution concerns associated with plastic waste, and the demand for sustainable feedstock for their production constitute grand challenges facing our society with regard to the production and use of plastics. As a result, the materials science community is striving to generate sustainable and biodegradable plastics to substitute conventional synthetic plastics from resources that do not pose direct completion with food production. This manuscript aims to provide a general overview of the recent progress achieved in CO2 based polymers for sustainable biopolymers such as co-polymers, and polymer blends. The synthesis, material properties, processability, and performances of important CO2 based co-polymers are critically reviewed. Furthermore, a critical review of CO2 co-polymers as components of polymer blend with a focus on the most relevant CO2 based aliphatic polycarbonates, poly (propylene carbonates) (PPC), is conducted.Chemical Engineering Department and the Faculty of Engineering of the University of Waterloo - Startup Fundin

Effect of compatibilizers on lignin/bio-polyamide blend carbon precursor filament properties and their potential for thermostabilisation and carbonisation

Biobased blends from hydroxypropyl modified lignin (TcC) and a biobased polyamide (PA1010) were produced by continuous sub-pilot scale melt spinning process. A reactive compatibilization was employed with the help of two different compatibilizers (ethylene-acrylic ester-maleic anhydride (MA) and ethylene-methyl acrylate-glycidyl methacrylate (GMA)) to enhance the compatibility between the TcC and PA1010. The enhanced compatibility between the TcC and PA1010 achieved by reaction between hydroxyl groups with maleic anhydride groups in the MA compatibilizer or epoxy groups in the GMA compatibilizer via nucleophilic substitution, was confirmed by chemical (Fourier infrared measurements), physical (glass transition, melting and crystallization behaviour), rheological, morphological and tensile properties of the filaments from compatibilized blends. MA compatibilizer required a higher concentration (2 phr) than GMA (1 phr) to achieve an optimal performance because of the difference in the reactive group's concentration within the each compatibilizer. The MA compatibilizer though was more effective than GMA. The precursor blended filaments were successfully carbonized in a lab scale experiment to yield coherent carbon fibres with tensile stress values of 192 ± 77 and 159 ± 95 MPa; and moduli of 16.2 and 13.9 GPa respectively for uncompatibilised and 2% MA compatibilized blends. That the compatibilized carbon fibre properties are slightly inferior may be attributed to the need to accurately control and optimise applied stress during the thermostabilisation and carbonization stages. Notwithstanding, these differences, the results indicate the potential benefit of using compatibilized TcC/PA1010 blend filaments as carbon fibre precursors

Biodegradable compatibilized polymer blends for packaging applications A literature review

The majority of materials used for short-term and disposable packaging application are non-biodegradable which are not satisfying the demands in environmental safety and sustainability. Biodegradable polymers are an alternative for these non-biodegradable materials. The biodegradable polymeric materials can degrade in a reasonable time period without causing environmental problems. However, biodegradable polymers possess some limitations such as comparatively high cost, insufficient mechanical performances, and inferior thermal stability to extend their widespread application in packaging industry. To overcome these limitations, one of the most commonly used strategies is melt blending of dissimilar biodegradable polymers. Unfortunately, most of the biodegradable polymer blends exhibit insufficient performance because they are thermodynamically immiscible as well as exhibit poor compatibility between the blended components. It has been established that the compatibilization is a well-known strategy to improve the performances of the immiscible biodegradable polymer blends by enhancing the adhesion between the phases. As a result, recent studies focus on various compatibilizers to enhance the performances of the resulting biodegradable polymer blends. This review summarizes the recent developments on a variety of biodegradable polymer blends compatibilized by melt processing with a main focus of ex situ and in situ compatibilization strategies. (C) 2017 Wiley Periodicals, Inc

Hydroxypropyl modified /organosolv lignin - biobased polyamide blend filaments as carbon fibre precursors

Hydroxypropyl modified lignin (TcC) and organosolv lignin (TcA) were melt blended with two types of bio-based polyamides (PA) (PA1010 and PA1012) before being melt spun into filaments. With a lignin/bio-PA ratio 50/50 wt.%, the filaments could be continuously produced and spooled having tensile strengths ≥20 MPa and moduli ≥500MPa. The influence of each polyamide blended with each lignin on structural (FTIR), thermal (DSC, TGA, DMA), mechanical, rheological and morphological properties of the resultant extrudates and/or filaments were studied. The melting point of each polyamide was reduced in the presence of TcA and TcC lignin and, shifts in the glass transition temperature (Tg) and FTIR characteristic peaks occurred, which suggests that the selected polyamides and lignins are compatible with each other.The improved lignin/polyamide compatibilities were further supported by Pukanszky interfacial adhesion modelling. Despite the evidence for strong interactions, heterogeneous morphologies were observed in the resulting blends and scanning electron microscopy (SEM) was used to determine dispersed lignin domain sizes which decreased when stronger lignin/polyamide interactions resulted. As a possible indicator of carbonisation efficiencies, blends were subjected to a simulated stabilisation/cross-linking process and subsequent TGA char residues were higher than those theoretically calculated at 880oC, indicating that the bio-polyamide acted as a char-promoting agent for the lignin besides being a good blending partner. Overall, this study has indicated that the developed lignin/bio-polyamide filaments have potential as melt-extrudable precursors for carbon fibre production

Biopolymer blends from hardwood lignin and bio-polyamides: Compatibility and miscibility

The compatability of hardwood lignin (TcA)/bio-polyamide (PA) blends, prepared by melt compounding TcA with three different biobased polyamides, PA 1012, PA 1010 and PA 11 in a twin screw extruder have been studied. FTIR studies indicated the existence of physicochemical interactions between the TcA and polyamide. The melting temperatures of the blends were significantly reduced compared to the respective neat polyamides, which was attributed to the enhanced compatibility between the two components. The compatibility was also attributed to the increased glass transition (Tg) of the polyamide. Thermogravimetric studies, while not indicating any interaction during the processing stage, suggested that there was some during the thermal degradation stage, which assisted formation of carbonaceous residue. The addition of each polyamide to TcA considerably reduced its viscosity and enhanced its processability even at high lignin contents. Morphological analysis showed that heterogeneity for all the blends was quite uniform, although TcA domain sizes were considerably smaller (~ 0.5 μm) in the PA11 matrix compared to those in PA1010 and PA1012, suggesting better compatibility in the TcA/PA11 blends. This observation was consistent with the thermodynamic Gibbs’ free enery values of the respective blends. Overall, the order of blend compatibility was TcA/PA11 > TcA/PA1010 > TcA/PA1012

Bioresourced fillers for rubber composite sustainability: current development and future opportunities

Ending the fossil fuel era towards a sustainable future will require high-performing renewable materials with a low environmental impact. Carbon black, produced by partial combustion or thermal decomposition of petroleum hydrocarbons, is by far the most dominant filler of rubber composites, followed by mineral fillers (e.g. silica, talc, clay, calcium carbonate, etc.). However, the manufacture of carbon black has a considerable carbon footprint. Similarly, mineral fillers also do not come without challenges, including poor compatibility with rubber matrices and high density. Consequently, the need for sustainable and green fillers with a low or even zero carbon footprint has dramatically increased. In recent years, plant-derived sustainable materials, such as cellulose nanocrystals, natural fibers, lignin, biochar, polysaccharides, etc., have been extensively investigated as substitute or complementary fillers of rubbers. In this work, we critically reviewed recent developments in the innovation and utilization of sustainable biofillers for rubber composite applications, emphasizing the effect of the filler on the structure–processing–property relationships in rubber composites. A wide range of biofillers with an array of structure, morphology, and physico-chemical properties and their various attributes in different rubbers are intensively reviewed and discussed. Effective preparation strategies and surface modification platforms on the different biofillers to develop high-performance sustainable rubber biocomposites were critically reviewed. Finally, future perspectives for biofillers in rubber composite applications and challenges are discussed.The financial support of Natural Science and Engineering Research Council (NSERC), Canada Foundation for Innovation (CFI), and MITACS is greatly appreciated

Vapor and Pressure Sensors Based on Cellulose Nanofibers and Carbon Nanotubes Aerogel with Thermoelectric Properties

In this work, thermally insulating and electrically conductive aerogels were prepared from cellulose nanofibers (CNF) and carbon nanotubes (CNTs) by environmentally friendly freeze-drying process. The thermal conductivity of neat CNF aerogel is 24 mW/(m.K) with a density of 0.025 g/cm(3). With the addition of CNTs into CNF aerogel, the electrical conductivity was significantly increased while the thermal conductivity was increased to 38 mW/(m.K). Due to these interesting properties, the Seebeck coefficient and the figure of merit (ZT) of the CNF/CNTs aerogels were measured and showed that CNF/CNTs aerogel thermoelectric properties can be improved. The compressibility and electrical resistance of the CNF/CNTs aerogel highlighted its pressure-responsive property. A set of volatile organic compounds (VOCs) were exposed to aerogels to monitor the resistance change. The CNF/CNTs aerogel showed high sensitivity and good response to both nonpolar and polar vapors due to the absorption by both CNF and CNTs networks. The prepared CNF/CNTs aerogel is therefore a good candidate for thermal insulation, thermoelectric material, VOCs sensing, and pressure-sensing applications

Nitrogen doped fluorescent carbon dots from Delonix regia for Fe(III) and cysteine sensing, DNA binding and bioimaging

The current work primarily deals with the synthesis of nitrogen rich carbon dots from Delonix regia along with characterisation using several analytical techniques for fluorescent sensing of Fe(III) and cysteine, electrochemical sensing of hydrogen peroxide and DNA binding. The average particle size of the spherical N-CDs is calculated to be 2.23 nm with a quantum yield of 33.5%. The SAED pattern from HR-TEM confirms the slight graphitisation of the N-CDs along with the amorphous carbon core. The synthesised N-CDs served as an efficient turn off sensor for Fe(III) with a detection limit of 5.76 × 10-7 M and turn on sensor for L-Cysteine with a detection limit of 3.76 × 10-4 M. The nature and extent of binding of the N-CDs with ctDNA was evaluated and the binding constant from the Benesi Hildebrand plot is calculated to be 6.49 (mg/mL)-1. The limit of detection was found to be 71 µM for electrochemical sensing of hydrogen peroxide. The less cytotoxic and excellent biocompatible nature of the N-CDs have been taken advantage to image L6 cells and SKMEL cells