Showing papers on "Polycarbonate published in 2020"

Switchable Catalysis Improves the Properties of CO2-Derived Polymers: Poly(cyclohexene carbonate-b-ε-decalactone-b-cyclohexene carbonate) Adhesives, Elastomers, and Toughened Plastics.

Abstract: Carbon dioxide/epoxide copolymerization is an efficient way to add value to waste CO2 and to reduce pollution in polymer manufacturing. Using this process to make low molar mass polycarbonate polyols is a commercially relevant route to new thermosets and polyurethanes. In contrast, high molar mass polycarbonates, produced from CO2, generally under-deliver in terms of properties, and one of the most widely investigated, poly(cyclohexene carbonate), is limited by its low elongation at break and high brittleness. Here, a new catalytic polymerization process is reported that selectively and efficiently yields degradable ABA-block polymers, incorporating 6-23 wt % CO2. The polymers are synthesized using a new, highly active organometallic heterodinuclear Zn(II)/Mg(II) catalyst applied in a one-pot procedure together with biobased e-decalactone, cyclohexene oxide, and carbon dioxide to make a series of poly(cyclohexene carbonate-b-decalactone-b-cyclohexene carbonate) [PCHC-PDL-PCHC]. The process is highly selective (CO2 selectivity >99% of theoretical value), allows for high monomer conversions (>90%), and yields polymers with predictable compositions, molar mass (from 38-71 kg mol-1), and forms dihydroxyl telechelic chains. These new materials improve upon the properties of poly(cyclohexene carbonate) and, specifically, they show good thermal stability (Td,5 ∼ 280 °C), high toughness (112 MJ m-3), and very high elongation at break (>900%). Materials properties are improved by precisely controlling both the quantity and location of carbon dioxide in the polymer chain. Preliminary studies show that polymers are stable in aqueous environments at room temperature over months, but they are rapidly degraded upon gentle heating in an acidic environment (60 °C, toluene, p-toluene sulfonic acid). The process is likely generally applicable to many other lactones, lactides, anhydrides, epoxides, and heterocumulenes and sets the scene for a host of new applications for CO2-derived polymers.

Complex refractive indices measurements of polymers in infrared bands

Abstract: Polymers are widely used in many fields such as radiative cooling, infrared stealth, optical fibers and solar cells. In this work, the complex refractive indices of seven polymers such as polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), polycarbonate (PC), polystyrene (PS), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polyetherimide (PEI) are measured by spectroscopic ellipsometry (SE) combined with the ray tracing method (RTM) from near-infrared to mid-infrared bands (2–20 µm). The measured results of PDMS have been proved to be accurate by comparing them with previous data in the literature. The obtained refractive indices of polymers in this paper have been compared with the results calculated by the Kramers-Kronig relations. Finally, we analyze the reasons of absorption peaks of these materials in infrared bands by the vibration of chemical bonds in molecules.

Synthesis of Functionalized Cyclic Carbonates through Commodity Polymer Upcycling

Abstract: Functionalized cyclic carbonates are attractive monomers for the synthesis of innovative polycarbonates or polyurethanes for various applications. Even though their synthesis has been intensively i...

From plastic waste to polymer electrolytes for batteries through chemical upcycling of polycarbonate

Abstract: The constant increase of plastic waste released into the environment is a global problem which is raising concern to the general population Although there are many different approaches for recycling plastics, chemical recycling is currently seen as one of the most promising technologies in that it allows plastic waste to fit into a sustainable, circular economy Herein we investigate the chemical recycling of bisphenol A polycarbonate (BPA-PC) using diols of different chain lengths to yield bisphenol A and innovative carbonate-containing diols Subsequently, the latter are polymerised into a series of unique value-added aliphatic polycarbonates (APC) The new polymers obtained by this method have shown promising values of ionic conductivity that make them attractive candidates to be implemented as sustainable polymer electrolytes for solid-state batteries This procedure opens the way for recycling methods to produce unique, innovative materials using plastic waste as an alternative sustainable feedstock

Influence of the cyclic versus linear carbonate segments in the properties and performance of CO2-sourced polymer electrolytes for lithium batteries

Abstract: Polycarbonates bearing linear carbonate linkages and polyether segments have demonstrated to be highly attractive solid electrolyte candidates for the design of safe energy storage devices, for exa...

Dielectric and conductivity investigation of polycarbonate-copper phthalocyanine electrospun nonwoven fibres for electrical and electronic application

Abstract: Nonwoven fabric composite formulating polycarbonate (PC) and CuPc was fabricated using electrospun (CuPc: 0 to 10 wt%). Spatial presence of CuPc in composites was ascertained by virtue of F...

Sustainable Plastics from Biomass: Blends of Polyesters Based on 2,5-Furandicarboxylic Acid

Abstract: Intending to expand the thermo-physical properties of bio-based polymers, furan-based thermoplastic polyesters were synthesized following the melt polycondensation method. The resulting polymers, namely, poly(ethylene 2,5-furandicarboxylate) (PEF), poly(propylene 2,5-furandicarboxylate) (PPF), poly(butylene 2,5-furandicarboxylate) (PBF) and poly(1,4-cyclohexanedimethylene 2,5-furandicarboxylate) (PCHDMF) are used in blends together with various polymers of industrial importance, including poly(ethylene terephthalate) (PET), poly(ethylene 2,6-naphthalate) (PEN), poly(L-lactic acid) (PLA) and polycarbonate (PC). The blends are studied concerning their miscibility, crystallization and solid-state characteristics by using wide-angle X-ray diffractometry (WAXD), differential scanning calorimetry (DSC) and polarized light microscopy (PLM). PEF blends show in general dual glass transitions in the DSC heating traces for the melt quenched samples. Only PPF–PEF blends show a single glass transition and a single melt phase in PLM. PPF forms immiscible blends except with PEF and PBF. PBF forms miscible blends with PCHDMF and PPF, whereas all other blends show dual glass transitions in DSC and phase separation in PLM. PCHDMF–PEF and PEN–PEF blends show two glass transition temperatures, but they shift to intermediate temperature values depending on the composition, indicating some partial miscibility of the polymer pairs.

Effect of ionising radiation on the mechanical and structural properties of 3D printed plastics

Abstract: This work investigates the evolution of the tensile and structural properties of fused filament fabrication (FFF), formed polymers under gamma irradiation. Commercial off-the-shelf print filaments of Poly(lactic acid) (PLA), Thermoplastic polyurethane (TPU), Chlorinated polyethylene elastomer (CPE), Nylon, Acrylonitrile butadiene styrene (ABS) and Polycarbonate (PC) were exposed to gamma-ray doses of up to 5.3 MGy. The suitability of FFF-formed components made from these materials for use in radiation environments is evaluated by considering their structural properties. We identify clear trends in the structural properties of all the materials tested and correlate them with changes in the chemical structure. We find that Nylon shows the best performance under these conditions, with no change in ultimate tensile strength and an increase in stiffness. However, some of our findings suggest that the effect of additives to this type of filament may result in potentially undesirable adhesive properties. The organic polymer PLA was notably more radiation-sensitive than the other materials tested, showing 50% decrease in Young’s Modulus and ultimate tensile strength at order of magnitude lower radiation dose. A mechanism is proposed whereby FFF-processed components would have substantially different radiation tolerances than bulk material.

Processing and characterizations of polycarbonate/alumina nanocomposites by additive powder fed friction stir processing

Abstract: The powder fed friction stir process (FFSP) is a new and attractive solid-state manufacturing technique that enables the fabrication of polymer matrix nanocomposites (PNC). Herein, we present the fabrication of polycarbonate (PC)-based nanocomposites by in-situ injection of colloidal alumina nanoparticles (

Cost-Effective Synthesis of High Molecular Weight Biobased Polycarbonate via Melt Polymerization of Isosorbide and Dimethyl Carbonate

Abstract: Green synthesis of poly(isosorbide carbonate) (PIC) with remarkable properties is a huge challenge in industrial applications due to low molecular weight and harsh reaction conditions. We reported ...

Tuning the Structure and Performance of Bulk and Porous Vapor Sensors Based on Co-continuous Carbon Nanotube-Filled Blends of Poly(vinylidene fluoride) and Polycarbonates by Varying Melt Viscosity.

Abstract: This work describes a new concept of porous vapor sensor materials based on co-continuous polycarbonate/poly(vinylidene fluoride)/multiwalled carbon nanotube (PC/PVDF/MWCNT) blend composites. The blend composites were fabricated by melt mixing in a one-step mixing process, and the MWCNT containing component (here PC) was extracted, leaving a MWCNT network on the continuous surface of the remaining component (here PVDF). First, by selecting three PCs with different molecular weights, the blend viscosity ratio and blend fineness and interfacial area were varied. At the chosen blend composition of 40/60 wt %, the desired co-continuous structure was achieved with MWCNTs selectively localized in PC. The conductive polymer composites (CPCs) with low-viscosity PC had the highest conductivity due to a combination of the best MWCNT dispersion and the coarsest blend morphology. The vapor sensing of CPC sensor materials with 1 wt % MWCNT was tested using saturated vapors of dichloromethane, acetone, tetrahydrofuran, and ethyl acetate, showing good interaction with PC. The compact compression molded CPC materials with low-viscosity PC showed the lowest relative resistance changes (Rrel) during the cyclic sensing tests, but a better recovery compared to corresponding CPCs with medium and high viscosity PC. The porous CPC sensors showed remarkable vapor sensing performance compared to the corresponding compact sensors with better sensing stability, reproducibility, and reversibility. Scanning electron microscopy (SEM) confirmed that a fraction of the nanotubes remained on the surface of the continuous, nonsoluble PVDF after PC extraction. The porous sensor material from which the low-viscosity PC was extracted showed the highest Rrel (e.g., around 1300% after 100 s immersion in acetone vapor) compared to all other organic vapors investigated. The difference in vapor measurement between compact and porous sensor materials was attributed to the different sensing mechanisms of polymer swelling for the compact and vapor absorption on the free CNT networks for the porous samples.

Effects of carbon nanotube length on interfacial properties of carbon fiber reinforced thermoplastic composites

Abstract: To improve the interfacial properties between carbon fibers (CFs) and polycarbonate (PC) resin, multi-walled carbon nanotubes (MWCNTs) were deposited onto desized CF surfaces using an ultrasonic-assisted electrophoretic deposition method, forming a multi-scaled hierarchical structure. The results showed that morphologies and geometrical structures of the as-prepared hierarchical structures could be readily tailored by varying in length and concentration of the CNT suspension. The optimum conditions were determined to be CNT length of 1-5 μm with suspension concentration of 0.5–1 wt%. A post-treatment, in combination of a polymer binder and laser irradiation, was followed to solidify the morphology and geometry of the CNT network structures formed by the CNTs with length 1-5 μm, which allowed a 22.9% ± 1.6% improvement in the interfacial bonding strength than that without the post-treatment and 68.1% ± 2.3% improvement than bare CF, evaluated by a single-filament fragmentation test. It was the well-defined CNT porous network structures that are favorable for thermoplastic resin infiltration through channels for resin flow and capillary action, thus enhancing the composite interfacial properties.

Achieving Flat-on Primary Crystals by Nanoconfined Crystallization in High-Temperature Polycarbonate/Poly(vinylidene fluoride) Multilayer Films and Its Effect on Dielectric Insulation.

Abstract: To meet the stringent requirements of next-generation film capacitors for power electronics, multilayer films (MLFs) are fabricated with the advantage of achieving high temperature rating, high ene...

Hydrophilic Stars, Amphiphilic Star Block Copolymers, and Miktoarm Stars with Degradable Polycarbonate Cores

Abstract: A facile one-pot synthetic approach toward the realization of star polymers made of degradable carbonate cores is reported. The synthetic strategy involved triethylborane-activated anionic copolymerization of a difunctional epoxide with CO2 initiated by bis(triphenylphosphine)iminium chloride (PPNCl). Vinyl cyclohexene dioxide (VCD) was, thus, used as a difunctional cross-linker, and core compositions with 80–90% carbonate content were achieved. Poly(ethylene oxide) (PEO) arms were grown from these in-situ generated polycarbonate core anions to build a range of star polymers, including hydrophilic PEO stars and star-shaped block copolymers. Poly(propylene oxide) (PPO) precursors were used in a second approach as macroinitiators to form carbonate cores through the arm-first method; miktoarm stars having a large number of arms, both hydrophilic and hydrophobic, could be derived by this method. The carbonate cores of the synthesized stars were readily degraded through hydrolysis of the core carbonate linkage...

Preparation of cross-linked poly(methyl methacrylate) microspheres using an asymmetric cross-linker via dispersion polymerization and its application in light diffusers

Abstract: Cross-linked poly(methyl methacrylate) (PMMA) microspheres have been successfully prepared by using the asymmetric cross-linker allyl methacrylate (AMA) via dispersion polymerization. The influence of the AMA amount and polymerization process on the PMMA particle size and morphology has been studied thoroughly. It was found that micron-sized, cross-linked PMMA particles with narrow size distributions could be obtained by a semi-continuous process with the asymmetric cross-linker AMA. The obtained micron-sized, cross-linked PMMA particles could be further used as a light diffusion agent in a polycarbonate matrix, and their light diffusion properties were significantly enhanced by increasing the gel content in the cross-linked particles. Moreover, the influence of the polymerization process, cross-linker content in PMMA and PMMA content in the polycarbonate matrix on light diffusion was carefully investigated. The results showed that the PMMA particles containing 5.0 wt% AMA, obtained by semi-continuous polymerization, had a higher haze and gel content and exhibited a better light diffusion effect than did the other particles.

SnS2/Polycarbonate Nanocomposites: Structural and Optical Characterizations

Abstract: Undoped and doped polycarbonate (PC) polymer nanocomposites with nano tin disulfide (SnS2) were synthesized by the thermolysis and casting methods. The effect of nano SnS2 doping on the absorption behavior of polycarbonate nanocomposites was studied in details using Fourier transform infrared spectroscopy technique. Structural analysis for undoped and doped films was investigated using X-ray diffraction technique. Detailed absorption measurements were performed in the wavelength range of 200–800 nm using UV spectroscopy technique. Results showed that our nanocomposites films exhibited a direct optical energy gap that decreased from 4.68 to 4.32 eV with the increment of the doping concentration up to 5 wt%. The optical constants of polymer nanocomposites such as absorption coefficient, extinction coefficient, refractive index, dielectric constant, average oscillator strength and wavelength revealed an enhancement in the optical values of polymer nanocomposites compared with undoped polymer. The improvement in the refractive index values with the doping content revealed the uniform distribution of the nanoparticles within the PC matrix. Scanning electron microscope images confirmed these results. Wemple–Didomenico single oscillator model was applied in order to examine different dispersion parameters such as single-oscillator and dispersion energies, the high frequency dielectric constant and the ratio of free charge carrier amount to the effective mass. The resulting improvements in the optical properties of the inspected polymer nanocomposites referred to the possibility of future usage as UV blocking materials in the industry such as contact lenses and optoelectronic devices.

Importance of Sub-Nanosecond Fluctuations on the Toughness of Polycarbonate Glasses

Abstract: This article explores the relationship between the nano- to picosecond dynamics, as quantified by elastic incoherent neutron scattering, in polycarbonate (PC) glasses with their mechanical toughnes...

Mechanically Stable UV‐Crosslinked Polyester‐Polycarbonate Solid Polymer Electrolyte for High‐Temperature Batteries

Abstract: Due to the mechanism with which solid polymer electrolytes use to conduct ions, these materials are generally more suitable for high-temperature applications where the ionic conductivity is suffici ...