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Introduction
Published in S. T. Lee, Polymeric Foams, 2022
Shoe sole is a medium-density foam between 5 and 12 times in expansion. For decades, cross-linked ethylene-vinyl-acetate (EVA) and thermoset polyurethane foam were the dominant products for athletic and leisure shoes. Both are great in offering comfort and durability. In the last decade, bead foam technology and pressure mold for microcellular have been found favorable in foaming temperature control which improves cell uniformity and its integrity. Not only thermoplastic polyurethane (TPU) but engineered polymer (Polyetherimide) is also being used to make elastomeric foam. Figure 1.7 shows the TPU-based shoe sole for sport shoes [26]. Furthermore, shoe sole property is noticeably improved that the application window could be extended into health care [27].
Organic matrices
Published in A.R. Bunsell, S. Joannès, A. Thionnet, Fundamentals of Fibre Reinforced Composite Materials, 2021
R. Bunsell, S. Joannes, A. Thionnet
A group of resins, which can be both thermosetting or thermoplastic, are known as thermostable resins. Such resins retain sufficient mechanical properties to be used above 200°C. Among highly thermostable polymers, some can be employed for limited lengths of time up to and sometimes above 400°C. A wide variety of thermostable resins in which aromatic rings are linked to form the polymer chains has been formulated. The major high-temperature resins include bismaleimide (BMI), cyanate ester, phenolic, … for thermosets and polyether ether ketone (PEEK), polyphenylene sulfone (PPSU), polysulfone (PSU), polyimide (PI, TPI), polyaryletherketone family (PAEK) or polyetherimide (PEI) for high-temperature thermoplastics. Such resins mainly find use in high-performances composite applications as in the aerospace industry. Many studies are nevertheless underway to improve heat-resistant properties of polymers while optimising costs and further widen the applicability of composites.
Miscibility and Relaxation Processes in Blends
Published in Gabriel O. Shonaike, George P. Simon, Polymer Blends and Alloys, 2019
John M. G. Cowie, Valeria Arrighi
Enthalpy relaxation studies have also been used to assess the aging of polyether ether ketone blends with polyetherimide, PEEK/PEI = 50/50 (70). The preparation of the blend produced an amorphous system with Tg ~215°C, but crystallization of the PEEK occurred after raising the temperature above Tg. Enthalpic relaxation could only be observed in the temperature range Tg to (Tg − 50), and no aging could be detected at temperatures below 150°C (Table 7). The system was analyzed using the KWW, Eq. (8), that yielded values of β = 0.4, intermediate between those of the component polymers. When the blends were examined using dielectric relaxation measurements that probe the dipole relaxation spectrum, values of β were found to be much lower (0.1–0.22). This was interpreted as indicating the development of heterogeneity at the molecular level caused probably by the crystallization of the PEEK component.
Radiation Compatibility of Geopolymer, Polymer, and Composite Materials for Use as Inner Shielding in Radioactive Waste Containers—A Simulation-Based Study
Published in Nuclear Technology, 2022
Materials other than cement have previously been considered for use as inner shielding in radioactive waste containers.6–17 The present study surveys the prospects of using geopolymers, polymers, and polymer-based composites as inner shielding in such containers, with regard to the radiation hardness of these materials. Radiolytic gas production (which raises the pressure within the container) and molecular weight change (which can affect the material’s mechanical properties) are inspected for several select materials, based on absorbed dose values in the container’s shielding layer. The investigated materials include three geopolymers (with three different alkali cations: cesium, potassium, and sodium) and five polymers [high-density polyethylene (HDPE), polyether ether ketone (PEEK), polyetherimide (PEI), polystyrene (PS), and polysulfone (PSU)], as well as composite materials with one of these five polymers as a matrix reinforced by boron fibers.
Hybrid MF and membrane bioreactor process applied towards water and indigo reuse from denim textile wastewater
Published in Environmental Technology, 2018
Carolina Fonseca Couto, Larissa Silva Marques, Janine Balmant, Andreza Penido de Oliveira Maia, Wagner Guadagnin Moravia, Miriam Cristina Santos Amaral
Figure 1 shows a schematic of the laboratory-scale MF–MBR hybrid system. The effluents were treated by MF in order to recover the dye in a concentrated form. A commercial hollow fibre polyetherimide-based membrane module (PAM membranas Ltda.) with average pore diameter of 0.4 µm and a filtration area of 1 m2 was used as an MF module. In all experiments, pressure was measured by a manometer and was adjusted by a needle-type valve. MF was performed at concentrated mode filtration, where the permeates were collected in a separated tank and concentrates were returned to the feed tank, at a constant pressure of 1 bar, a cross-flow rate of 2.4 L/min and up to a concentration ratio (volume concentration ratio (VCR)) of 5. The MF permeate was treated in the MBR. The biological tank volume was 6 L. The system possessed five process currents: (1) MBR feeding line, containing raw effluent to be treated, (2) compressed air line for bioreactor aeration, (3) biologically degraded and microfiltered effluent line, (4) vacuum line connected to the vacuum tank and (5) permeated backwash line. A submerged polyetherimide hollow fibre module was utilized up to the 294th monitoring day, consisting of an average pore size of 0.5 µm, membrane area of 0.044 m² and packing density of 500 m²/m³. After that a submerged polyvinylidene difluoride hollow fibre module (having an average pore size of 0.04 µm, membrane area of 0.047 m², and a non-ionic and hydrophilic surface) was used.
Thermally enhanced polyolefin composites: fundamentals, progress, challenges, and prospects
Published in Science and Technology of Advanced Materials, 2020
A.U. Chaudhry, Abdel Nasser Mabrouk, Ahmed Abdala
Among thermoplastics, polyethylene (PE) and polypropylene (PP) account for more than ~50% of the global polymer production due to their low cost and toxicity, and availability of a wide range of commercial grades in terms of PP forms with different chain structures, crystallinity, and density levels, and stereo configurations of varying densities: isotactic, syndiotactic, and atactic forms of PP. According to a 2020 report, polyolefins are the world’s fastest-growing polymer family with PE and PP accounting to nearly ~30% and ~20%, respectively, of total world polymer demand in 2018 [14]. The production of PE and PE represents a market size of valued 270.7 USD billion and ‘is forecasted to grow at a compound annual growth rate of 6.2% from 2018 to 2026’ [15]. Furthermore, they are the two largest thermoplastics by volume, which are fabricated into filaments, films, profiles, and moldings [16]. The main advantages of polyolefins, PE and PP in particular, over other polymers include the lightweight, low price, recyclability, easy and low-temperature processability, inertness, hydrophobicity, inertness and non-toxicity, excellent resistance to corrosive solvents, biocompatibility, rigidity, malleability, stiffness, low-temperature impact resistance, and high impermeability. These are the simplest and among the well-studied polymers having a wide range of commodity and engineering applications ranging from plastic bags to medical devices, including orthopedic implants, automobile parts, consumer goods, durable equipment, and industrial machinery [17–20]. Despite many benefits associated with neat polyolefins, polyolefin composites/nanocomposites emerged to meet the increased applications not satisfied by neat polyolefins. The recent advances in pristine polyolefin, polyolefin composite, and nanocomposite materials were comprehensively reviewed [19,21,22]. However, advances in the application of polymers in heat management areas such as circuit boards, heat exchangers, as replacement of metals or other materials, have also driven several recent studies on κ enhancement in polyolefin as well as other polymer composites. It was reported that κp of a single PE nanofiber could reach 100 W/m·K, indicating the potential it can achieve after altering the molecular structure or the morphology [23]. κ enhancement of other polymers filled with fillers having high κf has been investigated extensively. For instance, the study of κc of poly(vinyl butyral), poly(ethylene vinyl alcohol), poly(methyl methacrylate), and polystyrene-based nanocomposites filled with 24 wt.% boron nitride nanotubes exhibited κc of 1.80, 2.50, 3.16, and 3.61 W/m·K, respectively [12,24]. Similarly, the addition of 15 and 40 wt.% graphite to thermoplastic polyetherimide improved κp from 0.07 to κc of 0.87 and 1.73 W/m·K, respectively. Moreover, incorporation of 50 wt.% glass fiber into thermoset polyetherimide increased κ to 0.41 W/m·K. In their reports, κ of increased from κp polyethylene terephthalate, i.e., 0.15 W/m·K, increased to κc of 0.31, 0.71 and 0.72 W/m·K using 45% glass fiber, 30% graphite fiber, and 40 wt.% PAN carbon fiber, respectively [11].