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Emergence, Chemical Nature, Classification, Environmental Impact, and Analytical Challenges of Various Plastics
Published in Hyunjung Kim, Microplastics, 2023
Poly(methyl methacrylate) (PMMA), also known as acrylic or acrylic glass, is a transparent and rigid thermoplastic material widely used as a shatterproof replacement for glass. PMMA has many technical advantages over other transparent polymers (PC, polystyrene, etc.); a few of them include high resistance to UV light and weathering and excellent light transmission. PMMA or poly (methyl 2‐methyl propionate) is produced from monomer methyl methacrylate. PMMA is a transparent, colorless polymer available in pellet, small granules, and sheet forms, formed with all thermoplastic methods (including injection molding, compression molding, and extrusion). The highest quality PMMA sheets are produced by cell casting, but in this case, the polymerization and molding steps occur concurrently. It is commonly called acrylic glass. The strength of the material is higher than molding grades owing to its extremely high molecular mass. Rubber toughening has been used to increase the toughness of PMMA owing to its brittle behavior in response to applied loads.16
Polymers
Published in Yip-Wah Chung, Monica Kapoor, Introduction to Materials Science and Engineering, 2022
Polymers can exhibit elastomeric (large elastic strain), plastic, and brittle mechanical behavior, depending on their structure and testing temperature. In case of polymers, elastic deformation means reversible deformation and is not necessarily equivalent to having a linear stress-strain curve, so the definition of 0.2% offset yield strength used for metals does not apply to polymers. Figure 7.12 shows schematically the stress-strain response of PMMA at different temperatures. At 60°C, PMMA behaves like rubber bands, capable of sustaining large elastic strains. At lower temperatures (40°C), plastic deformation occurs. At even lower temperature (4°C), PMMA is brittle like glass. The influence of temperature on the mechanical properties is due to the thermally activated motion of polymer chains.
Influence of Surface Structure on Polymer Surface Behavior
Published in Kunio Esumi, Polymer Interfaces and Emulsions, 2020
Because block copolymers usually consist of more than two components with different surface free energies, a microphase-separation structure is generally formed at surfaces of block copolymers. Due to the microphase-separation morphology at the surface, block copolymers exhibit unique surface properties. For example, the incorporation of microphase-separated PDMS domains into a PMMA matrix allows the system to exhibit many of the desirable properties of both components. The PMMA matrix is known to possess very good optical clarity, good UV stability, high electrical resistivity, and hydrolytic stability. Some of the desirable properties of PDMS include a very low glass transition temperature, biocompatibility, low surface energy, high oxygen permeability, and resistance toward degradation by atomic oxygen and oxygen plasmas. Therefore, a heterophase material consisting of microphase-separated PDMS domains embedded in a PMMA matrix should illustrate the desirable properties of both components.
Corrosion monitoring at the interface using sensors and advanced sensing materials: methods, challenges and opportunities
Published in Corrosion Engineering, Science and Technology, 2023
Vinooth Rajendran, Anil Prathuru, Carlos Fernandez, Nadimul Haque Faisal
Titanium dioxide nanowire (TiO2 NW) has various applications such as optoelectronics, electronic and electrochemical nanodevices [225]. Single crystalline TiO2 NW is typically fabricated by the chemical vapour deposition method. The electrical conductivity of TiO2 NW is normally low (2.2438 × 10−4 Scm−1 (for 40 mg weight of TiO2)) [226]. However, it can be enhanced through a combination of chemical compounds. Polymethyl methacrylate (PMMA) has high stability, excellent weather ability, optical clarity and excellent dimensional stability. PMMA can be provided the potential to reduce gas permeability, improve physical performance and increase heat resistance. Hybrid PMMA/TiO2 NW (PA/AgNO3) is fabricated by emulsion polymerisation, and its maximum electrical conductivity is 20 Scm−1 [224,226]. The fabrication of the TiO2 nanowire by a modified hydrothermal process is shown in Figure 25a. The diameter of the TiO2 nanowire directly impacts density, thermal conductivity and thermal diffusivity. With the diameter increase from 250 to 370 nm, the thermal conductivity improves from 1.3 to 4.9 Wm−1K−1, density rises from 1430 to 3180 kgm−3 and thermal diffusivity goes up from 1 × 10−6 m2/s to close to 2 × 10−6 m2/s, as shown in Figure 25b [228]. The high thermal conductivity needs high filler loading, which often reduces various mechanical properties [230].
Synthesis and properties of photochromic polymer contain spiro-oxazine induced by ultraviolet light
Published in Soft Materials, 2023
Cheng-Dong Su, Yi-Yuan Shi, Jun Gao
PMMA is a promising material with good mechanical qualities, great transparency, and human body histocompatibility.[8] It has been applied in a wide variety of industries, such as building,[9] automobiles,[10,11] and medicine.[12] But it would be much more attractive for scientists if it had light-responsive features. Bahareh R. et al.[13] synthesized a few polymer assemblies with micellar geometry based on amphiphilic copolymer chains from PMMA and poly-n-isopropyl acrylamide (PNIPAM) with spiro-pyran chain end groups, where PNIPAM was responsive to temperature variation and PMMA with spiro-pyran was reversibly responsive to ultraviolet and visible light. The polymer assemblies could serve as novel multi-stimuli-responsive smart drug delivery systems for the controlled release of doxorubicin (DOX) upon different stimuli such as temperature, pH, and light.
Electrical and optical percolations in PMMA/GNP composite films
Published in Phase Transitions, 2018
Ertan Arda, Ömer Bahadır Mergen, Önder Pekcan
Thermoplastic polymers are known as insulating materials with high electrical resistance. Poly(methyl methacrylate) (PMMA) is a member of thermoplastic polymers family with amorphous structure, linear chain, low production cost and wide industrial applications (optics, vehicle industry, electrical engineering, medicine, etc.). Graphene-doped PMMA composites have the advantage related to the hardness, toughness, dimensional and heat balance. Studies have shown that the microstructure and viscoelastic properties of the PMMA are significantly improved by the addition of a low amount of graphene [16]. The hard surfaces of PMMA/graphene composites show high heat and electrical conductivity. Therefore, it is expected that such composites will be evaluated in various application areas such as aviation, tissue scaffolding, composite electrodes, biosensors, energy production and storage [17]. Graphene/PMMA composites can be obtained by three different methods. These are in situ polymerization, melt intercalation and solution intercalation [2]. Physical properties of such composite materials as a function of filler concentration generally show a non-linear increase [18]. This behavior is called percolation [19]. A critical threshold level during the percolation process is known as percolation threshold which the physical properties of the polymer material are influenced maximum by addition of the fillers [20,21]. For example, the thermal and electrical properties of normally insulating polymers increase by the addition of some CF such as graphene or carbon nanotubes. In the literature, studies on the electrical, mechanical, thermal and rheological properties of composites produced by these methods are examined by percolation theory [7–9,20,22–27].