China
Africa
Explore chapters and articles related to this topic
Glove Selection for Work with Acrylates Including Those Cured by Ultraviolet, Visible Light, or Electron Beam
Published in Robert N. Phalen, Howard I. Maibach, Protective Gloves for Occupational Use, 2023
Common UV or light-cured composites for dental fillings and sealants include bisphenol A-diglycidyl methacrylate (BIS-GMA), triethyleneglycol dimethacrylate (TREGDMA), 2-HEMA, TMPTA, and sometimes methyl methacrylate (MMA; Figure 23.2).66,67 The most common ACD reactions are to 2-HEMA and TREGDMA;62,65 however, reactions to 2-HPMA, THFMA, EMA, butanediol dimethacrylate (BUDMA), and urethane dimethacrylate (UDMA) are common among dental workers.62 In the latter, cross-allergy to other methacrylates is suspected. Methyl methacrylate (MMA).The figure shows the chemical structure for methyl methacrylate (MMA) with a carboxylic acid group (–COOH), bound to a carbon-carbon double bond (C=C), and bound to a methyl group (–CH3).
Resin-Based Composites in Dentistry—A Review
Published in S. M. Sapuan, Y. Nukman, N. A. Abu Osman, R. A. Ilyas, Composites in Biomedical Applications, 2020
Z. Radzi, R. A. Diab, N. A. Yahya, M. A. G. Gonzalez
In 1956, the era of dental RBCs started when Bowen synthesized a new monomer, 2,2-bis[4-(2-hydroxy-3-methacrylyloxypropoxy)phenyl]propane, which is also known as Bis-GMA. It resembles an epoxy resin; however, the epoxy groups are replaced by methacrylate groups. It is prepared from bisphenol A and glycidyl methacrylate or diglycidyl ether of bisphenol A and methacrylic acid; therefore, it is a dimethacrylate (Bowen, 1959). Polymerization of the monomer occurs through carbon-carbon double bonds (C=C) of the two methacrylate groups. Bis-GMA is superior to methyl methacrylate because of its large molecular size and chemical structure, providing lower volatility, lower polymerization shrinkage, more rapid hardening, and production of stronger and stiffer resins.
Technical View
Published in Eberhard Lucke, Edgar Amaro Ronces, Leveraging Synergies Between Refining and Petrochemical Processes, 2020
Eberhard Lucke, Edgar Amaro Ronces
Polycarbonate – used in construction Acetone – used in bisphenol A and in solvents – Methyl methacrylate (MMA). – Polymethyl methacrylate (PMMA) – used in unbreakable glass
Developing of thermoregulating cotton fabric by incorporating of the poly(methyl methacrylate-co-methacrylamide)/fatty alcohol latent heat storing nanocapsules
Published in The Journal of The Textile Institute, 2022
Simge Özkayalar, Sennur Alay-Aksoy
Encapsulation is the most effective method used to overcome the problems referred to above. Solid-liquid PCMs have been generally encapsulated into the micro or nano-sized wall structures in order to increase heat transfer area, inhibit leakage in liquid phase, prevent odour and evaporation, provide durable application, and control the volume changes during phase change process. Encapsulation is a packaging technology that a tiny particle or droplet is enveloped by an organic or inorganic wall in order to develop micro or nano-sized capsule. Nowadays, microencapsulated PCMs prepared using various methods are available in commercial. Some of the commercial microencapsulated PCMs, which can be incorporated into the fibres, yarns and fabrics by various application methods, are ThermoculesTM (Outlast®), Thermic® (Devan Chemical), Micronal® (Microtek Laboratories), PureTemp® (PureTemp LLC, originally known as Entropy Solutions Inc.,) (Mattila, 2006; Paul, 2015). In the literature, spray drying as a physical method, complex coacervation as a physico-chemical method and chemical methods such as interfacial polymerization, suspension polymerization, in situ and emulsion polymerization, have been generally used for production of the microencapsulated PCMs (Jamekhorshid et al., 2014). Microencapsulation method is mainly chosen depending on chemical nature of the shell materials and the desired mean diameter. In situ polymerization is a suitable method to fabricate melamine derivatives shell, whereas interfacial polymerization method is a suitable method to fabricate polyurea and polyurethane shells. Poly(methyl methacrylate) (PMMA) and its copolymers with various monomers such as acrylic acid, methacrylic acid are produced by emulsion polymerization and suspension-like polymerization processes. The wall material plays an important role in meeting the requirements of the usage areas of the microcapsules. In recent years, PMMA and its co-polymers have attracted attention in the encapsulation of the PCMs as thermal energy storage materials, due to being transparent, lightweight, easy processable, environmental stable, non-toxicity, and low cost (Alkan et al., 2009; 2011; Al-Shannaq et al., 2015; Altun-Anayurt et al., 2017; Chang et al., 2009; Chen et al., 2012; Iqbal & Sun, 2018; Ma et al., 2012; Qiu et al., 2012; Rezvanpour et al., 2018; Sarı et al., 2010; 2014; 2016; Shi et al., 2015; Wang et al., 2012; 2014; Zhang et al., 2012; Zhao et al., 2017). The shell materials of the encapsulated PCMs used in production of the thermoregulation textiles should have stability to the high temperatures and mechanical impacts, which they are exposed during the textile application processes and daily usage (Salaün, 2011). Polymethyl methacrylate is transparent acrylic polymer with thermoplastic property and has a relatively good mechanical stability and protection against outside environments (Sarı et al., 2010). Besides to be lower cost, it also allows the production of copolymers with co-monomers containing reactive groups such as carboxylic acid or epoxy groups in order to product capsule wall providing affinity to the textile fibres.