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Synthesis of Nanomaterials and Nanostructures
Published in Vidya Nand Singh, Chemical Methods for Processing Nanomaterials, 2021
Preeti Kaushik, Amrita Basu, Meena Dhankhar
Luminescent materials, color pigments, and nanoscale functional materials are produced by polyol method [17], and they are usually in the crystalline, spherical form within the range of 20-200 nm in size, which is characterized by SEM, XRD, and other spectroscopic techniques [17]. There are many advantages associated with this polyols as it provides for adaptability and flexibility, and the boiling point increases with increasing molecular weights, and similarly, the polarity and viscosity also increases [18]. There is a wide application of polyols in the form of standard solvents, cosmetics, or in food additives and pharmaceutical industries due to its property of moderate toxicity and being highly biodegradable. In studies done by Byeon and group, it was seen that ultrasonic irradiation played an important role in the polyol method for the synthesis of colloidal silver nanoparticles, resulting in morphological uniformity and better formation kinetics [19].
Atmospheric Pollution and Pollutants
Published in Wayne T. Davis, Joshua S. Fu, Thad Godish, Air Quality, 2021
Wayne T. Davis, Joshua S. Fu, Thad Godish
Alcohols, for example, methanol (CH3OH) and ethanol (C2H5OH), are characterized by having an −OH moiety attached to one of their carbon atoms. The substitution of an –OH in the structure of CH4 produces CH3OH. Short-chain alcohols are liquid at ambient conditions and are commonly used as solvents. Methanol is used as an automotive fuel and C2H5OH as a fuel additive. Alcohols with two or more −OH moieties are called polyols. Low-volatility polyols such as ethylene glycol are used as motor vehicle coolants and in water-based paint and varnish products. Because of their widespread use, alcohols and polyols are frequently emitted to the atmosphere.
Bio-polyurethane and Others
Published in Abdullah Al-Mamun, Jonathan Y. Chen, Industrial Applications of Biopolymers and their Environmental Impact, 2020
Jointly DuPont Tate & Lyle Bio Products and BioAmber have developed multiple bio-based polyols using bio-succinic acid and bio-based 1,3-propanediol via the fermentation of corn. These polyols are the building blocks that deliver high performance in a variety of polyurethane applications, from footwear and waterproof films to artificial leather and coating, adhesives, and elastomer applications.
Research on the flow and dropping behaviour of droplets generated by burning of flexible polyurethane foam
Published in Combustion Science and Technology, 2023
Yangui Chen, Hongzhou He, Zhongqing Liu
Droplet formation during FPUF combustion is primarily attributed to the flow of liquid-phase products, with polyols being a major component (Chen, He, and Liu 2021). Various polyols are utilized for manufacturing polyurethane foams. Allen et al. (Allan, Daly, and Liggat 2013), reported that trimethylolpropane gas could be used as an approximation for polyether polyol gas, given their similar thermal physical properties. The thermal physical parameters of the trimethylolpropane gas were obtained from the “AP1700 online platform for the calculation and query of physical parameters” (http://www.ap1700.com/). The fitted parameters of trimethylolpropane as a function of temperature, based on the data provided by the platform, are presented below:
Polyurethane asphalt binder: a promising candidate for steel bridge deck-paving material
Published in International Journal of Pavement Engineering, 2022
Meng Jia, Aimin Sha, Jinghui Lin, Zengping Zhang, Bing Qi, Dongdong Yuan
Polyols are substances with at least two functional hydroxyl groups and other functional groups such as esters, ethers and amides. Polyether polyols and polyester polyols are two common types of polyols with considerably different properties owing to their divergent molecular structures (Xie et al. 2019, Wongsamut et al. 2020). In particular, polyether polyols with non-polar and rotatable ether bonds realise flexible PU; in contrast, certain ester groups in polyester polyols possess large polarity and easily create strong hydrogen bonds, which is conducive to synthesising PU with high hardness and mechanical strength (Cong et al. 2019a, Das and Mahanwar 2020). From the perspective of chain length, long-chain polyols tend to form PU with only few rigid urethane linkages (−NH−COO−) and highly flexible alkyl chains. In addition, bifunctional polyols yield more flexible PU than multifunctional polyols which produce cross-linked PU (Das and Mahanwar 2020).
Biodegradability and ecotoxicity of polyurethane foams: A review
Published in Critical Reviews in Environmental Science and Technology, 2022
Kateřina Skleničková, Sabina Abbrent, Martin Halecký, Vladimír Kočí, Hynek Beneš
Compared to polyisocyanates, polyols present a much larger variety of chemical structures as well as molecular masses. The oligo-polyols with high molecular weight in the range of 2000–6500 g mol−1 and low functionality of around 2–3 are used for the flexible PUF, while highly branched polyols with high functionality of ca 3–8 and low molecular weight ranging from around 300 to 1000 g/mol are used for the rigid PUF (Ionescu, 2005). Molecular weight, functionality and hydroxyl number are the three main polyols’ characteristics affecting the final properties of PUF. Generally, the polyols are divided into two main groups, namely polyester and polyether polyols. The most usable polyethers in the industry are for example polypropylene glycol (PPG), glycerin, trimethylolpropane (TMP), propylene or ethylene oxide. Polyesters are formed by reaction between alcohols and dicarboxylic acids, for example adipic acid and diethylene glycol (DEG) or oleic acid and TMP. By choosing particular mixture of alcohols and carboxylic acids desired type of foam is produced (Oertel, 1994). Polyester polyols are highly resistant to oxidation, increased temperature and degradation by weather. On the other hand, polyester polyols are more sensitive to hydrolysis as compared to polyether polyols (Bayer Material Science AG, 2005).