Synthetic polymers melamine-formaldehyde

The first commercially successful synthetic polymer was phenol-formaldehyde (PF) [Smith, 1899]. The resin was introduced in 1909 by Baekeland as Bakelite . The urea-formaldehyde resins (UF), were discovered in 1884, but production of Beetle moldable resin commenced in 1928. Three years later, Formica , phenolic paper covered with decorative layer protected by UF, was introduced. The thiourea-formaldehyde molding powders were commercialized in 1920, while in 1935, Ciba introduced Cibanite , anihne-formaldehyde (AF) molding materials, then two years later, the melamine-formaldehyde (MF). 

In the early 1920s, experimentation with urea—formaldehyde resins [9011-05-6] in Germany (4) and Austria (5,6) led to the discovery that these resins might be cast into beautiful clear transparent sheets, and it was proposed that this new synthetic material might serve as an organic glass (5,6). In fact, an experimental product called PoUopas was introduced, but lack of sufficient water resistance prevented commercialisation. Melamine—formaldehyde resin [9003-08-1] does have better water resistance but the market for synthetic glass was taken over by new thermoplastic materials such as polystyrene and poly(methyl methacrylate) (see Methacrylic polymers Styrene plastics). 

Phenol-formaldehyde was reported as the first commercially synthetic polymer (1899) which was introduced as BakeliteT by Baekeland in 1909. This was the period which marked the dawn for the production of commercial synthetic thermosetting polymers. Other advances in the field included the discovery of urea-formaldehyde resins in 1884 and the beginning of their commercialization as Beetle moldable resin in 1928, followed by thiourea-formaldehyde (1920), aniline-formaldehyde (Cibatine by Ciba, 1935) and melamine-formaldehyde (1937) moulding powders. The year 1909 marked the discovery of epoxy compounds by Prileschaiev, which were not used until World War 2. The first thermoset polyesters, invented by Ellis, date back to 1934 and in 1938 was reported their first use in the forms of glass-reinforced materials [1]. 

In order to improve the physical properties of paper, especially strength and resistance to erasure, natural polymers, like starches and gums, are added to the stock, as well as cellulose compounds, like carboxy-methyl cellulose, or synthetic polymers, e.g. polyacrylamides and polyamines. Wet-strength resins, such as polyamide resins, are also often added to the stock. Urea-formaldehyde and melamine-formaldehyde resins are no longer in wider use for improving wet strength. 

The first completely synthetic plastic material was made from the condensation of phenol and formaldehyde in the presence of a catalyst. The production of this material was perfected by Leo Hendrik Baekland (1863-1944), a Belgian chemist working in the United States, and it was marketed from 1909 under the name Bakelite. Bakelite is a highly crosslinked three-dimensional thermosetting polymer, and in the 1920s and 1930s a number of similar materials were developed such as urea formaldehyde and melamine formaldehyde. 

Chemical admixtures They are generally water-soluble, added mainly to control setting and early hardening of fiesh concrete, and to reduce water requirements. Chemical admixtures include accelerators, normal water reducers, superplasticizers, and retarders. The accelerators may contain calcium chloride, alkali hydroxide, calcium formate, calcium nitrate, etc. Examples of retarders are Na, Ca, or NH4 salts of lignosulfonic acids, hydroxy carboxylicacids,orderivativesofcarbohydrates.Normal water reducers may contain salts of refined lignosulfonic acids, hydroxycarboxylic acids, hydroxylated polymers, etc. Superplasticizers may contain sulfonated melamine formaldehyde, sulfonated naphthalene formaldehyde, car-boxylated synthetic polymers, etc. 

The first synthetic plastics were the phenol-formaldehyde resins introduced by Baekeland in 1907 [1], Melamine and urea also react with formaldehyde to form intermediate methylol compounds which condense to cross-linked polymers much like phenol-formaldehyde resins. Paper, cotton fabric, wood flour or other forms of cellulose have long been used to reinforce these methylol-functional polymers. Methylol groups react with hydroxyl groups of cellulose to form stable ether linkages to bond filler to polymers. Cellulose is so compatible with these resins that no one thought of an interface between them, and the term reinforced composites was not even used to describe these reinforced systems. 

The solvency of cycloaliphatic hydrocarbons is between that of aliphatic and aromatic hydrocarbons. They have a high solvency for fats, oils, oil-modified alkyd resins, styrene-modified oils and alkyd resins, bitumen, rubber, and other polymers. Polar resins (e.g., urea-, melamine-, and phenol-formaldehyde resins), as well as alcohol-soluble synthetic resins and cellulose esters are, however, insoluble. 

Isophorone [14.268], [14.269] is an unsaturated cyclic ketone. It consists of a-isophorone [78-59-1] (3,5,5-trimethyl-2-cyclohexen-l-one), which contains about 1-3% of the isomer P-isophorone [471-01-2] (3,5,5-trimethyl-3-cyclohexen-l-one). Isophorone is a stable, water-white liquid with a mild odor that is miscible in all proportions with organic solvents. It dissolves many natural and synthetic resins and polymers, such as poly(vinyl chloride) and vinyl chloride copolymers, poly(vinyI acetate), polyacrylates, polymethacrylates, polystyrene, chlorinated rubber, alkyd resins, saturated and unsaturated polyesters, epoxy resins, cellulose nitrate, cellulose ethers and esters, damar resin (dewaxed), kauri, waxes, fats, oils, phenol-, melamine-, and urea-formaldehyde resins, as well as plant protection agents. However, isophorone does not dissolve polyethylene, polypropylene, polyamides. 

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