Phenol-formaldehyde polymers commercially available

Copolymers of furfural with phenol or phenol-formaldehyde polymers have been available commercially for many years. Since the acid-catalyzed reaction of furfural and phenol has been difficult to control, most industrial applications involve the use of alkaline catalysts. Furfural-phenol resins are used for their alkali resistance, enhanced thermal stability, and good electrical properties compared to phenol-formaldehyde resins. 

Phenol-formaldehyde polymers, phenolics, were not only one of the first commercially available plastics, but they were the first commercially used thermosets. Normally one does not think of thermosetting polymers as useful for packaging applications because of the need to reshape the material. Phenolics were commonly used for closure manufacture in the past, because of their excellent chemical resistance. Phenolic closures have nearly disappeared from the market today. 

Commercially successful fully synthetic polymeric materials were produced in the early years of this century, the first example being Bakelite. This was made from phenol and formaldehyde by Leo Bakeland in 1909. Before the end of the 1920s, a large number of other synthetic polymers had been created, including polyvinyl chloride and urea-formaldehyde. Today, there are literally hundreds of synthetic polymers commercially available with ranges of properties making them suitable for applications in many industrial sectors, including the electrical and electronics industries. 

The use of adhesives can be traced back many centuries, while the production of adhesives, on an industrial scale, started about 300 years ago. The birth of modern structural adhesives can be dated from about 1910, with the introduction of the phenol-formaldehyde resins.Table II summarizes the historical development of structural adhesives, with the dates referring to the approximate time period during which each adhesive became commercially available. The introduction dates for the high-temperature polymers (polyimide, polybenzimidazole, and polyquinoxa-line) have been included for reference, although, as previously mentioned, there are presently few commercial products based on these polymers. 

Formulators can choose from a variety of commercially available phenolic compounds, including, in addition to phenol itself, the isomers of cresol, the isomers of xylenol, resorcinol, catechol, hydroquinone, bisphenol A, and various alkylphenols. Formaldehyde is usually used as the second major component, but acetaldehyde, furfuraldehyde, and paraformaldehyde (the polymer of... 

Another compound which has been found to somewhat imitate the active site of peroxidases is the commercially available Fe(II)-salen catalyst. This catalyst was used successfully to produce phenol polymers, which could be of interest for industrial production [153,154]. For example, cardanol can be polymerized by the Fe(II)-salen catalyst [155]. Due to the unsaturated bonds in the side chain of the cardanol components, the resulting polymers could be thermally cured, or cured by use of cobalt naphthenate to give brilliant films with a high-gloss surface. This reaction proves that reactive prepolymers can be synthesized from renewable resources (cardanol is the main component obtained by thermal treatment of cashew nutshell liquid). This process could be a true alternative to conventional phenol-formaldehyde resins (Scheme 25) [ 155]. Other non-heme iron complexes have been foimd to... 

The most commonly used polymer precursors for carbon membranes have been reported to be polyimides, polyfurfuryl alcohol, phenol formaldehyde resins and cellulose. Their common characteristic is that they do not melt during pyrolysis at high temperature, which keeps their original shape and structure during the thermal heating and decomposition process. In this sense, the commercially available Matrimid and Kapton are the fully imidized polyimides with high values. They do not abruptly change their... 

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