Phenol-formaldehyde polymers development

Articles that are not made from synthetic polymers are often held together or coated with polymers. A bookcase may be made from wood, but the wood is bonded by a phenol-formaldehyde polymer and painted with a latex polymer. Each year, about 400 billion pounds of synthetic organic polymers are produced worldwide, mostly for use in consumer products. Large numbers of organic chemists are employed to develop and produce these polymers. 

Positive Photoresists. Positive resists are entirely different from negative resists. For the purposes of this discussion we restrict ourselves to visible-light-sensitive materials. Typically, these materials are mixtures of low-molecular-weight phenol-formaldehyde polymers and derivatives of naphtho-1,2-quinone diazide, the photosensitive component. The former is soluble in aqueous alkali, but the presence of the latter, a hydrophobic species, inhibits attack of this developer on the film. On irradiation the "sensitizer" is converted to a ketene, which, after reaction with water, forms a base-soluble carboxylic acid. Thus the irradiated part of the film is rendered soluble in the developer and it can be removed selectively. The important feature of this system is that the unirradiated areas are not swollen by the developer and the resolution of this material is quite high. It is possible to prepare gratings having several... 

An emulsion polymer-isocyanate adhesive, a crosslinked polyvinyl acetate adhesive, a resorcinol-formaldehyde adhesive, a phenol-resorcinol-formalde-hyde adhesive, and an acid-catalyzed phenolic-formaldehyde adhesive developed bonds of high shear strength and wood failure at all levels of acetylation in the dry condition. A neoprene contact bond adhesive and a moisture-curing polyurethane hot-melt adhesive performed as well on acetylated wood as untreated wood in tests of dry strength. Only a cold-setting resorcinol-formal-... 

Data of low-temperature nitrogen adsorption were used to evaluate the parameters characterizing the pore structure of the obtained polymeric materials in dry state. The BET specific surface area, Sbet, and the total pore volume, V, were estimated by applying the standard methods Sbet from the linear BET plots and F/ from adsorption at relative pressure p/po=0.975) [7]. The mesopore structure was characterized by the distribution function of mesopore volume calculated by the Barret-Joyner-Halenda (BJH) method [27]. In Table 2 the values of these parameters are given for both synthesized polymers. The melamine-formaldehyde resin MEA has a more developed pore structure (5 B 7=220mVg, F,=0.45cm /g) and narrower mesopores (D=7.3nm) in comparison to the phenolic-formaldehyde polymer PHD. 

Novolak diazonaphthoquinone positive-tone resists, the most important imaging system of semiconductor production today1510,1511 is an archetypal example of the industrial applications of photochemistry. Novolak is a phenol formaldehyde polymer (Bakelite) that dissolves in aqueous hydroxide, but the addition of a small amount of the diazonaphthoquinone 585 dramatically decreases the solubility. When irradiated, 585 undergoes the photo-Wolff rearrangement (see also Scheme 6.171), leading to ring contraction and subsequently to carboxylic acid formation (Scheme 6.284). Such a photochemically altered site is readily soluble and can be removed with a basic developer solution. 

Some polymers are easier to foam than others. Indeed, it was not until methods were found to circumvent the inclusion of cells in the early history of the phenol formaldehyde polymer that it gained any commercial significance. The development of foamed phenolic resins only became important much later when a specific need arose to produce rigid foam with reduced flammability. This consideration also led to the development of polyisocya-nurate foams and carbodiimide foams. On the other hand, the polypropylene family of polymers, although having a tonnage far exceeding that of phenol formaldehyde resins, is... 

Baekeland in America obtained his first patent for materials prepared from these two compounds. In 1910 he founded the General Bakelite Company to exploit this development, in the process making phenol-formaldehydes, the first synthetic polymers to achieve commercial importance. 

The initial research objectives included developing a simple experimental procedure to study how the graft polymers, polystyrene, and a commercial phenol formaldehyde resin interact when combined with wood under heat and pressure. Two-ply lap shear test specimens were used for a comparative test. 

The first truly synthetic resin was developed by Baekeland in 1911 (phenol-formaldehyde). This was soon followed by a petroleum-derived product called coumarone-indene, which did indeed have the properties of a resin. The first synthetic elastomer was polychloroprene (1931) originated by Nieuwland and later called neoprene. Since then many new types of synthetic polymers have been synthesized, perhaps the most sophisticated of which are nylon and its congeners (polyamides, by Carothers), and the inorganic silicone group (Kipping). Other important types are alkyds, acrylics, aminoplasts, polyvinyl halides, polyester, epoxies, and polyolefins. 

We learned much from nature with these early attempts to produce useful polymer products based on modified, or reconstituted ( semisynthetic ) natural polymers, and many of these processes are still in use today. The first of the purely synthetic commercial polymers came with the small-scale introduction of Bakelite in 1907. This phenol-formaldehyde resin product was developed by Leon Baekeland. It rapidly became a commercial reality with the formation of The General Bakelite Company by Baekeland, and construction of a larger plant at Perth Amboy, New Jersey, in 1910. At about this time styrene was being combined with dienes in the early commercialization of processes to produce synthetic rubber. Polystyrene itself was not a commercial product in Germany until 1930 and in the U.S.A. in 1937. The only other purely synthetic polymers that made a commercial appearance during this early development period were polyvinyl chloride and polyvinyl acetate, both in the early 1920s. 

Historically, the reaction of phenol with formaldehyde was of vital importance to the polymer industry, being one of the first totally synthetic commercial polymer resin systems developed. In 1907, Leo H. Baekeland commercialized, under the tradename Bakelite , a range of cured phenol-formaldehyde resins, which were useful in producing heat-resistant molded products . Since this early work, phenol-formaldehyde resins have been used in many applications, including refractory compounds, adhesives, thermal insulation and electrical industries ". ... 

Electrical and electronic products such as computers, cell phones, TVs, and stereos are becoming a more visible part of the MSW. Some of the resins used in electronic products are PS, HIPS, ABS, PC, PP, PU, PV, PVC, polyamides, phenol formaldehyde, and blends of some of these polymers. Several technologies are being developed for the separation of different plastic types. Since the electronic parts are made from many engineering plastics, and with many different additives, it is more difficult to identify and separate the individual resins. 

The development of ACF and AC cloths is closely related to that of carbon fibers (CFs). This makes that the raw materials used for the preparation of ACFs be, chronologically, the same as for CFs. Thus, in 1966, viscose and acetate cloths were, like for CFs, the first materials used to obtain ACFs [4, 5]. The low yield of the ACFs, and CFs, obtained from the above precursors, oriented the research towards the seek of other raw materials for the preparation of cheaper CFs and ACFs with a higher yield. In this way, ACFs were prepared from 1970 using lignin (with the brand of Kayacarbon ALF), polyvinylchloride [6] (i.e., Saran polymer, already used to obtain ACs) and phenolic precursors [7]. The high yield and the good mechanical properties of the ACFs obtained make these precursors very useful for this application. In fact. Economy and Lin [8] developed ACFs from a phenol formaldehyde precursor, which are commercialized since 1976 under the name of Novolak. In 1980, Kuray Chemical Co. Ltd commercialized ACFs from phenolic resin under the name of Kynol. ... 

The formation of crosslinked networks has been the basis for polymer technology since the development of phenol-formaldehyde resins by Baekeland in 1910. The changes to the rheology of the phenolic system, as it develops from a liquid to a rubber and then to a glass, arise from the formation of a three-dimensional network as the step-growth chemical reactions occur. Water is evolved and the end product is a solid infusible mass. 

Cellulose nitrate is derived from cellulose, a natural polymer. The first truly man-made plastic came 41 years later (in 1909) when Dr. Leo Hendrick Baekeland developed phenol-formaldehyde plastics (phenolics), the source of such diverse materials as electric iron and cookware handles, grinding wheels, and electrical plugs. Other polymers — cellulose acetate (toothbrushes, combs, cutlery handles, eyeglass frames) urea-formaldehyde (buttons, electrical accessories) poly(viryl ehloride) (flooring, upholstery, wire and cable insulation, shower curtains) and nylon (toothbrush bristles, stockings, surgical sutures) — followed in the 1920s. 

In Chapter 2 we indicated that the formation of a polymer requires that the functionality of the reacting monomer(s) must be at least 2. Where the functionality of one of the monomers is greater than 2, then a cross-linked polymer is formed. Thermosets like phenol-formaldehyde, urea-formaldehyde, and epoxy resins develop their characteristic properties through cross-linking. In this section our discussion is confined to those polymeric systems designed with latent cross-linkability that under appropriate conditions can be activated to produce a polymer with desirable properties. 

The first completely synthetic plastic, phenol-formaldehyde, was introduced by L. H. Baekeland in 1909, nearly four decades after J. W. Hyatt had developed a semisynthetic plastic—cellulose nitrate. Both Hyatt and Baekeland invented their plastics by trial and error. Thus the step from the idea of macromolecules to the reality of producing them at will was still not made. It had to wait till the pioneering work of Hermann Staudinger, who, in 1924, proposed linear molecular structures for polystyrene and natural rubber. His work brought recognition to the fact that the macromolecules really are linear polymers. After this it did not take long for other materials to arrive. In 1927 poly(vinyl chloride) (PVC) and cellulose acetate were developed, and 1929 saw the introduction of urea-formaldehyde (UF) resins. 

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