Synthetic polymer, first

Vinylidene chloride copolymers were among the first synthetic polymers to be commercialized. Their most valuable property is low permeabiUty to a wide range of gases and vapors. From the beginning in 1939, the word Saran has been used for polymers with high vinylidene chloride content, and it is still a trademark of The Dow Chemical Company in some countries. Sometimes Saran and poly (vinylidene chloride) are used interchangeably in the Hterature. This can lead to confusion because, although Saran includes the homopolymer, only copolymers have commercial importance. The homopolymer, ie, poly (vinylidene chloride), is not commonly used because it is difficult to fabricate. 

Acrylic Resins. The first synthetic polymer denture material, used throughout much of the 20th century, was based on the discovery of vulcanised mbber in 1839. Other polymers explored for denture and other dental uses have included ceUuloid, phenolformaldehyde resins, and vinyl chloride copolymers. Polystyrene, polycarbonates, polyurethanes, and acryHc resins have also been used for dental polymers. Because of the unique combination of properties, eg, aesthetics and ease of fabrication, acryHc resins based on methyl methacrylate and its polymer and/or copolymers have received the most attention since their introduction in 1937. However, deficiencies include excessive polymerization shrinkage and poor abrasion resistance. Polymers used in dental appHcation should have minimal dimensional changes during and subsequent to polymerization exceUent chemical, physical, and color stabiHty processabiHty and biocompatibiHty and the abiHty to blend with contiguous tissues. 

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 first synthetic polymers to be used as paint varnishes were acrylic and vinylic resins. Poly(vinyl acetate) (PVAc), commercialized under the name Mowilith by Hoechst and Vinylite by Union Carbide, has been used in conservation as an adhesive since 1932 and in 1937 it was proposed as a picture varnish by Stout and Cross [63]. PVAc was soon rejected as a varnish because, despite its light stability and good solubility in organic solvents, it demonstrated poor optical properties in terms of colour saturation and the tendency to pick up dirt due to its low glass transition temperature. 

He found out in 1909 that a resinous plastic substance is formed in this reaction. This substance could be heated and moulded into a shape. Further heating of a substance in the mould sets it in the fine shape. Further heating does not resoften this substance. Baekeland patented this substance and called it Bakelite. Bakelite was the first Synthetic polymer. The industry of Bakelite led to a study and establishment success of polymer science. 

The first synthetic polymer utilized on a large commercial scale was Bakelite produced by Leo Baekeland, one of many foreign-born scientists who helped create American technology. By 1909 he had demonstrated a number of Bakelite articles to members of the recently formed Chemists Club of New York. 

By 1924 Bakelite had become so popular that it was featured on the cover of Time magazine as a substance that will not burn and will not melt. Bakelite jewelry, telephones, pens, radios, car parts, airplane propellers, ashtrays, billiard balls, and cameras were everywhere. Just about the only item that did not become popular was the Bakelite coffin. People would wear, cook in, and eat off plastic, but they refused to be buried in it. Bakelite s success stimulated research to improve the material even further, especially after scientists pointed out that in the manufacture of Bakelite the small phenol and formaldehyde molecules had joined together to make a giant three-dimensional lattice. In other words. Bakelite was the world s first synthetic giant molecule, the first synthetic polymer. 

Polystyrene was the first synthetic polymer used for blow molding during World War II and polyethylene was the first material to be implemented in commercial applications. Until the late 1950s, the main application for blow molding was the manufacture of PE-LD articles such as squeeze bottles. Blow molding produces hollow articles that do not require a homogeneous thickness distribution. Today, PE-HD, PE-LD, PP, PET, and PVC are the most common materials used for blow molding. 

Polyglycolide was one of the first synthetic polymers used as a degradable surgical suture [122]. Fig. 8 shows the glycolide monomer and polymer structures. This aliphatic polyester is biodegradable and exhibits negligible toxicity when implanted in tissue. It is also possible to fabricate a strong fiber of this polyester with satisfactory mechanical properties. 

One of the first synthetic polymers to be blended with starch was poly(vinyl alcohol) (PVA). Otey et al.129,130 prepared cast films of starch and PVA from aqueous solutions containing a plasticizer (glycerol). Films were cast onto glass plates and air-dried at 130°C. Small amounts of crosslinking agent, such as formaldehyde,... 

At the beginning of the twentieth century, the first synthetic polymer, bakelite, was obtained and later, after the First World War, it was proposed that polymers consisted of long chains of atoms held together by covalent bonds. The Second World War gave a huge stimulus to the creation of polymers, which firmly established the held of polymers. 

Bakelite, the first synthetic polymer, is an example of a thermoset polymer. It is prepared by the polymerization of phenol and formaldehyde in the presence of ail acid. Carbocations produced by protonation of formaldehyde bond to the ortho and para positions of the highly reactive phenol molecules in a Friedel-Crafts alkylation reaction. The benzylic alcohols that are produced in this step react to produce carbocations that then alkylate additional phenol molecules. A mechanism for the first few steps of this polymerization process is shown in Figure 24.4. 

We now well appreciate, of course, that polymers are virtually everywhere. Some of them occur naturally, and we continue to better understand their compositions, structures, and properties. Many of these materials have been used since the dawn of human existence, for food, obviously. Cellulose alone has been essential for clothing, fire, shelter, tools, weapons, writing, and art. Leather is probably the result of the first synthetic polymer reaction, essentially the crosslinking of protein (elastin). How we progressed over time to the Polymer Age is a fascinating series of stories, some of which are well worth recounting here. 

Before Synthetic Polymers Polymers before World War I Improving Natural Rubber Behind the Eight Ball—The First True Plastic The Picture of Things to Come Other Cellulose Derivatives The First Synthetic Polymer Polymer Chemistry Defined by the World Wars... 

The first synthetic polymers to be of any use were the phenol formaldehyde resins of which the most famous, Bakelite, was discovered by Bakeland at the turn of the century. He combined phenol and formaldehyde in acid solution and got a reaction that starts like the bisphenol A synthesis. 

Polyvinyl chloride (PVC) and polyvinyl acetate (PVA) are considered to be the first synthetic polymers created. Safe-handling cellulose acetate soon replaced explosive cellulose nitrate. Polyacrylonitrile and polyamides (Nylon) soon followed. American companies such as DuPont pioneered the development of plastics. England was responsible for the early development of polyester polymerization. 

The first synthetic polymers were produced as by-products of various organic reactions and were regarded as unwanted contaminants. Thus the first preparations of many of the polymers now regarded as essential to our modern lifestyle were thrown away in disgust. One chemist who refused to be defeated by the tarry products obtained when he reacted phenol with... 

In Chapter 52 you met Bakellte, the first synthetic polymer, which results from unselective reactions between these two compounds. 

The first synthetic polymer was Bakelite, synthesized in 1909. Bakelite is still used today in stove-top appliances because of its resistance to heat. Since... 

Within the specific context of this chapter, renewable resources represent the obvious answer to the quest for macromolecular materials capable of replacing their fossil-based counterparts [2, 3]. This is not as original as it sounds, because, apart from the role of natural polymers throughout our history evoked above, the very first synthetic polymer commodities, developed during the second half of the nineteenth century, namely cellulose esters, vulcanized natural rubber, rosin derivatives, terpene resins , were all derived from renewable resources. What is new and particularly promising, has to do with the growing momentum that this... 

The first synthetic polymers were produced as by-products of various organic reactions and were regarded as unwanted contaminants. Thus the first preparations of many of the polymers now regarded as essential to our modern lifestyle were thrown away in disgust. One chemist who refused to be defeated by the "tarry" products obtained when he reacted phenol with formaldehyde was the Belgian-American chemist Leo H. Baekeland (1863-1944). Baekeland s work resulted in the first completely synthetic plastic (cal led Bakelite), a substance that when molded to a certain shape under high pressure and temperature cannot be softened again or dissolved. Bakelite is a thermoset polymer. In contrast, cellulose nitrate is a thermoplastic polymer that is, it can be remelted after it has been molded. 

The first synthetic polymer, synthesized in 1909, was a hard, brittle plastic called Bakelite. Because of its resistance to heat, it is still used today in stove-top appliances. Since 1909, hundreds of other synthetic polymers have been developed. Because of the widespread use of polymers, people might refer to this time as the Age of Polymers. 

Figure 22.18 shows milestones leading to the Age of Polymers and highlights of polymer development. Although the first synthetic polymer was developed in 1909, the industry did not flourish until after World Warn. 

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