Polyester polymers description

For those familiar with polymer chemistry, polyurethane may be a confusing term. Unlike polyethylene, the polymerization product of ethylene, a polyurethane is not the result of the polymerization of urethane. To add to the confusion, a urethane is a specific chemical bond that comprises a very small percentage of the bonds of a polyurethane. Since we are interested in chemical and physical effects, polyether or polyester is a more descriptive term for the most common bond in a polyurethane. Despite this complication, it is instructive to begin by talking about the methane bond from which the polyurethane name is derived. The general structure or bond that forms the basis of this chemistry is the urethane linkage shown in Figure 2.1. 

In a similar report utilizing triethylene glycol dimethacrylate, the polymer was described as a linear polyester.330 Again, this description is probably incomplete, though it is possible at high catalyst loadings to prepare methacrylic dimers. Under ideal conditions, this would lead to the linear, unsaturated polymer 97. 

We can classify the different biodegradable and bio-based polymers into two major families agropolymers (categoiy a) and biodegradable polyesters (categories b and c). To illustrate the latter, the next section focuses on the description of biodegradable polyesters, from synthesis to application. 

When the number of repeating units in a polymer chain is low, that is when the molecular weight of the polymer is low (2000-10000 g mol ), the polymer is defined as a resin, provided it possesses sufficient numbers of active sites in its structures for chemical cross-linking to occur. The resins can form three-dimensional network structures if sufficient external energy (heat/light/radiation) is applied, with or without the use of any other chemical(s) in their finished state. They are free flowing materials of low viscosity. Polyester resins, epoxy resins, and polyurethane resins are examples of this type of polymer. This book contains descriptions of the different types of resins derived from various vegetable oils. 

Description Silane surface-modified calcined clays very pure high brightness/low residue clay/silane/polymer interaction improves tensile strength and compression set used for cross-linked PE and polyester. EP elastomers amino silane for mineral-filled PA ... 

The connection between liquid crystallinity (mesomorphism) and polymers can arguably be dated from 1950 with Elliott and Ambrose s description of birefringent chloroform solutions of the synthetic polypeptide polyCybenzyl-L-glutamate). Robinson s reports, begun in 19562, on careful studies of such solutions, firmly established the phenomenon of lyotropic (solvent induced) liquid crystallinity in polymers. In the 1960 s industrial research into what later proved to be thermotropic liquid crystalline polymers - linear para-substituted aromatic polyesters - was actively pursued. The now famous discovery in 1965 by Kwolek at du Pont of lyotropic liquid crystallinity in aromatic polyamides led to the highly successful Kevlar materials. 

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