Thermosets vs. thermoplastics

Unlike thermoplastics, which are simply melted, thermoset resins chemically react from low-viscosity liquids to solid materials during processing, a process termed curing. Structurally, thermosets differ from thermoplastics because of the presence of cross-links in the former, which means that thermosets cannot be reshaped or recycled once the chemical reaction occurs. One advantage of thermosets vs. thermoplastics is that wetting the filler becomes much easier with a low-viscosity material. By far the most common thermoset composite is automobile tires, which consist of a polymer made from styrene and butadiene monomers and carbon-black filler. The actual recipe used is much more complicated, and can include other monomers or polymers, as well as other fillers. In the absence of filler, the cured resin is rubbery at room temperature, which makes tires a... 

Table 9.24 Property guide for unreinforced and reinforced thermoplastics and thermosets vs. metals...

For over a century plastics have successfully competed with other materials in old and new applications providing cost-performance advantages, etc. In fact within the plastic industry there is extensive competition where one plastic competes with another plastic. Examples include many such as thermoplastic elastomers vs. thermoset... 

Resins vs. Plastics Thermoplastics vs. Thermoset Homopolymers vs. Copolymers Bifuncrional vs. Polyfunctional Linear vs. Branched vs. Cross-Linked Addition vs. Condensation... 

Adhesives, as all plastics, are viscoelastic materials combining characteristics of both solid materials like metals and viscose substrates like liquids. Typically, the adhesive shear stress vs. shear strain curve is non-linear. This behaviour is characteristic especially for thermoplastic adhesives and modified thermosetting adhesives. Thermosetting adhesives are, by their basic nature, more brittle than thermoplastic adhesives but, as discussed earlier, are often modified for more ductile material behaviour. 

Besides the chemical structures of the polymers in the plastics, there are several other characterizations that are important, including molecular weight, thermoplastics vs. thermosets, and crystallinity. 

Name the five regions of viscoelastic behavior of a polymer and give a sketch of the 10 second modulus vs. temperature for thermoplastic (amorphous and crystalline) and thermoset polymers. 

---