Mr. Rogers' IB Design Technology Objectives

Plastics - thermoplastics or thermosets

Describe a covalent bond. outer electrons of atoms come close enough to overlap and are shared between the nuclei, each pair of electrons is called a covalent bond. strong bonds Describe the structure and bonding of a thermoplastic. Longchains called polymers of a repeating molecule called a monomer chains can be linear or have either short or long chain branches Chains have some folding or coiling Bonding within the chain: covalent Bonding between chains: weak bonds Describe the effects of load on a plastic or polymer elastic region: the chains ten to straighten or uncoil like tiny springs plastic region: adjacent molecules slide past each other temperature effect: increased temperature favors plastic deformation Draw and describe the structure and bonding of a thermoset.

Thermoplastic Examples (thermoplastics can generally be recycled.) Plastic Application polyethylene plastic bags polypropylene rope PVC (polyvinyl chloride) vinyl siding,  pipe, upholstery,  flexible hoses PET (Polyethylene terephthalate) drink bottles   Thermosetplastic Examples (thermoplastics generally cannot be recycled) Plastic Application urea–formaldehyde adhesives, finishes, MDF, and molded objects epoxy adhesives, molded parts, coatings Polyurethanes foam padding, wear resistant parts