1 / 8

Section 11.3—Polymers

Section 11.3—Polymers. How do polymer properties vary for various applications?. Polymers & Monomers. Polymer – Very large molecules built from chains or networks of smaller molecules (usually 1,000 to 50,000 smaller molecules). Monomer – The smaller molecules making up the polymer.

kita
Télécharger la présentation

Section 11.3—Polymers

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Section 11.3—Polymers How do polymer properties vary for various applications?

  2. Polymers & Monomers Polymer– Very large molecules built from chains or networks of smaller molecules (usually 1,000 to 50,000 smaller molecules). Monomer– The smaller molecules making up the polymer.

  3. Polymer Structures • Polymers can be made of: • Repeating patterns of monomers • One monomer over and over again • Random combinations of polymers • Structure of polymer determines the properties of the polymer • Functional groups can affect properties • Sequence and type of monomers can affect properties

  4. Thermoplastic & Thermoset Thermoplastic polymer– can be heated and molded into another shape and then cooled. This can be done over and over again. Thermoset polymer– Cannot be heated and re-molded.

  5. Why can’t thermoset plastics be re-molded? • When thermoset polymers are shaped for the first time, cross-linkages are formed. • Cross-linkages are connections between various polymer strands that hold the polymers in place next to each other • Heating does not break these cross-linkages • So even when heated you can’t break these chains apart and reshape them.

  6. Polymer Properties • Strength of intermolecular forces between polymer chains depends on functional groups and side-branching of polymers • More intermolecular forces between polymer chains = • Higher melting & boiling points • More rigid polymers • More side-branching = • Chains less able to pack closely and form IMF’s • Lower melting & boiling points • Less rigid polymers

  7. Polymer Properties • Cross-linkages are chemical bonds (as opposed to the physical attractions of intermolecular forces) • Once formed, a chemical reaction must occur to break them (remember thermoset plastics!) • Cross-linkages can change a liquid polymer into a solid or gel-like polymer • The properties of the polymer determine the recycling needs of the polymer • Triangles on the bottom of plastics with numbers in them indicate how the plastic is to be recycled

  8. Polymers in Biology • Polymers are found everywhere in nature: • Proteins • DNA • RNA • The monomers that form these polymers are called amino acids • There are 20 different amino acids, that in different combinations make up the different polymers in our body.

More Related