Lecture 7 6pp - 1 Polymers Rubber band experiment - feeling...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1 Polymers Rubber band experiment - feeling the temperature change when stretching and releasing a rubber band warmer cooler 2 A Typical Polymer - Polyethylene • Typically used in household containers, electrical insulation, chemical containers, tubings, packaging, prosthetic implants etc. • Chemical formula: – CH 2 – CH 2 – CH 2 – CH 2 –…, or (–C 2 H 4 –) n • Polymer = many units • Properties controlled by average molecular weight or average n • n = degree of polymerization 3 Paraffin Boiling Point ( ° C) CH 4 ! 164 C 2 H 6 ! 89 C 3 H 8 ! 42 C 4 H 10 ! 1 C 5 H 12 36 C 6 H 14 69 4 Polymer Structures • Stereoisomers • Linear • Branched • Cross-linked • Networked 5 Stereoisomers • Start with polyethylene (–C 2 H 4 –) n • Replace one of the H atoms with Cl - polyvinyl chloride • Replace one of the H atoms with benzene ring - polystyrene • Location of the replacement species? C C 6 Stereoisomers isotactic syndiotactic atactic 7 Linear Polymers • Linear chains • When the backbone consists of single- bonded carbon atoms, the chain is Fexible, e.g., polyethylene • When the backbone consists of ! bonded carbon atoms, the chain is much more rigid, e.g. Kevlar 8 109.5 ° carbon hydrogen Average length L of polyethylene (–C 2 H 4 –) n given by: L = d 2 n 9 network linear branched cross-linked branches Cross-linking typically with S 10 O O Can We Crosslink with Oxygen? 11 C C CH 2 OH C C C O H H OH H H OH OH OH H C C CH 2 OH O H H OH CH 2 OH C OH C H OH glucose fructose C C CH 2 OH C C C O H H O H H OH OH OH H C C CH 2 OH O H H OH CH 2 OH C C H OH sucrose – H 2 O 12 C C CH 2 OH C C C O H Cl O H H OH OH H H C C CH 2 Cl O H H OH CH 2 Cl C C H OH sucralose 13 Effects of Branching • Interferes with sliding ---> stronger • DifFcult to pack molecules tight --> lower...
View Full Document

This note was uploaded on 11/21/2011 for the course MAT SCI 201 taught by Professor Matsci during the Spring '10 term at Northwestern.

Page1 / 7

Lecture 7 6pp - 1 Polymers Rubber band experiment - feeling...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online