Class Notes (808,646)
Canada (493,319)
Chemistry (260)
CHEM 211 (40)

Lab 10 - Polymerization

3 Pages
Unlock Document

Queen's University
CHEM 211
Philip G Jessop

Discussion: Sodium acetate plays a crucial role in the stability of the glyptal chain that is formed. Its role is twofold: Firstly sodium acetate improves the ability of the cured elastomer to retain its physical properties at elevated temperature (Behrens, 1971). And secondly, it drastically slows down the rate of vulcanization of the glyptal forming chains (see Figure 1). This allows the resin to remain a liquid as it is poured into the mold. Sodium acetate then quickly decomposes and the glyptal chains increase in size resulting in a harder product over time. Figure 1:Chemical pathway showing the polymerization of phthalic anhydride and glycerol forming glyptal chains H 2(CH ) NH2 6ClCO(2H ) COCl  -[-NH2 8 ) NHCO(CH ) CO-]- + 2HCl 2 6 2 8 Figure 2: Balanced chemical formula for the syntpolyhexamethylenecebacamide The NaOH used in the lab is an addition to the regular synthesis (see Figure 2) that helps control the pH. The regular pathway expells HCl and by adding basic NaOH, which reacts with HCl to form H O 2 and NaCl, the pH can be controled through the neutralization of HCl. The polyamide formed in this reaction (see Figure 3) is joined as a chain at the end of the molecule, unlike the glytpal polymer. This end-to-end connection makes the molecule a linear macromolecule. On top of this, it is bonded with only single bonds as well as the interactions with other monomers lack hydrogen bonds. These two factors result in the material being soft and pliable, able to easily twist and turn within itself. Figure 3: Structural representation of the synthesis of 1,6-diaminohexane and sebacoyl dichloride to form polyhexamethylenecebacamide When boric acid is added to dichlorodimethylsilane at a high temperature, the dichlorodimethylsilane crosslinks within the boric acid to produce a hard, but malleable, bouncing material (see Figure 4). If the boric acid concentration was higher,
More Less

Related notes for CHEM 211

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.