Home Podcasts THMG030 – Polymerization

THMG030 – Polymerization

3323
0
SHARE

In this episode, Mike and Bob discuss polymerization and why it matters to first responders.

Complete Show Notes

3:30 What is Polymerization?

  • Scientific definition: the process of monomer molecules reacting together in a chemical reaction to form polymer chains or three-dimensional networks
  • A monomer is a molecule of low molecular weight that’s capable of reacting with similar molecules that also have a low molecular weight
  • Monomers are precursors for plastics – they want to come together to create polymers via thermodynamics
  • Monomers cannot be shipped or stored unless something has been added to them to prevent an uncontrolled reaction – this is polymerization
  • Inhibitors are materials that prevent reactions by stabilizing the monomer – it doesn’t chemically interact with the material, though
  • Inhibitors work via cold, chemical, or time – they’re frequently utilized in highly-controlled environments like laboratories
  • Department of Transportation regulations prohibit the transportation of most monomers without the addition of an inhibitor
  • Polymers are substances with molecular structures consisting chiefly or entirely of a large number of similar units bonded together (i.e. synthetic organic materials used as plastics and resins)
  • We’re encountering monomers and polymers in an uncontrolled environment, so we need to be ready for the unexpected – it’s key to fully understand that we’re not in control and should plan accordingly

12:30 What Triggers Polymerization?

  • Polymerization occurs due to a bunch of different mechanisms that may or may not be present in a chemical formula
  • Polymerization is an expanding exothermic chemical reaction that’s sometimes slow and sometimes remarkably fast
  • There’s a rough timeframe, but responders don’t have any concrete way of determining if polymerization has taken place
  • The biggest danger of the reaction to humans is the buildup of pressure in the container, but there are many factors involved
  • Even if we can predict what’s going to happen, we still have no idea when and how the tank might fail

14:05 Hazmat Drill Nugget from HazSim

  • Grab a 5-gallon spackle bucket and fill it with 2-5 gallons of water – spill it on the pavement outside the firehouse
  • Have your guys come down and ask them to tell you how much product is there – most times, they’ll overestimate
  • It’s important to know how to visually judge how much of something has spilled – frequently, you’ll be prepared for a much larger spill than you’d need to due to misjudgment

17:10 The Steric Effect and Examples of Polymers

  • When atoms are squished together, they change from being a round shape to something more misshapen – this is the steric effect
  • This changes their energy profile, and ultimately, their reactivity – this means they may be more or less able to polymerize
  • The terms “plastic”, “polymer”, “resin”, “compound”, and “high-polymer macromolecular substance” are often used interchangeably
  • Common examples of polymers include thermosets, thermoplastics, elastomers, epoxies, ABS, butadiene, polyesters, nylons, natural rubber, polyurethane, vinyls, neoprene, silocones, acrylics, and urethane

19:30 Real-World Polymerization Incidents

  • Railroad tank car ruptured at a transfer station at a facility in Freeport, Texas on 9/13/2002
  • Waste the tank was carrying was a combination of cyclohexanone oxime, water, and cyclohexanone
  • 28 people were injured, and residents within one mile of the site had to shelter in place for 5.5 hours
  • Incident in Bhopal, India also partially involved this type of dangerous polymerization reaction

22:30 More Information on Polymerization

  • Emergency Response Guidebook (ERG) – the identification of materials in transportation that may undergo polymerization create a danger for response personnel
  • When looking up a chemical by its four-digit identification number in the yellow section or alphabetically in the blue section, you will be referred to a three-digit guide page in the orange section of the book
  • That three-digit number will have a “P” after it if the material in question has the potential to undergo polymerization
  • National Institute for Occupational Safety and Health (NIOSH) – polymerization can be found in incompatibilities and reactivities

24:20 How Do We Handle Polymerization in the Field?

  • You can identify polymerization by looking for an exothermic or endothermic reaction using anything that can give you a temperature reading
  • Polymerization can’t be stopped – it stops when either the bonds being created/destroyed have run out or when it gets bored of getting bigger
  • Catalysts are the opposite of inhibitors – they’re things that help something begin to react
  • Runaway polymerization
    • Most polymerization reactions or exothermic, which means they give off heat
    • Ideally, the total heat produced is small and dissipates
    • However, if a large amount of monomer is involved (and if the reaction is strongly exothermic), the monomers may combine too quickly
    • This causes excessive heat and pressure to build up in the reaction vessel, which melts the equipment or causes an explosion

29:10 How Do Things Polymerize?

  • Polymerization occurs when monomers combine to become polymers via covalent bonding
  • Their expanded form results in an increase of volume – like going from a 2D structure to a 3D structure
  • Polymers are often referred to as homopolymers, which means they’re a redundant chain of the same type of molecule repeated hundreds (if not thousands) of times
  • You’ll also find copolymers, which contain more than one type of molecule
  • The free radical mechanism can be divided into three stages – chain initiation, chain propagation, and chain termination

31:30 How Are Different Polymers Made?

  • Condensation/step growth method – water molecules are ejected from the equation (i.e. polyurethane)
  • You can also break polymers into monomers by using the method of hydrolysis
  • Chain-growth polymerization/addition polymerization – involves the linking together of molecules that incorporate double or triple carbon-carbon bonds (i.e. polyethylene, polypropylene, and PVC)

Have a question? Send an email to feedback@thehazmatguys.com or leave a message on our Haz Mat Guys comment hotline: 843-628-1484

Show Sponsors
Related Episodes

Author: The HazMat Guys


Warning: A non-numeric value encountered in /home/thehazmatguys/public_html/wp-content/themes/Newsmag/includes/wp_booster/td_block.php on line 997