Reactive Group Datasheet

Polymerizable Compounds

Due to the very general nature of this classification, flammability properties vary widely. The low MW materials (example vinyl chloride) are extremely flammable gases. and others that are liquid at room temperature can have flash points that are below or above room temperature.
These materials (commonly called monomers) are those compounds which have the capability of thermally induced or chemically initiated radical type polymerization reactions which can generate significant amounts of heat (up to -100 kJ/mol). This can result in large adiabatic temperature rises, which also can trigger gassy decomposition reactions for some species (acrylates and acrylics in particular). These are mainly the vinyl monomers common to the chemical industry such as styrene and its derivatives (including divinyl benzene), acrylamide and its derivatives, butadiene, acrylonitrile, vinyl acetate, and others. Also included here are the acrylates and acrylic acid derivatives but note that these materials are also captured in this tool in a separate and distinct category due to their unique hazards and their high volume of use in the industry. Other high volume materials in this category are ethylene oxide (oxirane) and propylene oxide which require acid or base catalysts to initiate polymerization.

These materials are typically inhibited with low levels (ppm range) of antioxidants to prevent premature polymerization chain reactions and these inhibitors may require dissolved oxygen to be effective. The inhibitors can be depleted with time and are depleted faster at higher storage temperatures. These materials are known to be susceptible to destabilization due to contaminants, even at low levels of contamination. Although there are obvious contaminants that are known to possibly be immediately initiatory to the monomer (radical generating species such as peroxides, azides, etc.), other effects on stability from even seemingly benign materials are harder to predict. Therefore extreme caution should be used in any contamination event and the material should be presumed to be destabilized until testing and consultation with experts occurs and determines otherwise. If the inhibitor and inhibition mechanism are compromised via some interaction with the contaminant, the monomer may polymerize and if contained in a storage container at relatively large volume, the system may become adiabatic and lead to a serious runaway reaction with high temperatures and pressures. The general hazards of monomers are discussed in Frurip et al., Process Safety Progress (Vol. 14, No. 2) 1995.
Due to the very general nature of this classification, toxicity properties vary widely from highly toxic acrylonitrile to relatively benign monomers such as styrene. Many of the acrylates possess very low odor thresholds. For example, ethyl acrylate has an odor detection threshold in the ppb range, but at that level the toxicity is very low.
Other Characteristics
These materials are a general and widely used class of chemicals that can react exothermically to form long chains of repeating "monomer" units with potentially high molecular weights. So in general the potential chemistry can be represented as nM -> (M)n where M is the monomer. The polymerization process can be via a radical mechanism, anionic or cationic mechanisms, or condensation reactions. Polymers are ubiquitous in commerce and consumer products and therefore many of the corresponding monomers are produced, shipped and stored at extremely large volumes.
Styrene, acrylic acid, acrylonitrile, vinyl acetate, vinyl chloride, ethyl acrylate, methyl methacrylate. vinylidene dichloride, methacrylic acid, divinyl benzene, ethylene oxide, propylene oxide.