What is the initiator efficiency in chain initiation step of free radical polymerization?
What is the initiator efficiency in chain initiation step of free radical polymerization? Explanation: the initiator efficiency is the fraction of free radicals actually contributing in chain initiation and is less than unity. 3.
What is initiator efficiency?
Initiator efficiency f is defined as the fraction of primary (initiator-derived) free-radical species that add to monomer molecules. The reported data refer to ideal CSTR mixing conditions.
Which initiator is used in free radical polymerization?
Benzoyl peroxide is the initiator used in free radical addition polymerization.
Which of the following factors does initiator efficiency depend on?
2. Which of the following factors does initiator efficiency depend on? Explanation: The initiator efficiency not only depends on initiator molecules but is also affected by condition of polymerization and the solvent used.
What is free radical initiator?
In chemistry, radical initiators are substances that can produce radical species under mild conditions and promote radical reactions. These substances generally possess weak bonds—bonds that have small bond dissociation energies. Radical initiators are utilized in industrial processes such as polymer synthesis.
How does an initiator function in free radical polymerization?
To initiator: a polymer chain reacts with an initiator, which terminates that polymer chain, but creates a new radical initiator (Figure 21). This initiator can then begin new polymer chains. Therefore, contrary to the other forms of chain transfer, chain transfer to the initiator does allow for further propagation.
What is initiator in polymerization?
initiator, a source of any chemical species that reacts with a monomer (single molecule that can form chemical bonds) to form an intermediate compound capable of linking successively with a large number of other monomers into a polymeric compound.
Which catalyst is used for free radical polymerization?
Radical Chain-Growth Polymerization When radical polymerization is desired, it must be started by using a radical initiator, such as a peroxide or certain azo compounds. The formulas of some common initiators, and equations showing the formation of radical species from these initiators are presented below.
What is the order of free radical polymerization?
There are three general stages of free radical polymerization: 1) initiation, 2) propagation, 3) termination. Let’s consider these stages in the order which they occur.
How do you choose a polymerization initiator?
How does one choose the appropriate initiator? In a free radical addition polymerization, the choice of polymerization initiator depends mainly on two factors: a) its solubility and b) its decomposition temperature.
What is the rate determining step in free radical polymerization?
Formation ofinitiating radicals
Formation ofinitiating radicals is the rate-determining step in the initiation reaction. The process can result, as shown in Table 2.1, from cleavage of compounds, like peroxides, or from other sources. Many reactions lead to formations of free radicals.