Table of Contents
What is novolac polymer?
Novolaks (sometimes: novolacs) are low molecular weight polymers derived from phenols and formaldehyde. They are related to Bakelite, which is more highly crosslinked.
What is novolac resin?
Novolac resins are amorphous (not crystalline) thermoplastics. As they are most typically used, they are solid at room temperature and will soften and flow between 150° and 220°F (65°C – 105°C). The number average molecular weight (Mn) of a standard phenol novolac resin is between 250 and 900.
Is novolac a phenol?
Novolacs, or two-stage phenolics, are produced by the reaction of phenol with formaldehyde in a strongly acidic environment. The reaction mixture is usually deficient in formaldehyde, with 0.75–0.85 moles of formaldehyde for each mole of phenol.
How novolac is formed?
The monomers used in the preparation of novolac polymer are phenol and formaldehyde. They undergo polymerisation in presence of alkali or acid as catalyst. Phenol reacts with formaldehyde to form ortho or p-hydroxy methyl phenols, which on further reaction with phenol form a linear polymer called Novolac.
How is novolac produced?
Novolac is one of the phenolic resins made under acidic conditions using excess phenol, the acid catalyzes the reaction of phenol and formaldehyde to form the cross-linkable polymeric resin. It is widely used for the formation of molded pieces and articles [1].
How is novolac formed?
The phenol reacts with formaldehyde at the ortho and para positions and leads to the formation of hydroxymethyl phenol. The hydroxymethyl group is capable of reacting with either another free ortho or para group or with another hydroxymethyl group. Now, this leads to the formation of a linear polymer called novolac.
What is novalac coating?
Five Star® Epoxy Novolac Coating is a two-component, 100% solids, highly chemical resistant epoxy coating for horizontal and vertical applications effective on both steel and concrete.
Is bakelite a novolac?
Bakelite is obtained when Novolac is allowed to undergo cross-linking in the presence of a cross-linking agent. In general, phenol taken in excess acts as the cross-linking agent. The preparation of bakelite involves several steps, as illustrated below.
What is difference between novolac and bakelite?
A linear product of Phenol formaldehyde polymer is Novolac used in paints. Novolac on heating with formaldehyde undergoes cross linking to form an infusible solid mass called bakelite. It is used for making combs phonograph records electrical switches and handles of various utensils.
What are the uses of novolac?
Novolacs have multiple uses as tire tackifier, high temperature resin, binder for carbon bonded refractories, carbon brakes, photoresists and as a curing agent for epoxy resins.
What is the use of novolac?
What Does Novolacs Mean? These are resins produced by the complete poly-condensation of phenol and aldehydes for industrial uses as a replacement of natural resin such as shellac. They are available in solid and liquid form and is used in binders, articles, paints, molded pieces, laminated plastics and adhesives.
Is novolac a polyester?
Answer is (1) Novolac Novalac is a linear polymer of [Ph–OH + HCHO]. So ester linkage not present. So novalac is not a polyester.
Which can convert Novolac to Bakelite?
Novolac on heating with formaldehyde undergoes cross-linking to form an infusible solid mass called bakelite.
How Bakelite is formed from Novolac?
Bakelite is obtained when Novolac is allowed to undergo cross-linking in the presence of a cross-linking agent. In general, phenol taken in excess acts as the cross-linking agent.
Is Bakelite a polyester?
Thermoplastic polymers are the ones which become soft when heated and hard when cooled. Polyesters are a common example. Thermosetting polymers is a polymer that becomes hard on heating. Bakelite is an example to these types of polymers.