Polymer scientia

Chemistry of Novolak resin: The word Novolak is derived from two words Novo + lack. Latin word "Novo" refers to novel or new and Swedish word "lack" refers to lacquer. The name Novolak was termed since it had replaced the natural lacquers like shellac and copal resin. Novolak resins are formed by reaction of excess moles of phenol to moles of formaldehyde in the presence of acid catalysts. Generally, the mole ratio (formaldehyde: phenol) of Novolak resins range from 0.5 to 1.0 depends on the demand from the application. Novolaks are stable at room temperature and therefore shelf life of the resin is longer and generally it's six months. But, it can last long if its stored in controlled conditions. In chemistry point of view, in the first step, addition of formaldehyde forms a methylol group in either ortho-para positions of phenol. Under normal conditions, o-p isomer has more possibility compared to p-p' and o-o' bridges. As a next step, methylol group f...

What are Friction materials?  Friction Material is composite material used in brake applications such as brake linings, brake pads and clutch facings used in the automotive vehicles, brake blocks and disc pads used in railways and Sintered brake pads used in aerospace.  The material is called as friction materials because it is exposed to very high frictional forces. Though it's called as friction material by name, it also exposed to wear and lubrication in addition to friction. Please refer the disc brake system assembly and disc pads in the below images                                       Disc pads                                                  Brake linings Image references:  6 Wa...

 At present, there  are many kinds of plastics used for myriad number of applications starting from FMCG to aerospace industries which has a significant impact on our daily lives. Generally, Plastics are classified into two major types according to their thermal behaviour. Thermoplastics : Plastics materials which can melt upon heating and forms the required shape. If the material is heated , it can melt and form into different shapes again. Thermosetting plastics : Plastics materials which can melt upon heating and forms the required shape. If the material is heated again, it cannot melt again since the material is crosslinked / cured. The topic of interest for us is thermosetting plastics and there are various types of thermosetting plastics used commercially because of its unique properties. Phenol Formaldehyde Resins (PFR) is the oldest plastic with the history of more than a century. After World War II, many kinds of plastics were developed and commercialized succe...