Lignin as a plasticizer in nitrile rubber, it's effect on properties

Plasticizer is an additive that serves to increase the polymer flexibility, elongation or ease of processing, workability, reduction in viscosity, reduction in stiffness and improve certain properties such as low temperature flexibility, glass transition temperature (Tg). There is ban on phthalate plasticizers in many countries, due to health effects. Phthalates are often classified as endocrine disruptors or hormonally-active agents (HAAs) because of their ability to interfere with the endocrine system in the body.¹ But still plasticizers such as dioctyl phthalate (DOP) are used in nitrile rubber compound due to low cost, lack of knowledge of end user. Technical papers suggests.^{2, 3, 4, 5}, there is improvement in flexibility, elongation, workability, viscosity reduction after addition of lignin, experiments are done to see the possibility of replacing completely and partially processing oil by lignin. It is observed that addition of sodium lignosulfonate (here in after called as lignin) in acrylonitrile rubber compound reduces viscosity like plasticizer, reduces curing rate like accelerator and also increasing modulus and hardness like filler. Though for certain properties its not competing conventional plasticizer, it has a potential and can be used like plasticizer, if certain properties are not required in product such as low temperature resistance.