ABSTRACT
In multi-zone tubular reactors, the reaction mixture is cooled slightly, more peroxide is added and the polymerization is reinitiated. Low-density polyethylene (LDPE) was first produced in the laboratories of ICI; due to its versatility, it is the largest tonnage polymer in the world. Linear LDPE (LLDPE) offers a cost performance advantage over LDPE which it is replacing in many of its traditional outlets. Increasing use is being made of LDPE grades containing either higher olefin comonomers such as hexene and octene or polar comonomers which extend the range of properties. Film is the largest application for LDPE, consuming 60–70% of total demand. Foil is also coated with LDPE in multilayer structures as it can be heat sealed. LLDPE is replacing LDPE in many of its traditional film outlets, but the increasing number of applications – such as extrusion coating, laminating and speciality grades – has ensured its continued growth.
