Chemistry Reference
In-Depth Information
4
Rosin-derived Polymers and their Progress
in Controlled Polymerisation
Jifu Wang, Perry A. Wilbon, Kejian Yao, Chunpeng Wang, Fuxiang
Chu, Chuanbing Tang
4.1. Introduction
Synthetic plastics account for the consumption of approximately 7% of fossil fuels
worldwide [1-5]. Energy shortage and environmental concerns prompt opportunities
to seek and develop renewable resources for the manufacture of 'green' plastics [3,
6-11]. In the age of depleting fossil oil reserves, it is obvious that the utilisation of
renewable plant or crop raw material resources for renewable materials, wherever
and whenever possible, is one necessary step towards a sustainable development. It
is obvious that, at this stage, it is challenging to find a low cost and efficient way
to replace fossil fuels. There are two major classes of natural resources. The first
class of natural resources is natural polymers including cellulose, hemicellulose and
lignin [7, 8, 12-14]. These natural polymers have long been exploited without any
modifications. Currently, common approaches involve physical blending and limited
chemical modifications. Due to their complexity and their macromolecular skeletons,
it is virtually impossible to carry out precise macromolecular engineering in order to
increase their range of properties. In contrast, the second class of natural resources is
small molecules such as lactic acids and vegetable oils, which can be derivatised into
monomers for polymerisation [1-3]. Particularly, caprolactone or lactic acid-derived
polymers have achieved enormous success due to their ability to be molecularly
engineered to allow precise and controlled polymerisation. The goal of current
efforts is to develop renewable polymers replacing and resembling existing polymeric
materials derived from petroleum chemicals [7, 8, 12-15]. As one of the major classes
of petroleum chemicals, cycloaliphatic and aromatic compounds provide rigidity and
chemical stability to polymers derived from them. However, such important polymeric
materials are much less utilised in the communities of renewable polymers.
According to its source, rosin is classified into three main types: gum rosin, wood rosin
and tall rosin. Of these, gum rosin is the most common rosin obtained from various
species of pine trees [16-18] and is the major product from pine resin obtained by
