INGENIEUR
Figure 3: Percentage Waste Materials Recycled under SAS Programme in 2018 (Total waste materials
recycled: 2,012.52 tonnes), Solid Waste Management Malaysia Compendium 2019, SWCorp
KEY CHALLENGES IN PLASTICS WASTE
RECYCLING
In general, plastics are a material which can be
easily melted and remoulded into a new product.
However, given the context of the scenario in
Malaysia and characteristics of plastic products
available today, recycling of plastics remains a
challenging task considering several issues as
follows:
1) Cross-linked molecular structure of thermoset
plastics
As a monolithic material, recycling of plastics
particularly the thermoplastic seems very
straightforward. Theoretically, thermoplastics can
be melted and remoulded [9]. However, usage
of plastics’ inactive applications usually involves
thermoset resins such as epoxy and unsaturated
polyester. For instance, an aeroplane structural
composite is mainly made of carbon fibre
reinforced epoxy. Recycling of cured thermoplastic
waste is far more complicated. Thermoset resin
has a three-dimensional cross-linked molecular
structure, which prevents the cured plastic to be
melted and remoulded [10]. Thermoset-based
composite product requires attentive process such
as pyrolysis or chemical recycling to decompose
the resin and recover the fibre or reinforcement.
2) Material complexity of the plastic products
Plastic products usually consist of several
materials. The plastic component of a product
may be bonded to a metal part or composite
sandwich structure. For instance, food
packaging usually contains aluminium coated
plastic laminates. Separation of plastics from
these foreign materials is an arduous and timeconsuming
process [11]. Such a complex product
has different individual material properties that
affect the colour, shape, structure and melting
point. The products require sorting technology.
The mixture between plastics would be more
complicated as a chemical approach may be
required to separate the individual components.
The involvement of additional process for the
separation needs to be assessed from a life cycle
perspective. The requirement of such processes
would increase energy consumption [12].
Besides, the cost of separation could be high.
Some processes may have by-products which
could further adversely impact the environment.
The disassembly or separating of co-materials
is not economically viable for business entities.
50 VOL 82 APRIL-JUNE 2020