Thermosets
Thermosets, thermosetting plastic or thermosetting resins cure to a solid state when they reach a certain temperature (as opposed to melting like many materials), that is, their parts and properties become set. They create an infusible, insoluble network via a chemical reaction in which the whole entire heated finished object becomes in effect a single large molecule. These materials cannot be melted back down they just burn or char, so cannot be reshaped or restored to their original properties.
These thermosets have covalent intermolecular cross-links, and consist of major resin classes such as isocyanate, unsaturated polyester, formaldehyde, epoxies, and alkyds, and because of the cross-links they are extremely strong, whilst often also being lightweight. It is the strength in the cross-links that also make these products difficult to recycle.
Whilst thermoplastics have the characteristic of being able to be moulded, remoulded or recycled repeatedly, thermosets don't - although some plastics such as PVC (Polyvinyl Chloride) and PE (Polyethylene) can be processed as thermoplastics or as thermosets.
Other well known thermoset materials include:
- Polyester
- Silicone
- Melamine
- Epoxy
- Urea formaldehyde
The main advantages of thermosets are that they are very hard and rigid, very stable and resistant to high temperatures. These types of plastics can also be reinforced for extra tensile strength with materials such as Kevlar, carbon, and fibreglass. Of the total global production of plastic, thermosets account for around 11%, whilst 75% are thermosplastics that can be recycled, although it is estimated that only about 5-9% of global plastic is recycled.
Whilst most commercial plastic, both thermoset and thermoplastic, is made from fossil-based resources, both types of plastic can also be made from renewable sources, often referred to as bio-plastics. Monomers are extracted or synthesised from biomass compounds (such as sugar) and then polymerised to make bioplastics in a similar way to standard plastics.
[edit] Related articles on Designing Buildings
- Biogenic.
- Biobased materials.
- Glass reinforced plastic GRP.
- Glass fibre reinforced plastic.
- Polycarbonate plastic.
- Plastic cladding.
- Plastic coating market.
- Plastic in construction.
- Plastic in concrete.
- Recycled plastic bridges.
- Types of biobased materials.
- Thermoplastic.
- Wood plastic composites market for construction.
Featured articles and news
C20 Society; Buildings at Risk List 2025
10 more buildings published with updates on the past decade of buildings featured.
Boiler Upgrade Scheme and certifications consultation
Summary of government consultation, closing 11 June 2025.
Deputy editor of AT, Tim Fraser, discusses the newly formed society with its current chair, Chris Halligan MCIAT.
Barratt Lo-E passivhaus standard homes planned enmasse
With an initial 728 Lo-E homes across two sites and many more planned for the future.
Government urged to uphold Warm Homes commitment
ECA and industry bodies write to Government concerning its 13.2 billion Warm Homes manifesto commitment.
From project managers to rising stars, sustainability pioneers and more.
Places of Worship in Britain and Ireland, 1929-1990. Book review.
The emancipation of women in art.
Call for independent National Grenfell oversight mechanism
MHCLG share findings of Building Safety Inquiry in letter to Secretary of State and Minister for Building Safety.
The Architectural Technology Awards
AT Awards now open for this the sixth decade of CIAT.
50th Golden anniversary ECA Edmundson awards
Deadline for submissions Friday 30 May 2025.
The benefits of precast, off-site foundation systems
Top ten benefits of this notable innovation.
Encouraging individuals to take action saving water at home, work, and in their communities.
Takes a community to support mental health and wellbeing
The why of becoming a Mental Health Instructor explained.
Mental health awareness week 13-18 May
The theme is communities, they can provide a sense of belonging, safety, support in hard times, and a sense purpose.
Mental health support on the rise but workers still struggling
CIOB Understanding Mental Health in the Built Environment 2025 shows.
Design and construction material libraries
Material, sample, product or detail libraries a key component of any architectural design practice.
Comments
[edit] To make a comment about this article, or to suggest changes, click 'Add a comment' above. Separate your comments from any existing comments by inserting a horizontal line.