Recent Developments in Synthesis, Properties, Applications and Recycling of Bio-Based Elastomers

Abstract

In 2021, global plastics production was 390.7 Mt; in 2022, it was 400.3 Mt, showing an increase of 2.4%, and this rising tendency will increase yearly. Of this data, less than 2% correspond to bio-based plastics. Currently, polymers, including elastomers, are non-recyclable and come from non-renewable sources. Additionally, most elastomers are thermosets, making them complex to recycle and reuse. It takes hundreds to thousands of years to decompose or biodegrade, contributing to plastic waste accumulation, nano and microplastic formation, and environmental pollution. Due to this, the synthesis of elastomers from natural and renewable resources has attracted the attention of researchers and industries. In this review paper, new methods and strategies are proposed for the preparation of bio-based elastomers. The main goals are the advances and improvements in the synthesis, properties, and applications of bio-based elastomers from natural and industrial rubbers, polyurethanes, polyesters, and polyethers, and an approach to their circular economy and sustainability. Olefin metathesis is proposed as a novel and sustainable method for the synthesis of bio-based elastomers, which allows for the depolymerization or degradation of rubbers with the use of essential oils, terpenes, fatty acids, and fatty alcohols from natural resources such as chain transfer agents (CTA) or donors of the terminal groups in the main chain, which allow for control of the molecular weights and functional groups, obtaining new compounds, oligomers, and bio-based elastomers with an added value for the application of new polymers and materials. This tendency contributes to the development of bio-based elastomers that can reduce carbon emissions, avoid cross-contamination from fossil fuels, and obtain a greener material with biodegradable and/or compostable behavior.

Graphene-Based Hybrid Fillers for Rubber Composites

“…Rubber is an elastomer material that can sustain large reversible deformations and can be used in different products, such as tires, gloves, shoe soles, seals, insulators, and dampers [ 1 , 2 , 3 , 4 ]. The different types of rubber include natural rubber (NR), styrene–butadiene rubber (SBR), nitrile rubber (NBR), butyl rubber (BR), isobutylene isoprene rubber (IIR), ethylene-propylene-diene monomer (EPDM) rubber, and polydimethylsiloxane (PDMS)/silicone rubber (SR) [ 5 , 6 ]. They can be applied in transportation, construction, machinery, electronics, and energy sectors.…”

“…(4) Graphene and its derivatives have a high specific area, which can lead to more interfacial contacts, larger effects on molecular chains, and an enhanced strain-induced crystallization ability in comparison with other common rubber fillers. (5) In the case of GO, certain polar groups exist, such as epoxide, hydroxyl, and carboxyl. These groups render the modification of graphene easy, based on functionality molecules that can enhance the interaction between the filler and rubber matrix [2,8,21,22].…”

Chemical degradation of oxygenated polymers: the case of polyethers and polysiloxanes

“…As of 2022, of the 400 million Mt per year of plastics produced globally, 8 more than 75% consists of those with a C–C backbone, namely polyolefins, including HDPE, LDPE, LLDPE, PP, PS and PVC. The second most important type of polymer is polyethers with 10.2% of the total.…”

Synthesis and Characterization of Graft Copolymers with Poly(ε-caprolactone) Side Chain Using Hydroxylated Poly(β-myrcene-co-α-methyl styrene)

“…In recent years, with the growing emphasis on environmental protection, polymer chemistry is moving towards sustainability, which includes the development of environmentally friendly production processes and the use of renewable feedstocks instead of fossil fuel sources [28][29][30][31]. Various research teams are already working on preparing novel raw materials from renewable sources and using them to produce new materials [32].…”