Limitations and Future Development of Epoxy Resins: Safety, Environmental Protection, Recycling, Bio-Based Materials, and High-Performance Trends

1. The Core Contradiction in the Development of Epoxy Resins

Epoxy resins have good adhesion, chemical resistance, mechanical properties, electrical insulation performance, and formulation design flexibility. Therefore, they are widely used in adhesives, coatings, composite materials, electronic encapsulation, and electrical insulation materials. However, epoxy resins are not without limitations. Their advantages and problems often originate from the same source: the stable crosslinked network formed after curing.

The crosslinked network provides strength, heat resistance, and dimensional stability, but it also brings brittleness, difficulty in recycling, difficulty in repair, and lifecycle pressure. Uncured systems are reactive, which also means that skin contact, inhalation, irritation, and sensitization risks may exist during application and processing.

The future development of epoxy resins is not simply about pursuing materials that are “harder, stronger, and more heat-resistant.” Instead, it needs to address the following issues at the same time:

Development Dimension	Current Challenge	Future Direction
Safety	Uncured resins, curing agents, and diluents may cause irritation or sensitization	Lower-hazard raw materials, low-exposure application, improved protection, and alternative systems
Environmental protection	VOCs, residual monomers, waste, and lifecycle pressure	Low VOC, waterborne, solvent-free, low-residue systems, and lifecycle assessment
Recycling	Thermoset networks are difficult to melt and reprocess	Chemical recycling, dynamic covalent networks, and reprocessable epoxy systems
Raw materials	Traditional epoxy systems are highly dependent on petrochemical resources	Bio-based monomers, renewable carbon sources, and low-carbon manufacturing
Performance	High crosslinking leads to brittleness, and thermal conductivity and insulation are difficult to balance	High toughness, high thermal conductivity, low stress, and multifunctional synergy
Applications	A single performance attribute is difficult to meet the needs of high-end applications	High-performance development for high-reliability electronics, new energy, aerospace, wind power, heavy-duty anticorrosion, and other fields

2. Safety Risks: Uncured Systems Are the Main Risk Focus

2.1 Safety Risks Mainly Arise During Application and Processing

The safety of epoxy resins should be assessed by distinguishing between different material states:

1. Uncured resin

It contains reactive epoxy components and may cause skin irritation or sensitization.

2. Curing agents

Amine- and anhydride-based curing agents may irritate the eyes, skin, and respiratory tract. Some systems may also cause sensitization.

3. Reactive diluents and solvents

These may increase the risks of skin contact, volatile inhalation, and occupational exposure.

4. Mixing and application stage

Exposure opportunities increase during coating, encapsulation, spraying, troweling, casting, and cleaning.

5. Grinding, cutting, and repair stage

Dust, incompletely cured components, and thermal decomposition products may introduce new exposure risks.

6. Fully cured materials

They are usually more stable than uncured systems, but still need to be evaluated according to their intended use in special scenarios such as grinding, heating, combustion, cutting, or food contact.

OSHwiki notes that the main health risks of epoxy products are closely related to skin contact. Key components such as epoxy resins, polyamine or anhydride curing agents, and reactive diluents may all be irritants and occupational sensitizers. The OSHA Technical Manual also classifies curing agents such as aliphatic amines, cycloaliphatic amines, polyamides, and anhydrides as categories that may cause eye, skin, or respiratory irritation and sensitization risks.

2.2 Main Exposure Risks of Epoxy Systems

Risk Source	Main Risks	Key Control Measures
Uncured epoxy resin	Skin irritation, contact dermatitis, sensitization	Avoid skin contact; use suitable gloves and protective clothing
Amine curing agents	Aliphatic/cycloaliphatic amine curing agents: relatively strong eye, skin, and respiratory irritation; some may cause sensitization. Polyamide/polyamidoamine systems are usually less irritating, but may still cause sensitization.	Ventilation, safety goggles, protective gloves, and avoidance of splashing
Anhydride curing agents	Eye and respiratory irritation, respiratory sensitization	Control dust and vapor; avoid high-temperature exposure
Reactive diluents	Skin penetration and sensitization risks	Reduce direct contact; control volatilization and splashing
Solvent-based systems	Inhalation, flammability, skin defatting	Ventilation, fire prevention, explosion protection, and low-VOC alternatives
Spray application	Inhalation of mist droplets and aerosols	Respiratory protection, local exhaust ventilation, and enclosed application
Grinding dust	Dust inhalation and skin irritation	Dust removal, wet grinding, or respiratory protection
High-temperature processing	Volatiles and decomposition products	Control temperature; avoid overheating and unidentified smoke

2.3 Directions for Safety-Oriented Design

Improving the safety of epoxy resins should not rely solely on personal protective equipment. It should be controlled jointly through materials, processes, and on-site management. Risk control should be shifted forward from “protection after problems occur” to the stages of “material design, application method, and exposure management.”

Improvement Direction	Specific Measures	Value
Reduce hazard sources	Select systems with lower irritation, lower volatility, and lower residue	Reduce risks at the source
Reduce exposure	Closed mixing, automatic metering, local exhaust ventilation	Reduce skin and inhalation exposure
Improve application methods	Use less spraying and more brushing, or adopt enclosed encapsulation	Reduce aerosol exposure
Optimize packaging	Two-component pre-measured packaging and static mixing tubes	Reduce manual batching and splashing
Improve PPE	Select appropriate glove materials according to SDS and glove permeation/breakthrough time; use safety goggles, protective clothing, and respiratory protection	Reduce direct contact
Strengthen SDS management	Control storage, use, and disposal according to the product safety data sheet	Establish traceable safety management
Train sensitive individuals	Identify dermatitis, allergic reactions, and respiratory symptoms	Avoid repeated exposure after sensitization

3. Environmental Pressure: Low VOC, Low Residue, and Lifecycle Requirements

3.1 VOCs Are an Important Environmental Issue in Coating and Application Systems

VOCs, or volatile organic compounds, are an important environmental concern in coatings, solvents, industrial coating processes, and cleaning operations. The U.S. EPA states that VOCs can react with nitrogen oxides under sunlight to form ground-level ozone. Industrial coating, printing, paints, and household chemical products are among the sources of VOCs.

In the coatings field, low VOC is an important development direction for epoxy resin systems. One of the objectives of the EU Coatings Directive 2004/42/EC is to limit the total VOC content caused by the use of organic solvents in certain paints, varnishes, and vehicle refinishing products.

3.2 Main Routes for Low-VOC Epoxy Systems

Route	Basic Idea	Advantages	Challenges
Waterborne epoxy	Use water as the dispersion medium to reduce organic solvents	Lower VOC, reduced odor and flammability risks	Water resistance, drying conditions, film formation, and storage stability need optimization
High-solids epoxy	Reduce the solvent ratio and increase the film-forming material content	Maintain good coating-film performance while reducing solvent emissions	More difficult viscosity control
Solvent-free epoxy	Use no or very little volatile solvent	Very low VOC; suitable for flooring, encapsulation, and thick-film coating	Exotherm, flowability, and application window need to be controlled
Powder epoxy	Solid powder is heated, melted, and cured into a film	Almost no solvent emission and high utilization efficiency	Requires heating equipment; has requirements for substrates and processing
Reactive diluent systems	Use diluents that can participate in the curing reaction to reduce viscosity	Reduce the use of volatile solvents	May affect Tg, shrinkage, chemical resistance, and safety
UV/light-curable epoxy	Use photoinitiation for rapid curing	Fast curing and strong low-VOC potential	Curing in thick layers, shadowed areas, and complex shapes is limited

3.3 Control of Low Residues and Restricted Substances

The environmental and compliance requirements for epoxy systems have shifted from “whether they can be used” to “raw material sources, residues, migration risks, and long-term impacts.” Key concerns include:

1. Residual epichlorohydrin, or ECH

ECH is one of the important raw materials used in the production of traditional epoxy resins. Residual ECH control is an important quality and compliance indicator for liquid epoxy resins and reactive diluents. The 2024 voluntary guideline from Epoxy Europe/Cefic proposes that unreacted ECH should not exceed 5 ppm in unmodified liquid bisphenol A/bisphenol F epoxy resins, 20 ppm in reactive diluents, and 10 ppm in related mixtures.

2. Restrictions related to bisphenol A, or BPA

BPA is an important upstream raw material for bisphenol A-type epoxy resins. Commission Regulation (EU) 2024/3190, later technically corrected by EU 2026/250, prohibits or restricts the use of BPA and other bisphenols/bisphenol derivatives with specific hazard classifications in food contact materials, with limited exceptions. This will drive food-contact coatings, can coatings, adhesives, and related materials toward BPA alternatives.

3. Compliance of solvents and additives

Solvents, diluents, flame retardants, plasticizers, catalysts, pigments, and fillers used in coatings, flooring, anticorrosion systems, and electronic materials must comply with applicable regional regulations and target restricted substance lists.

4. Ionic impurities and extractables

Electronic encapsulation, electrical insulation, medical, food-contact, and high-reliability applications need to pay attention to hydrolyzable chlorine, metal ions, low-molecular-weight migration, and extractables.

4. Recycling Challenges: How Can Thermosets Move Toward Circularity?

4.1 Why Traditional Epoxy Resins Are Difficult to Recycle

Traditional epoxy resins form permanent crosslinked networks after curing. This network gives the material good heat resistance, chemical resistance, and dimensional stability, but it also leads to the following problems:

1. They cannot be heated, melted, and reprocessed like thermoplastics.

2. After crushing, they are usually only used as low-value fillers.

3. In composite materials, it is difficult to efficiently separate resin and fibers.

4. Adhesives and coatings bond tightly to substrates, making disassembly difficult.

5. Chemical recycling requires selective bond cleavage, and the process is complex.

Related reviews indicate that the recycling of waste epoxy resins is limited by their stable and rigid crosslinked structures. Current research directions include chemical recycling at the waste end and the design of reversible or dynamic networks at the source.

4.2 Main Recycling Routes for Epoxy Resins

Recycling Route	Basic Method	Advantages	Limitations
Mechanical recycling	Crushing and grinding, followed by reuse as fillers	Simple process and relatively low cost	Mostly downcycling, with reduced performance
Thermal recycling	Thermal cracking or heat treatment to decompose the resin	Can recover some fibers or energy	High energy consumption; may damage fibers or generate by-products
Chemical recycling	Use solvents, acids, bases, catalysts, etc. to selectively cleave bonds	May recover fibers, oligomers, or functional products	High requirements for resin structure, sorting, and process conditions
Solvolysis/alcoholysis	Cleave the network under solvent and catalytic conditions	Suitable for recycling research on certain composite materials	Solvent safety, cost, and scale-up issues are prominent
Reversible network design	Introduce dynamic covalent bonds into the cured network	Repairable, reprocessable, and chemically recyclable	Performance, cost, and industrial stability need to be balanced
Debondable adhesives	Trigger debonding through heat, electricity, light, or chemicals	Beneficial for repair and disassembly	Needs to match actual assembly processes

4.3 Dynamic Covalent Networks and Epoxy Vitrimers

A vitrimer, also known as a vitrimer-like polymer, usually refers to a crosslinked polymer network with an associative dynamic covalent exchange mechanism. Under normal use conditions, it exhibits a stable structure similar to that of a thermoset material. Under heating, catalysis, or specific triggering conditions, however, dynamic covalent bonds in the network can undergo exchange, giving the material the potential for reprocessing, repair, welding, or recycling.

The significance of epoxy vitrimers lies in the following aspects:

1. They retain the dimensional stability and mechanical properties of thermoset materials.

2. They enable hot-press reshaping or welding through dynamic bond exchange.

3. They enable network degradation or recycling through chemical triggers.

4. They provide debonding possibilities for composite materials and structural adhesives.

5. They reduce the limitation of thermoset materials being “cured once and permanently non-processable.”

4.4 Engineering Challenges Still Facing Recyclable Epoxy Resins

Challenge	Specific Manifestation
Performance retention	Dynamic bonds may reduce Tg, modulus, heat resistance, or chemical resistance
Cycle stability	Whether performance deteriorates after multiple reprocessing cycles still needs to be verified
Industrial cost	New monomers, catalysts, and processes are relatively costly
Recycling conditions	Temperature, pressure, solvent, and time need to be suitable for scale-up
Complex waste streams	Actual waste contains fibers, fillers, coatings, metals, and contaminants
Lack of standards	Evaluation of recyclability, recycling rate, and reuse performance still needs standardization
Application certification	Aerospace, electronics, wind power, and other fields require long-term reliability data

A 2024 study in Nature Sustainability demonstrated an epoxy thermoset material with both high toughness and reprocessability. By using boronate ester dynamic bonds and nanoscale phase separation, the material improved the brittleness and non-recyclability problems of traditional epoxy resins at the same time. Such research shows that the direction is feasible, but long-term validation of processing, cost, and reliability is still required before moving from laboratory materials to large-scale industrial applications.

5. Bio-Based Epoxy Resins: From Renewable Raw Materials to a Balance Between Performance and Sustainability

5.1 The Significance of Bio-Based Epoxy Resins

Traditional epoxy resins rely heavily on petrochemical raw materials. The goal of bio-based epoxy resins is to partially or fully replace petrochemical raw materials with renewable carbon sources, reduce dependence on fossil resources, and provide possibilities for low-carbon material systems. Common bio-based sources include:

1. Plant oils

Examples include epoxidized soybean oil, linseed oil, and castor oil.

2. Lignin and its derivatives

Examples include vanillin, guaiacol, and eugenol.

3. Cardanol

Derived from cashew nut shell liquid, it can be used for flexible, hydrophobic, or corrosion-resistant applications.

4. Rosin and its derivatives

These contain rigid ring structures, which are beneficial for heat resistance and mechanical property design.

5. Furan compounds

Derived from renewable biomass such as glucose, fructose, cellulose, or hemicellulose, furan compounds can be chemically converted and used to build rigid structures and dynamic networks.

6. Renewable platform chemicals such as isosorbide, lactic acid, citric acid, and itaconic acid

These can be used to synthesize epoxy monomers or curing agents with different functionalities and different rigid-flexible characteristics, thereby regulating the crosslinked structure, heat resistance, toughness, and sustainability attributes of epoxy materials.

5.2 Main Routes for Bio-Based Epoxy Resins

Route	Basic Idea	Suitable Directions
Bio-based epoxy monomers	Convert plant oils, vanillin, rosin, furans, etc. into epoxy compounds	Adhesives, coatings, composite materials, and electronic materials
Bio-based curing agents	Use bio-based anhydrides, amines, phenols, or carboxylic acids for curing	Low-carbon curing systems, recyclable networks, degradable networks, and sustainable thermoset material design
Bio-based toughening agents	Use flexible plant-oil segments or hyperbranched structures for toughening	High-toughness and low-stress materials
Bio-based dynamic networks	Introduce dynamic structures such as imines, transesterification structures, acetals, and disulfide bonds	Repairable, recyclable, and reprocessable materials
Bio-based flame-retardant systems	Introduce phosphorus-containing, nitrogen-containing, or naturally aromatic structures	Flame retardancy and low-smoke applications

Bio-based epoxy resins are not simply about replacing petrochemical raw materials with plant-derived raw materials. The truly valuable direction is to integrate renewable sources, performance improvement, recyclability, and low environmental burden.

5.3 Bio-Based Does Not Mean Naturally Harmless, Nor Does It Mean Degradable

Bio-based epoxy resins need to avoid three misunderstandings:

1. Bio-based does not mean completely non-toxic

Bio-based monomers, curing agents, and additives may still have irritation, sensitization, or environmental hazards and need to be evaluated according to SDS and regulations.

2. Bio-based does not mean degradable

If the material still forms a stable crosslinked network after curing, it may still be difficult to degrade.

3. Bio-based does not necessarily mean low-carbon

The full lifecycle must be considered, including raw material cultivation, extraction, chemical modification, transportation, curing, service life, and end-of-life treatment.

Key evaluation dimensions for bio-based epoxy resins should include:

Evaluation Dimension	Key Concern
Bio-based carbon content	What proportion of the carbon source is renewable?
Performance retention	Do strength, heat resistance, and chemical resistance meet application requirements?
Process compatibility	Are viscosity, curing speed, and storage stability suitable for industrialization?
Safety and compliance	Do monomers, curing agents, and additives meet health and regulatory requirements?
Lifecycle	Are carbon emissions, energy consumption, water consumption, and end-of-life treatment improved?
Recyclability	Does the material have mechanisms for reprocessing, chemical recycling, or degradation?

6. High-Toughness Trend: From Toughening Modification to Structured Toughness Design

6.1 Epoxy Resins Need to Address Brittleness

After curing, epoxy resins usually have relatively high hardness and modulus. However, under impact, peel, fatigue, and thermal cycling conditions, brittle cracking may limit their applications in structural adhesives, composite materials, electronic encapsulation, and high-reliability coatings. The development goal of high-toughness epoxy is not simply to make the material softer, but to improve the material’s ability to resist crack initiation and crack propagation.

6.2 Main Directions for High-Toughness Epoxy Resins

Direction	Basic Idea	Future Value
Core-shell rubber toughening	Introduce controlled rubber particles into the epoxy network	Improve impact and peel performance
Thermoplastic resin toughening	Form a toughened structure through phase separation	Improve fracture toughness and interlaminar performance of composite materials
Hyperbranched polymer toughening	Use highly branched structures to improve compatibility and energy dissipation	Achieve a better balance between strength and toughness
Nanoparticle toughening	Toughen through crack deflection, pinning, and interfacial energy dissipation	Suitable for high-strength and functional composite systems
Flexible segment design	Introduce controlled flexible structures	Reduce stress and improve crack resistance
Dynamic bond toughening	Use reversible bonds to dissipate energy and provide repairability	Combine toughness, repairability, and recyclability potential
Nanoscale phase-separation design	Form uniform and stable multiscale energy-dissipation structures	Synergy between high toughness and high modulus

6.3 High Toughness and Recyclability May Converge

Traditional toughening often relies on second-phase materials, but the second phase may reduce Tg, modulus, or chemical resistance. A more promising future route is to use dynamic bonds, hyperbranched structures, controlled phase separation, and multiscale network design so that the material can simultaneously achieve: high strength; high toughness; low internal stress; repairability; reprocessability; and recyclability potential.

The 2024 study in Nature Sustainability demonstrated the possibility of improving both the toughness and reprocessability of epoxy thermosets through curing chemistry design. This suggests that the future development of epoxy resins may move from “simple toughening” toward “synergistic design of toughness, recyclability, and high performance.”

7. High Thermal Conductivity Trend: Electronics, Electrical Applications, and New Energy Drive Performance Upgrading

7.1 The Intrinsic Thermal Conductivity of Ordinary Epoxy Resins Is Limited

Electronic encapsulation, power modules, motor potting, LEDs, new energy vehicles, battery systems, and high-voltage electrical equipment all impose higher requirements for heat dissipation. Ordinary epoxy resins have relatively low intrinsic thermal conductivity and can easily become bottlenecks in heat transfer.

7.2 Main Technical Routes for High-Thermal-Conductivity Epoxy Resins

Route	Basic Method	Advantages	Key Difficulties
Ceramic thermally conductive fillers	Add alumina, aluminum nitride, boron nitride, magnesium oxide, etc.	Can balance thermal conductivity and electrical insulation	High filler loading leads to increased viscosity and difficulty in deaeration
Carbon-based thermally conductive fillers	Add graphite, graphene, carbon nanotubes, etc.	High thermal-conduction efficiency	May introduce electrical conductivity and is not suitable for all insulation scenarios
Hybrid filler systems	Combine thermally conductive fillers with different particle sizes, morphologies, and properties	Easier to form heat-conduction pathways	Dispersion, sedimentation, and interface control are complex
Oriented structure design	Orient sheet-like or fibrous fillers	Improve thermal conductivity in specific directions	Complex processing and possible anisotropy
Liquid-crystalline epoxy	Improve intrinsic thermal conductivity through molecular ordering	Reduce dependence on high filler loading	Monomer design and processing window requirements are demanding
Interface modification	Improve heat transfer at the filler-resin interface	Reduce interfacial thermal resistance	Coupling agents and surface treatments need to match the curing system

7.3 Balancing High Thermal Conductivity and Electrical Insulation

In electronic and electrical applications, thermal conductivity and insulation often need to be met simultaneously. The future focus of high-thermal-conductivity epoxy resins is shifting from “increasing the thermal conductivity value” to “integrated design of thermal, electrical, mechanical, processing, and reliability performance.”

Design Goal	Optional Directions	Risks
High thermal conductivity + insulation	Alumina, aluminum nitride, boron nitride, magnesium oxide, etc.; spherical silica powder can serve as a synergistic filler for filling, reducing the coefficient of thermal expansion (CTE), and improving rheology and particle packing	High filler loading leads to high viscosity and poor flowability
High thermal conductivity + low stress	Flexible segments, low-modulus systems, and low-thermal-expansion design	Heat resistance and mechanical strength may decrease
High thermal conductivity + flame retardancy	Synergy between ceramic fillers and phosphorus/nitrogen flame-retardant systems	Compatibility and processing complexity increase
High thermal conductivity + low dielectric properties	Low-polarity resins and specific ceramic fillers	Material selection is limited
High thermal conductivity + high reliability	Low ionic impurities, low water absorption, and low void content	Manufacturing and quality control requirements increase

8. High-Performance Trend: From Single-Property Optimization to Multifunctional Synergy

8.1 High-Performance Epoxy Is Not About Maximizing a Single Indicator

Future application scenarios for epoxy materials will become increasingly complex. Structural adhesives require high strength, high toughness, resistance to damp heat, and debondability. Electronic encapsulation materials require thermal conductivity, electrical insulation, low stress, and low ionic impurities. Composite materials require high Tg, impact resistance, fatigue durability, and recyclability. Coatings require low VOC, long-term corrosion protection, and weather-resistant supporting systems. The trend toward high performance is to integrate multiple properties into the same system.

High-Performance Direction	Objective	Main Challenge
High-Tg epoxy	Improve rigidity and dimensional stability at high temperatures	May increase brittleness and processing difficulty
Low-stress epoxy	Reduce encapsulation cracking, interfacial debonding, and thermal cycling damage	May reduce modulus and heat resistance
Low-dielectric epoxy	Adapt to high-speed communication and electronic encapsulation	Polarity, moisture, and fillers need to be controlled
Flame-retardant epoxy	Meet safety requirements for electronics, electrical applications, and transportation	Smoke toxicity, migration, and mechanical property loss need to be reduced
Highly weather-resistant epoxy	Improve surface stability in outdoor applications	Conventional aromatic epoxy matrices have relatively weak UV resistance; outdoor systems usually require weather-resistant topcoats, stabilizers, or supporting systems
Self-healing epoxy	Extend service life	Healing efficiency, strength recovery, and triggering conditions need to be optimized
Debondable epoxy	Support repair and recycling	Service strength and triggered debonding need to be balanced
Low-temperature fast-curing epoxy	Adapt to on-site application and cold environments	Pot life, exotherm, and final properties are difficult to balance

8.2 Future Requirements in Different High-End Application Scenarios

Scenario	Future Requirements	Key Development Focus for Epoxy
Power electronics	High thermal conductivity, insulation, low stress, and damp-heat resistance	Electrically insulating thermally conductive fillers, low ionic impurities, and low-water-absorption systems
New energy vehicles	Structural bonding, thermal conductivity, flame retardancy, and repairability	Multifunctional adhesives, debondable connections, and thermal management materials
Wind turbine blades	Fatigue durability, toughness, and recyclability	High-toughness matrices, low-exotherm infusion systems, and recyclable composite materials
Aerospace composites	High Tg, low void content, impact resistance, and low weight	High-toughness prepregs, strict curing protocols, and long-term reliability
Heavy-duty anticorrosion	Low VOC, long-term barrier protection, and chemical resistance	Waterborne systems, high-solids systems, functional fillers, and supporting surface treatment
Electrical insulation	High dielectric strength, heat resistance, and low partial discharge	Low-defect encapsulation, insulating thermal conductivity, and low-moisture control
Architectural flooring	Low odor, low VOC, wear resistance, and ease of application	Waterborne or solvent-free systems, and optimized application windows
Consumer-grade transparent materials	Low odor, low yellowing, and low shrinkage	Low residue, low exotherm, and light-aging resistance

9. Common Misconceptions to Avoid

Misconception	Accurate Understanding
It is stable after curing, so it is also safe during application	The key risks lie in uncured resins, curing agents, diluents, and application exposure
Waterborne epoxy always performs better	Waterborne systems have strong low-VOC potential, but water resistance, film formation, and storage stability require careful design
Bio-based always means environmentally friendly	Bio-based content, synthesis route, performance, service life, and lifecycle results all need to be considered
Recyclable epoxy is already fully mature	Dynamic networks and chemical recycling have clear prospects, but scale-up, cost, and certification remain challenges
High thermal conductivity only requires adding more fillers	High filler loading can introduce viscosity, voids, interface, and insulation risks
High toughness simply means the material is softer	High toughness should improve resistance to crack propagation, rather than simply reducing modulus
Low VOC means no risk	Low VOC only reduces volatile emissions; skin contact, curing agents, and additive-related risks still need attention
High performance means the higher the indicator, the better	True high performance is a balance among strength, toughness, heat resistance, processability, reliability, and environmental performance

10. Representative Chemicals Related to Safety, Environmental Protection, Bio-Based Development, Recyclability, and High-Performance Trends in Epoxy Resins with Tables 1–4

Note: The products listed in the tables are representative reagents/materials for related research, formulation screening, or compliance analysis. They do not necessarily represent low-hazard, low-carbon, or sustainability-certified products. Actual use should be confirmed based on the SDS, applicable regional regulations, target application, residue/migration requirements, and the latest product specifications.

Table 1. Products Related to Safety Compliance and Low-Emission Systems

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Raw material of safety and compliance concern	106-89-8	E401255	(±)-Epichlorohydrin	Industrial grade	Used for research on upstream raw materials for epoxy resins, development of residue-control methods, evaluation of resin synthesis routes, and safety compliance analysis.
Raw material of safety and compliance concern	80-05-7	B108652	Bisphenol A	Moligand™, ≥99% (GC)	Used for research on raw materials for bisphenol-type epoxy resins, comparison of BPA alternative routes, migrant detection, and regulatory compliance analysis.
Low-emission solvent system	108-32-7	P105726	Propylene carbonate	Anhydrous, ≥99.7%	Used for low-volatility solvent systems, epoxy coating formulations, resin dissolution and dispersion, and green solvent substitution research.
Low-emission reactive diluent	68609-97-2	D133554	Dodecyl and tetradecyl glycidyl ethers	Industrial grade	Used for low-solvent epoxy systems, reactive dilution, application-viscosity adjustment, and low-emission coating and adhesive formulation research.
Low-emission reactive diluent	2425-79-8	B109380	1,4-Butanediol diglycidyl ether (BDDE)	≥95%	Used for reactive-dilution epoxy systems, low-solvent casting and encapsulation materials, flexible network adjustment, and curing-performance research.

Table 2. Products Related to Bio-Based Routes and Renewable-Source Research

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Bio-based epoxy material	8013-07-8	E107074	Epoxidized soya bean oil (ESO)	Chemically pure (CP)	Used for bio-based epoxy modification, introduction of flexible segments, toughening and plasticizing systems, and renewable-source epoxy material research.
Bio-based phenolic raw material	121-33-5	V431597	Vanillin	Suitable for synthesis	Used for bio-based epoxy monomers, bio-based curing agents, introduction of aromatic structures, and renewable resin synthesis research.
Bio-based phenolic raw material	97-53-0	E110640	Eugenol	Moligand™, ≥99%	Used for bio-based epoxy monomers, aromatic-ring-containing epoxy resins, flame-retardant modification, and renewable-source thermoset material research.
Bio-based diol raw material	652-67-5	I157515	Isosorbide	≥98% (GC)	Used for bio-based rigid epoxy monomers, renewable polymers, heat-resistant resins, and low-carbon material systems.
Bio-based diacid raw material	97-65-4	I106140	Itaconic acid	Chemically pure (CP), ≥99%	Used for bio-based curing agents, polymerizable carboxylic acid monomers, dynamic-network precursors, and renewable resin structure design.
Bio-based glycidyl ether	5380-87-0	H111929	Furfuryl glycidyl ether	≥96%	Used for furan-derived epoxy monomers, low-viscosity bio-based epoxy systems, and renewable glycidyl ether material research.
Bio-based polyphenol material	1401-55-4	T305809	Tannic acid	≥95%	Used for bio-based polyphenol curing systems, flame-retardant synergy, adhesive interface modification, and renewable polymer network research.

Table 3. Products Related to Recyclability, Reprocessability, and Dynamic Networks

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Dynamic disulfide-bond monomer	722-27-0	A101817	4-Aminophenyl disulfide	≥98%	Used for disulfide-containing reprocessable epoxy networks, self-healing thermoset materials, debondable adhesives, and dynamic covalent system research.
Dynamic disulfide-bond monomer	56-17-7	C755572	Cystamine dihydrochloride	BioReagent	Used for disulfide-containing epoxy curing systems, reductively degradable networks, self-healing materials, and chemical recycling model research.
Dynamic-network catalyst	14024-63-6	B152965	Bis(2,4-pentanedionato)zinc(II)	≥96%	Used for transesterification-type epoxy dynamic networks, reprocessable thermoset materials, weldable resins, and dynamic bond-exchange catalysis research.
Dynamic-network catalyst	5807-14-7	T161639	1,5,7-Triazabicyclo[4.4.0]dec-5-ene (Hhpp)	≥98%	Used for base-catalyzed dynamic bond exchange, epoxy transesterification networks, remoldable thermoset materials, and recyclable resin systems.

Table 4. Products Related to High Toughness, High Thermal Conductivity, and Flame-Retardant High Performance

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
High-toughness flexible epoxy modifier	26142-30-3	P774175	Poly(propylene glycol) diglycidyl ether	Viscosity 30–70 mPa·s	Used for flexible-segment epoxy modification, low-stress encapsulation, crack-resistant resins, and high-toughness cured network research.
High-toughness flexible epoxy modifier	26403-72-5	P475492	Poly(ethylene glycol) diglycidyl ether	Mₙ 1000	Used for flexible epoxy networks, low-modulus systems, toughening modification, and aqueous or hydrophilic structure regulation.
High-toughness rubber toughening agent	68891-46-3	P477906	Poly(acrylonitrile-co-butadiene), dicarboxy terminated	Average Mₙ ~3,800; acrylonitrile 8–12 wt.%	Used for rubber toughening of epoxy resins, peel resistance of structural adhesives, crack resistance of composite matrices, and fracture-toughness research.
High-toughness flexible curing agent	9046-10-0	P108072	Poly(propylene glycol) bis(2-aminopropyl ether)	Average Mₙ ~400	Used for flexible amine-cured epoxy systems, low-stress electronic encapsulation, elastic-tough adhesives, and flexible cured-network research.
High-thermal-conductivity insulating filler	1344-28-1	A431930	Aluminum oxide	Nanopowder, <50 nm (TEM)	Used for thermally conductive and electrically insulating epoxy composites, electronic encapsulation, power-device packaging, and highly filled thermal-management systems.
High-thermal-conductivity insulating filler	24304-00-5	A432363	Aluminum nitride	Nanopowder, ≤100 nm	Used for high-thermal-conductivity insulating epoxy encapsulation, electronic and electrical thermal management, low-thermal-resistance composite systems, and thermally conductive filler interface research.
High-thermal-conductivity insulating filler	10043-11-5	B489779	Boron nitride	≥99.8% metals basis	Used for thermally conductive and electrically insulating epoxy materials, sheet-like thermal-conduction networks, low-dielectric composite systems, and power-electronics packaging research.
High-thermal-conductivity filler	1309-48-4	M492985	Magnesium oxide	≥99% metals basis, 50–100 nm	Used for thermally conductive epoxy composites, electronic encapsulation, thermal-management coatings, and surface modification of inorganic fillers.
High-thermal-conductivity filler	409-21-2	S104653	Silicon carbide	≥99.9% metals basis, 40 nm	Used for heat-resistant and thermally conductive epoxy composite systems, wear-resistant coatings, thermal-management materials, and high-temperature stability research.
Thermally and electrically conductive filler	7782-42-5	G123640	Graphite	≥99.95% metals basis, 5000 mesh	Used for thermally and electrically conductive epoxy composites, antistatic coatings, electromagnetic shielding, and carbon-based filler network research.
Flame-retardant filler	1309-42-8	M104280	Magnesium hydroxide	Ultrapure, ≥99% (KT)	Used for halogen-free flame-retardant epoxy systems, smoke-suppression materials, electrical insulation composites, and flame-retardant filler synergy research.
Flame-retardant filler	21645-51-2	A110527	Aluminium hydroxide	PrimorTrace™, ≥99.99% metals basis, 2–10 μm	Used for halogen-free flame-retardant epoxy encapsulation, coatings, flooring, and flame-retardant modification of electrical insulation materials.
Phosphorus-containing reactive flame retardant	35948-25-5	D102416	9,10-Dihydro-9-oxa-10-phosphaphenanthrene 10-Oxide (DOPO)	≥97%	Used for phosphorus-containing flame-retardant epoxy resins, reactive flame-retardant structure design, low-migration flame-retardant systems, and heat-resistant flame-retardant materials.
Nitrogen-based flame retardant	37640-57-6	M303597	Melamine cyanurate	≥99%	Used for nitrogen-based flame-retardant epoxy composites, electronic and electrical flame retardancy, halogen-free flame-retardant synergy, and heat-release control research.

Note: The above are representative Aladdin products. More product specifications can be searched on the Aladdin website by “product name/CAS/catalog number.”

References

[1] European Agency for Safety and Health at Work, OSHwiki. Occupational exposure to epoxy resins.

[2] Occupational Safety and Health Administration. OSHA Technical Manual, Section III: Chapter 1.

[3] DermNet. Epoxy resin contact allergy.

[4] U.S. Environmental Protection Agency. Ground-level Ozone Basics.

[5] European Union. Directive 2004/42/EC on the limitation of emissions of volatile organic compounds due to the use of organic solvents in certain paints and varnishes.

[6] Sinha S., Dey K. P. Advancements and Diverse Applications of Waterborne Epoxy Coatings: A Comprehensive Review. In: Recent Advances on Waterborne Epoxy Coatings. Springer, 2025, pp. 245–256.

[7] Epoxy Europe/Cefic. Voluntary Guideline on Residual Epichlorohydrin in Liquid Epoxy Resins, Reactive Diluents and Mixtures Thereof. 2024.

[8] European Union. Commission Regulation (EU) 2024/3190, as corrected by Commission Regulation (EU) 2026/250.

[9] Wang Y. et al. Chemical Recycling of Epoxy Thermosets: From Sources to Wastes. Actuators, 2024, 13(11): 449.

[10] Memon H., Wei Y., Zhu C. Recyclable and reformable epoxy resins based on dynamic covalent bonds – Present, past, and future. Polymer Testing, 2022, 105: 107420.

[11] Wu W. et al. Reprocessable and ultratough epoxy thermosetting plastic. Nature Sustainability, 2024, 7: 804–811.

[12] Jiang Y. et al. Bio-based hyperbranched epoxy resins: synthesis and recycling. Chemical Society Reviews, 2024, 53: 624–655.

[13] Mi X. et al. Toughness and its mechanisms in epoxy resins. Progress in Materials Science, 2022, 130: 100977.

[14] Zhou M.-H., Yin G.-Z., González Prolongo S. Review of thermal conductivity in epoxy thermosets and composites: Mechanisms, parameters, and filler influences. Advanced Industrial and Engineering Polymer Research, 2024, 7(3): 295–308.

For more related articles, see below:

Understanding Amine Curing Agents: Structure, Types, and Application Selection

A Complete Guide to Selecting Epoxy Curing Systems: Amines vs. Anhydrides vs. Latent Curing — with Aladdin’s Recommended Selection Table

Formulation Design and Selection of Amine Curing Agents in Epoxy Systems

Epoxy Silane Coupling Agents: Structural Features, Classification, Typical Applications, and Precautions for Use