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epoxy adhesive
- best for: structural applications requiring maximum strength and rigidity
- strengths: very high bond strength, excellent chemical resistance, low shrinkage
- limitations:
- rigid (can crack under impact)
- requires precise mixing
- higher cost
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- best for: applications requiring flexibility and impact resistance
- strengths: high flexibility, excellent impact absorption, easier application
- limitations
- moderate shrinkage
- moisture-sensitive storage
- lower temperature resistance
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epoxy vs polyurethane adhesive comparison
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chemical properties
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| feature | epoxy adhesive | polyurethane adhesive |
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| chemical basis | epoxy resin + hardener (2-component) | polyurethane polymer (often moisture-cure, single or 2-component) |
| bond strength | very high, rigid, structural bonds | high, flexible to moderately rigid bonds |
| flexibility | low (rigid after cure) | moderate to high (retains elasticity) |
| shrinkage | very low | moderate (some shrinkage during curing) |
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| feature | epoxy adhesive | polyurethane adhesive |
|---|
| impact resistance | lower (can fracture under impact) | high (absorbs vibration and impacts well) |
| water resistance | excellent after curing | excellent after curing |
| uv resistance | moderate (requires protective coatings) | good (some formulations excellent) |
| temperature resistance | high (~100–150°c), varies by product | moderate (~80–120°c), varies by product |
| chemical resistance | excellent against many chemicals | good but slightly lower than epoxy |
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application properties
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| feature | epoxy adhesive | polyurethane adhesive |
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| curing time | variable (minutes to hours), typically faster, adjustable by component ratios | typically slower moisture cure (hours to a day), not easily adjusted |
| application ease | requires accurate mixing (2-component), sensitive to ratios | simpler, usually single-component ready-to-use |
| adhesion surfaces | excellent on metals, composites, ceramics, concrete | excellent on metals, glass, wood, plastics |
| shelf life/storage | longer shelf life, separate components (months to years) | limited once opened; sensitive to moisture |
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environmental & economic factors
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| feature | epoxy adhesive | polyurethane adhesive |
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| environmental concerns | uncured resins/hardeners toxic, irritant; safe after full curing | uncured contains isocyanates; hazardous before curing, safe after full curing |
| microplastic potential | minimal (rigid, stable polymer - degradation over 50-100+ years) | moderate (elastic polymer prone to gradual degradation over 20-40 years) |
| price | higher ($15-40 per 100ml) | moderate ($8-25 per 100ml) |