Condensed silicone E additive silicone are two dominant silicone polymer types, each with unique chemical compositions, curing behaviors, and performance traits. The choice between them directly impacts project costs, precisione, and application suitability—whether you’re making DIY crafts, industrial molds, o dispositivi medici. This article breaks down their differences across 7 dimensioni critiche, with clear comparisons, Esempi del mondo reale, and selection guidelines to help you choose the right silicone for your needs.
1. Composizione chimica & Struttura molecolare
The fundamental difference between the two silicones lies in their base components and molecular chains—this drives all other performance variations.
| Aspetto | Condensed Silicone | Additive Silicone |
| Main Chain | Terminated dimethicone (contains active hydroxyl groups (-OH)). | Vinyl-terminated dimethicone (no active hydroxyl groups). |
| Crosslinking Agent | Methyl triethoxysilane or similar compounds (triggers condensation reactions). | Hydrogen-containing silicone oil (enables addition reactions via silicon-hydrogen bonds). |
| Catalyst | Organotin compounds (PER ESEMPIO., dibutyltin dilaurate). | Platinum complexes (PER ESEMPIO., chloroplatinic acid complexes). |
| Molecular Stability | Low—hydroxyl groups react easily with moisture in air (prone to premature curing). | High—no active groups; resistant to environmental interference (stable in storage). |
Impatto chiave: Additive silicone’s stable molecular structure makes it ideal for long-term storage and precision applications (PER ESEMPIO., medical device molds), while condensed silicone’s reactive hydroxyl groups require tight sealing to avoid waste.
2. Curing Mechanism & By-Products
How each silicone hardens and the substances it releases during curing are critical for safety and application suitability.
| Curing Trait | Condensed Silicone | Additive Silicone |
| Reaction Type | Condensation reaction (hydroxyl groups react with crosslinkers). | Addition reaction (silicon-hydrogen bonds (Si-H) react with vinyl groups (Vi)). |
| By-Products | Releases small molecules: Etanolo, acqua, or acetic acid (acetic acid types have a mild vinegar-like odor). | No by-products—clean curing (Nessun odore, no volatile emissions). |
| Environmental Dependence | Relies on air moisture for curing (faster in high humidity; slow or incomplete in dry environments). | No moisture dependence—curing speed depends on temperature or catalyst concentration. |
| Curing Speed Control | Hard to adjust—largely determined by humidity (PER ESEMPIO., 24–48 hours at 50% umidità). | Highly controllable—accelerate with heat (60°C cuts time by 50%) or higher catalyst dosage. |
Esempio nel mondo reale: A DIY enthusiast making candle molds with condensed silicone finds curing takes 36 hours in a dry winter room (30% umidità), ma solo 20 hours in a humid summer (70% umidità). An electronics manufacturer using additive silicone for LED lens potting cures parts in 2 hours at 80°C—consistent results regardless of weather.
3. Performance Characteristics
This dimension directly affects precision, durata, and application scope—especially for industrial or high-stakes uses.
| Metrica delle prestazioni | Condensed Silicone | Additive Silicone |
| Tasso di restringimento | Alto (1–2%)—causes minor detail distortion (Non per parti di precisione). | Basso (0.1–0,5%)—retains fine details (ideal for semiconductor molds or jewelry). |
| Gamma di durezza | Stretto (Shore A 20–40)—mostly soft, flexible variants. | Largo (Shore A 10–60)—adjustable for soft (PER ESEMPIO., cateteri medici) or rigid (PER ESEMPIO., parti ottiche) esigenze. |
| Allungamento a pausa | Moderare (200–250%)—may tear under high stress. | Alto (300–400%)—handles stretching (PER ESEMPIO., flexible gaskets for machinery). |
| Corrosiveness | Acetic acid variants may corrode sensitive metals (PER ESEMPIO., rame, ottone) or electronic components. | Non-corrosive—safe for metals, elettronica, and food-contact applications. |
Critical Use Case: A dental lab cannot use condensed silicone for crown molds (1–2% shrinkage ruins fit), but additive silicone’s 0.3% shrinkage ensures perfect patient-specific replicas.
4. Scenari di applicazione
Their performance differences make each silicone suited to distinct use cases—matching the right type to your project avoids rework and costs.
| Categoria | Condensed Silicone Ideal For | Additive Silicone Ideal For |
| Cost-Sensitive Projects | Low-precision, high-volume uses: door/window sealants, ordinary craft molds, low-end electronic potting. | High-value, low-volume uses: componenti del dispositivo medico, food-grade baking molds, precision electronic packaging. |
| Environmental Requirements | Non-critical environments: DIY workshops, outdoor sealing (resistant to moisture but not chemicals). | Ambienti severi: camere bianche (nessun sottoprodotto), trasformazione alimentare (Conformità FDA), strutture mediche (sterilizzabile). |
| Esigenze di precisione | Parti con tolleranze allentate (± 0,5 mm): componenti giocattoli, targhe decorative. | Parti con tolleranze strette (± 0,1 mm): Lenti LED, wafer a semiconduttore, corone dentali. |
Esempio di industria: Una fabbrica automobilistica utilizza silicone condensato per guarnizioni di porte non critiche (basso costo, Volume elevato), ma silicone additivo per guarnizioni del sistema di alimentazione (non corrosivo, adattamento preciso per evitare perdite).
5. Magazzinaggio & Operation Precautions
Una corretta manipolazione garantisce la durata di conservazione e il successo della polimerizzazione: ogni silicone ha requisiti unici.
| Tipo di precauzione | Condensed Silicone | Additive Silicone |
| Condizioni di conservazione | – Sigillare ermeticamente per bloccare l'umidità dell'aria (Se esposto, si verifica una polimerizzazione prematura).- Shelf life: 6–12 mesi (unopened). | – Store away from sulfur, amines, or phosphides (poison platinum catalysts).- Avoid high temperatures/UV (denatures silicone).- Shelf life: 12–24 mesi (unopened). |
| Operation Safety | – Ventilate work areas (acetic acid fumes irritate airways).- Wear gloves to avoid skin contact with organotin catalysts. | – No special ventilation needed (nessun sottoprodotto).- Avoid contact with rubber gloves (sulfur in rubber ruins curing). |
| Substrate Preparation | Low requirements: accepts slightly oily or dusty surfaces (forte adesione). | High requirements: substrates must be clean/dry (oils/dust block curing). |
Errore comune: Un hobbista lascia aperta una lattina di silicone condensato durante la notte: l'umidità innesca una polimerizzazione parziale, rendendolo inutilizzabile. Un produttore utilizza lubrificanti contenenti zolfo vicino al silicone additivo: l'avvelenamento del catalizzatore al platino provoca un indurimento incompleto.
6. Costo & Disponibilità
Il costo è un fattore chiave per i progetti attenti al budget: ogni silicone varia in termini di spese materiali e operative.
| Aspetto costo | Condensed Silicone | Additive Silicone |
| Costo materiale | Basso (\(10- )20 per kg per le qualità standard). | Alto (\(30- )60 per kg per le qualità standard; fino a $ 100/kg per i prodotti medicali/alimentari). |
| Costo operativo | Basso: nessuna attrezzatura speciale (funziona con strumenti di base come le spatole). | High—may need vacuum degassing machines (for bubble-free curing) or temperature-controlled ovens. |
| Tasso di rifiuti | Higher—premature curing from moisture exposure or incorrect mixing. | Lower—stable in storage; curing failures are rare if platinum catalyst is protected. |
Cost Tradeoff: Una startup 1000 ordinary toy molds saves \(4,000 using condensed silicone (\)15/kg) instead of additive (\(40/kg). Tuttavia, a bakery using additive silicone for food-grade molds avoids \)10,000 in FDA fines (condensed silicone is non-compliant).
7. Quick Selection Guide
Use this table to quickly match your project needs to the right silicone:
| Your Project Need | Choose Condensed Silicone? | Choose Additive Silicone? |
| Basso costo, Volume elevato, bassa precisione | ✅ Yes | ❌ No |
| Food/medical contact or cleanroom use | ❌ No | ✅ Yes |
| Tolleranze strette (± 0,1 mm) o dettagli fini | ❌ No | ✅ Yes |
| Curing in humid environments (no oven) | ✅ Yes | ❌ No (but works, just not dependent) |
| Long-term storage (12+ mesi) | ❌ No | ✅ Yes |
8. Yigu Technology’s Perspective on Condensed vs. Additive Silicone
Alla tecnologia Yigu, we’ve resolved countless project failures from misselecting silicone. A common issue: clients use condensed silicone for precision electronic molds—1–2% shrinkage ruins component fit, conducendo a \(5,000+ nella rielaborazione. We always recommend additive silicone for high-value projects (medico, elettronica) despite higher costs—it eliminates shrinkage and corrosion risks. For budget projects (PER ESEMPIO., outdoor seals), condensed silicone is ideal, but we advise clients to seal containers tightly and test humidity levels. Our key insight: Don’t just choose based on cost—match silicone to your project’s precision, ambiente, and compliance needs. UN \)10/kg savings on condensed silicone isn’t worth $100,000 in FDA fines for non-compliant food molds.
9. Domande frequenti: Common Questions About Condensed & Additive Silicone
Q1: Can I use condensed silicone for food-contact projects (PER ESEMPIO., stampi da forno)?
A1: No—even non-acetic acid condensed silicones lack FDA compliance (may leach chemicals). Additive silicone is the only safe choice for food contact (look for FDA 21 Cfr 177.2600 certificazione) as it has no by-products and meets strict purity standards.
Q2: Why does my additive silicone fail to cure even with the right ratio?
A2: Platinum catalyst poisoning is the main cause—check for contact with sulfur (rubber gloves, lubrificanti), amines (some adhesives), or phosphides (certain cleaning products). Replace contaminated tools/substrates and use fresh additive silicone to fix the issue.
Q3: Which silicone is better for outdoor use (PER ESEMPIO., garden fountain seals)?
A3: Condensed silicone is better for outdoor, non-critical seals—it’s cheaper and moisture accelerates curing (ideal for rainy environments). Tuttavia, if the seal contacts drinking water or needs to withstand chemicals (PER ESEMPIO., pool chlorine), use additive silicone (non corrosivo, più durevole).