Compounding — Process Challenge

Silane Coupling Agents for Filled Polymers

Mineral-filled thermoplastics/thermosets suffer poor filler-polymer bonding, low mechanical strength, and moisture-driven debonding; silane coupling agents bridge the inorganic filler and organic matrix
Updated Jun 2026
Solution Approach

RawSource supplies the base chemicals that go into these programs. We can help with product selection, grade matching, and sourcing from multiple origins for supply security.

Typical Formulation Workflow
1
Polymer & Process Definition
Identify the resin and process (extrusion, molding, film) and the targets — thermal stability, clarity, flame retardance, slip, or color.
2
Additive Selection
Match stabilizers, antioxidants, plasticizers, lubricants, flame retardants, or masterbatch carriers to the polymer and processing temperatures.
3
Compounding Trial
Confirm loading and dispersion on a compounding or molding trial, checking processability, mechanicals, and aesthetics against the control.
4
Validation & Scale-Up
Verify long-term performance (heat aging, migration, weathering) and lock the formulation, packaging, and lot specs for production.
Recommended Chemistries (10)
3-aminopropyltriethoxysilane (APTES)
CAS 919-30-2
Silanes & Organosilanes
Primary amino silane
Triethoxy end hydrolyzes to silanols that condense onto mineral-filler hydroxyls while the pendant primary amine reacts with the polymer, forming a covalent filler-to-matrix bridge
Melting Point: -70 °C   Boiling Point: 217 °C   Density: 0.94 at 25 °C
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3-aminopropyltrimethoxysilane (APTMS)
CAS 13822-56-5
Silanes & Organosilanes
Methoxy amino silane
Methoxy version hydrolyzes faster than ethoxy for quicker filler surface anchoring; the amine couples to acidic/anhydride-functional polymers
Physical Description: Clear to straw-colored liquid with an ammoniaca…
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3-(2-Aminoethylamino)propyltrimethoxysilane (diamine silane)
CAS 1760-24-3
Silanes & Organosilanes
Enhanced adhesion
Two amine groups give higher reactive-site density at the interface, raising bond durability under moisture for filled compounds
Physical Description: Light yellow liquid   Vapor Pressure: 0.03
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(3-Aminopropyl)silanetriol
CAS 58160-99-9
Silanes & Organosilanes
Pre-hydrolyzed
Pre-hydrolyzed water-borne aminosilane needs no in-situ hydrolysis, useful for aqueous filler-slurry treatment
Physical Description: 0.1-5.0% aqueous solution: Colorless odorless l…
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Hydrophobic Modified Fumed Silica
CAS 68909-20-6
Silanes & Organosilanes
Treated silica for non-polar systems
A filler already silane-surface-treated, demonstrating the hydrophobized-interface effect that improves wet-out and dispersion in non-polar matrices
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Vinyltris(2-Methoxyethoxy)Silane
CAS 1067-53-4
Silanes & Organosilanes
Moisture-cure systems
Silane A-172. Methoxyethoxy groups hydrolyze onto ATH/silica filler; vinyl grafts into peroxide/silane-crosslinked PE. The standard coupling agent for mineral-filled crosslinkable PE and wire & cable compounds. Genuine filler-matrix adhesion role. CAS correct.
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Vinyltrimethoxysilane
CAS 2768-02-7
Silanes & Organosilanes
PE crosslinking and polyester
Silane A-171. Trimethoxy bonds the mineral filler while vinyl co-reacts during crosslinking of filled polyethylene/EPDM, raising strength and resisting moisture debonding. Established vinyl coupling agent for filled polyolefins. CAS correct.
Melting Point: ˆ'97°C   Boiling Point: 123°C at 1013 hPa (converted to 101.3 kPa) (760…   Density: Specific Density: 0.94 (water = 1)
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3-glycidoxypropyl methyldiethoxy silane
CAS 2897-60-1
Monoalkyl epoxy silane
Difunctional epoxy silane (PubChem CID 62467, C11H24O4Si). Diethoxy anchors to filler; glycidoxy cures into epoxy/urethane/amine matrices, the single methyl giving a flexible, lower-stress interphase in filled thermosets. Legitimate coupling agent. CAS verified.
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3-glycidoxypropyltriethoxysilane
CAS 2602-34-8
Silanes & Organosilanes
Ethoxy epoxy silane
Trialkoxy epoxy silane (PubChem CID 102856, C12H26O5Si, triethoxy-[3-(oxiran-2-ylmethoxy)propyl]silane). Triethoxy densely bonds mineral filler; glycidoxy cures into epoxy/urethane, bridging filler and resin in filled thermoset composites. Genuine fit. CAS verified.
Physical Description: Liquid
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3-Methacryloxypropylmethyldimethoxysilane
CAS 14513-34-9
Silanes & Organosilanes
Coupling / Adhesion Promotion
Difunctional methacrylate silane (PubChem CID 84485, C10H20O4Si). Dimethoxy binds filler; methacryloxy copolymerizes into radical-cured unsaturated-polyester/acrylic matrices (e.g., ATH-filled cast composites), with a flexible interphase. Legitimate coupling agent. CAS verified.
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