{"product_id":"modifier-2-5","title":"Modifier 2.5 – Si-H Terminated Chain Extender for Addition Cure Silicones","description":"\u003ch2\u003eSi-H terminated chain extender for addition cure silicones\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eModifier 2.5\u003c\/strong\u003e is a linear silicone fluid that carries a reactive Si-H group at both ends of the molecule only, with no Si-H along the chain. During addition cure those two end groups react with vinyl groups, so the polymer chain is extended instead of adding further crosslinking points. The result is a lower crosslink density, a lower hardness and more elongation, at an SiH content of approximately 2.5 mmol\/g and a viscosity of approximately 5 cSt. Depending on stock we supply this product as BRB Modifier 1439 or as AToro CE-5.\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eThis product is intended for the business market. For larger quantities, a specific variant or custom products you can reach us at info@siliconesandmore.com or +31 (0)85 485 83 11.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch3\u003eKey benefits\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eLowers hardness without lowering the crosslinker:\u003c\/strong\u003e the two terminal Si-H groups extend the chain and lower the average functionality of the system. You control hardness with a separate raw material rather than with the crosslinker dosage.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTerminal Si-H only:\u003c\/strong\u003e no reactive groups along the chain, so no unwanted additional crosslinking.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLow viscosity, approximately 5 cSt:\u003c\/strong\u003e keeps formulations free flowing and easy to degas, also at high filler loading.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCures without by-products:\u003c\/strong\u003e hydrosilylation with vinyl functional components produces no cleavage products, so no shrinkage through evaporation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSuitable for gels:\u003c\/strong\u003e makes it possible to formulate soft, addition cure gels and encapsulants.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLow dosage:\u003c\/strong\u003e the high SiH content per gram means little product is needed to see an effect.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSynergy with crosslinkers:\u003c\/strong\u003e combined with a multifunctional SiH crosslinker you tune hardness, elongation and tear strength independently.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cdiv style=\"background: #fff3cd; border: 2px solid #ffc107; color: #856404; padding: 25px; border-radius: 10px; margin: 30px 0;\"\u003e\n\u003ch3 style=\"color: #856404; margin-top: 0;\"\u003e⚠️ Two sources, one product, check the safety data sheet supplied with your delivery\u003c\/h3\u003e\n\u003cp\u003eDepending on stock we supply this product as \u003cstrong\u003eBRB Modifier 1439\u003c\/strong\u003e or as \u003cstrong\u003eAToro CE-5\u003c\/strong\u003e. Functionally they are interchangeable, both fall within the same range for SiH content and viscosity. Their hazard classification, however, differs:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e✓ \u003cstrong\u003eBRB Modifier 1439:\u003c\/strong\u003e flash point approximately 25 °C, classified as H226 flammable liquid and vapour and as H361f. Contains 3 to 10 % octamethylcyclotetrasiloxane (D4), a substance on the candidate list of substances of very high concern.\u003c\/li\u003e\n\u003cli\u003e✓ \u003cstrong\u003eAToro CE-5:\u003c\/strong\u003e flash point higher than 61 °C, which under CLP is not a flammable liquid.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe hazard information on this page deliberately follows the stricter of the two, that of BRB. Always work with the safety data sheet that comes with your delivery and not with this summary. If you specifically need one of the two variants, for example because your formulation has to be free of cyclic siloxanes or because your storage does not allow flammable liquids, state this with your order or enquiry. We will then confirm which variant is available.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003ch3\u003eTypical applications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e✓ Lowering the hardness of addition cure RTV-2 silicones\u003c\/li\u003e\n\u003cli\u003e✓ Formulating soft, addition cure gels and encapsulants\u003c\/li\u003e\n\u003cli\u003e✓ Chain extension in RTV and LSR formulations\u003c\/li\u003e\n\u003cli\u003e✓ Free flowing casting systems where viscosity has to stay low\u003c\/li\u003e\n\u003cli\u003e✓ Fine tuning hardness and elongation alongside a multifunctional SiH crosslinker\u003c\/li\u003e\n\u003cli\u003e✓ Damping and vibration absorbing gels for electronics\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eProcessing\u003c\/h3\u003e\n\u003col\u003e\n\u003cli\u003eAdd Modifier 2.5 to the component that contains the crosslinker, that is the component \u003cstrong\u003ewithout\u003c\/strong\u003e platinum catalyst. Si-H and platinum together in one component causes hydrogen evolution and an unstable stock product.\u003c\/li\u003e\n\u003cli\u003eStir the product in until the mixture is homogeneous. The low viscosity makes this easy, also when cold.\u003c\/li\u003e\n\u003cli\u003eThere is no fixed dosage. Start low and work up in small steps, assessing hardness, elongation and cure speed on a test casting at every step.\u003c\/li\u003e\n\u003cli\u003eKeep an eye on the overall SiH:Vinyl ratio. Modifier 2.5 raises the SiH content of your system but adds only two reactive groups per molecule, lowering the average functionality.\u003c\/li\u003e\n\u003cli\u003eDegas the mixture under vacuum before casting.\u003c\/li\u003e\n\u003cli\u003eTest every change on a small scale before scaling up. Besides hardness, working time and cure time usually change as well.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003cp\u003eWe deliberately do not give a fixed dosage table. The effect depends on your vinyl polymer, your crosslinker, the filler and the final hardness you want, and can only be established reliably on your own formulation.\u003c\/p\u003e\n\n\u003ch3\u003ePoints to watch\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e✓ Treat the product as flammable. The BRB variant has a flash point of approximately 25 °C. Keep it away from heat, sparks, open flame and hot surfaces, ensure good ventilation and take measures against static electricity.\u003c\/li\u003e\n\u003cli\u003e✓ Si-H reacts with water, alcohols, acids and bases and with many metals and metal compounds, releasing hydrogen gas. Store dry, in the original tightly closed packaging, and keep tools clean and dry.\u003c\/li\u003e\n\u003cli\u003e✓ Do not mix with oxidising agents.\u003c\/li\u003e\n\u003cli\u003e✓ Above 150 °C traces of formaldehyde may be released. Provide sufficient extraction when heating.\u003c\/li\u003e\n\u003cli\u003e✓ The BRB variant contains cyclic siloxanes (D4, D5 and D6). Check whether your application falls under the restrictions of REACH Annex XVII before scaling up.\u003c\/li\u003e\n\u003cli\u003e✓ Wear nitrile gloves, safety glasses with side shields and protective clothing. The product causes skin irritation and serious eye irritation.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eProfessional support\u003c\/h3\u003e\n\u003cp\u003eNot sure how much you need to go from Shore A 30 to Shore A 15, or whether chain extension or a lower crosslinker dosage is the better route in your case? Contact us at info@siliconesandmore.com or +31 (0)85 485 83 11. Tell us which vinyl polymer and crosslinker you use and the final hardness you are aiming for, and we will help you think through the formulation and which of the two variants fits best.\u003c\/p\u003e","brand":"BRB International BV","offers":[{"title":"0.9 kg Modifier 2.5  B2B","offer_id":49531878342997,"sku":"S11112","price":44.96,"currency_code":"EUR","in_stock":true},{"title":"4.5 kg Modifier 2.5  B2B","offer_id":49531878408533,"sku":"S11113","price":202.5,"currency_code":"EUR","in_stock":true},{"title":"20 kg Modifier 2.5  B2B","offer_id":49531878441301,"sku":"A10096","price":880.0,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0896\/4096\/0341\/files\/brb-international-bv-modifier-26-si-h-48098049982805.png?v=1757509838","url":"https:\/\/siliconesandmore.com\/en\/products\/modifier-2-5","provider":"siliconesandmore","version":"1.0","type":"link"}