Why Silane Coupling Agents Are Used

When organic polymers are reinforced with glass fibers or minerals, the interface, or interphase region, between the polymer and the inorganic substrate is involved in a complex interplay of physical and chemical factors. These factors are related to adhesion, physical strength, coefficient of expansion, concentration gradients and retention of product properties. A very destructive force affecting adhesion is migration of water to the hydrophilic surface of the inorganic reinforcement. Water attacks the interface, destroying the bond between the polymer and reinforcement, but a “true” coupling agent creates a water-resistant bond at the interface between the inorganic and organic materials. Silane coupling agents have the unique chemical and physical properties not only to enhance bond strength but also, more importantly, to prevent de-bonding at the interface during composite aging and use. The coupling agent provides a stable bond between two otherwise poorly bonding surfaces. Figure 2 shows (via an SEM of the fracture surface) the difference in adhesion between a silica-filled epoxy resin with silane vs. without silane. With silane, the epoxy coating on the silica particles is apparent; without silane, clean silica particles can be seen in the epoxy matrix.
In composites, a substantial increase in flexural strength is possible through the use of the right silane coupling agents. Silane coupling agents also increase the bond strength of coatings and adhesives as well as their resistance to humidity and other adverse environmental conditions.

Other benefits silane coupling agents can provide include:
•    Better wetting of inorganic substrates
•    Lower viscosities during compounding
•    Smoother surfaces of composites
•    Less catalyst inhibition of thermoset composites
•    Clearer reinforced plastics

silane coupling agent

A method for preparing a silane coupling agent palygorskite, comprising the steps of: acid treatment (a) a silane coupling agent: A silane coupling agent was added to acetic acid using ethanol adjusting PH = 3 ~ 3.5, stirring at room temperature 0.2 ~ I h, acidified to give the silane coupling agent; said silane coupling agent is vinyl trimethoxy silane; (2) activation of palygorskite: palygorskite clay was added to the NaOH solution, at 45 ~ 65 ° C under magnetic stirring for 12 ~ 48h, then washed with distilled water to neutral, centrifuged and dried to yield the activated palygorskite, grinding stand; (3) Preparation of silane coupling agent palygorskite: A Activated palygorskite dispersed in ethanol - water mixture, the ultrasonic dispersion 15 ~ 40 min, then added to the above acidified silane crosslinker, the reaction mixture was stirred at room temperature 12 ~ 24h, centrifuged, dried, and then sew xylene solution in s extract 24 ~ 48 h; After Soxhlet extraction is complete, drying, grinding, that was grafted>silane coupling agent palygorskite.

Effect of Silane Crosslinker on the Thermal Properties of Rice Straw/HDPE Biocomposite

A formulation was designed to produce silane crosslinkable rice straw/high density polyethylene (RSPE) compound suitable for injection molding process. The formulations consist of high density polyethylene (HDPE) as the base polymer, rice straw as the filler, processing aids and a mixture of crosslink chemicals. Crosslink chemicals consist of vinyltrimethoxysilane (VTMO) as crosslinking agent, dicumyl peroxide (DCP) as the initiator, dibutyltin dilaurate (DBTL) as the condensation catalyst. Lignocellulosic material, rice straw was oven dried at 70°C for 24 h, grinded and sieved. A counter rotating twin shaft high speed mixer was utilized to mix the rice straw, HDPE and the processing aids. Blends were then compounded on co-rotating and intermeshing twin screw extruder. Test specimens were prepared via injection molding process followed by oven curing at 90°C. Fourier Transform Infra Red (FTIR) was used to determine the chemical group involved in the crosslinking reaction. Degree of crosslinking in the silane crosslinked compound was measured by determining their gel content. Thermal properties were analyzed on the Differential Scanning Calorimetry (DSC) for the melt temperature, Tm, whereas Thermogravimetric (TGA) analysis for its thermal stability behavior. The degree of crosslinking in RSPE increases with an increased in VTMO and DCP concentration. The results from FTIR showed the presence of Si-O-Si bond and Si-O-C indicative of crosslinks formation. Thermal behavior of the compound illustrated that the crosslinked RSPE was more stable than the uncrosslinked RSPE and pure HDPE, while the Tm was unchanged.

Epoxy Silane ——Protocol for DNA

The decision to use epoxy silane is frequently made by what you are interested in spotting and how you choose to attach to a surface. Epoxy silane slidesfunction by offering an epoxide ring that reacts with an amine group on thespotted material. Most proteins, as well as DNA, have available amine groupsthat covalently attach to the epoxide ring at high pH. Since these slides are'looking for' amine groups, we do not recommend the use of printing buffers thatmight also contain amines (such as Tris), since these will compete with thespotted material for attachment sites. If you are using a proprietary printingbuffer, you may want to check with the manufacturer.Whichever chemistry you require on a microarray slide (epoxy silane, aldehyde,aminosilane, poly-L-lysine), Thermo Fisher Scientific now offers the sameattachment chemistries on a new es surface. es can be described asmicroscopic mountains and valleys with uniformly coated functional groups.Arrayer spot-size is often controlled by the surface energy of the coating—hydrophobic coatings give smaller spot sizes, while hydrophilic coatings givelarger spot sizes. The benefit of es is more uniform spot size without altering your chemistry. The es surface will not affect the focusing or use of microarrayspotters and scanners because it is microscopic.The principles behind epoxy silane slidesThe epoxy silane slide surface provides available epoxide rings that react with anamine group on the spotted material. The DNA or protein can subsequently beattached covalently to theslide by incubating or by UV cross-linking. The epoxybond is probably the most robust attachment chemistry available to themicroarray scientist today. Thermo Fisher Scientific manufactures this productwithout the use of solvents or diluents that might leave a residue resulting in highbackground.

Silane coupling agents

Silane coupling agents are silicon-based chemicals that contain two types of reactivity–inorganic and organic–in the same molecule. A typical general structure is (RO)3SiCH2CH2CH2-X,where RO is a hydrolyzable group, such as methoxy, ethoxy, or acetoxy, and X is an organofunctional group, such as amino, methacryloxy, epoxy, etc.
A silane coupling agent will act at an interface between an inorganic substrate (such as glass, metal or mineral) and an organic material (such as an organic polymer, coating or adhesive) to bond, or couple, the two dissimilar materials.