Different types (focusing on primarily VMQ
, not fluoro or phenyl)
Based on ASTM D1418, there are different classes for silicone rubbers: MQ (methyl substituent group), VMQ
(methyl vinyl substituent groups), PMQ (methyl phenyl substituent groups), PVMQ (methyl, phenyl, vinyl substituent groups), and FVMQ (fluoro, vinyl and methyl substituent groups).
Commercial trials in VMQ were so effective that DBPH-50-EZD was overwhelmingly chosen over liquid DBPH, as it provided a fast, safe and effective way to properly disperse the peroxide, while providing equivalent transparency.
DBPH-50-EZD provided a clear VMQ compound with good dispersion and no opaque white specks, versus DBPH-50 containing calcium carbonate.
Once all the vinyl groups of VMQ are reacted, no significant increase in MH will be obtained.
3) Degradation of VMQ
silicones in engine sealing applications.
As noted, due to the temperatures involved, the incumbent materials have traditionally been FKM, VMQ and FVMQ.
They were introduced to fulfill the performance deficiencies of standard ACM and/or AEM TDI hoses (150[degrees]C to 160[degrees]C) and provide a more cost-effective alternative to the more expensive current high-temperature solutions, such as FKM, VMQ and FVMQ hoses.
The typical construction for turbocharger hoses uses VMQ silicone with a fluoroelastomer liner (FVMQ fluorosilicone or FKM fluorocarbon).
In the case of liquid VMQ silicone, even with a price premium typically realized (vs.
Compressed fuel permeation rates of FLSR have been shown to be comparable to LoPerm VMQ and significantly better than uncompressed rates.