There are experiments that study the influence of particle size, volume of addition and modification of MDH to the vertical flame test of EVA cable compound system, here is what they got.
1. The impact of MDH particle size
Subject: 3000 mesh MDH and 5000 mesh MDH( without surface treatment)
For 3000 mesh MDH, when the volume of addition is 63%, the system could reach V-0 grade during verticle flame test; and for 5000 mesh MDH, it could reaches V-0 when the volume of addition is 60% , and below is test result:
The Impact of different addition amount of 3000 mesh MDH to verticle flame test
UL 94 V-0 Vertical Burn; Burning stops within 10 seconds, NO flaming drips are allowed
UL 94 V-1 Vertical Burn; Burning stops within 60 seconds, NO flaming drips are allowed
UL 94 V-2 Vertical Burn; Burning stops within 60 seconds, Flaming drips are allowed.
The Impact of different addition amount of 5000 mesh MDH to verticle flame test
And by comparing above results, we can see that the particle size of MDH has great influence to the flame rating of system and the smaller the particle size, the smaller the amount of addition, the better flame retardant performance. This phenomenont might caused by the smaller MDH has better dispersion in EVA resin, so the affinity between two is improved and MDH could better play its role in flame retardant.
2. The impact of modification of MDH
When the particle size of MDH is 5000 mesh, the experiment compared the influence of MDH and silane coupling agents MDH to verticle flame test. the result see below chart:
The Impact of different addition amount of Silane coated 5000 mesh MDH to verticle flame test
And here is the explanation for this phenomenon: the modifiacation of MDH improved the hydrophobic property, decreased the polarity so that it can have better compatibility with EVA and improve flame retardant performance.
KMT Industrial Ltd. supplies both Brucite and precipiated MDH in different particle sizes (325 mesh, 1250 mesh and 5000 mesh …), purities (88%, 90%, 92%, 99% …) whiteness (85%, 90% 100%), and we also manufactures surface treated MDH (silane, stearic acid…).
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