Robyn Gai and Frank Chen
KMT industrial HK limited
Abstract: KMT R&D center have conducted several comparison test between PM5SN from KMT industrial and M5SM from NikoMag. The article analyzes the differences in mechanical performance of the compound when applying different grades of MDH in the same EVA-based compound.
Key Words: magnesium hydroxide, Mg(OH)2, HFFR compounds, polymer science
Magnesium hydroxide is a filled flame retardant, which can reduce the surface temperature of the filled synthetic material in the flame by releasing water and absorbing a large amount of heat during thermal decomposition. It can inhibit the decomposition of polymers and cool the combustible gas produced. The magnesium oxide produced by the thermal decomposition of magnesium hydroxide is a good refractory material, which can also help improve the fire resistance of synthetic materials, and the water vapor released when it decomposes also has a smoke-suppressing effect. Therefore, magnesium hydroxide is recognized as an excellent flame retardant with triple functions of flame retardancy, smoke suppression and filling in the rubber and plastic.
2. Test Preparation
2.1. Materials Preparation
Prepare the following materials:
Ethylene-vinyl acetate copolymer (EVA), grade 7470K, vinyl acetate (vA) content is 26%, from Formosa Plastics Group; Magnesium hydroxide (MDH) KMT PM5SN, particle size of 1~2μm, from KMT INDUSTRIAL HK LIMITED. Magnesium hydroxide (MDH) M5SM, particle size of 2μm, from NikoMag.
2.2. Test Machine
Pare the following machines:
Sample making: Banbury, Plate Curing Press; Mould; SY-6210-A Electronic Pulling Force Machine.
Test: universal testing machine, melt flow tester, oxygen index meter.
2.3. Test Condition
Keep the test lab site temperature at 23 degrees Celsius and the humidity at 40%.
2.4. Samples Preparation
Preheat the Banbury to 100 °C-120 °C, the mixing time is 30 minutes, the mixing temperature is 200 ± 10 °C.
Put the dough into the mould which is preheated well in advance (the thickness of the mould frame is 1 ± 0.1 mm), then use plate Curing Press tabletting (prepress: 10MPA, pressure: 10-15mpa, temperature: 220 °C, preheat for 2 Min), After tabletting cooled to 40-50 °C and got the samples.
3. Test Result
Table 1 Basic technical data of two kinds of MDH
|MDH||Particle size(D50）||Purity||Coated or Not|
|KMT PM5SN||1~2 μm||≥99%||Coated|
|NikoMag M5SM||2.0 μm||≥99.8%||Coated|
3.1. Differences of Elongation at Break
|Sample||Elongation at Break(%)|
As shown in the Table 2, Elongation of PM5SN is higher than M5SM.
3.2. Differences of Tensile Strength
From table 3, we can tell the tensile strength of PM5SN is higher than that of M5SM.
3.3. Differences of MFI
From table 4, it can be seen that the MFI of PM5SN is lower than that of M5SM, which means PM5SN’s mechanical processing performance is better.
3.4. Differences of LOI
Table 5 shows PM5SN’s flame retardant performance is better.
Table 6 M5SM and PM5SN comparison test
According to the above tests, KMT-PM5SN shows better flame retardant performance and mechanical processing performance in this EVA-based formula.
KMT INDUSTRIAL HK LIMITED, headquartered in Gansu, China, research and manufacturer magnesium hydroxide, natural brucite powder and aluminum hydroxide.