Fire retardancy of melamine-modified ureaformaldehyde resin (MUF) containing intumescent fire-retardant ammonium polyphosphate (APP) (MUF/APP) was conducted by cone calorimeter with surface treatment of medium density fiberboard (MDF). The results showed that the six MUF resins synthesized with different F/(M ? U) and M/U molar ratios containing APP significantly improved the fire retardancy of the MDF by prolonging ignition time, reducing heat release rate and total heat release, and decreasing mass loss rate. The fire-retardant properties of the six synthesized MUF/APP acted differently even though each MUF resin containing the same mass ratio of APP. The melamine content in the MUF should not be too high, otherwise it would decrease the fire-retardant properties of MUF/APP. Based on this study, the higher the APP amounts, the better the fire-retardant performance of the resin was. The fire retardancy of MUF/APP increased with the increase in the amount of glue that spread on the material surface. However, only the amount of glue spread exceeded 250 g/m 2 , whereas the ability of MUF/APP in inhibiting heat release did not increase significantly any longer.
This paper reports a study on self–organized striation plasmas generated under kPa pressure level. It focuses especially on the characteristics of argon striation plasmas, the role of metastable atoms on the generation of striation argon plasmas, and the effect of addition of gas species to the argon striation plasmas. Under our discharge conditions, the generation of argon striation plasmas is related to ionization instability, which is caused by the step‐wise ionization, deviation of the distribution from Maxwellian electron energy distribution, and inhomogeneous gas heating. Nitrogen can effectively quench the argon metastable atoms; therefore, it significantly affects the formation of striation plasma.
This letter reports the detailed observations and investigations of striations in the positive column region of helium glow discharges with a pin-to-plate copper electrode geometry in the pressure range 9–101 kPa. The striations are characterized by several plasma layers with alternate brightness and darkness. In this discharge, features such as negative glow, Faraday dark space, and striated positive column regions can be clearly observed. The evolution of a striation structure in the positive column region was found to be sensitive to gas pressure and electrode spacing. The striated discharge propagates in the form of an ionization wave with a velocity of 20.78 m/s and a frequency of 5.2 kHz.
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