Flammability/flame retardation UL94 rating

It has been shown that the required loading levels of metal hydroxides to flame retard polyolefins can be reduced by the addition of transition metal oxides as synergistic agents. For example, a combination of 47.6% MH modified with nickel oxide in PP gave a UL94 V-0 flammability rating, which would require -55% of unmodified MH.4 These systems, however, can only be used where the color of the product is not important. 

The most commonly used specification for base materials is IPC-4101. This specification presents a classification scheme and specification sheets for the various materials in use. Table 6.2 summarizes the various materials by specification sheet number. Each specification sheet in IPC-4101 includes property requirements for that particular material type. As these specification sheets are updated periodically, it is recommended that the latest revision of this document be reviewed. This is particularly true in light of new requirements for materials that must be compatible with lead-free assembly.Table 6.2 is presented for reference only and is not all-inclusive. UL94 comments in Table 6.2 reference the minimum flammability requirements for that material. Materials may exceed these minimum ratings. Also note that where a non-halogen-based flame retardant is used, it is shown along with the resin system description. Definitions of the UL flammability ratings are given in Chap. 8. 

The flame retardance of LCPs is very high, complying with UL94 V-0 as rated by Underwriters Laboratories (self-extinguishing, non-dripping), and they therefore require no additive packages that may leech out of the compound and lead to plate out, variations in electrical contact resistance or even corrosion. LCPs also exhibit low smoke generation and exceed current FAA flammability standards for aircraft interiors (some flammability properties are shown in Table 7.7). 

Flame retardancy tests were performed following the procedure of Underwriter s Laboratory Bulletin 94 entitled Tests for Flammability of Plastic Materials, UL94. According to this procedure, materials may be classified as HB, VO, VI, V2, VA and/or VB on the basis of the test results obtained for five samples. In this study, UL test was done at 0.8 mm thickness for all samples. Heat deflection Temperature (HDT, ISO 75/Be flat, 1.8 Mpa load) and Vicat softening temperature (Vicat, ISO 306, Vicat B, heating rate 120 °C/min load of 50 N) were used to determine thermal properties of compositions. Standard impact bars were used to measure these properties. Duplicate measurements were done and average of two samples were reported. 

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