Chapter 3
Flame-Retardancy Testing
Standard FR activity testing methods and procedures have been developed to
evaluate the FR activity of polymers [1]. Generally, the FR activity of a material
can be evaluated on the basis of some specific parameters, such as ease of ignition,
flame spread rate, HRR, smoke-production rate (SPR), and ease of fire extinction.
All these properties depend on the chemical structure of the polymer, type of FR
used, and nature of the degradation components. When heated, a polymer degrades
and evolves combustible and non-combustible components. For example, flammable hydrocarbon gases, such as methane and ethane, may be released and they
can be used to monitor the rate of flame propagation. Similarly, non-combustible
components, such as water, carbon dioxide, NH 3 , and CO may also be released and
they decrease the flammability of the material by reducing the heat at the flame
zone. Therefore, HRR is an important parameter to analyze polymer degradation.
Hence it is important to measure the HRR and total heat-releasing rate (THR) to
assess the susceptibility of polymers to fire. According to the target application, the
flammability of polymers can be measured using various established methods.
Some commonly used methods are described below.
3.1 Cone Calorimeter
The cone colorimetry test method (ASTM E1354) was developed in the United
States; in this method, polymer flammability is determined by measuring the volume of oxygen in a mixture of combustion gases evolved from the sample.
Figure 3.1 shows below is a schematic of Cone. A sample is placed below a “cone”
shaped radiant heater. Typically the samples are exposed to an external flux form
the heater of 35 kW/m
2
. However, for more fire resistant materials the heater
frequently increased to 50 kW/m
2 . Once enough pyrolysis products are generated,
ignition occurs. The combustion product travel through the Cone heater and
through an instrument exhausted pipe. The values measured/calculated that are
© Springer Nature Switzerland AG 2020
S. Sinha Ray and M. Kuruma, Halogen-Free Flame-Retardant
Polymers, Springer Series in Materials Science 294,
https://doi.org/10.1007/978-3-030-35491-6_3
11
Flame-Retardancy Testing
Standard FR activity testing methods and procedures have been developed to
evaluate the FR activity of polymers [1]. Generally, the FR activity of a material
can be evaluated on the basis of some specific parameters, such as ease of ignition,
flame spread rate, HRR, smoke-production rate (SPR), and ease of fire extinction.
All these properties depend on the chemical structure of the polymer, type of FR
used, and nature of the degradation components. When heated, a polymer degrades
and evolves combustible and non-combustible components. For example, flammable hydrocarbon gases, such as methane and ethane, may be released and they
can be used to monitor the rate of flame propagation. Similarly, non-combustible
components, such as water, carbon dioxide, NH 3 , and CO may also be released and
they decrease the flammability of the material by reducing the heat at the flame
zone. Therefore, HRR is an important parameter to analyze polymer degradation.
Hence it is important to measure the HRR and total heat-releasing rate (THR) to
assess the susceptibility of polymers to fire. According to the target application, the
flammability of polymers can be measured using various established methods.
Some commonly used methods are described below.
3.1 Cone Calorimeter
The cone colorimetry test method (ASTM E1354) was developed in the United
States; in this method, polymer flammability is determined by measuring the volume of oxygen in a mixture of combustion gases evolved from the sample.
Figure 3.1 shows below is a schematic of Cone. A sample is placed below a “cone”
shaped radiant heater. Typically the samples are exposed to an external flux form
the heater of 35 kW/m
2
. However, for more fire resistant materials the heater
frequently increased to 50 kW/m
2 . Once enough pyrolysis products are generated,
ignition occurs. The combustion product travel through the Cone heater and
through an instrument exhausted pipe. The values measured/calculated that are
© Springer Nature Switzerland AG 2020
S. Sinha Ray and M. Kuruma, Halogen-Free Flame-Retardant
Polymers, Springer Series in Materials Science 294,
https://doi.org/10.1007/978-3-030-35491-6_3
11