Primary explosives collision factor

Table 6.3 Values for the activation energy E and collision factor A for some primary and secondary explosive substances...

Primary explosives have low values for the activation energy and collision factor compared with secondary explosives. Therefore, it takes less energy to initiate primary explosives and makes them more sensitive to an external stimulus, i.e. impact, friction, etc., whereas secondary explosives have higher values for the activation energy and collision factor, and are therefore more difficult to initiate and less sensitive to external stimulus. 

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