from the Earth to the Sun, the tota

from the Earth to the Sun, the total weight would be about 1 g.
The specific surface area is normally determined by iodine adsorption, and is
stated in m^ g~^. With pre-dried samples, this is a quick and simple method.
However, both surface groups and adsorbed PAHs influence the method and it is
therefore important that volatile content is below 1.5% and toluene extract
below 0.25%. The method is limited to furnace blacks and lampblacks. It is not
usually stated for pigment blacks, but it is possible to avoid this limitation if the
black is heated to 950°C in the absence of air, before determination.
DBP absorption. Only indirect methods are available for determination of the
structure, the best known of which is DBP absorption. In this method, dibutyl
phthalate (DBP) is added drop by drop to a certain amount of carbon black,
placed in a calibrated kneading machine. During this titration, the torque
exerted by the kneading machine is registered, on the principle that when all
voids between the carbon black aggregates have been filled with DBP the surface
will have been wetted, which will be reflected in a change in torque. From the
amount of DBP required to achieve this stage, it is possible to determine the
degree of aggregation of the black. The higher the DBP absorption (in ml
(100 g)~^), the higher is the structure of the carbon black.
However, the structure of the carbon black in its normal pelletized state is
made up of two components: the primary (or permanent) structure, as formed
in the reactor when the primary particles fuse to form aggregates, which is
regarded as indestructible; and a secondary (or temporary) structure formed
by weak agglomeration of the primary aggregates, which can easily be destroyed
by the forces of mixing and processing. To take this into account, the so-called
24M4 or 'crushed' DBP absorption methods are used, in which the sample of
black is mechanically pressed four times under a specified pressure, before
normal DBP measurement. Values are lower than DBP numbers of the pelletized
material and the difference between the two is often referred to as the 'delta'
DBP.
Oil absorption. This is also used to characterize pigment blacks. Carbon black is
ground into linseed oil and the oil absorption is the maximum amount of oil
permitting a non-deliquescent cone to be formed from the mixture. This test gives
information more relevant to production of paints.
Nitrogen surface area. This is based on covering the surface with nitrogen, a
molecule of which has a known space requirement, and which can readily be
converted to m^ g"^. The smaller nitrogen molecule can also penetrate pores and
surface imperfections inside the carbon black particle.
Geometrical surface area. This can be determined from particle size, by
measurement of particle size, determination of distribution curves, and
calculation of surface area values, with the aid of an electron microscope.
Although of fundamental importance, this method is too time consuming for
production of characteristic data for everyday use.