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Chapter 13 · Elastomers from Nature! - Polyterpenes
13
molecular weight distribution of natural rubber
is bimodal, i.e. has two maxima. . Figure 13.9
shows a typical distribution curve for a ribbed
smoked sheet RSS1 (standard quality).
Natural rubber is difficult to process because
of its high molecular weight. Therefore, the
molecular weight of NR is often reduced by splitting the polymer chains. This process developed
at low temperatures (e.g. ambient temperature)
because its crystallization is strongly inhibited. However, natural rubber has the effect of
elongation crystallization: When tensile stress
is applied, the random molecular chains orient themselves toward parallel chains and form
crystalline areas. This effect results that, e.g.,
the rubber in car tires solidifies under load. The
. Fig. 13.8 Rubber sheets suspended in the air for drying (©Voy_ager/Fotolia)
Occurence
Molecular weight [g/mol]
10
4
10
5
10
6
10
7
. Fig. 13.9 Molar mass distribution curve for a natural rubber RSS1
Chapter 13 · Elastomers from Nature! - Polyterpenes
13
molecular weight distribution of natural rubber
is bimodal, i.e. has two maxima. . Figure 13.9
shows a typical distribution curve for a ribbed
smoked sheet RSS1 (standard quality).
Natural rubber is difficult to process because
of its high molecular weight. Therefore, the
molecular weight of NR is often reduced by splitting the polymer chains. This process developed
at low temperatures (e.g. ambient temperature)
because its crystallization is strongly inhibited. However, natural rubber has the effect of
elongation crystallization: When tensile stress
is applied, the random molecular chains orient themselves toward parallel chains and form
crystalline areas. This effect results that, e.g.,
the rubber in car tires solidifies under load. The
. Fig. 13.8 Rubber sheets suspended in the air for drying (©Voy_ager/Fotolia)
Occurence
Molecular weight [g/mol]
10
4
10
5
10
6
10
7
. Fig. 13.9 Molar mass distribution curve for a natural rubber RSS1