A. Citterio

G. Guerra

L. Castellani

L. Tiné

M. Galimberti

S. Musto

V. Barbera

V. Cipolletti

This work was focused on poly(1,4-cis-isoprene) from Ziegler-Natta catalysis and from different
natural sources: Hevea Brasiliensis (HNR), Parthenium Argentatum (GR) and Taraxacum KokSaghyz (TKS). Chemical composition of poly(isoprene) samples and main polymer characteristics
were determined. The following aspects were investigated: strain induced crystallization and
reinforcement and behaviour in sulphur based crosslinking. The role of low molecular mass
components of poly(isoprene) samples was investigated.
It was found that NR samples amorphous at low strains generate highly oriented crystallites under
stretching, because crystallization involves chains that are mostly oriented along the stretching
direction. The presence of terpenes or unsaturated fatty acids seem to favour the amorphous nature
at low strains of GR and TKS samples, respectively. The HNR sample, crystalline at rest, was not
able to develop oriented crystallinity. Oriented crystalline phase led to the highest mechanical
reinforcement, shown by TKS sample.
GR showed the fastest vulcanization. Reaction of terpenes with sulphur based chemicals was
demonstrated by performing the reaction between a thiol and a sesquiterpene such as Guayuline A.
GR crosslinked samples revealed the lowest crosslinking density, with a large amount of short
sulphur bridges, suggesting the effect of mobile hydrogen atoms on terpene molecules

Laura Tiné

Archivio istituzionale della ricerca - Politecnico di Milano

Natural rubber from alternative sources. The key role of low molecular mass components

Natural rubber from alternative sources. The key role of low molecular mass components

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Archivio istituzionale della ricerca - Politecnico di Milano