  There is a growing interest in producing materials with mechanical behaviours
similar to those of internal organs. An artificial tissue may be expected to
experience several types of compressive and shear deformation in the course of
normal usage. Thus research into mechanical modelling of these types of
materials which behave similar to biological tissues, or can be used in making
implants, is of importance to understand their usability and performance when
subjected to different types of stresses. Here we study the behaviour of
plasticised silicone elastomers and comment on the feasibility for modelling
the behaviour of tissues. We perform compression tests on samples made of a
silicone elastomer which is diluted with (plasticiser) silicone oil in the
cross-linking stage. We show that the modification of material broadly follows
a simple law of mixtures. Further, we use samples with a specific periodic
structure which has neatly separated behavioural regimes under compression
where it first extends outwards and then undergoes internal buckling. In terms
of material behaviour, this results in two neatly separated regimes where the
deformation is averaged throughout the length in the first regime, and highly
localised in the later regime. This allows us to disentangle the two types of
deformations (simple compression and shear of the same material) and study how
the recovery of the material upon re-crosslinking, if any, affects its elastic
properties.
