Hose Life
Dr. Zumbrum uses Scanning Electron Microscopy (SEM)
to characterize the surface morphology of bioprocess hoses.
Significant changes in morphology are
often the result of polymer degradation which leads to increased
leachables and extractables. Hose life can then be established
by understanding changes that occur in the morphology and chemical
properties of these materials.
The morphology of a new silicone hose exhibits a relatively smooth surface. The only features evident are from dust particles resting on the surface and the light tooling marks. The product contact surface consists of polydimethyl siloxane polymer reinforced with fumed silica filler.
The used silicone hose shows evidence of scouring of the surface and concavities on the order of tens of microns in diameter. The surface pitting is most likely due to polymer degradation from the strong base used to CIP the silicone hose. Strong bases degrade the silicone backbone to produce low molecular weight cyclic oligomers. These oligomers are a known source of leachables and TOCs.