(518c) Sorption and Diffusion By 3D Printable Polymeric Materials

Sorption and diffusion by 3D
printable polymeric materials

Hom N. Sharma*, Jeremy M. Lenhardt, Yunwei Sun, and
Elizabeth A. Glascoe

Lawrence Livermore National
Laboratory

L288, 7000 East Ave., Livermore, CA
94550

925-423-5368

sharma11@llnl.gov

Dynamic
sorption and diffusion of moisture in polymeric materials is important due to
their use in many products we use daily, including electronic devices,
pharmaceuticals, food packaging, medical devices, and automotive parts. Moisture
interactions with polymeric materials may cause undesirable changes to their
mechanical properties, chemical compatibility, and durability that may
ultimately result in failure of the part or product. The sorption diffusion
process is dynamic and consists of different sorption modes and varies
dramatically in different materials. Therefore, a detailed understating of the
moisture uptake and diffusion is crucial.

In
this study, we investigate the moisture sorption and diffusion phenomena using
a combined experimental and modeling approach. A 3D printable siloxane polymer
(synthesized using 3D printing and compression molding techniques) with hydrophobic
surface treated Aerosil R8200 filler is used for a
detailed sorption diffusion study. A wide range of temperatures and relative
humidities (RH) are considered to quantify the moisture transport mechanism. Gravimetric
type dynamic vapor sorption (DVS) experiments were employed to measure the moisture
uptake and used for the modeling. A reactive transport model is used which
includes a triple-mode (Henry, Langmuir and pooling) sorption model and
chemical reaction kinetics. Results show that the surface-treated silica filler
greatly influences the moisture uptake mechanism and total moisture uptake in
3D printed and compression molded polymers. Our model accurately captures
experimental moisture sorption profiles with specific sorption mode
contributions. Moisture sorption behavior from siloxane silicones with untreated
silica (fumed silica) fillers will be compared to this custom 3D printable
siloxane material.

LLNL-ABS-771869-DRAFT

This work performed under
the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory
under Contract DE-AC52-07NA27344.