Halidi, Siti Nur Amalina Mohd
(2013)
Effects Of Moisture On Acrylonitrile
Butadiene Styrene (Abs) Filament
Material In Fused Deposition Modeling
(Fdm) Rapid Prototyping Machine.
Masters thesis, Universiti Sains Malaysia.
Abstract
Acrylonitrile butadiene styrene (ABS) is a type of thermoplastic that becomes brittle
after a few months or even weeks, when left outdoors. Due to its hygroscopic nature,
this material gradually degrades and becomes unsuitable for use in Fused Deposition
Modeling (FDM). In this work, a study on the effects of moisture in ABS properties is
conducted. Experiments were conducted such that filaments were exposed to different
types of humidity conditions for a certain amount of time. Experimental test on the
effect of moisture on physical, thermo mechanical, rheological, and chemical structure
changes were observed. The filaments’ diameter and weight changes are measured to
assess the ABS’s suitability for use in FDM liquefier. Weight difference measurement
was done to observe the material’s moisture sorption ability. After being exposed for a
certain amount of time, the ABS filament diameter increased up to 3.93% (for ambient
condition) and 1.86% (for desiccated environment) from its as-received diameter. Using
DSC, thermo-mechanical behavior, in terms of glass transition temperature (Tg) was
found to decrease over time in all environmental conditions. Raw data curve shifted to
the left indicates a decrease in Tg. FTIR analysis was done to observe the presence of OH
bond with moisture absorption by the filament. O-H bond exists with moisture
absorption as shown in region 3600-3200 cm-1. Capillary rheometer was used to
observed melt flow behavior. ABS filament exposed to wet condition showed the
highest viscosity (ranged between 52.6 to 258 Pa•s) while ABS filament exposed to dry
condition showed the lowest viscosity (ranged between 49.65 to 212 Pa•s). Based on
simulations on FLUENT, temperature profiles remained constant throughout the
liquefier. Viscosity decreases as with increase of shear stress, agreeing to the data from
rheometry experiment. In summary, moisture causes degradation of ABS to the extent
that it becomes unfit for use in RP due to decrease in thermal and rheological properties.
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