The main purpose of this page is demonstrate the chemical compatibility of HP MJF PA12 with various fluids found in the automotive and general manufacturing industries as part of characterizing the technical feasibility of this material for fluid management applications.
Chemicals can affect visual, dimensional and mechanical properties. Therefore, properties such as tensile strength, Young’s modulus, elongation at breakpoint, weight variation and surface appearance have been evaluated in this study in order to evaluate for possible chemical attacks.
In relation to mechanical properties:
The following group of chemicals have been tested for general compatibility (non reactive) with HP PA12 but have not been tested for changes in the samples tensile strength, Young’s modulus, or Elongation at break.
In conclusion, the chemical compatibility of HP MJF PA12 with these fluids seems to be acceptable as no sample showed evidence of chemical reactions, stress cracking, or solvation.
In a chemical interaction, one of the main consequences is interference with the polymer chains of the given plastic, which likely reduces its mechanical properties. To determine any possible changes in the mechanical behavior of the tensiles that were in contact with the fluids in the climatic chamber or possible solvation or plasticization, a tensile test was performed, evaluating the tensile strength, the Young’s modulus and the elongation at breakpoints of the samples. The following charts show the results each mechanical property for the fluids tested in comparison with the control zone created between the control group (the orange line) and the datasheet values (the blue line).
The tensile strength of a material is the maximum amount of tensile stress that it can withstand before failure (for example: breaking).
The tensile strength values obtained after the heating process in test 1 show that there were no negative interactions with most fluids (motor oil, Valvoline Gear Oil, lubricating grease and ATF Steering Fluid). No variations seemed to appear when the samples were in contact with brake fluid either. Only with antifreeze did the strength of the samples decrease.
Young’s modulus characterizes how difficult it is to deform a material in terms of elastic behavior. As in the previous subsection, the following charts show the test values obtained with the datasheet (the blue line) and the control group values (the orange line).
Motor oil, Valvoline Gear Oil, lubricating grease and ATF Steering Fluid increased the materials’ strengths and their Young’s moduli slightly with respect to their natural values.
Brake fluid and antifreeze decreased the materials’ Young’s moduli.
The elongations at breakpoints were studied in order to evaluate whether the fluids had any effect on the plastic behavior of the material. Plasticization tends to soften polymers, increasing their ductility and thus causing an increase in elongation, while at the same time lowering their tensile strengths and Young’s moduli.
Concerning Valvoline Gear Oil, lubricating grease and ATF Steering Fluid: Elongation values were between the control group values and those of the datasheets.
As can be seen, the average value for the tensiles which were in contact with motor oil was also in the control zone. The main difference with the other results was the range of the values obtained, which was wider compared to the results of the other groups and reached a maximum near 80% of elongation. This high variability could be due to the measurements of the type-V tensiles. However, as the average value is under the baseline and in the control zone, we can consider that contact with motor oil does not have a significant effect on this mechanical property.
Brake fluid did not cause any alterations to the samples (in terms of elongation) either.
Antifreeze produced an increase in the elongation, which reaffirms the natural behavior because the tensile strengths and Young’s moduli both decreased. They were inverse to the elongation at breakpoint. If all the properties increased or decreased at the same time, this would mean that a sure chemical reaction had occurred, but this is not the case, as only a plasticizing phenomenon took place. This will be confirmed in the weight absorption analysis.
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