Hello and welcome to this post in which I present additional multipoint data of reinforced PolyArylAmides (PA MXD6; PARA) as support during your material selection journey.
Basic data of PARA I discussed in the following posts:
Design Properties for Engineers: The ABCs of Polyarylamide (PARA; MXD6)
In this post, we focus on:
- Tensile strength properties as a function of temperature
- Flexural strength properties as a function of temperature
- Impact properties as a function of temperature
- Tensile strength and modulus at equilibrium as a function of relative humidity
Tensile strength properties as a function of temperature
Figure 1 presents the tensile strength and tensile modulus as a function of temperature of a PARA with 50 wt% glass-fiber reinforcement (DAM = Dry as moulded). We can see a decrease in strength with increasing temperature and once we reached the glass transition temperature (85°C), this decrease becomes sharper (semi-crystalline region is still providing strength).
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| Figure 1: Tensile strength properties of PARA GF 50 wt% as a function of temperature [1]. |
Flexural strength properties as a function of temperature
Figure 2 shows the flexural strength and flexural modulus as a function of temperature of a PARA with 50 wt% glass-fiber reinforcement. Flexural strength values are higher compared to tensile strength values since this test combines compressive, tensile, and shear stresses (ISO 178 or ASTM D790) leading to a greater plasticizing effect than in a pure tensile test.
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| Figure 2: Flexural strength properties of PARA GF 50 wt% as a function of temperature [1]. |
Impact properties as a function of temperature
Figure 3 shows the Izod impact strength (notched and unnotched) of a 50 wt% glass fiber reinforced PARA compound. The figure illustrates how temperature affects the PARA compound's ability to withstand impacts. We can see that this characteristic essentially stays unchanged below the glass transition threshold of 85°C. The viscous condition of the amorphous portions causes an increase in impact resistance above this temperature.
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| Figure 3: Impact properties of PARA GF 50 wt% as a function of temperature [1]. |
Tensile strength and modulus at equilibrium as a function of relative humidity
Figure 4 presents the tensile strength at equilibrium and Figure 5 the tensile modulus at equilibrium of a PARA-GF 50 wt%, PARA-GF 60 wt%, and PARA-GF 50 wt% with impact modification. All aforementioned PARA compounds use a PA MXD6 resin which contains amide functions. In case the amide function is exposed to water, a reversible plasticizer complex is formed (as with all Polyamides). The water absorption leads to three major consequences which need to be considered during the design phase:
-The plasticzing leads to a reduction in mechanical properties (as shown in Figure 4 and 5).
-Swelling of the material and as a consequence, dimensional changes of the part
-Reduction in the glass transition temperature. PARA-GF 50 wt% which is saturated with water reduces its glass transition from 85°C down to 25 °C. This is influencing the creep resistance of the material and in case the part was injection moulded below 120°C, post-crystallization takes place. This leads to a deformation of the part.
Therefore, testing the PARA compound at actual use conditions, especially if permanent water contact is present, is crucial in order to avoid problems related to water uptake.
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| Figure 4: Tensile strength at equilibrium of PARA compounds as a function of relative humidity. [1] |
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| Figure 5: Tensile modulus at equilibrium of PARA compounds as a function of relative humidity [1]. |
The advantage of having multipoint mechanical properties of PARA compounds plotted in a graph is that it enables a better decision making during the part design and material selection phase.
More on high performance polymers can be found here and here.
Thanks for reading and #findoutaboutplastics
Greetings,
Herwig Juster
Interested in having a second opinion on your material selection and high performance polymers, including price evaluation or discuss with me about your current sustainability, and part design needs - here you can contact me
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Literature:
[1] https://www.syensqo.com/en/brands/ixef-para/documents
[2] https://www.albis.com/dam/jcr:3e0fc093-ea63-466f-9a67-43f796bc08ea/Ixef-PARA-Design-Guide_EN.pdf
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