Uniaxial cold drawing of plastic - What happen to the material's modulus?

In summary, the conversation discusses the effects of uniaxial cold drawing on the properties of a semicrystalline polymer, polybutylene succinate. Along the machine direction, strength and elongation at break increase with increasing draw ratio, while modulus decreases slightly. Along the transverse direction, strength decreases as expected, but elongation at break increases slightly and modulus increases significantly from 500MPa to 750MPa at the highest draw ratio. The speaker is seeking an explanation for this unexpected result in the modulus along the transverse direction.
  • #1
yijing84
4
0
Hi all.
I am now working on the uniaxial cold drawing on the plastic sheet (polybutylene succinate, a semicrystalline polymer).
After uniaxial cold drawing, as expected, strength increased along the drawing direction/ machine direction (MD).
Strength and elongation at break drastically increased with increasing draw ratio along the MD.
However, modulus slightly reduced with the draw ratio.

Along the transverse direction (TD), strength reduced as expected with the draw ratio.
However, elongation at break slightly increased with draw ratio.
Furthermore, modulus significantly increased with draw ratio from 500MPa to 750MPa at the highest draw ratio along the TD.

According to most of the study, modulus should reduce along the TD with draw ratio as the less regid molecular bond along the TD as compared to along the MD (rigid covalent bond). However in my case, it is totally different.
I am here kindly ask for any possible explanation on this phenomena on the modulus along the TD?
Thank you so much.
 
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  • #2
Have you found the answer to your question?
 

Related to Uniaxial cold drawing of plastic - What happen to the material's modulus?

What is uniaxial cold drawing of plastic?

Uniaxial cold drawing of plastic is a process in which a plastic material is stretched in one direction at room temperature to increase its length and decrease its cross-sectional area. This results in a stronger, more durable material with improved mechanical properties.

How does uniaxial cold drawing affect the material's modulus?

Uniaxial cold drawing causes the polymer chains in the plastic material to align in the direction of stretching, resulting in a higher modulus. This means that the material becomes stiffer and more resistant to deformation under stress.

What factors affect the outcome of uniaxial cold drawing?

The outcome of uniaxial cold drawing can be influenced by several factors, including the type of plastic material, the temperature and rate of stretching, and the amount of stretching applied. The molecular structure of the plastic and its initial modulus also play a role in the final outcome.

Are there any limitations to uniaxial cold drawing of plastic?

Yes, there are some limitations to this process. It is not suitable for all types of plastic materials, and some may not respond well to cold drawing. Additionally, excessive stretching can cause the material to become brittle and prone to breaking.

What are the benefits of uniaxial cold drawing of plastic?

Uniaxial cold drawing offers several benefits, including improved mechanical properties such as increased strength and stiffness, as well as enhanced dimensional stability. It can also result in cost savings, as it allows for the use of less material to achieve the same strength and performance.

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