Adhesion Improvement between PE and PA in Multilayer Rotational Molding

Area of Science:

• Polymer Science and Engineering
• Materials Science
• Manufacturing Processes

Background:

• Achieving strong adhesion between polyethylene (PE) and polyamide (PA) layers in rotational molding is challenging due to differing polymer polarities.
• Weak interlayer adhesion can lead to delamination and reduced mechanical performance in multilayer polymer structures.
• Existing methods for enhancing PE-PA adhesion in rotational molding require optimization.

Purpose of the Study:

• To investigate methods for improving the interfacial adhesion between polyethylene and polyamide in multilayer structures fabricated via rotational molding.
• To evaluate the effectiveness of plasma surface modification and controlled melt-stage addition of polyamide on enhancing layer adhesion.
• To quantify the improvements in mechanical properties, specifically peel strength and delamination resistance.

Main Methods:

• Fabrication of multilayer PE-PA structures using rotational molding.
• Application of plasma modification to polyethylene powder to introduce functional groups.
• Controlled addition of polyamide during different stages of the polyethylene melting process.
• Mechanical testing, including peel strength measurements and bending tests, to assess joint strength and delamination resistance.

Main Results:

• Plasma modification of polyethylene enhanced specific adhesion through hydrogen bonding with polyamide.
• Controlled addition of polyamide during PE melting created entanglements, increasing peel strength up to eightfold compared to untreated samples.
• Treated samples exhibited significantly improved peel strength (7.657 ± 1.024 N∙mm⁻¹) compared to untreated samples (3.662 ± 0.430 N∙mm⁻¹).
• Delamination was observed only in samples made with untreated polyethylene during bending tests.

Conclusions:

• Plasma modification and strategic polyamide addition are effective methods for enhancing PE-PA adhesion in rotational molding.
• These methods significantly improve mechanical properties, offering a viable solution for producing robust multilayer polymer structures.
• The findings provide valuable insights for optimizing rotational molding processes for dissimilar polymer combinations.