Process Factors in Long-Fiber Thermoplastic Compression Molding Materials

Area of Science:

• Materials Science
• Polymer Engineering
• Composite Materials

Background:

• Long-fiber thermoplastic (LFT) materials offer lightweight, recyclable solutions, with the LFT-D process gaining traction beyond automotive applications.
• Understanding LFT-D process-microstructure-property relationships is crucial for optimizing material performance.

Purpose of the Study:

• To summarize mechanical properties and findings on LFT-D process-microstructure-property relationships.
• To present a design of experiments (DoE) study optimizing LFT-D compounding parameters.

Main Methods:

• A DoE study was conducted using Polyamide 6 (PA6) reinforced with glass fibers (GF) at varying mass fractions (20-60%).
• Key LFT-D compounding parameters (screw speed, fiber roving amount, polymer throughput) were investigated.
• Tensile, flexural, and impact properties were characterized as output parameters.

Main Results:

• All mechanical properties exhibited a linear relationship with glass fiber mass fraction (w_f).
• Interactive relationships between DoE factors and w_f significantly influenced mechanical properties.
• Advanced response contour plots were developed to account for w_f dependence on DoE factors.

Conclusions:

• Parameter recommendations for screw speed are provided based on w_f and polymer throughput for maximizing mechanical properties or minimizing variation.
• A low screw speed is recommended for w_f < 30% to enhance mechanical properties and reduce coefficient of variation.