Extrusion & Post
2 views
Large Disparity Between Longitudinal and Transverse Strength of LCP Extruded Cast Film
Problem Phenomenon
【Problem Phenomenon】LCP cast film can reach 20000MPa-level longitudinal tensile strength while the transverse is only 3500MPa-level; it tears immediately in the transverse direction and cannot be used
Cause Analysis
In cast extrusion, molecular chains are highly oriented in one direction, strong longitudinally and weak transversely; the Buffalo review records that cast LCP film has longitudinal/transverse modulus of about 20000/3500MPa, while blown film can achieve isotropy of about 7000/7000MPa
Solution
For film products, change to the blown film process using biaxial stretching to achieve isotropy; for the cast process, add transverse stretching or a rotating die; avoid unidirectional casting in occasions requiring high strength balance
Key Takeaway
For LCP film, choose blown film if isotropy is wanted; cast film's unidirectional orientation is inherently weak transversely; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence; include this case in the defect archive as a troubleshooting reference for subsequent similar problems
Was this helpful?
0 people found this helpful
Thank you for your feedback!