Heat Flow Estimation in Polymer Films during Orientational Drawing at the Local Heater

Area of Science:

• Materials Science
• Polymer Physics
• Mechanical Engineering

Background:

• Polymer film orientational drawing with local heaters is crucial for producing high-strength fibers.
• A key challenge is the discrepancy between theoretical strength predictions and actual fiber strength.
• This disparity is linked to temperature gradients across the film during localized heating.

Purpose of the Study:

• To investigate the impact of unilateral heating on polymer film drawing.
• To analyze the relationship between temperature differences and plastic deformation rates.
• To determine optimal processing parameters for enhanced polymer fiber strength.

Main Methods:

• Numerical calculation of heat conduction and temperature distribution in polymer films.
• Analysis of temperature gradients across film thickness and width during drawing.
• Correlation of temperature homogeneity with film thickness and drawing speed.

Main Results:

• A small temperature difference (1°C) between film surfaces significantly alters plastic deformation rates.
• Tensile stress concentrates on the colder side, potentially generating defects and microcracks.
• Homogeneous temperature distribution, crucial for fibrillar structure transformation, is achieved only for films <50 μm thick.

Conclusions:

• Unilateral heating in local heater drawing processes leads to non-uniform deformation and defects.
• Film thickness is a critical parameter, with <50 μm optimal for uniform temperature distribution.
• This research provides a scientific basis for optimizing drawing speed and film thickness for high-performance polymer filaments like UHMWPE.