PBT Thermoforming Necking Reduction via Low-Melting Polymer Additive
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Solution Overview
Problem
Polybutylene terephthalate (PBT) thermoforming processes face issues with necking upon elongation, leading to non-uniform material thickness and mechanical weakness due to increased stress during strain, which is exacerbated at lower thermoforming temperatures.
Innovation Solution
Incorporating a thermoplastic polymer with a melting point below 220 °C, such as a polyester based on aliphatic and aromatic dicarboxylic acids and dihydroxy compounds, into the PBT molding composition to reduce necking and homogenize elongation behavior, thereby broadening the thermoforming temperature window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polybutylene terephthalate is used for thermoforming, then the material provides structural integrity, but necking upon elongation occurs leading to non-uniform material thickness
Solution Approach 1:
The patent applies composite materials by combining polybutylene terephthalate with a thermoplastic polymer having a melting point below 220°C. This composite formulation modifies the elongation behavior of the base material, reducing necking upon elongation and achieving more uniform material thickness distribution during thermoforming processes.
Solution Approach 2:
The patent changes the thermal parameters of the molding composition by incorporating a polymer with a lower melting point (below 220°C) than the standard PBT melting point. This parameter change broadens the processing temperature window and modifies the stress-strain characteristics during forming, preventing excessive necking.
2Use of energy by moving object
If lower thermoforming temperatures are used, then energy consumption is reduced, but stress increase upon strain is exacerbated leading to worsened necking
Solution Approach 1:
The patent changes the thermal and mechanical parameters of the material system by adding a low-melting-point polymer. This modification allows the material to maintain lower stress increase upon strain even at reduced thermoforming temperatures, effectively decoupling energy consumption from stress behavior and enabling energy-efficient processing without compromising formability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The addition of the lower-melting thermoplastic polymer smooths the stress-strain curve, reduces stress increase upon strain, and achieves more uniform material thickness, enhancing the mechanical properties and processability of PBT thermoformed products.
Implementation Method 1
a thermoplastic polymer having a melting point below 220 °C as additive in polybutylene terephthalate molding compositions for reducing the necking upon elongation of sheets or films
Implementation Method 2
heating a sheet or film containing or preferably made of the polybutylene terephthalate molding composition to a pliable forming temperature and thermoforming the heated sheet of film
Data Source
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AI summary
The invention relates to the use of a thermoplastic polymer having a melting point below 220 °C as additive in polybutylene terephthalate molding compositions for reducing the necking upon elongation of sheets or films of the polybutylene terephthalate molding composition, preferably wherein the polybutylene terephthalate molding composition comprises a) 50 to 95 wt% of polybutylene terephthalate as component A, b) 5 to 50 wt% of the thermoplastic polymer having a melting point below 220 °C, as component B, c) 0 to 45 wt% of filler as component C, d) 0 to 20 wt% of further additives as component D, wherein the total of components A to D is 100 wt%.