Impact Modified PBT Compositions from Recycled Polyesters
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Solution Overview
Problem
There is a challenge in producing poly(butylene terephthalate) (PBT) compositions from recycled or scrap polyesters that have properties comparable to those derived from virgin materials, as existing methods struggle to achieve consistent quality and performance.
Innovation Solution
A PBT composition is developed using a dimethyl terephthalate residual composition, which includes specific amounts of residual components like dimethyl isophthalate, cyclohexane dimethanol, and diethylene glycol, combined with 1,4-butanediol, to create a copolymer with a polycarbonate and impact modifier, resulting in a material with desired thermal and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If recycled or scrap polyester is used to manufacture PBT, then ecological acceptability and material cost are improved, but consistent quality and performance comparable to virgin material are worsened
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration of residual components (dimethyl isophthalate, cyclohexane dimethanol, diethylene glycol, triethylene glycol) in the dimethyl terephthalate residual composition to less than 4.2 wt.%. This quantitative control transforms the variable quality of recycled material into a consistent, controllable parameter that ensures reliable PBT performance while maintaining ecological benefits of using recycled polyester
Solution Approach 2:
The patent creates a composite material system by combining dimethyl terephthalate residual composition with specific additives including polycarbonate (10-30 wt.%), impact modifiers (0.1-5 wt.%), and various functional additives. This composite approach compensates for variations in recycled material quality while maintaining consistent overall performance, allowing ecological acceptability to improve without sacrificing reliability
2Manufacturing precision
If impurities are removed completely from dimethyl terephthalate residual composition, then PBT quality is improved, but manufacturing complexity and cost are worsened
Solution Approach 1:
Instead of complete purification, the patent establishes specific acceptable ranges for residual components (less than 4.2 wt.% total). This parameter-based approach simplifies manufacturing by eliminating complex purification equipment while ensuring PBT quality consistency through controlled impurity levels that account for natural variations in recycled material
Solution Approach 2:
The patent converts the presence of impurities from a harmful factor into a beneficial simplification of the manufacturing process. By accepting and controlling specific residual components rather than removing them completely, the patent reduces purification process complexity while maintaining adequate PBT quality, effectively turning the challenge of impurity removal into a simpler controlled-composition approach
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 resulting PBT composition exhibits heat deflection temperatures and tensile elongation comparable to PBT derived from virgin monomers, demonstrating that recycled PBT can achieve equivalent properties to virgin PBT when specific impurities are carefully controlled within the dimethyl terephthalate residual composition.
Implementation Method 1
a poly(butylene terephthalate) copolymer reaction product of a dimethyl terephthalate residual composition with 1,4-butanediol
Data Source
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AI summary
A dimethyl terephthalate residual composition comprising a. dimethyl terepthalate derived from a terephthalic-containing polyester homopolymer, terephthalic-containing polyester copolymer, or a combination thereof; and b. from more than 0 to less than 4.2 wt.% of a residual component selected from dimethyl isophthalate, cyclohexane dimethanol, diethylene glycol, triethylene glycol, and combinations thereof.