Optical Fiber Buffer Tube Composition for Kink-Resistant Extrusion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional polybutylene terephthalate (PBT) and polyethylene (PE) blends used in optical fiber buffer tubes, when replaced with injection-molding-grade PBT, exhibit reduced zero-shear viscosity and dimensional stability issues, leading to kinking and crush resistance problems.
Innovation Solution
Incorporating both maleic anhydride grafted polyethylene (MAH-g-PE) and ethylene-n-butyl acrylate-glycidyl methacrylate terpolymer (ENBAGMA) as compatibilizers in the PBT-PE blends to increase zero-shear viscosity and maintain morphology stability during extrusion, allowing the use of injection-molding-grade PBT while preventing kinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If injection-molding-grade PBT is used to replace extrusion-grade PBT, then cost is reduced, but zero-shear viscosity decreases below 3000 PaS at 250°C, leading to poor extrudability and kinking
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer blend by incorporating ENBAGMA terpolymer (5-15 wt%) in addition to MAH-g-PE compatibilizer. This compositional parameter change increases the zero-shear viscosity of injection-molding-grade PBT-PE blends to exceed 3000 PaS at 250°C, enabling proper extrudability while maintaining kink resistance
Solution Approach 2:
The patent creates a composite polymer system combining injection-molding-grade PBT, PE, MAH-g-PE compatibilizer, and ENBAGMA terpolymer. This composite material formulation achieves synergistic effects where the combination of compatibilizers and the specific terpolymer components work together to maintain both high viscosity for extrudability and morphological stability for kink resistance
2Reliability
If injection-molding-grade PBT is used, then cost is reduced, but dimensional stability deteriorates, resulting in non-uniform tube wall thickness and poor crush resistance
Solution Approach 1:
The patent modifies the blend composition parameters by adding ENBAGMA terpolymer (5-15 wt%) to the system. This parameter change ensures that even with injection-molding-grade PBT, the extruded buffer tubes achieve uniform wall thickness and maintain dimensional stability, thereby improving crush resistance
Solution Approach 2:
The ENBAGMA terpolymer acts as an intermediary component that mediates between the incompatible PBT and PE phases. It stabilizes the blend morphology during extrusion, preventing phase separation that would lead to non-uniform wall thickness, thereby ensuring dimensional uniformity and crush resistance
3Reliability
If PBT and PE are blended to improve flexibility and kink resistance, then mechanical properties are improved, but phase segregation occurs due to polar and non-polar nature of the polymers
Solution Approach 1:
The patent employs two compatibilizers: MAH-g-PE (maleic anhydride grafted polyethylene) and ENBAGMA terpolymer. These intermediaries reduce the interfacial tension between polar PBT and non-polar PE phases, preventing phase segregation and maintaining morphological stability throughout the extrusion and cooling process
Solution Approach 2:
The patent creates a stable composite system by combining PBT, PE, and a dual compatibilizer system (MAH-g-PE plus ENBAGMA). The composite formulation ensures thermodynamic compatibility between the polar and non-polar phases, preventing macro-phase separation and maintaining fine dispersion morphology for optimal kink resistance
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 combination of MAH-g-PE and ENBAGMA in PBT-PE blends achieves a zero-shear viscosity greater than 3000 Pascal-seconds at 250°C, preventing kinking and ensuring dimensional uniformity and mechanical stability of buffer tubes.
Implementation Method 1
The inventors discovered that the ENBAGMA may bind to multiple PBT polymeric chains thereby increasing the zero-shear viscosity to greater than 3000 PaS at 250° C.
Implementation Method 2
Stability of the mixed phase morphology prevents phase segregation that results in poor mechanical properties and kinking of the buffer tube
Data Source
AI summary
A polymeric composition includes (a) 1 wt % to 45 wt % of an ethylene-based polymer; (b) 50 wt % to 90 wt % of a polybutylene terephthalate having a melt flow index from 21 g/10 min. to 35 g/10 min at 250 C and 2.16 Kg; and (c) 3.5 wt % to 10 wt % of a compatibilizer comprising a maleated ethylene-based polymer and ethylene n-butylacrylate glycidyl methacrylate.