Propylene Terpolymer Pipe Composition Balancing Impact and Flexural Modulus
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Solution Overview
Problem
Existing propylene-based terpolymers struggle to balance improved impact resistance with maintaining a long time to brittle failure and good flexural modulus, which is crucial for pipes and pipe fittings.
Innovation Solution
A polypropylene composition comprising two terpolymer fractions with different melt flow rates, prepared under distinct reaction conditions, featuring specific ethylene and 1-hexene content ratios, enhances impact resistance while maintaining a long time to brittle failure and good flexural modulus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If propylene/ethylene/1-hexene terpolymers are used to improve impact resistance, then impact resistance is improved, but time to brittle failure and flexural modulus deteriorate
Solution Approach 1:
The patent divides the polymer composition into two distinct terpolymer fractions with different melt flow rates (0.030-1.0 dg/min and 0.30-70 dg/min). Each fraction contributes different properties: the first fraction provides structural integrity and long-term durability, while the second fraction enhances impact resistance. This segmentation allows the composition to achieve both improved impact resistance and maintained time to brittle failure simultaneously.
Solution Approach 2:
The patent specifies precise parameter ranges for the terpolymer fractions including melt flow rate (MFR), ethylene content (1.6-3.0 wt%), 1-hexene content (1.7-4.0 wt%), and the ratio of ethylene to 1-hexene derived units (at least 0.70). By controlling these parameters within specific ranges, the composition achieves optimal balance between impact resistance, time to brittle failure, and flexural modulus.
2Strength
If propylene/ethylene/1-hexene terpolymers are used to improve impact resistance, then impact resistance is improved, but flexural modulus deteriorates
Solution Approach 1:
The patent segments the polymer system into two terpolymer fractions with complementary properties. The first fraction with lower MFR (0.030-1.0 dg/min) maintains structural rigidity and flexural modulus, while the second fraction with higher MFR (0.30-70 dg/min) provides impact enhancement. This segmentation enables simultaneous achievement of improved impact resistance and maintained flexural modulus.
Solution Approach 2:
The patent creates a composite polymer composition by combining two different propylene/ethylene/1-hexene terpolymer fractions in specific proportions. This composite structure leverages the strengths of each fraction: the first fraction contributes to stiffness and structural integrity, while the second fraction enhances impact resistance, resulting in a material that exhibits both improved impact resistance and maintained flexural modulus.
3Device complexity
If single terpolymer fraction is used to simplify composition, then composition complexity is reduced, but balance of impact resistance, time to brittle failure and flexural modulus deteriorates
Solution Approach 1:
The patent divides the polymer composition into two functionally distinct terpolymer fractions with different melt flow rates and complementary properties. This segmentation enables each fraction to specialize in providing specific performance characteristics, with the first fraction optimizing for structural integrity and the second for impact resistance, achieving a superior balance of all three performance parameters despite increased compositional complexity.
Data Source
AI summary
The invention relates to a polypropylene composition comprising a terpolymer composition comprising (A) a first terpolymer fraction containing propylene, ethylene and 1-hexene, wherein the first terpolymer fraction has a melt flow rate of 0.005 to 0.20 dg/min determined by ISO 1133-1:2011 (230° C., 2.16 kg) and (B) a second terpolymer fraction containing propylene, ethylene and 1-hexene, wherein the second terpolymer fraction has a melt flow rate of 0.30 to 70 dg/min determined by ISO 1133-1:2011 (230° C., 2.16 kg),wherein the first terpolymer fraction is prepared using a first set of reaction conditions, the second terpolymer fraction is prepared using a second set of reaction conditions and the first and second set of reaction conditions are different, wherein the polypropylene composition(i) has a melt flow rate of 0.10 to 0.70 dg/min determined by ISO 1133-1-2011 (230° C., 2.16 kg),(ii) has a content of ethylene derived units in the range from 1.6 to 3.0 wt %;(iii) has a content of 1-hexene derived units in the range from 1.7 to 4.0 wt %; and(iv) has a ratio of the content of ethylene derived units to the content of 1-hexene derived units in the composition of at least 0.70.