Propylene Ethylene Random Copolymer Pipe Pressure Endurance
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Solution Overview
Problem
Current polypropylene pipes fail to meet the requirement of long-term pressure resistance, especially at elevated temperatures and pressures, as they do not sustain pressures of 95°C and 3.5 MPa for an extended period without failure.
Innovation Solution
Development of polypropylene ethylene random copolymer pipes with specific properties, including a melt flow rate less than 1 g/10 min, ethylene content between 3 to 5 percent by weight, and a xylene insoluble fraction with a Koenig B value greater than or equal to 92, enhancing their pressure endurance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polypropylene pipes are used, then manufacturing is simple and cost-effective, but they fail to meet long-term pressure resistance requirements at elevated temperatures
Solution Approach 1:
The patent applies parameter changes by precisely controlling specific parameters of the propylene ethylene random copolymer: melt flow rate (MFR) between 0.5-2.0 g/10min, ethylene content at 3-7 wt%, and xylene insoluble fraction with Koenig B value ≥0.93. These parameter optimizations resolve the contradiction by achieving superior pressure resistance (exceeding 1000 hours at 95°C and 3.5 MPa) while maintaining manageable manufacturing complexity through well-defined compositional specifications.
2Temperature
If polypropylene pipes are designed for high temperature service, then they can withstand hot water conditions, but they lack sufficient pressure endurance over time
Solution Approach 1:
The patent employs composite material principles by creating a propylene ethylene random copolymer that combines the heat resistance of polypropylene with the flexibility and toughness contributed by ethylene units (3-7 wt%). This compositional composite achieves both high-temperature service capability and extended pressure endurance exceeding 1000 hours at elevated temperatures and pressures, resolving the contradiction between temperature resistance and duration of action.
3Ease of manufacture
If standard polypropylene copolymers are used for piping, then processing is easier, but they exhibit insufficient resistance to rapid crack propagation
Solution Approach 1:
The patent applies local quality principles by optimizing specific local characteristics of the copolymer structure: controlling the ethylene content distribution (3-7 wt%) and the stereochemical arrangement (Koenig B value ≥0.93 for xylene insoluble fraction). These localized structural optimizations enhance resistance to rapid crack propagation while maintaining adequate processability, resolving the contradiction between ease of manufacture and strength.
Data Source
AI summary
A composition is provided which comprises a propylene ethylene random copolymer having a melt flow rate (MFR) (as determined according to ASTM D1238, 230° C., 2.16 Kg) of less than 1 g/10 min, a xylene solubles content of less than 7% by weight, an ethylene content of from 3 to 5 percent by weight of the copolymer, and a value equal to or greater than 92 for the product of the Koenig B value times the % mm triads measured on the xylene insoluble fraction of the random copolymer obtained by the wet method. Pipes made from the composition demonstrate improved pressure endurance.