Propylene Terpolymer Pipe Composition for Impact and Brittle Failure Balance
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Solution Overview
Problem
Current propylene-based terpolymer compositions for pipes lack a balanced combination of high impact resistance and long time to brittle failure, especially at elevated temperatures, which is crucial for ensuring the longevity and handling of hot and cold water pressure pipes.
Innovation Solution
A polypropylene composition comprising a terpolymer with at least 1.5 wt% ethylene and 1.5 wt% 1-hexene derived units, a melt flow rate of 0.10 to 0.70 g/10 min, and a weight average molecular weight to number average molecular weight ratio of 7.0 to 20.0, processed using a Ziegler-Natta catalyst system, which enhances impact resistance and processability while maintaining a high ratio of ethylene to 1-hexene content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the ethylene content is increased to improve impact resistance, then the impact resistance is improved, but the time to brittle failure decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ethylene content (1.4-7.0 wt%) and 1-hexene content (0.2-5.0 wt%) within specific ranges, along with controlling the Mw/Mn ratio (7.0-20.0) and melt flow rate (0.10-0.70 g/10 min). This multi-parameter optimization resolves the contradiction by finding the optimal balance point where impact resistance is sufficiently high while time to brittle failure remains acceptably long.
2Productivity
If the extrusion speed is increased to improve production efficiency, then the productivity is improved, but the energy consumption increases
Solution Approach 1:
The patent optimizes the melt flow rate parameter to a specific range (0.10-0.70 g/10 min) which enables the polymer to be extruded at higher speeds with reduced energy consumption. This parameter optimization improves the flow characteristics of the polymer melt during extrusion, allowing for more efficient processing with lower energy input while maintaining high productivity.
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 composition achieves a superior balance of impact resistance and time to brittle failure, allowing for higher extrusion speeds and reduced energy consumption, resulting in improved pipe production efficiency and environmental benefits.
Implementation Method 1
processed using a Ziegler-Natta catalyst system
Data Source
AI summary
The invention relates to a polypropylene composition comprising a terpolymer containing propylene, ethylene and 1-hexene wherein the polypropylene composition (i) has a content of ethylene derived units of at least 1.5 wt%; (ii) has a content of 1-hexene derived units of at least 1.5 wt%; (iii) has a melt flow rate of 0.10 to 0.70 g/10 min determined by ISO 1133-1:2011 (230°C, 2.16 kg); and (iv) has a ratio of weight average molecular weight (Mw) to numeric average molecular (Mn) weight of the terpolymer of 7.0 to 20.0, wherein Mw and Mn are measured according to ASTM D6474-12.