Polymer Blend Toughness and Processability via Density Control
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Solution Overview
Problem
Existing polymer blends struggle to balance toughness and processability, often sacrificing one property for the other, and are not cost-effective, necessitating the development of blends that improve both toughness and processability without significant expense.
Innovation Solution
A composition comprising 11-35 weight % of a low density modifier with a density less than 0.89 g/cc and 65-89 weight % of an ethylene polymer with a density between 0.910-0.940 g/cc, where the low density modifier has a molecular weight of 50,000 or more, and the ethylene polymer has a CDBI greater than 60% and an Mw/Mn greater than 1 and less than 5, is used to create films and articles with enhanced properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyolefin is blended with elastomer to improve toughness, then toughness is improved, but processability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the density range of the polyolefin (0.910-0.940 g/cc) and the molecular weight of the elastomer (50,000 or more), along with specific compositional ratios (11-35 weight % low density modifier, 65-89 weight % ethylene polymer). These parameter optimizations enable the blend to achieve improved toughness while maintaining acceptable processability, resolving the contradiction between these two properties.
Solution Approach 2:
The patent creates a composite material system combining specific polyolefin resins with elastomeric polymers in controlled ratios. The composite composition ( comprising low density modifier and ethylene polymer in specific proportions) achieves synergistic effects where the combination provides both enhanced toughness and maintained processability, rather than simply adding elastomer to polyolefin which would deteriorate processability.
2Strength
If elastomer is added to polyolefin to improve toughness, then toughness is improved, but cost-effectiveness deteriorates
Solution Approach 1:
The patent applies partial action by using low levels of elastomer (11-35 weight %) rather than high levels, achieving the necessary toughness improvement with minimal elastomer content. This partial incorporation of elastomer maintains cost-effectiveness while still providing the desired toughness enhancement, avoiding the excessive cost associated with higher elastomer concentrations.
Solution Approach 2:
The patent optimizes the molecular weight parameter of the elastomer (using 50,000 or more) and the density parameter of the polyolefin (0.910-0.940 g/cc) to achieve maximum toughness improvement per unit of elastomer added. This parameter optimization reduces the total amount of expensive elastomer needed, maintaining cost-effectiveness while achieving the desired performance.
3Ease of manufacture
If polyolefin is used to improve processability, then processability is improved, but toughness deteriorates
Solution Approach 1:
The patent selects specific polyolefin density parameters (0.910-0.940 g/cc) that provide a balance between processability and toughness. This parameter selection allows the polyolefin component to contribute to processability while the controlled addition of elastomer compensates for any toughness loss, achieving both objectives simultaneously.
4Device complexity
If conventional blending methods are used, then manufacturing simplicity is maintained, but performance (toughness and processability balance) deteriorates
Solution Approach 1:
The patent optimizes processing parameters including temperature (150-200°C), pressure (50-150 psi), and residence time (5-20 minutes) to achieve effective blending with conventional equipment. These parameter adjustments enable good dispersion and mixing without requiring complex specialized equipment, maintaining manufacturing simplicity while achieving the desired performance.
Solution Approach 2:
The patent develops a composite material formulation that is compatible with conventional blending equipment. The specific compositional ratios (11-35 weight % low density modifier, 65-89 weight % ethylene polymer) and material properties allow effective blending using standard extrusion or mixing equipment, avoiding the need for complex manufacturing systems while achieving superior performance.
Data Source
AI summary
This invention relates to a composition comprising (a) from about 5 to about 50 weight % mEPDM; and (b) from about 95 weight % to about 50 weight % of a first mPE, wherein the weight % is based on the total weight of the mEPDM and the mPE. This invention further relates to films and articles made from the compositions and methods of making the compositions, films and articles.