Recycled Polyolefin Composition for Injection Molding
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Solution Overview
Problem
Recycled polypropylene (PP)/polyethylene (PE) blends from post-consumer waste suffer from deteriorated mechanical and optical properties, poor compatibility, and are often excluded from high-quality applications due to the minor component's impact on performance, particularly when polyethylene forms the continuous phase.
Innovation Solution
A polyolefin composition comprising 50-90 wt% of a recycled polyolefin mixture with specific properties, combined with 10-50 wt% of a polyolefin component including a propylene homopolymer, ethylene homopolymer, and a terpolymer, optimized through sequential polymerization using Ziegler-Natta catalysts to enhance tensile performance and compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If recycled PP/PE blends are used, then waste polyolefins can be reused, but mechanical and optical properties deteriorate
Solution Approach 1:
The patent applies parameter changes by carefully controlling the composition ratios of PP and PE in the recycled blend, targeting specific ranges (PP: 70-90 wt%, PE: 10-30 wt%) to optimize properties. It also controls molecular weight distribution and viscosity characteristics to achieve desired mechanical performance while maintaining reusability of waste materials.
Solution Approach 2:
The patent creates a composite material system by combining PP and PE in specific proportions with controlled molecular weight distributions. The composite structure leverages the stiffness of PP and the toughness of PE to achieve balanced mechanical properties that are superior to simple recycling, enabling use in high-quality applications.
2Stability of the object's composition
If PE forms the continuous phase in recycled blends, then compatibility between polymer phases improves, but tensile strength and heat deflection resistance decrease
Solution Approach 1:
The patent changes the compositional parameters by limiting PE content to 10-30 wt% and controlling its molecular weight distribution. This parameter control ensures PE forms a dispersed phase rather than continuous phase, maintaining compatibility while preserving tensile strength and heat deflection resistance through PP's stiff continuous matrix.
3Productivity
If recycled PP/PE blends are used in high quality parts, then material utilization increases, but performance requirements are not met
Solution Approach 1:
The patent applies parameter changes by optimizing blend composition (PP: 70-90 wt%, PE: 10-30 wt%), controlling molecular weight distributions, and adjusting viscosity characteristics to meet performance requirements for high-quality applications while maximizing material utilization from recycled sources.
Solution Approach 2:
The patent develops a composite material with controlled PP/PE ratios and molecular weight distributions that achieves the necessary mechanical properties, optical characteristics, and thermal stability for high-quality applications, transforming recycled blends from low-value to high-value material.
Data Source
AI summary
A polyolefin composition made from or containing:T1) 50-90 wt % of a recycled polyolefin mixture andT2) 10-50 wt % of a polyolefin component, containingA) 5-35% by weight of a propylene homopolymer or a propylene ethylene copolymer;B) 20-50% by weight of an ethylene homopolymer; andC) 30-60% by weight of a terpolymer of ethylene, propylene, and 1-butene made from or containing 45 to 65 percent by weight of ethylene units and from 15 to 38 percent by weight of 1-butene units.