LLDPE and EVA Thermoplastic Blend for High Strength
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Solution Overview
Problem
Existing thermoplastic compositions based on ethylene vinyl acetate (EVA) copolymers often face challenges in achieving high tensile strength, flex modulus, and temperature resistance, particularly when blended with low density polyethylene, where the addition of fillers can compromise these properties.
Innovation Solution
A thermoplastic composition comprising a blend of linear low density polyethylene and ethylene vinyl acetate copolymers, with specific vinyl acetate content and melt index ranges, along with suitable fillers, which enhances tensile strength, flex modulus, and temperature resistance without the need for oil as a processing aid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If EVA copolymer is blended with LLDPE to improve processing and ductile properties, then processing and ductility are improved, but tensile strength deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the vinyl acetate content (1-40 wt%) and melt index (0.1-100) of the EVA copolymer, along with the ratio of EVA to LLDPE (10-90 wt%), to achieve an optimal balance between processing properties and tensile strength. This quantitative adjustment of compositional parameters resolves the contradiction between improved processing and maintained strength.
Solution Approach 2:
The patent creates a composite material system by blending EVA copolymer with LLDPE and incorporating fillers (20-80 wt%). This composite approach allows the synergistic combination of EVA's processing advantages with LLDPE's structural integrity, while fillers provide reinforcement to maintain or enhance tensile strength despite the blending.
2Strength
If filler is added to EVA/LLDPE blend to enhance mechanical properties, then tensile strength and flex modulus improve, but temperature resistance may be compromised
Solution Approach 1:
The patent addresses this contradiction by optimizing the filler content within 20-80 wt% and selecting fillers with appropriate thermal properties. The specific composition parameters are tuned to ensure that the filler reinforcement does not excessively compromise the matrix's temperature resistance, achieving a balanced performance.
Solution Approach 2:
The EVA copolymer acts as an intermediary between the filler and LLDPE matrix. It provides a compatible interface that allows filler incorporation for strength enhancement while maintaining the overall thermal stability of the blend through proper compositional design.
Data Source
AI summary
The present invention provides a highly-filled thermoplastic composition comprising a linear low density polyethylene and an ethylene vinyl acetate copolymer. The thermoplastic composition exhibits high tensile strength, high flex modulus, high temperature resistance and high tear strength.