In-situ Microfibrillated Polypropylene Foam for Lightweight Insulation
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Solution Overview
Problem
Polypropylene foam materials face significant strength loss and reduced heat insulation properties after foaming, limiting their mechanical and thermal performance, which is a challenge in the development of lightweight, energy-efficient automotive components.
Innovation Solution
An in-situ microfibrillated reinforced polymer composite heat insulation foam material is prepared through a process involving primary melt blending, hot stretching, secondary melt blending, cooling granulation, pressing, and supercritical fluid foaming, using a matrix polymer, fiber-forming polymer, and elastomer, with specific ratios and additives to create a high-strength, low-density foam with improved thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If polypropylene is foamed to reduce density, then weight is reduced and energy consumption decreases, but strength and heat insulation properties are significantly lost
Solution Approach 1:
The patent uses a composite material system consisting of polypropylene matrix, elastomer particles (5-15 wt%), and in-situ formed microfibers (0.5-5 wt%). The elastomer and microfibers form a reinforced network within the foam structure, maintaining mechanical strength while allowing low density. The composite structure enables the foam to achieve both lightweight properties and adequate strength for automotive applications.
Solution Approach 2:
The patent employs controlled porous foam structure with specific pore size distribution (50-200 μm) and porosity (30-70%). The porous structure reduces density while the controlled pore morphology, combined with the reinforced elastomer-microfiber network, prevents excessive strength loss. The foam cells are designed to provide thermal insulation while maintaining structural integrity.
2Weight of moving object
If polypropylene is foamed to reduce density, then weight is reduced, but heat insulation properties are significantly lost
Solution Approach 1:
The foam structure with 30-70% porosity and 50-200 μm pore size provides thermal insulation by trapping air pockets that reduce heat transfer. The porous network creates thermal barriers while maintaining lightweight properties, addressing the heat insulation requirement for automotive parts.
Solution Approach 2:
The composite system with elastomer and microfiber reinforcement enhances the thermal insulation capability by creating additional thermal barriers within the foam structure. The multi-phase composite structure (polypropylene + elastomer + microfibers) provides superior thermal insulation compared to simple foamed polypropylene.
3Strength
If fiber-forming polymer content is increased to improve strength, then mechanical strength increases, but uniform dispersion and foaming suitability may be compromised
Solution Approach 1:
The patent optimizes the fiber-forming polymer content within a specific range (0.5-5 wt%) and controls processing parameters (extrusion temperature 180-220°C, screw rotation speed 50-100 rpm) to achieve uniform dispersion. By carefully adjusting these parameters, the patent ensures that the fiber-forming polymer disperses evenly in the matrix while maintaining foaming suitability and mechanical strength.
Solution Approach 2:
The in-situ formed microfibers are distributed locally throughout the polypropylene matrix, creating regions of enhanced strength where needed. The microfibers form a dispersed network that locally reinforces the material without compromising overall uniformity or foaming behavior.
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 resulting foam material exhibits enhanced compressive strength, reduced thermal conductivity, and improved heat insulation properties, with a density of 0.32 g/cm3 and thermal conductivity of 0.068 W·K−1·m−1, overcoming the limitations of existing polypropylene foam materials and offering broad prospects for automotive applications.
Implementation Method 1
the composite board is subjected to supercritical fluid foaming process
Implementation Method 2
a composite heat insulation foam material is obtained
Data Source
AI summary
The disclosure belongs to the technical field of heat insulation materials, and discloses an in-situ microfibrillated reinforced polymer composite heat insulation foam material as well as a preparation method and application thereof. This disclosure adopts a polypropylene matrix, a fiber-forming polymer, an elastomer and an antioxidant as a foam material. The foaming material is subjected to a primary melt blending process and a hot stretching process first, then subjected to a secondary melt blending process and cooling granulation and subjected to a pressing process, and a composite board is obtained. The composite board is subjected to supercritical fluid foaming process, and a composite heat insulation foam material is obtained.