Block-Copolymer Dispersants for Asphalt Emulsion Stability
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Solution Overview
Problem
Asphalt compositions face challenges with adhesion to aggregates, setting times, and viscosity, leading to increased energy consumption and pavement durability issues, particularly when using polymer-modified asphalt emulsions that can separate and require lengthy traffic restrictions.
Innovation Solution
Incorporating a block-copolymer dispersant with a polybutyl acrylate hydrophobic block and a sodium polystyrene sulfonate hydrophilic block into asphalt emulsions, which improves adhesion and stability, allowing for lower temperature polymerization and reduced setting times, thereby enhancing the asphalt's properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer is added to improve adhesion and durability of asphalt, then adhesion and durability are improved, but setting time and drying time are significantly delayed
Solution Approach 1:
The patent changes the chemical parameters of the polymer by using block copolymer architecture with specific hydrophobic and hydrophilic blocks, and controls the polymerization temperature parameter to achieve both improved adhesion and reduced setting time compared to conventional polymers
Solution Approach 2:
The patent uses a composite block copolymer structure combining hydrophobic polybutyl acrylate blocks (for adhesion to asphalt and aggregate) and hydrophilic poly(sodium styrene sulfonate) blocks (for water solubility and stability), creating a material that simultaneously addresses adhesion and setting time requirements
2Strength
If polymer modified asphalt emulsion is used to improve pavement properties, then adhesion and ductility are improved, but the emulsion becomes too fluid and separates from aggregate
Solution Approach 1:
The patent adjusts the molecular weight parameter of the block copolymer to greater than 5000 g/mol and optimizes the ratio of hydrophobic to hydrophilic blocks to maintain appropriate viscosity and prevent emulsion separation while preserving adhesion properties
Solution Approach 2:
The amphiphilic block copolymer acts as a composite material where the hydrophobic blocks provide strong adhesion to asphalt and aggregate surfaces while the hydrophilic blocks provide steric stabilization and prevent emulsion separation, simultaneously achieving both adhesion and stability
3Reliability
If conventional polymerization process is used to prepare polymer modified asphalt, then polymer properties are achieved, but energy consumption is high due to high temperature requirements
Solution Approach 1:
The patent changes the polymerization temperature parameter from conventional high temperatures to low temperatures below 25°C, and adjusts the block copolymer composition to enable polymerization under these milder conditions, significantly reducing energy consumption while maintaining polymer functionality
Solution Approach 2:
The block copolymer's specific architecture with hydrophobic and hydrophilic blocks enables low-temperature polymerization by facilitating controlled radical polymerization mechanisms that proceed efficiently at reduced temperatures, achieving energy savings without compromising polymer properties
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 use of block-copolymer dispersants in asphalt emulsions improves adhesion, reduces separation, and enhances durability, leading to faster setting and increased viscosity, thus addressing the challenges of energy efficiency and pavement longevity.
Implementation Method 1
The hydrophobic block attaches to the asphalt particle
Implementation Method 2
the hydrophilic block provides stability
Data Source
AI summary
Disclosed herein are asphalt compositions containing a block-copolymer additive, for example for use as a dispersant. In some embodiments, the asphalt compositions can include asphalt, a block-copolymer dispersant, and an SBR latex. The block-copolymers have a molecular weight exceeding 5000 g/mol with a polybutyl acrylate hydrophobic block that attaches to the asphalt particle and a sodium polystyrene sulfonate hydrophilic block for stability, wherein the block copolymer has a first block comprising of alkyl acrylate and a second block comprising units of an ethylenically unsaturated monomer with sulfonic acid groups.The asphalt compositions can include asphalt in an amount of from 50 wt. % to 95 wt. %, based on the weight of the asphalt composition. In some embodiments, the asphalt compositions can include a styrene-butadiene copolymer in an amount of from 0.05 wt. % to 10 wt. %, based on the weight of the asphalt composition. Methods of making and using the asphalt compositions are also disclosed.