Radial Copolymer Additive for Asphalt Viscosity Reduction
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Solution Overview
Problem
The existing polymer-modified asphalt additives, such as SBS, increase viscosity and energy consumption during manufacturing and pavement, and may separate into non-uniform phases due to low affinity with asphalt, while adding sulfur as a phase stabilizer increases viscosity and poses environmental hazards.
Innovation Solution
An additive composition comprising a first copolymer compound with a radial structure and a second copolymer compound, both derived from aromatic vinyl and conjugated diene compounds, with specific molecular weight ratios and vinyl content, is used to reduce viscosity and maintain asphalt properties, along with a coupling agent to enhance processability and pavement performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SBS is used as an additive to improve high and low temperature properties, then resistance to plastic deformation at high temperature and flexibility at low temperature are improved, but viscosity of asphalt composition increases and energy consumption increases
Solution Approach 1:
The patent changes the molecular weight parameters of the copolymer compounds, specifically using a first copolymer with molecular weight 10,000-100,000 and a second copolymer with molecular weight 1,000-10,000. This parameter optimization reduces viscosity and energy consumption while maintaining the high and low temperature performance improvements provided by SBS-like copolymers.
Solution Approach 2:
The patent uses a composite additive system comprising two different copolymer compounds with different molecular weights and structures. The first copolymer (higher molecular weight) provides the primary modification effect for temperature resistance, while the second copolymer (lower molecular weight) acts as a viscosity reducer and compatibilizer, creating a synergistic composite material system.
2Reliability
If SBS is used as an additive, then high and low temperature properties are improved, but polymer-modified asphalt separates into non-uniform phase due to low affinity for asphalt
Solution Approach 1:
The patent optimizes the molecular weight parameters of both copolymer compounds, with the second copolymer having lower molecular weight (1,000-10,000) which enhances its ability to interact with asphalt molecules. This parameter adjustment improves affinity and prevents phase separation while maintaining the temperature performance benefits.
Solution Approach 2:
The second copolymer compound acts as an intermediary substance between the first copolymer and the asphalt. Its lower molecular weight and specific structural characteristics enable it to bridge the interface between the polymer additive and asphalt matrix, improving compatibility and preventing phase separation.
3Stability of the object's composition
If sulfur is added as a phase separation stabilizer, then phase separation is reduced, but viscosity increases and hazardous substances such as sulfur oxides are discharged
Solution Approach 1:
The patent extracts and eliminates sulfur from the additive composition entirely, replacing it with sulfur-free copolymer compounds. The second copolymer compound with lower molecular weight performs the phase stabilization function previously achieved by sulfur, without generating harmful sulfur oxide emissions.
Solution Approach 2:
The patent replaces the harmful but effective sulfur additive with environmentally friendly copolymer compounds that, while having different mechanisms, achieve the same phase stabilization goal without persistent environmental harm. The copolymers provide stable performance without the toxic byproducts of sulfur.
4Stability of the object's composition
If sulfur is added as a phase separation stabilizer, then phase separation is reduced, but viscosity of asphalt composition increases
Solution Approach 1:
The patent removes sulfur from the composition and replaces it with copolymer compounds, particularly the second copolymer with lower molecular weight (1,000-10,000), which provides phase stabilization without the viscosity-increasing side effect associated with sulfur addition.
Solution Approach 2:
The patent changes the molecular weight parameters of the copolymer additives, using a bimodal distribution with the second copolymer having significantly lower molecular weight (1,000-10,000) compared to the first copolymer (10,000-100,000). This parameter optimization enables phase stabilization at lower viscosity levels.
Data Source
AI summary
One aspect of the present invention provides an additive composition for polymer-modified asphalt including a block copolymer having a radial structure and a copolymer of an aromatic vinyl compound of which two ends have different molecular weights and a conjugated diene compound, and a method of preparing the same. When asphalt is prepared using the additive composition for polymer-modified asphalt, properties of the existing polymer-modified asphalt may be maintained while content of sulfur may be reduced, viscosity may decrease, and thereby processability and pavement performance may be improved.