Acrylic Bone Cement Dispersion Stability via Equilibrium Water Content
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Solution Overview
Problem
Hardenable multi-part acrylic compositions used in bone cements face issues with increased viscosity over time and potential settling of polymer beads due to high water content, leading to reduced shelf life and stability.
Innovation Solution
The composition includes an aqueous dispersion of acrylic polymer particles and beads, where the polymer beads are at equilibrium water content with the aqueous phase, maintaining viscosity between 10 and 10,000 centipoise and preventing destabilization, thereby increasing the shelf life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the water content of the formulation is increased to decrease viscosity, then the formulation viscosity decreases, but the dispersion becomes unstable and polymer beads settle
Solution Approach 1:
The patent controls the water content parameter within a specific range (5-20% by weight) to optimize the balance between viscosity and dispersion stability. This parameter change ensures the formulation remains pumpable while preventing bead settlement and maintaining homogeneous dispersion throughout the shelf life.
2Reliability
If polymer beads are added to the dispersion, then the cement properties are improved, but the beads settle over time reducing shelf life
Solution Approach 1:
The patent optimizes the concentration of polymer beads within the dispersion (5-50% by weight of total composition) to achieve reliable cement properties while preventing settlement. This controlled parameter ensures adequate bead distribution throughout the liquid carrier during storage.
Solution Approach 2:
The liquid carrier acts as an intermediary medium that suspends the polymer beads uniformly. The carrier composition and its interaction with the beads prevent direct bead-to-bead contact and settlement, extending the shelf life while maintaining cement functionality.
3Reliability
If the composition is stored as a liquid dispersion, then the monomer remains storage stable, but the viscosity increases over time
Solution Approach 1:
The patent maintains the liquid dispersion state by controlling water content (5-20% by weight) and polymer bead concentration (5-50% by weight). These parameter changes prevent excessive viscosity increase during storage while preserving the storage stability of the separated monomer and initiator components.
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
This approach stabilizes the dispersion, extending the shelf life of the hardenable acrylic composition and maintaining its stability and viscosity, ensuring effective use in applications like bone cements.
Implementation Method 1
the polymer beads in the dispersion are at an equilibrium water content with the aqueous phase of the dispersion
Data Source
AI summary
A hardenable multi-part acrylic composition having at least two parts that react upon mixing to form a cement, such as bone cement, which hardens to a solid is described that includes storage stable liquid first and second parts, and optionally, further liquid parts. The parts react upon mixing to form a cement that hardens to a solid. The composition includes an acrylic monomer component and an initiator component in an amount effective to polymerize the acrylic monomer component when mixed and/or activated with it. The liquid first part comprises an aqueous dispersion of acrylic polymer particles and acrylic polymer beads. The polymer beads are at an equilibrium water content with the aqueous phase of the dispersion that generally has a viscosity between 10 and 10,000 centipoise. A twin barreled syringe, caulking gun or other cement mixing and delivery device and a method of producing the composition are also described.