Acrylic Bone Cement Radiopacity via Encapsulated Fillers
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Solution Overview
Problem
Hardenable liquid-liquid multi-part acrylic compositions face challenges in maintaining mechanical properties and viscosity when incorporating radiopacifying fillers, often resulting in reduced compression strength and increased porosity, which affects their suitability for applications like bone cements.
Innovation Solution
The composition encapsulates radiopacifying fillers within acrylic polymer particles, allowing for reduced filler concentration in the continuous matrix, thereby minimizing stress concentrations and enhancing mechanical properties while maintaining low viscosity, achieved by using sub-populations of acrylic polymer particles with varying sizes and types, such as emulsion and bead particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If radiopacifying fillers are incorporated into the continuous matrix of liquid-liquid multi-part acrylic compositions, then radiopacity is improved, but mechanical properties (compression strength, flexural strength) are reduced and porosity increases
Solution Approach 1:
The radiopacifying filler particles are encapsulated within acrylic polymer particles, creating a nested structure where one material is contained within another. This allows the filler to be distributed throughout the composition without directly compromising the continuous matrix structure, thereby maintaining mechanical strength while achieving radiopacity.
Solution Approach 2:
Acrylic polymer particles act as an intermediary carrier between the radiopacifying filler and the continuous matrix. Instead of adding filler directly to the liquid matrix, the filler is first incorporated into polymer particles, which then disperse in the matrix. This intermediary structure prevents stress concentrations and reduces porosity while maintaining radiopacity.
2Ease of manufacture
If radiopacifying fillers are incorporated into the continuous matrix, then radiopacity is improved, but viscosity increases
Solution Approach 1:
Encapsulating filler within polymer particles creates a nested structure that prevents filler particles from directly interacting with each other in the continuous matrix. This reduces inter-particle friction and maintains lower viscosity compared to direct filler incorporation.
Solution Approach 2:
The filler concentration is localized within discrete polymer particles rather than being uniformly distributed in the continuous matrix. This localized distribution allows the bulk matrix to maintain its original flow properties and low viscosity while still achieving radiopacity through the encapsulated filler.
3Ease of operation
If higher levels of monomer are used to prepare liquid solutions, then ease of mixing is improved, but polymerization exotherm increases and shrinkage increases
Solution Approach 1:
The invention changes the formulation parameters by using lower monomer levels and incorporating pre-formed polymer particles with encapsulated filler. This parameter change reduces the polymerization exotherm while maintaining workable mixing characteristics through the particle suspension approach.
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 maintains or improves mechanical properties like flexural and tensile strength, reduces viscosity, and allows for better handling and delivery of the multi-part composition, particularly in bone cement applications, without significantly increasing porosity or exotherm temperatures.
Implementation Method 1
at least some of the radiopacifying filler is encapsulated within and/or adsorbed on the acrylic polymer particles in a liquid part
Implementation Method 2
the initiator component being present in an amount effective to polymerize the acrylic monomer component upon being mixed and/or activated therewith
Data Source
AI summary
The invention relates to a hardenable multi-part liquid acrylic composition. The composition comprises a storage stable liquid first part, a storage stable liquid second part and optionally, a third or further liquid parts. The parts are operable to form a cement which hardens to a solid upon mixing of the parts together. The composition comprises an acrylic monomer component, an initiator component, acrylic polymer particles and a radiopacifying filler. The initiator component is present in an amount of effective to polymerize the acrylic monomer component upon being mixed and/or activated therewith. At least some of the radiopacifying filler is encapsulated within and/or adsorbed on the acrylic polymer particles in a liquid part. The invention extends to an at least twin barreled syringe or caulking gun accommodating the multi-part composition, a method of producing the multi-part composition, a composition for use as bone cement composition or in dental repairs, a liquid composition comprising a first sub-population of emulsion or non-emulsion polymerized acrylic polymer particles and radiopacifying filler encapsulated and/or adsorbed in the first sub-population of acrylic polymer particles and bone cement compositions or dental compositions.