Low Chlorine Polyarylene Sulfide via Disulfide Chain Scission
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Solution Overview
Problem
High molecular weight polyarylene sulfides have high melt viscosity, making them difficult to process and increasing the challenge of incorporating fillers, which further raises melt viscosity, while low molecular weight options have high chlorine content and require high additive levels to achieve desired physical characteristics, complicating processibility.
Innovation Solution
A method involving the melt processing of a mixture containing a starting polyarylene sulfide, a disulfide compound, and a filler, which reduces melt viscosity and chlorine content, enhancing processibility and mechanical properties, and includes a disulfide compound to lower melt viscosity and improve filler integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If high molecular weight polyarylene sulfides are used to reduce chlorine content, then chlorine content is reduced, but melt viscosity increases making processing difficult
Solution Approach 1:
The patent changes the molecular weight parameter of the polyarylene sulfide from high to low molecular weight, which increases processibility while accepting higher chlorine content. This parameter change is then compensated by adding fillers and modifiers to achieve the desired final properties without requiring high molecular weight polymer.
Solution Approach 2:
The patent creates a composite material system by combining low molecular weight polyarylene sulfide with various fillers (glass fibers, minerals, metals) and modifiers. This composite approach allows the base polymer to be easily processable while the fillers and modifiers provide the necessary mechanical properties and reduce the overall chlorine content of the final composition.
2Strength
If fillers are added to improve physical characteristics, then mechanical properties are improved, but melt viscosity increases further complicating processing
Solution Approach 1:
The patent performs preliminary action by selecting and preparing fillers with appropriate surface treatments and characteristics before incorporation into the polymer matrix. The fillers are pre-selected to have sizes, shapes, and surface properties that minimize their impact on melt viscosity while maximizing their reinforcement effect, allowing easier processing despite the presence of fillers.
Solution Approach 2:
The patent changes parameters of the filler system including particle size distribution, filler morphology, and filler concentration to optimize the balance between mechanical properties and processibility. By controlling these parameters, the patent achieves good reinforcement without excessive viscosity increase that would complicate processing.
3Ease of manufacture
If low molecular weight polyarylene sulfides are used to improve processibility, then processibility is improved, but chlorine content increases and high additive levels are required
Solution Approach 1:
The patent applies the extraction principle by removing or reducing the chlorine-containing terminal groups through chemical modification reactions. The low molecular weight polyarylene sulfide is subjected to treatments that selectively remove chlorine atoms, thereby reducing the overall chlorine content of the composition while maintaining the low molecular weight and good processibility of the base polymer.
Solution Approach 2:
The patent uses fillers and chemical modifiers as intermediaries to address the chlorine content issue. These intermediaries react with or adsorb the chlorine-containing species, effectively reducing the harmful chlorine content of the low molecular weight polyarylene sulfide without requiring high additive levels that would compromise processibility.
4Strength
If high additive levels are used to improve physical characteristics of low molecular weight compositions, then physical properties are improved, but processibility deteriorates
Solution Approach 1:
The patent changes the concentration parameters of additives to optimized levels that provide sufficient mechanical property enhancement without exceeding the threshold that would cause excessive viscosity increase. By carefully controlling additive levels and selecting additives with appropriate characteristics, the patent achieves the desired physical characteristics while maintaining good processibility of the low molecular weight composition.
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 melt processed polyarylene sulfide composition exhibits lower melt viscosity, improved mechanical properties, and reduced chlorine content, facilitating easier processing and achieving desirable physical characteristics without complex processing steps.
Implementation Method 1
the mixture can include a starting polyarylene sulfide, a filler, and a disulfide compound... The ratio of the melt viscosity of the starting polyarylene sulfide to the melt viscosity of the melt processed polyarylene sulfide composition can be greater than about 1.25
Data Source
AI summary
Melt processed polyarylene sulfide compositions are described as are methods of forming the melt processed polyarylene sulfide compositions. The melt processed polyarylene sulfide compositions are formed according to a melt processing method that includes melt processing a mixture that includes a starting polyarylene sulfide, a disulfide compound and a filler. The melt processed polyarylene sulfide compositions may provide low chlorine content products having excellent strength characteristics.