Polyarylene Sulfide Injection Molding with Aromatic Amide Oligomers
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Solution Overview
Problem
The challenge in injection molding of polyphenylene sulfide (PPS) is its slow crystallization rate, which requires high mold temperatures and long cycle times, necessitating expensive and corrosive cooling mediums, and existing attempts to improve crystallization properties with additives have been unsatisfactory.
Innovation Solution
A method for injection molding a thermoplastic composition comprising polyarylene sulfide and an aromatic amide oligomer, allowing for cooling at mold temperatures between 50° C. to 120° C., reducing energy requirements and using less corrosive cooling mediums like water, while maintaining good mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high mold temperature is used to achieve desired crystallization, then crystallization degree is improved, but energy consumption increases and corrosive cooling mediums are required
Solution Approach 1:
The invention changes the chemical composition parameter of the polymer system by incorporating aromatic amide oligomers (1-10 wt%) into polyarylene sulfide. This compositional modification alters the crystallization kinetics, enabling adequate crystallization at lower mold temperatures (50-120°C) while maintaining mechanical properties, thus reducing energy consumption and eliminating the need for corrosive cooling mediums.
2Stability of the object's composition
If high mold temperature is used to achieve desired crystallization, then crystallization degree is improved, but cooling cycle time increases
Solution Approach 1:
The invention modifies the crystallization parameters of polyarylene sulfide by adding aromatic amide oligomers, which act as nucleating agents. This changes the crystallization kinetics to proceed more rapidly at lower temperatures, reducing the cooling cycle time while achieving the required crystallization degree for mechanical property development.
3Speed
If traditional additives are used to improve crystallization properties, then crystallization rate is improved, but mechanical properties deteriorate
Solution Approach 1:
The invention uses aromatic amide oligomers with specific molecular weight ranges (50-2000 g/mol) and controlled purity (90-99%) to achieve the desired crystallization rate enhancement. This precise parameter control allows the oligomers to act as effective nucleating agents without adversely affecting the mechanical properties of the final molded part.
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 method enables efficient injection molding at lower temperatures with shorter cooling cycles, minimizing energy consumption and reducing flash production, while achieving the same degree of crystallization as traditional high-temperature methods.
Implementation Method 1
a thermoplastic composition comprises a polyarylene sulfide and aromatic amide oligomer
Implementation Method 2
cooling the thermoplastic composition within the mold cavity at a mold temperature of from about 50° C. to about 120° C.
Data Source
AI summary
A method for injection molding a thermoplastic composition that contains a polyarylene sulfide and an aromatic amide oligomer is provided. Due to the improved crystallization properties imparted by the oligomer, the present inventors have discovered that the thermoplastic composition can be molded at lower temperatures to still achieve the same degree of crystallization. In addition to minimizing the energy requirements for the molding operation, such low mold temperatures may be accomplished using heating mediums that are less corrosive and expensive than some conventional techniques.