Self-Reinforced Polymeric Materials with Enhanced Processability and Toughness
The invention provides a strategy for simultaneously improving many physical and mechanical properties of organic synthetic polymers (such as process viscosity, modulus, fracture toughness, and coefficient of thermal expansion) by the introduction of a new type of reinforcement. This reinforcement is comprised of a low molecular weight crystalline compound that simultaneously improves the impact or fracture toughness, increases or does not otherwise detrimentally decrease the modulus, and enhances the processability (through reduced viscosity).
For the case of a thermoplastic, the low molecular weight crystalline compound is selected such that, at process temperatures, it resides as either a miscible or immiscible liquid in the polymer melt, thereby reducing the melt viscosity. Upon cooling, the compound undergoes thermally induced phase separation (TIPS) and crystallizes into domains that provide the morphology necessary for enhanced toughness and stiffness in the composite. This can be applied to both semi-crystalline and amorphous thermoplastics.
In the case of semi-crystalline thermoplastics, the low molecular weight crystalline compound will provide an additional crystalline phase that will increase the overall degree of crystallinity and may also nucleate crystallinity in the original polymer. In other polymer systems and thermosets, the additive can undergo reaction induced phase separation (RIPS) to enhance the same properties. Anisotropic reinforcements (fibers) can also be generated under quiescent conditions if compounds are selected with anisotropic growth planes.
Virtually any polymeric material can be modified using this strategy. By doing so, it is possible to improve its properties and allow it to compete in markets currently using more expensive compounds.
This methodology can be used by polymer producers:
- to increase the portfolio of polymer products to users.
- by companies who make additives for such materials
- by technology based companies to make high performance materials for specific applications.
- for product improvement can span virtually every market where polymeric compounds are used ranging from automotive, electronic packaging to a broad variety of materials goods found in society
The compounds can be tailored to meet the requirements for safety, medical and toy usage.
Current methods for reinforcing thermoplastics and thermosets either use rubber for toughening, which otherwise reduces the modulus of the composite and increases the melt viscosity, or uses rigid particles that increase melt viscosity. Our method provides a reinforcement that reduces viscosity of the melt thereby enhancing processability of the material while providing all other benefits realized with other rigid-particle reinforced thermoplastics.
In addition, other physical properties may also be enhanced including lower coefficients of thermal expansion, improved barrier properties, and enhanced flame retardance. The technology consists of an additive that can be introduced to semi-crystalline and amorphous thermoplastics, as well as thermosets.
The additive may potentially increase the cost of the polymer, but enhances so many properties that cost is offset by the improvements. In applications where the more traditional impact modifiers are already used (either rigid particles, or rubber particles), it is anticipated that no additional cost would be incurred for additional improvements in properties.
Current manufacturing equipment can be used in production.
Patent Pending - view published US application
Ling X. Shen, Ph.D., M.B.A.
Senior Licensing Officer
Commercial Ventures and Intellectual Property