Crosslinkable Thermoplastic Polyurethane via Electron Beam

The patent introduces crosslinkable unsaturated moieties (carbon-carbon double bonds) into the TPU polymer chains, fundamentally changing the chemical parameter of the material. This allows the material to transition from a purely thermoplastic state to a crosslinkable state, enabling both melt processing before crosslinking and thermoset properties after crosslinking. The unsaturated groups serve as reactive sites that can form crosslinks under electron beam irradiation while maintaining thermoplastic processability in the uncrosslinked state.

The patent incorporates crosslinkable unsaturated moieties into the TPU polymer chains during the initial polymerization step, before any crosslinking occurs. This preliminary incorporation of reactive groups allows the material to be processed as a thermoplastic first, then crosslinked later under electron beam irradiation. The crosslinking reaction is activated only when needed, enabling flexible processing and the possibility of recycling uncrosslinked material.

The patent replaces conventional thermal or chemical curing mechanisms with electron beam irradiation. Instead of using heat, catalysts, or chemical crosslinking agents that require lengthy curing processes, the invention uses high-energy electron beams to directly activate the unsaturated moieties in the TPU chains, inducing rapid crosslinking. This substitution of the curing mechanism dramatically reduces processing time and eliminates the need for complex curing equipment and conditions.

The electron beam irradiation process applies energy in a controlled, periodic manner to initiate crosslinking only when and where needed. The irradiation can be applied locally or uniformly, and the crosslinking reaction proceeds rapidly under the electron beam exposure without requiring prolonged curing times. This periodic energy input replaces continuous thermal or chemical curing processes.

The patent creates a composite structure at the molecular level by forming a crosslinked network within the TPU matrix. The crosslinks act as additional structural elements that reinforce the polymer chains, creating a hybrid architecture that combines the flexibility and processability of thermoplastics with the dimensional stability and chemical resistance of thermosets. This molecular-level composite structure provides superior performance in harsh industrial environments.

The crosslinked network formed in the TPU creates a three-dimensional spatial structure that constrains polymer chain movement and maintains dimensional integrity. The network architecture provides a curved, interconnected framework that resists deformation under thermal and chemical stress, improving dimensional stability and creep resistance compared to linear thermoplastic chains.