Amit K. Naskar

Consolidation of Reactive Ultem®Powder-coated Carbon Fiber Tow for Space Structure Composites by Resistive Heating

In this exploratory study, polyacrylonitrile (PAN)-based carbon fiber tows are coated with a commercial, heat-crosslinkable polyetherimide (Ultem®) powder. Then an electrical current is applied across the powder-coated fiber tows (towpreg) to melt the thermoplastic powder and form rigidized composites. These consolidated composite samples are characterized by scanning electron microscopy (SEM) and conventional tensile testing. Measuring the applied current and the degree of consolidation yielded the power requirement for successful wetting of the carbon fiber tows by Ultem melt, both on earth and in outer space. The results show that resistive heating is a feasible route for the rigidization of inflatable composite structures in space.

Morphology of PET cords at different stages of simulated tire building

The effect of simulated tire-building steps on morphological characteristics of polyethylene terephthalate (PET) cords and their final dimensional stability is reported. Twisted single-ply cords were sequentially processed for mimicking dip coating (without real latex treatment), thermal curing (without embedding them in rubber matrix), and creep deformation. The degree of crystallinity and crystalline orientation factor (f c) of the samples remained essentially unchanged in the course of the simulated manufacturing steps. As measured by birefringence, overall orientation of the cords increased in the coating step but decreased during simulated curing. Overall orientation again increased after creep testing. As measured by wide-angle X-ray diffraction, the cords having higher oriented amorphous (mesophase) content displayed the least variation in overall orientation during processing steps and the best dimensional stability.