SPCs by in situ creation of nanofibrils and hot compaction

In this case study, the results of attempts to prepare nanofibrillar composite materials starting from nanofibrils are presented. This approach is based on (i) the concept of polymer/polymer NFCs produced by in situ formation using polymer blends, which have recently been manufactured by Fakirov et al. [33], (ii) on the opportunity to isolate aligned neat nanofibrils through selective dissolving of the second blend component, and (iii) subsequent consolidation via hot-compaction. 

The observed narioporosity demonstrates that in this type of composite, as well as in previously reported polymer-polymer nanofibrillar composites [111], the reinforcing elements are fused together in truss-like structures of single nanofibrils and not adhered in bundles or aggregates as is the case with other nano-sized materials used as reinforcement. 

Dable 19.4. Tensile modulus, i (chord 0.05-0.25%), and ultimate tensile strength, of PET matrix film, 

PET nanoflbriUar SPCs (PET-NSPC) prepared by the one-constituent approach, PET single-poljnner nanoflbrillar composites (PET-NFC) prepared by the two-constituent approach [32], (aU averaged from five specimens), and PET single-polymer composite prepared by hot-compaction (PET-SPC) [63] 

There are at least four reasons that explain the impressive improvements in the mechanical performance (i) in the current SPCs, the reinforcing component dominates strongly, and has much better mechanical properties when compared with the isotropic matrix, (ii) excellent adhesion between matrix and reinforcement is achieved since they have the same chemical composition, (iii) better orientation of PET macromolecules is expected in the nanofibrils compared to that in microfibrils and textile filaments of the same PET, and (iv) in the test specimens of SPCs, the nanofibrils are urdaxiaUy aligned and the testing has been pierformed in the drawing direction only. 

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