Study of the effect of modification of nano / microstructured thermosetting systems with block copolymers on morphology and mechanical properties

Resumen

The main aim of this investigation work was the design and characterization of nanostructuredunsaturated polyester (UP) matrices modified with polyethylene oxide homopolymer (PEO) orpoly(ethylene oxide-b-propylene oxide-b-ethylene oxide) block copolymers (PEO-b-PPO-b-PEO) and itsmodification with cellulose fibers. The work was mainly focused on the study of changes in themiscibility and microphase separation of fabricated thermosets systems before and after curing process.Moreover, the final mechanical and optical properties of designed nanostructured thermosetting materialswere examined.The motivation of this work and the main objectives were detailed in Chapter 1. Chapter 2 dealt with thestate-of-the-art and basic concepts about UP resins, curing mechanism, block copolymers (BCP),nanostructured thermosetting materials and cellulose fibers.Subsequently, Chapter 3 highlighted details regarding materials, protocols and experimental techniquesused along this investigation work.In Chapter 4, the influence of the curing temperature and contents of a PEO homopolymer or a BCP withstructure E75P34E75 on miscibility, morphology, transparency and mechanical properties of the designednanostructured thermosetting systems was investigated. Moreover, in this Chapter, the influence of PPOcentral block of the used BCP on the final properties of designed thermosetting mixture was examined.The main purpose of Chapter 5 was to study the influence of a BCP with structure E20P69E20 on the finalproperties of designed thermosetting materials paying especial attention to the relationships amongmorphology and optical and mechanical properties of final materials.The most important feature of Chapter 6 was to improve the final properties achieved for UP/E20P69E20mixtures by means of chemical modifications of the BCP with the structure E20P69E20 with maleic orsuccinic anhydrides. In this Chapter, one of the modified BCPs became a reactive component during thecuring process affecting the microphase separation and consequently the final properties of the designedthermosetting mixtures. Miscibility, morphology, transparency and mechanical properties of the UPmatrix mixed with the chemically modified BCPs were compared with the final properties ofUP/E20P69E20 mixtures analyzed in Chapter 5.The main objective of the Chapter 7 was to establish a pathway of isolation of cellulose nanofibrils viamechanical disintegration, and to employ them synergically as reinforcement into UP/E20P69E20 mixtures.The final properties of the designed thermosetting nanocomposites with well dispersed nanofibrils werecompared with the thermosetting mixtures without fibers.Finally, Chapter 8 closed this investigated work with general conclusions and future work