Simone Bidali

Synthesis and characterization of unsaturated polyester resins cured by frontal polymerization

Abstract Various crosslinking agents have been used to frontally cure the unsaturated polyester derived by the reaction of maleic anhydride and 1,2-propanediol. The effect of composition of the curing mixture on the front velocity and its maximum temperature, as well as on the thermal properties of the obtained materials, is described.

Synthesis and Characterization of a Polyurethane Prepared by Frontal Polymerization

Abstract Frontal polymerization (FP) has been successfully applied to the preparation of a polyurethane (PU) having practical interest. By comparing the classical PU synthetic route with FP, the latter allowed for the obtainment of both higher molecular weights and yields. Furthermore, reaction times have been significantly reduced. Eventually, FP materials are characterized by higher glass transition temperature and lower melting point than their batch counterparts.

Self-ignition of Polymerization fronts with convection : the ``Rainstorm Effect''

Abstract This work is devoted to an experimental and numerical study on the influence of natural convection on the ignition of polymerization reaction fronts. Numerical simulations confirm experimental findings. Indeed, it has been observed that under the same initial and boundary conditions the front ignition can occur either in the centre of the reactor or at the top. The difference between these two cases is determined by the viscosity of the medium and by other parameters that can influence the convective motion of a liquid monomer. If the viscosity is low, weak convective motion in the beginning of the development of the reaction will lead to the accumulation of the hotter monomer at the top of the reactor. In this case, front ignition occurs at the top and propagates downwards (rainstorm effect). If the viscosity is sufficiently high, the convective motion does not essentially change the position of the emerging hot spot; the front appears at the centre of the reactor and propagates almost spherically outwards.

Frontal atom transfer radical polymerization of tri(ethylene glycol) dimethacrylate

Abstract The first frontal atom transfer radical polymerization (FATRP) has been successfully carried out using tri(ethylene glycol) dimethacrylate as a monomer. The effect of the catalyst/initiator ratio has been investigated and related to the front velocity and its maximum temperature. By comparing this new approach with classical radical polymerization routes and with conventional frontal polymerization, it was found that the so-obtained polymer is characterized by higher conversion, shorter reaction times, higher degradation temperature, and does not contain entrapped bubbles.

Frontal polymerization as a convenient technique for the consolidation of tuff

Abstract Frontal Polymerization was successfully exploited as an innovative technique for the consolidation of Neapolitan Yellow Tuff, the main volcaniclastic rock of Campania region (Italy). The protocol used and the full characterization in terms of mechanical properties of the resulting consolidated stone are presented here and discussed together with the data obtained by X-ray tomography as a non destructive analytical technique for determining the internal map of the consolidated material. The proposed treatment definitely succeeded from the technical point of view resulting in an enhancement of mechanical properties.

X-ray tomography for the visualization of monomer and polymer filling inside wood and stone

Estimate of sorption of liquid materials inside porous stones and wood is an important parameter in industrial material testing and cultural heritage conservation. In the latter case, a suitable polymer can be used for both consolidation and conservation, it being applied either in the final form or as its parent monomer, which is subsequently allowed to polymerize in situ by the classical method or by frontal polymerization. In this paper a recently developed methodology based of X-ray tomography is presented. This technique has been applied to different types of wood and stone. The gradient of penetration has also been studied. Some of the results obtained are reported and discussed.