Formulation and Study of New Eco-Friendly Intumescent Polylactic Acid Based Materials

Polylactic acid (PLA) is a biodegradable and bio-based polymer obtained by polymerization of lactide or lactic acid, both arising from renewable resources like cereals’ starch. Polylactic acid is also a semycristalline thermoplastic polymer and has mechanical properties in between polystyrene and polyethylene terephthalate. In the last decades the interest on this polymer raised very fast and its industrial production increases very rapidly, in the same way the number of published researches have exponentially increased. Nowadays the main PLA applications consist on food packaging, disposable tableware, biomedical items and textiles. Future and new PLA applications are focusing towards electric, electronics, and transport field. The materials for this kind of applications must have good flame resistance properties and several flame and burning tests must be passed before these materials can be applied. PLA does not have flame resistance properties and burn in air in case of a fire source. Focusing my research to solve this issue, PLA based materials with different flame retardants additives have been formulated and tested. Intumescence has been studied as mechanism to achieve good flame resistance properties, and halogen-free, non-toxic and eco-friendly additives have been used trying to maintain the material biodegradability. New eco-friendly intumescent polylactic acid based materials have been developed, using low load of halogen-free, not toxic and biodegradable additives (6, 10 and 14%). Bio-based and biodegradable carbonizing agents such as starch, sorbitol, coffee grounds, glycerol phosphate, cellulose and Kraft lignin have been tested (2%), and V-0 UL94 classification, LOI values over 32% and GWIT over 775°C were archived in presence of different amount of ammonium polyphosphate (4, 8.5%) for all the carbonizing tested. The presence of zinc borate increased the flame resistance of the materials yielding the lowest total heat release in synergy among all carbonizing agents tested

Fire behaviour of modern façade materials – Understanding the Grenfell Tower fire

The 2017 Grenfell Tower fire spread rapidly around the combustible façade system on the outside of the building, killing 72 people. We used a range of micro- and bench-scale methods to understand the fire behaviour of different types of façade product, including those used on the Tower, in order to explain the speed, ferocity and lethality of the fire. Compared to the least flammable panels, polyethylene-aluminium composites showed 55x greater peak heat release rates (pHRR) and 70x greater total heat release (THR), while widely-used high-pressure laminate panels showed 25x greater pHRR and 115x greater THR. Compared to the least combustible insulation products, polyisocyanurate foam showed 16x greater pHRR and 35x greater THR, while phenolic foam showed 9x greater pHRR and 48x greater THR. A few burning drips of polyethylene from the panelling are enough to ignite the foam insulation, providing a novel explanation for rapid flame-spread within the facade. Smoke from polyisocyanurates was 15x, and phenolics 5x more toxic than from mineral wool insulation. 1kg of burning polyisocyanurate insulation is sufficient to fill a 50m3 room with an incapacitating and ultimately lethal effluent. Simple, additive models are proposed, which provide the same rank order as BS8414 large-scale regulatory tests

Sostituzione dell'epicloridrina con derivati del glicerolo nella preparazione di prepolimeri per resine epossidiche bio-based.

La recente e innovativa filosofia della green chemistry che si sta diffondendo nell’industria chimica e l’incombente esaurimento di risorse fossili, stanno indirizzando la ricerca del settore chimico verso la realizzazione di processi sempre più sostenibili. Tra i processi che necessitano maggiormente di questi cambiamenti, vi è quello della produzione di resine epossidiche che per il 90% è costituito attualmente da resine a base di bisfenolo-A, neuro tossico e pericoloso per la riproduzione umana, ed epicloridrina cancerogena; entrambi ottenuti da risorse fossili. Per tali motivi, in questo elaborato si è cercato di sviluppare un processo di sintesi il più possibile “green”, per l’ottenimento di una molecola derivante da risorse rinnovabili, da sostituire all’epicloridrina nella sintesi di prepolimeri per resine epossidiche bio-based. Lo sviluppo del lavoro è avvenuto tramite lo studio dei reagenti, solventi e parametri operativi, ottenendo il glicidil tosilato a partire da glicerolo e tosil cloruro attraverso una reazione in sistema bifasico, semplice dal punto di vista pratico e senza l’utilizzo di composti tossici. Il glicidil tosilato è meno problematico in quanto meno volatile rispetto all’epicloridrina, ed inoltre le prove di reazione con il bisfenolo-A hanno portato all’ottenimento del prepolimero con rese maggiori rispetto a quelle ottenute nelle stesse condizioni con epicloridrina

CO2 plasticization effect on glassy polymeric membranes

The effect of CO2 on the mechanical properties of three different glassy polymeric materials, polystyrene (PS), polymethylmethacrylate (PMMA) and Matrimid polyimide (PI), has been investigated by dedicated Dynamic Mechanical Analysis (DMA) at 35 degrees C on samples equilibrated at different penetrant pressures (0-30 bar). The experimental campaign has been designed to inspect the mechanical properties associated to the so-called plasticization phenomenon, which has been invoked as responsible for the increase of gas permeability versus feed pressure in glassy polymeric membranes. The main aim of the work is to find if any correlation holds between the effects induced on polymer mechanical properties and on gas permeability by the presence of different amounts of penetrant gas.The DMA analysis revealed that CO2 produces a decrease of polymer storage modulus E' and an enhancement of tan delta factor. Experimental data for both E' and tan delta vary regularly and monotonically with CO2 content in the membrane, with no indication of the onset of other new phenomena at pressures higher than the "plasticization pressure" associated to permeability data. The mechanical properties show very similar behaviors with CO2 content for all polymers analyzed, notwithstanding their CO2 permeability behaviors are different decreasing with upstream pressure for PS, increasing for PMMA and nonmonotonous for Matrimid. The results obtained indicate that there is no direct correlation between gas permeation dependence on CO2 content and the changes in the polymer mechanical properties induced by the same CO2 content

Metabolic implications of coenzyme Q10 in red blood cells and plasma lipoproteins

Plasma coenzyme Q10 (CoQ10) is currently assayed in our laboratory for its well-known diagnostic meaning; in fact plasma CoQ10 levels are inversely related to metabolic demand. Definite levels of CoQ10 are also found in white and red blood cell components, as well as in platelets. Plasma and erythrocyte CoQ10 has a well assessed antioxidant role, which was demonstrated through a series of experiments. Erythrocytes previously enriched with exogenous CoQ10 were found more resistant to a hemolysis induced by a free radical initiator. Several enzymatic activities of erythrocyte ghosts were also protected by different side chain CoQ homologues, both when reduced and, although at a lesser extent, in the oxidized state. CoQ was not effective in preventing metal-catalyzed oxidation of erythrocyte membrane enzymes, and this effect is likely to be due to lack of interaction of CoQ with the metal target. Moreover CoQ was able to protect isolated enzymes and erythrocyte membrane bound enzymes from the inactivating effect of free radicals generated by water sonolysis or radiolysis. As far as plasma lipoproteins are concerned it is well known that LDL isolated from healthy volunteers supplemented with CoQ10 are more resistant to peroxidation induced by an azoinitiator. We started to systematically investigate CoQ10 and vitamin E levels in isolated human LDL and HDL. Both CoQ10 and vitamin E concentrations, referred to protein, were found higher in LDL than in HDL. Susceptibility to exogenously applied peroxidation did not correlate with the endogeneous content of the two antioxidants, possibly on the basis of different lipid content of these lipoproteins