Durability of biodegradable polymers for the conservation of cultural heritage

The use of polymers for conservation of cultural heritage is related to the possibility to slow down or stop natural deterioration which, in many cases, corresponds to stopping the entrance of liquid water and to favor spontaneous water vapor removal. Unfortunately, hydrophobicity is generally favored by surface roughness and thus competitive with transparency. It is therefore important to find an optimal balance hydrophobicity, transparency and durability (especially to photooxidation). However, polymers typically used for applications in this field come from non-renewable resources and are not biodegradable. In this work, the mechanical, structural, and optical properties of PLA, PBAT, and a PBAT/PLA blends, as well as surface properties and water vapor permeability, were investigated before and after exposure to UV irradiation, in order to evaluate their durability and suitability for conservation of cultural heritage

Pachydema lopadusanorum n.sp. (Coleoptera Melolonthidae) from Lampedusa Island (Sicily Channel, Central Metditerranean Sea, Italy)

In this paper the populations of Pachydema Castelnau, 1832 (Coleoptera Melolonthidae) living in Lampedusa Island (Sicily Channel, Central Mediterranean Sea, Italy), so far attributed to P. hirticollis (Fabricius, 1787) of North Africa, are examined. The comparison of the main morphological characters between these two populations allowed to attribute those of Lampedusa to a new species that is described in the present work. Faunistic and biological observations on these species are provided

Photo-oxidative and soil burial degradation of irrigation tubes based on biodegradable polymer blends

Irrigation tubes based on biodegradable polymers were prepared via an extrusion-drawing process by Irritec and compared to conventional pipes made of high-density polyethylene (HDPE). A commercial polylactide/poly (butyleneadipate-co-butyleneterephthalate) (PLA/PBAT) blend (Bio-Flex®) and Mater-Bi® were used. The polymers were characterized from rheological and mechanical points of view. Irrigation pipes were subjected to photoaging with continued exposure to UV radiation up to 22 days. The degradability in the soil of irrigation tube samples was studied. The influence of temperature and UV irradiation on soil burial degradation was investigated. A soil burial degradation test was carried out at 30 °C and 50 °C for up to 70 days. The degree of degradation was evaluated from the weight loss percentage. The degradation rate of irrigation tube samples based on Mater-Bi® was higher at 30 °C and was stimulated after 14 days of UV irradiation. Higher temperatures or UV aging encouraged the disintegration in soil of Bio-Flex®-based irrigation tubes. Furthermore, tube samples, before and after UV and soil burial degradation, were analyzed by Attenuated Total Reflection-Fourier Transform Infra-Red (ATR-FTIR) spectroscop

An additive model to predict the rheological and mechanical properties of polypropylene blends made by virgin and reprocessed components

In this work, an additive model for the prediction of the rheological and mechanical properties of monopolymer blends made by virgin and reprocessed components is proposed. A polypropylene sample has been reprocessed more times in an extruder and monopolymer blends have been prepared by simulating an industrial process. The scraps are exposed to regrinding and are melt reprocessed before mixing with the virgin polymer. The reprocessed polymer is, then, subjected to some thermomechanical degradation. Rheological and mechanical experimental data have been compared with the theoretical predictions. The results obtained showed that the values of this simple additive model are a very good fit for the experimental values of both rheological and mechanical properties

A Green Approach for Recycling Compact Discs

Compact discs (CDs) and digital versatile discs (DVDs) are mainly made by polycarbonate disc, a thin layer of aluminum or silver, a thin layer of a coating and a thin layer of a label of paper or PET. The recycling of these discs is difficult due to the removal of these non-polymeric layers and to our best knowledge, no industrial plants have been resent for their recycling. In this work, we propose a facile way to remove the non-polymeric layers and investigate the effect of the repetitive extrusion process on the processability and on the mechanical properties of the recycled polycarbonate. A few works have been published dealing with both the removal of the non-polymeric layers and the mechanical recycling of the disk of polycarbonate. In our approach, the removal of the non-polymeric layers is easily obtained through a thermo-mechanical treatment in a basic solution by ammonia. This process can be considered green because is made at a low temperature with a small amount of water and a very small amount of ammonia, saving energy and water. The properties of the polycarbonate remain good if the mechanical recycling is made after drying the post-consumer polycarbonate

Qualità pomologica e sensoriale di 10 varietà di mango (Mangifera indica L.) coltivate in Sicilia

Il mango (Mangifera indica L.) è una pianta arborea originaria della regione Indo-Burmese, che appartiene botanicamente alla famiglia delle Anacardiaceae, principalmente coltivata nei paesi a clima tropicale e subtropicale ed oggi, complice il cambiamento climatico, diffusa anche nel bacino del mediterraneo. In Italia il mango viene coltivato solo in Sicilia dove areali della costiera tirrenica hanno fatto registrare produzioni di pregio e una crescente diffusione di nuove cultivar provenienti dai luoghi di origine. Limiti vegetazionali piuttosto stretti, soprattutto in termini di minime termiche stagionali, hanno, in passato, causato l’insuccesso di numerosi nuovi impianti basati sull’introduzione di varietà inedite negli areali a clima mediterraneo-subtropicale come in Sicilia. Per evitare il verificarsi di tali situazioni occorre, quindi, valutare con attenzione il comportamento vegeto-produttivo delle nuove introduzioni varietali. Il presente lavoro ha avuto come obiettivo quello di valutare l’adattamento di 10 cultivar di mango mettendo in relazione gli stadi fenologici con gli andamenti termici stagionali utilizzando la scala BBCH (Biologische Bundesantalt, Bundessortenamt und Chemische Industrie) e valutando la qualità fisico-chimica dei frutti. Per ciascun frutto delle 10 varietà in esame sono state analizzate le seguenti caratteristiche: peso del frutto, diametro trasversale del frutto, diametro longitudinale del frutto, consistenza della polpa, peso della polpa, peso della buccia, peso del seme, diametro trasversale del seme, diametro longitudinale del seme. Del succo di ogni frutto sono stati analizzati il contenuto in solidi solubili e l’acidità titolabile. Le prove sono state svolte presso l’azienda Cupitur sita in Caronia Marina, provincia di Messina. Le cv prese in esame sono state: Glenn, Osteen, Maya, Nam Dok Mai, Irwin, Calypso, Valencia Pride, Keitt, Kent e Tommt Atkyns. La correlazione tra stadi fenologici e temperatura nonché il confronto con i risultati ottenuti in ambienti vocati indicano che, seppur con alcuni limiti legati all’inverno, le aree della costa tirrenica della Sicilia, dove queste varietà sono state coltivate, risultano un ambiente climaticamente idoneo per il corretto evolversi delle fasi vegetative e produttive e l’ottenimento di frutti dalle interessanti qualità organolettiche. Tuttavia, l’analisi dei dati di questo ultimo anno ha evidenziato alcune problematiche in grado di influenzare negativamente lo sviluppo delle piante. Temperature al di sotto dei valori critici, infatti, ci obbligano all’uso di frangivento, per ridurre il rischio di esposizione a venti freddi, e al ricorso ad apprestamenti protettivi delle singole piante nei primi anni dell’impianto. Dalle analisi pomologiche risulta un’ampia variabilità delle caratteristiche fisico-chimiche in grado di offrire una ampia scelta commerciale. L’introduzione di queste nuove cultivar in Sicilia consentirebbe un ampliamento del calendario di maturazione da agosto fino a novembre, limitando il ricorso all’importazione, ma va ulteriormente approfondito in relazione ai fattori sopra esposti

Comparison of the Recycling Behavior of a Polypropylene Sample Aged in Air and in Marine Water

During the processing and during their lifetime, polymers are subjected to several environmental stresses—thermomechanical, photo-oxidative, etc.—that can strongly modify their chemical and molecular structure and, consequently, their morphology. Reduction of the molecular weight and formation of double bonds and oxygenated groups are the main changes observed as a consequence of the degradation. As a result of these changes, the macroscopic properties are dramatically modified. These changes can have a relevant effect if the post-consumer plastic manufacts are recycled. In this work, a sample of polypropylene subjected to two different degradation histories—photo-oxidation in air and in marine water—is reprocessed two times in a mini twin-screw extruder in the same processing conditions. The effect of the thermomechanical degradation during the reprocessing is different. Indeed, the less severe degraded sample shows a higher degradation level during reprocessing because the shear stress is larger. This means that the thermomechanical degradation kinetics is larger in the less degraded samples. Nevertheless, the final properties of the recycled polymers are different because the properties of the photo-oxidized samples before reprocessing were very different

The impact of winter flooding with saline water on foliar carbon uptake and the volatile fraction of leaves and fruits of lemon (Citrus limon) trees

We investigated the consequences of recurrent winter flooding with saline water on a lemon (Citrus limon (L.) Burm.f.) orchard, focussing on photosynthesis limitations and emission of secondary metabolites (isoprenoids) from leaves and fruits. Measurements were carried out immediately after flooding (December), at the end of winter (April) and after a dry summer in which plants were irrigated with optimal quality water (September). Photosynthesis was negatively affected by flooding. The effect was still visible at the end of winter, whereas the photosynthetic rate was fully recovered after summer, indicating an unexpected resilience capacity of flooded plants. Photosynthesis inhibition by flooding was not due to diffusive limitations to CO2 entry into the leaf, as indicated by measurements of stomatal conductance and intercellular CO2 concentration. Biochemical and photochemical limitations seemed to play a more important role in limiting the photosynthesis of flooded plants. In young leaves, characterised by high rates of mitochondrial respiration, respiratory rates were enhanced by flooding. Flooding transiently caused large and rapid emission of several volatile isoprenoids. Emission of limonene, the most abundant compound, was stimulated in the leaves, and in young and mature fruits. Flooding changed the blend of emitted isoprenoids, but only few changes were observed in the stored isoprenoids pool.

Biodegradable polymer-wood flour composites: main properties and biodegradability

During the last years, a considerably increasing rate of attention has arisen on biodegradable polymers. In the meanwhile, the use of wood-plastic composites (WPC) has grown in importance, especially in the United States. The combination of biodegradable polymers and wood-based fillers allows obtaining the typical advantages achievable with the use of WPCs, with the further advantage of the biodegradability and compostability of the matrix (and not only of the filler). In this work, the characterization and the biodegradability assessment of Mater-Bi®-wood flour composites have been carried out