Mariacristina Cocca

Polyacrylates for conservation: chemico-physical properties and durability of different commercial products

With the aim of identifying the most suitable commercial water dispersed polyacrylates to be used in the conservation and restoration field, the properties of four commercial polymers were compared with those shown by Primal AC33, a product made and commercialized by Rohm and Haas, widely used as a consolidating and adhesive agent for art works, and nowadays out of production. Chemical, molecular, thermal, mechanical and optical investigation techniques were applied on films obtained from the polymer water dispersions cast at room temperature. Selected polymers were characterized before and after artificial aging under a xenon-arc lamp in order to determine their photooxidative stability. It was found that Acrilem IC15, among the selected products, was the material with improved physico-chemical properties and photooxidative stability with respect to that shown by the discontinued Primal AC33.

Biodegradable PVOH-based foams for packaging applications

Biodegradable poly(vinyl alcohol) (PVOH) based foams were prepared through an ecofriendly methodology. Different amount of recycled multilayer cartons (MC), composed of cellulose and low-density polyethylene (80/20 wt/wt), were added as a direct cellulose source to PVOH. Foams were realized through a modified overrun process without using chemical agents or promoting chemical reactions. In particular, the air entrapped during the high-speed mixing of the PVOH/MC water dispersion was able to create a porous morphology. The effects of the addition of MC on microstructure, swelling behavior, and mechanical and thermal properties of foams were investigated. Materials were characterized by a dual-pore structure. Improvements of the swelling behavior, mechanical properties, and thermal stability were recorded as a function of MC content. These findings can be considered as a result of a good interaction between filler and polymer.

Polyvinyl alcohol biodegradable foams containing cellulose fibres

The preparation of polyvinyl alcohol (PVOH) based foams containing pulp cellulose fibres and microfibrillated cellulose (MFC) fibre is reported, aiming at the realization of sustainable “green-composites.” Foams were obtained through an eco-friendly preparation method able to generate a pore structure by entrapping air into the polymer/filler aqueous dispersion during a high-speed mixing. The effect of pulp cellulose fibres (Bc1000) and MFC on foam microstructure, water vapor absorption behavior, and mechanical properties was studied. The addition of small amount of MFC (1–5u2009wt%) induced a progressive decrease of the average cell diameter and an increase of the cell density; whereas Bc1000 cellulose fibres affected the cell shape and regularity of PVOH based foams. A reduction of the water vapor absorption in PVOH/MFC and PVOH/Bc1000 was recorded with respect to neat PVOH foam, in particular for foams containing pulp cellulose fibres. Finally, both MFC and Bc1000 increased the Young modulus and the compression deflection of PVOH based foams.

Amorphized cellulose as filler in biocomposites based on poly(ɛ-caprolactone)

Amorphous cellulose particles, obtained through a solvent-free mechano-chemical process, have been tested for the first time as a potential filler for biodegradable composites based on poly(ɛ-caprolactone) (PCL). Commercial cellulose fibers have been also tested for comparison. An effective interfacial strategy based on a compatibilizing agent, a modified PCL, has been used to improve the polymer/filler interfacial adhesion. Composites have been tested through physico-mechanical characterizations and soil burial degradation tests, in order to evaluate the influence of cellulose structure and morphology and polymer/filler interfacial adhesion on the final properties of the realized materials. The use of the amorphous cellulose particles combined with the presence of a suitable interfacial agent has allowed to modulate relevant technological properties of the realized composites, such as tensile and thermal properties, water absorption, water vapor transmission rate and biodegradation kinetic.

Uniaxial Tensile Properties of Yarns: Effects of Moisture Level on the Shape of Stress-Strain Curves

With the aim of clarifying the complex shapes of the stress-strain curves of yams such as wool and silk and improving the reproducibility of the experimental results achieved through their mechanical characterization, nylon 6,6 yams consisting of one, three, nine, and thirty filaments are selected as a modeling system. Moreover, the uniaxial tensile properties of commercial nylon 6,6 yarns are investigated and compared with the corre sponding properties of commercial wool and silk yarns. Moisture level plays a very relevant role in determining the mechanical behavior of yarns. With an increasing moisture level of conditioning, in fact, nylon 6,6, wool, and silk yarns show neat breaking points, and their stress-strain curves tend to assume the typical shape of the curve shown by respective single fibres. This suggests that high moisture levels minimize the multiple breakage phenomena occurring in the yam. Moreover, for all the yarns investigated and, in particular, for wool, the process of conditioning at 100% RH reduces the variability of the experimental results, thus inducing a significant improvement in the precision and reproducibility of uniaxial tensile tests.

Evaluation of microplastic release caused by textile washing processes of synthetic fabrics

A new and more alarming source of marine contamination has been recently identified in micro and nanosized plastic fragments. Microplastics are difficult to see with the naked eye and to biodegrade in marine environment, representing a problem since they can be ingested by plankton or other marine organisms, potentially entering the food web. An important source of microplastics appears to be through sewage contaminated by synthetic fibres from washing clothes. Since this phenomenon still lacks of a comprehensive analysis, the objective of this contribution was to investigate the role of washing processes of synthetic textiles on microplastic release. In particular, an analytical protocol was set up, based on the filtration of the washing water of synthetic fabrics and on the analysis of the filters by scanning electron microscopy. The quantification of the microfibre shedding from three different synthetic fabric types, woven polyester, knitted polyester, and woven polypropylene, during washing trials simulating domestic conditions, was achieved and statistically analysed. The highest release of microplastics was recorded for the wash of woven polyester and this phenomenon was correlated to the fabric characteristics. Moreover, the extent of microfibre release from woven polyester fabrics due to different detergents, washing parameters and industrial washes was evaluated. The number of microfibres released from a typical 5xa0kg wash load of polyester fabrics was estimated to be over 6,000,000 depending on the type of detergent used. The usage of a softener during washes reduces the number of microfibres released of more than 35%. The amount and size of the released microfibres confirm that they could not be totally retained by wastewater treatments plants, and potentially affect the aquatic environment.

Rational design of nanoparticle/monomer interfaces: a combined computational and experimental study of in situ polymerization of silica based nanocomposites

Interfaces between methylmethacrylate monomers, oligomers and silica nanoparticles (NPs) were explored by molecular dynamics simulations, infrared and solid state nuclear magnetic resonance spectroscopy. This knowledge allowed the control of the structure of the interfaces by employment of MMA macromonomers, and the design of an improved process for in situ polymerizations with a remarkable increase of NP dispersion.

Effect of cellulose structure and morphology on the properties of poly(butylene succinate-co-butylene adipate) biocomposites.

Composites based on poly(butylene succinate-co-butylene adipate) (PBSA) containing amorphized and crystalline cellulose reinforcements have been prepared and characterized. In order to improve the polymer/filler interfacial adhesion, an efficient compatibilizing agent has been synthesized by chemical modification of PBSA and characterized by FT-IR, FT-NIR and (1)H NMR spectroscopy. Uncompatibilized and compatibilized composites have been tested through morphological, mechanical, calorimetric and thermogravimetric analysis. Moreover, water vapor permeability and biodegradation kinetics of composites have been investigated. The addition to PBSA of cellulose fillers differing from each other by crystallinity degree and morphology, and the use of a compatibilizing agent have allowed modulating tensile and thermal properties, water vapor transmission rate and biodegradation kinetic of the composites.

Effects of Different Artificial Agings on Structure and Properties of Whatman Paper Samples

With the aim at controlling cellulose degradation phenomena, the natural aging of Whatman paper samples was simulated through different artificial aging processes: thermal oxidation in air at constant temperature, photo-oxidation under Xenon arc lamp, accelerating ageing in climatic chamber, and chemical oxidation with sodium methaperiodate. The cellulose degradation was studied by means of viscosimetric, Fourier transform infrared spectroscopy (FTIR), and wide angle X-ray scattering (WAXS) techniques together with thermogravimetric (TGA), mechanical, and optical analyses. All the treatments carried out were found to significantly modify paper structure and properties, the extent of the deterioration effects depending upon the aging kind. Direct correlations were, nevertheless, assessed among level of cellulose molecular degradation, formation of carboxyl, and/or carbonyl groups and paper strain at break.

Synthesis and adsorption study of hyper-crosslinked styrene-based nanocomposites containing multi-walled carbon nanotubes

New nanocomposite microporous materials obtained by adding functionalized multi-walled carbon nanotubes (MWCNT) to styrene/vinylbenzyl chloride/divinylbenzene hyper-crosslinked resins were prepared and characterized. In order to promote the embedding of the MWCNT within the gel-type precursor, a suitable surface modification strategy was set up, based on the grafting of a poly(vinylbenzyl chloride) (PVBC) resin, able to participate in the hyper-crosslinking step, onto the nanotube surface. Characterization of the nanocomposites by FTIR spectroscopy and electron microscopy enabled the assessment of the effect of the nanotubes on the structure and the morphology of the resin. Moreover, gas sorption measurements indicated that by addition of nanotubes it is possible to modulate the pore size distribution, the uptake of CO2 and H2 and the CO2/N2 selectivity. Finally, modified MWCNT are also able to improve the adsorption capacity of phenol from water solutions, suggesting the possible application of the new microporous nanocomposites for water remediation.