Master curves for the mechanical reinforcement of diene elastomers with sp2 carbon allotropes

sp2 carbon allotropes are efficient reinforcing fillers for polymer melt and elastomers: carbon black (CB) has been used since early 1900’s and nanofillers such as carbon nanotubes (CNT), graphene and graphene related materials (GRM) have increased their importance over the last decades. Nanofillers can definitely establish larger interfacial area with the polymer matrix than CB and great impact on material properties is thus expected. However, it is widely acknowledged that they will not be able to completely replace CB. Hence, increasing research efforts are on hybrid systems based on CB-CNT and CB-GRM [1]. Research objective is to identify common features and behaviour of nano (CNT, GRM) and nanostructured (CB) sp2 carbon allotropes. In this work, initial modulus was determined by means of dynamic-mechanical shear measurements of composites based on either poly(1,4-cis-isoprene) or poly(styrene-co-butadiene) as the rubber and either CB or CNT or GRM or hybrid systems as the reinforcing fillers. Filler-polymer interfacial area (i.a.), calculated as the product of filler surface area, density and volume fraction, was used to establish a common correlation with the composite initial modulus. A sort of master curve was derived, able to fit all the points up to interfacial area of about 27 μm-1, corresponding to remarkable filler content. Much better efficiency was shown by carbon fillers, when composites were prepared through latex blending. To allow easy dispersion in rubber latex, sp2 carbon allotropes were functionalized with a serinol derivative: 2-(2,5-dimethyl- 1H-pyrrol-1-yl)-1,3-propanediol (serinol pyrrole, SP) [2, 3], shown in Figure 1

Biosourced Aromatic Derivatives in the Upcycling of Recycled PET: Mellophanic Dianhydride as a Chain Extender

The synthesis of mellophanic dianhydride (MEDA) from biosourced 1,2,3,4-benzene tetracarboxylic derivatives and its use as a chain extender for mechanically recycled PET (R-PET) as an alternative to traditional oil-based pyromellitic dianhydride (PMDA) is reported. The rheological tests performed on the R-PET extruded with MEDA have shown similar results to those obtained with PMDA, and dynamic mechanical thermal analysis (DMTA) showed that, in the 90–110 °C range (i.e., the temperature range commonly used for blow molding of bottles), Young’s modulus of R-PET containing MEDA is about 20% higher in comparison to that of pristine R-PET. The advantage of MEDA is that it can be prepared using building blocks obtained from agricultural waste via a sustainable protocol, whereas PMDA is a product of oil-based chemistr

Bionanocomposites based on chitosan and few layers graphene. The effect of tailor-made functionalization

Bionanocomposites are an emerging class of material. They are designed and developed to achieve advanced structural and functional properties, by using biobased polymers. Among the bio-polymers, focus is on chitosan (CS), poly (N-acetyl-D-glucosamine), a copolymer of [1,4]-linked 2-acetamido-2-deoxy-D-glucopyranose and 2-amino-2-deoxy-D-glucopyranose. Research is steadily increasing on bionanocomposites with graphene and graphene related materials. It is here presented a research on bionanocomposites based on CS and graphene layers (G). Particular focus of the research was on the integration of the graphene layers in the nanocomposite. Materials were prepared based on the supramolecular interaction between CS and G. The core of the research was then on the edge functionalization of the layers. OH groups were added through the cycloaddition reaction with a biosourced pyrrole compound, serinol pyrrole (SP), carried out with the help of either thermal or mechanical energy, with an atom efficiency up to 96% and a very low E Factor. The preparation of CS/G adducts was very simple, even by using only mortar and pestle. OH groups were also added to the G edges by performing the reaction of G with KOH. The Reimer-Tiemann reaction on the G-OH adduct led to the introduction of aldehydic groups, which promote the crosslinking of CS. The CS/G adducts were characterized by means of wide angle X-ray diffraction, scanning and transmission electron microscopy, Fourier transform infrared, X-ray photoelectron and Raman spectroscopies. Thermal stability of the composites was studied by thermogravimetric analysis. Carbon papers and aerogels were prepared, studying the flexibility and the stability in various solvents in a wide pH range

Anisotropic effects and master curves for rubbers with sp2 carbon allotropes towards light weight materials

This work presents the preparation of lightweight rubber materials with nanosized sp2 carbon allotropes and discusses the anisotropic nonlinear mechanical behavior of composites based on these nanofillers. Composites were prepared with either poly(styrene-co-butadiene) or poly(1,4-cis-isoprene) as the polymer matrix and either carbon black (CB) or carbon nanotubes (CNT) or hybrid CB/CNT as the filler systems. The initial modulus of the composite (G’min) was determined through dynamic mechanical shear tests and was correlated with the specific interfacial area (i.a.), calculated through the product of filler surface area, density and volume fraction. Common correlation was established, the equation of the common interpolating curve was derived and was used to design composites with the same modulus and lower density, substituting part of CB with lower amount of the carbon allotrope with larger surface area, CNT. Anisotropic nonlinear mechanical behavior was found for nanocomposites based on CNT and poly(1,4-cis-isoprene), prepared by melt blending, calendering and compression molding. An orthotropic and transversally isotropic response was observed: dynamic-mechanical moduli were very similar inside the sheet plane and very different from those in the orthogonal direction. Hence, energy dissipation is not isotropic in CNT filled rubber composites. Such mechanical behavior was correlated with the material structure: alternate areas containing large or low CNT amount and preferential orientation of CNT were observed. In spite of this anisotropic behavior, the validity of the above mentioned mastercurve was confirmed

Association of Genetic Markers with CSF Oligoclonal Bands in Multiple Sclerosis Patients

Objective:to explore the association between genetic markers and Oligoclonal Bands (OCB) in the Cerebro Spinal Fluid (CSF) of Italian Multiple Sclerosis patients.Methods:We genotyped 1115 Italian patients for HLA-DRB1*15 and HLA-A*02. In a subset of 925 patients we tested association with 52 non-HLA SNPs associated with MS susceptibility and we calculated a weighted Genetic Risk Score. Finally, we performed a Genome Wide Association Study (GWAS) with OCB status on a subset of 562 patients. The best associated SNPs of the Italian GWAS were replicated in silico in Scandinavian and Belgian populations, and meta-analyzed.Results:HLA-DRB1*15 is associated with OCB+: p = 0.03, Odds Ratio (OR) = 1.6, 95% Confidence Limits (CL) = 1.1-2.4. None of the 52 non-HLA MS susceptibility loci was associated with OCB, except one SNP (rs2546890) near IL12B gene (OR: 1.45; 1.09-1.92). The weighted Genetic Risk Score mean was significantly (p = 0.0008) higher in OCB+ (7.668) than in OCB- (7.412) patients. After meta-analysis on the three datasets (Italian, Scandinavian and Belgian) for the best associated signals resulted from the Italian GWAS, the strongest signal was a SNP (rs9320598) on chromosome 6q (p = 9.4×10-7) outside the HLA region (65 Mb).Discussion:genetic factors predispose to the development of OCB

Genetic risk and a primary role for cell-mediated immune mechanisms in multiple sclerosis.

Multiple sclerosis is a common disease of the central nervous system in which the interplay between inflammatory and neurodegenerative processes typically results in intermittent neurological disturbance followed by progressive accumulation of disability. Epidemiological studies have shown that genetic factors are primarily responsible for the substantially increased frequency of the disease seen in the relatives of affected individuals, and systematic attempts to identify linkage in multiplex families have confirmed that variation within the major histocompatibility complex (MHC) exerts the greatest individual effect on risk. Modestly powered genome-wide association studies (GWAS) have enabled more than 20 additional risk loci to be identified and have shown that multiple variants exerting modest individual effects have a key role in disease susceptibility. Most of the genetic architecture underlying susceptibility to the disease remains to be defined and is anticipated to require the analysis of sample sizes that are beyond the numbers currently available to individual research groups. In a collaborative GWAS involving 9,772 cases of European descent collected by 23 research groups working in 15 different countries, we have replicated almost all of the previously suggested associations and identified at least a further 29 novel susceptibility loci. Within the MHC we have refined the identity of the HLA-DRB1 risk alleles and confirmed that variation in the HLA-A gene underlies the independent protective effect attributable to the class I region. Immunologically relevant genes are significantly overrepresented among those mapping close to the identified loci and particularly implicate T-helper-cell differentiation in the pathogenesis of multiple sclerosis

Effectiveness of cardiac resynchronization therapy in heart failure patients with valvular heart disease: comparison with patients affected by ischaemic heart disease or dilated cardiomyopathy. The InSync/InSync ICD Italian Registry

AimsTo analyse the effectiveness of cardiac resynchronization therapy (CRT) in patients with valvular heart disease (a subset not specifically investigated in randomized controlled trials) in comparison with ischaemic heart disease or dilated cardiomyopathy patients.Methods and resultsPatients enrolled in a national registry were evaluated during a median follow-up of 16 months after CRT implant. Patients with valvular heart disease treated with CRT (n = 108) in comparison with ischaemic heart disease (n = 737) and dilated cardiomyopathy (n = 635) patients presented: (i) a higher prevalence of chronic atrial fibrillation, with atrioventricular node ablation performed in around half of the cases; (ii) a similar clinical and echocardiographic profile at baseline; (iii) a similar improvement of LVEF and a similar reduction in ventricular volumes at 6-12 months; (iv) a favourable clinical response at 12 months with an improvement of the clinical composite score similar to that occurring in patients with dilated cardiomyopathy and more pronounced than that observed in patients with ischaemic heart disease; (v) a long-term outcome, in term of freedom from death or heart transplantation, similar to patients affected by ischaemic heart disease and basically more severe than that of patients affected by dilated cardiomyopathy.ConclusionIn 'real world' clinical practice, CRT appears to be effective also in patients with valvular heart disease. However, in this group of patients the outcome after CRT does not precisely overlap any of the two other groups of patients, for which much more data are currently available