Nanoparticle Dynamics in Polymer Melts

The effect of small amounts of nanoparticles on the melt-state linear viscoelastic behaviour is investigated for different polymer-nanoparticles model systems characterized by poor polymer-particles interactions and low particle contents.contents. The drastic increase of the rheological properties with respect to the matrices is related to the formation of a filler network above a critical particles volume fraction. Once formed, the filler network exhibits an elastic feature that mixes with the intrinsic viscoelastic response of the polymer matrix, resulting in a complex Φ- and ω-dependent viscoelastic response of the nanocomposite. However, we show that the contributions of filler network and suspending medium can be decoupled due to the weak polymer-particle interactions and the differences in temporal relaxation scales. The adopted approach is validated through the building of a master curve of the moduli, which reflects the scaling of the elasticity of composites along the viscosity of the suspending medium. The two-phase model well works irrespective of the structure of the filler network, making evident the strict interrelationships between the structure, both on nano- and micro-scale, and the melt- state behaviour of the studied PNCs

Solid particle erosion and viscoelastic properties of thermoplastic polyurethanes

The wear resistance of several thermoplastic polyurethanes (TPUs) having different chemical nature and micronscale arrangement of the hard and soft segments has been investigated by means of erosion and abrasion tests. The goal was correlating the erosion performances of the materials to their macroscopic mechanical properties. Unlike conventional tests, such as hardness and tensile measurements, viscoelastic analysis proved to be a valuable tool to study the erosion resistance of TPUs. In particular, a strict correlation was found between the erosion rate and the high-frequency (~10^7 Hz) loss modulus. The latter reflects the actual ability of TPU to dissipate the impact energy of the erodent particles

Fully Bio-Based Nanocomposite: Formulations For Packaging Application

The effect of a small amount of organoclay (OMMT) on mechanical, dynamic-mechanical, barrier and thermal properties of blown films based on blends of poly(lactic acid) (PLA) and polyamide 11 (PA11) was investigated. The addition of PA11 results in a decrease of elastic modulus (E) and tensile strength (σR) compared to neat PLA, which suggests poor interfacial adhesion between the polymer phases. Besides an enhancement of E and σR, the addition of 1 wt% of OMMT brings about a significant increase of the elongation at break. Neither blending with PA11 nor adding OMMT cause appreciable alterations of the barrier properties of the films, which remain essentially the same as those of pure PLA. Thermogravimetric analysis reveals that the onset of thermal degradation of the OMMT-filed blend is 15°C higher than of neat PLA. This improvement is probably due to the labyrinth effect of the PA11 phase. Finally, the OMMT brings about a slight enhancement of the glassy modulus compared to the unfilled blend, which suggests that the clay may exert some compatibilizing action. Such a beneficial effect of the OMMT endures up to the glass transition of PLA. he testing methods such as CCT, RCT, FCT, COBB, bursting etc. are supported by statistical technique and do not provide accurate results. The reason is the deviation of testing results. The same problem can be defined at the classification of different paper materials and qualities. This paper describes a new possible testing method to analyze the chemical and thermo-analytical nature of papers. This method can be used to specify effectively the limits of a given paper quality using in packaging industry and can help to ensure the exact traceability of paper identification. The results show that the this method on the one hand can be helpful to testing the paper during packaging producing process on the other hand after using as a packaging. To the testing a DSC measurement device was used as a thermo-analytical method to observe new specifics of paper based packaging

Dielectric behavior of biopolymer based composites containing multi wall carbon nanotubes: Effect of filler content and aspect ratio

Multi wall carbon nanotubes (MWCNTs) with different aspect ratios (30, 105 and 667) were included in a commercial fully biodegradable blend using melt mixing. Samples of composite systems prepared by hot molding and containing up to 1.2 vol% of MWCNTs were studied by means of DC electrical resistivity and dielectric spectroscopy in order to enhance effect of filler content and aspect ratio on their dielectric behavior. Raman spectroscopic investigations and morphological observations were also performed in order to correlate dielectric behavior with surface carbon nanotubes features and to check the actual level of dispersion of carbon nanotubes under the applied processing conditions. Results emphasized that the carbon nanotubes aspect ratio and their surface regularity determine the electrical properties of composites because they strongly influence percolation thresholds, dielectric permittivity and dissipation factor of produced materials. A satisfying dispersion of the filler seems to be achieved under the employed processing conditions. These preliminary results demonstrates possible applications of this type of biobased systems in many applications going from stress control to devices for high storage energy

Common genetic variants in NEFL influence gene expression and neuroblastoma risk

The genetic etiology of sporadic neuroblastoma is still largely obscure. In a genome-wide association study, we identified single-nucleotide polymorphisms (SNP) associated with neuroblastoma at the CASC15, BARD1, LMO1, DUSP12, HSD17B12, HACE1, and LIN28B gene loci, but these explain only a small fraction of neuroblastoma heritability. Other neuroblastoma susceptibility genes are likely hidden among signals discarded by the multiple testing corrections. In this study, we evaluated eight additional genes selected as candidates for further study based on proven involvement in neuroblastoma differentiation. SNPs at these candidate genes were tested for association with disease susceptibility in 2,101 cases and 4,202 controls, with the associations found replicated in an independent cohort of 459 cases and 809 controls. Replicated associations were further studied for cis-effect using gene expression, transient overexpression, silencing, and cellular differentiation assays. The neurofilament gene NEFL harbored three SNPs associated with neuroblastoma (rs11994014: Pcombined \ubc 0.0050; OR, 0.88; rs2979704: Pcombined \ubc 0.0072; OR, 0.87; rs1059111: Pcombined \ubc 0.0049; OR, 0.86). The protective allele of rs1059111 correlated with increased NEFL expression. Biologic investigations showed that ectopic overexpression of NEFL inhibited cell growth specifically in neuroblastoma cells carrying the protective allele. NEFL overexpression also enhanced differentiation and impaired the proliferation and anchorage-independent growth of cells with protective allele and basal NEFL expression, while impairing invasiveness and proliferation of cells homozygous for the risk genotype. Clinically, high levels of NEFL expression in primary neuroblastoma specimens were associated with better overall survival (P \ubc 0.03; HR, 0.68). Our results show that common variants of NEFL influence neuroblastoma susceptibility and they establish that NEFL expression influences disease initiation and progressio

Efficacy and durability of multifactorial intervention on mortality and MACEs:a randomized clinical trial in type-2 diabetic kidney disease

Background: Multiple modifiable risk factors for late complications in patients with diabetic kidney disease (DKD), including hyperglycemia, hypertension and dyslipidemia, increase the risk of a poor outcome. DKD is associated with a very high cardiovascular risk, which requires simultaneous treatment of these risk factors by implementing an intensified multifactorial treatment approach. However, the efficacy of a multifactorial intervention on major fatal/non-fatal cardiovascular events (MACEs) in DKD patients has been poorly investigated. Methods: Nephropathy in Diabetes type 2 (NID-2) study is a multicentre, cluster-randomized, open-label clinical trial enrolling 395 DKD patients with albuminuria, diabetic retinopathy (DR) and negative history of CV events in 14 Italian diabetology clinics. Centres were randomly assigned to either Standard-of-Care (SoC) (n = 188) or multifactorial intensive therapy (MT, n = 207) of main cardiovascular risk factors (blood pressure 40/50 mg/dL for men/women and < 175 mg/dL, respectively). Primary endpoint was MACEs occurrence by end of follow-up phase. Secondary endpoints included single components of primary endpoint and all-cause death. Results: At the end of intervention period (median 3.84 and 3.40 years in MT and SoC group, respectively), targets achievement was significantly higher in MT. During 13.0 years (IQR 12.4–13.3) of follow-up, 262 MACEs were recorded (116 in MT vs. 146 in SoC). The adjusted Cox shared-frailty model demonstrated 53% lower risk of MACEs in MT arm (adjusted HR 0.47, 95%CI 0.30–0.74, P = 0.001). Similarly, all-cause death risk was 47% lower (adjusted HR 0.53, 95%CI 0.29–0.93, P = 0.027). Conclusion: MT induces a remarkable benefit on the risk of MACEs and mortality in high-risk DKD patients. Clinical Trial Registration ClinicalTrials.gov number, NCT00535925. https://clinicaltrials.gov/ct2/show/NCT0053592

Altering the onset of cocontinuity in nanocomposite immiscible blends by acting on the melt-compounding procedure

The addition of nanoparticles to polymer systems with an existing phase-separated morphology, such as polymer blends, represents an innovative approach to controlling the microstructure and, hence, the macroscopic properties of the material. During the melt mixing of the constituents, the particles migrate toward specific regions of the material and are driven by more favorable thermodynamic interactions. Kinetic effects related to the high viscosity of the polymer melts, however, may lead to nonequilibrium morphologies. This makes the mixing procedure crucial for controlling the space distribution of the filler and, hence, the microstructure of the blend and its final properties. We focused on this topic by investigating the effect of the sequence of addition of the constituents in blends of polystyrene and polyamide 6 filled with an organoclay prepared by melt compounding. We show that the mixing procedure could bring about alterations in the onset of cocontinuity, which could be exploited to enhance the high-temperature mechanical strength of the blends