On the Improved Mechanical Properties of Ball-Milled GNPs Reinforced Short Chain Branched-Polyethylene Nanocomposite: Micromechanical Modeling and Fractography Study

Short-chain branched-Polyethylene (SCB-PE) is commonly utilized in hot and cold piping systems due to its high-temperature resistance. SCB-PE nanocomposites using graphene nanoplatelets (GNPs) as a reinforcing filler were synthesized in this work. The effect of the filler’s content and the ball-milling process on nanocomposites’ structure, tensile and shear properties was studied. Two series of nanocomposites have been prepared, one with and one without the ball-milling as a premixing step prior to the melt-mixing process. The ball-milling process induced a lower crystallinity degree of the SCB-PE nanocomposites than their solely melt-mixed counterpart. The tensile properties of the ball-milled samples presented a more profound enhancement with increasing filler content. The Ji and modified Halpin-Tsai micromechanical models were best fit to describe the experimental elastic modulus of the solely melt-mixed and the ball-milled nanocomposites, respectively. Fractography studies suggested that the detachment of the filler particles from the polymer matrix is avoided for lower GNPs contents of the ball-milled samples. Shear tests revealed that the shear strength increased and ductility decreased with increasing filler content in any case. The ball-milling process resulted in SCB-PE nanocomposites with superior mechanical properties compared to their solely melt-mixed counterparts.

Influence of Tire Rubber Particles Addition in Different Branching Degrees Polyethylene Matrix Composites on Physical and Structural Behavior

Waste from pneumatic wheels is one of the major environmental problems, and the scientific community is looking for methods to recycle this type of waste. In this paper, ground tire rubber particles (GTR) from disused tires have been mixed with samples of low-density polyethylene (LDPE) and high-density polyethylene (HDPE), and morphological tests have been performed using scanning electron microscopy (SEM), as well as the dynamic electric analysis (DEA) dielectric characterization technique using impedance spectroscopy. From this experience, how GTR reinforcement influences polyethylene and what influence GTR particles have on the branched polyethylene has been detected. For pure LDPE samples, a Debye-type dielectric behavior is observed with an imperfect semicircle, which depends on the temperature, as it shows differences for the samples at 30 °C and 120 °C, unlike the HDPE samples, which do not show such a trend. The behavior in samples with Debye behavior is like an almost perfect dipole and is due to the crystalline behavior of polyethylene at high temperature and without any reinforcement. These have been obtained evidence that for branched PE (LPDE) the Maxwell Wagner Sillars (MWS) effect is highly remarkable and that this happens due to the intrachain polarization effect combined with MWS. This means that the permittivity and conductivity at LDPE/50%GTR are high than LDPE/70%GTR. However, it does not always occur that way with HDPE composites in which HDPE/70%GTR has the highest values of permittivity and conductivity, due to the presence of conductive fraction (Carbon Black-30%) in the GTR particles and their dielectric behavior.

Novel Long-Acting Ropeginterferon Alfa-2b: Pharmacokinetics, Pharmacodynamics, and Safety in a Phase I Clinical Trial

AIM Ropeginterferon alfa-2b is a new site-specific conjugated 40 kDa branched polyethylene-glycol recombinant interferon (IFN). The aim of the study was to determine its safety, pharmacokinetics (PK) and pharmacodynamic (PD). METHODS Ropeginterferon alfa-2b was evaluated first in human in 48 healthy male volunteers after a single dose subcutaneous injection by either 24, 48, 90, 180, 225, 270mcg of the product or 180mcg of marketed pegylated (peg)-IFN alfa-2a. Within each dosing group, 6 subjects received ropeginterferon alfa-2b and 2 subjects received peg-IFN alfa-2a. RESULTS Dose-related increases in ropeginterferon alfa-2b PK parameters (Cmax, AUC, and AUC0-t) were observed over the dose range 24 to 270mcg. The geometric mean values for these PK parameters of ropeginterferon alfa-2b were higher than that of peg-IFN alfa-2a at the 180mcg dose level of 176%, 166%, and 182%, respectively. Mean PD parameters (Emax, Tmax, and AUC0-t) for ropeginterferon alfa-2b increased with dose for both biomarkers neopterin and 2’, 5’-OAS. Ropeginterferon alfa-2b has similar PD profiles as peg-IFN alfa-2a. The treatment related adverse events are similar between the two study drugs, but the overall incidence was numerically lower for ropeginterferon alfa-2b (83%) than peg-IFN alfa-2a (100%) at the 180mcg dose level. CONCLUSIONS Single subcutaneous dose of Ropeginterferon alfa-2b of up to 270mcg is safe and well tolerated. It displays dose related increase in PK and PD parameters, potentially less frequent injection, and better safety profiles. Ropeginterferon alfa-2b is being developed for diseases in which previous peg-IFN use has been limited by side effects.