A New Approach to Estimating the Parameters of Structural Formations in HDPE Reactor Powder.

The morphology of virgin reactor powder (RP) of high-density polyethylene (HDPE) with M = 160,000 g/mol was investigated using DSC, SEM, SAXS, and WAXS methods. The morphological SEM analysis showed that the main morphological units of RP are macro- and micro-shish-kebab structures with significantly different geometric dimensions, as well as individual lamellae of folded chain crystals. A quantitative analysis of an asymmetric SAXS reflection made it possible to reveal the presence of several periodic morphoses in the RP with long periods ranging from 20 nm to 60 nm, and to correlate them with the observed powder morphology.

EVALUATION OF D-DIMER LEVEL AS A BIOMARKER OF DISEASE SEVERITY AND MORTALITY IN PATIENTS WITH COVID-19.

Objective: The aim: To examine risk factors and evaluate the use of D-dimer as a biomarker of disease severity and mortality in patients with COVID-19.

Patients And Methods: Materials and methods: Data from a large NYU Langone Health system were analyzed to examine the prevalence of elevated D-dimer levels at first detection and the trend. A retrospective cohort study of 2,377 patients (NYU Langone Health) with severe COVID-19.

Tensile Strength Statistics of High-Performance Mono- and Multifilament Polymeric Materials: On the Validity of Normality.

Recently, the statistical distributions of the mechanical properties, including tensile strength (), of several high-strength high-modulus oriented polymeric materials have been analyzed by employing the Weibull's and Gaussian statistical models. However, a more detailed comprehensive analysis of the distributions of the mechanical properties of these materials aimed to estimate the validity of normality by employing some other statistical approaches, is needed. In the present work, the statistical distributions of the seven high-strength oriented polymeric materials based on the polymers with three different chain architectures and conformations, ultra-high-molecular-weight polyethylene (UHMWPE), polyamide 6 (PA 6), and polypropylene (PP), each in the form of both single and multifilament fibers, have been investigated using graphical methods, such as the normal probability and quantile-quantile plots, and six selected formal normality tests, such as the Kolmogorov-Smirnov, Shapiro-Wilk, Lilliefors, Anderson-Darling, D'Agostino-K squared, and Chen-Shapiro tests.

Evolution of Statistical Strength during the Contact of Amorphous Polymer Specimens below the Glass Transition Temperature: Influence of Chain Length.

A comprehensive study of the statistical distribution of the auto-adhesion lap-shear strength () of amorphous polymer-polymer interfaces using various types of statistical tests and models is a useful approach aimed at a better understanding of the mechanisms of the self-healing interface. In the present work, this approach has been applied, for the first time, to a temperature () range below the bulk glass transition temperature (). The interest of this range consists in a very limited or even frozen translational segmental motion giving little or no chance for adhesion to occur.

Fundamental Structural and Kinetic Principals of High Strength UHMWPE Fibers Production by Gel-Technology.

One of the main research work in the field of polymeric materials was, is and always will be the improvement of their mechanical properties. Comprehensive structural studies of UHMWPE reactor powder, the features of its dissolution and the formation of a gel-state, as well as UHMWPE films oriented up to various draw ratios, were carried out using scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction. For comparison, decalin and vaseline oil were chosen as solvents.