Barrier properties of GnP-PA-extruded films

It is generally known that significant improvements in the properties of nanocomposites can be achieved with graphene types currently commercially available. However, so far this is only possible on a laboratory scale. Thus, the aim of this study was to transfer results from laboratory scale experiments to industrial processes. Therefore, nanocomposites based on polyamide (PA) and graphene nanoplatelets (GnP) were prepared in order to produce membranes with improved gas barrier properties, which are characterized by reduced permeation rates of helium. First, nanocomposites were prepared with different amounts of commercial availably graphene nanoplatelets using a semi-industrial-scale compounder. Subsequently, films were produced by compression molding at different temperatures, as well as by flat film extrusion. The extruded films were annealed at different temperatures and durations. In order to investigate the effect of thermal treatment on barrier properties in correlation to thermal, structural, and morphological properties, the films were characterized by differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS), optical microscopy (OM), transmission electron microscopy (TEM), melt rheology measurements, and permeation measurements. In addition to structural characterization, mechanical properties were investigated. The results demonstrate that the permeation rate is strongly influenced by the processing conditions and the filler content. If the filler content is increased, the permeation rate is reduced. The annealing process can further enhance this effect

Highly efficient flame retardant and smoke suppression mechanism of polypropylene nanocomposites based on clay and allylamine polyphosphate.

Fire-retarded polymer nanocomposites (FRPN) based on polypropylene with clay and allylamine polyphosphate (PP/clay-AAPP) were designed and prepared by melt mixing. Their morphological, thermal and fire-safety properties were investigated by TEM, SEM, EDS, TG, UL-94, LOI, cone-calorimeter test and TG-FTIR. The results exhibited that the LOI of PP/2 wt%clay-20wt%AAPP nanocomposites was 29.5% with V-0 rating level in UL-94 vertical testing. Significant enhancements in fire safety performance were also observed for fire-retarded PP nanocomposites from cone-calorimeter test decreasing heat release as well as smoke and toxic gases. PP/clay-AAPP nanocomposites not only provided relatively stable char layer during polymer burning, but also exhibited better fire safety performance due to the exfoliation of clay platelets. It displayed that incorporation of clay and AAPP were very efficient in increasing the fire safety of PP composites.post-print6433 K

Causal effect of plasminogen activator inhibitor type 1 on coronary heart disease

Background--Plasminogen activator inhibitor type 1 (PAI-1) plays an essential role in the fibrinolysis system and thrombosis. Population studies have reported that blood PAI-1 levels are associated with increased risk of coronary heart disease (CHD). However, it is unclear whether the association reflects a causal influence of PAI-1 on CHD risk. Methods and Results--To evaluate the association between PAI-1 and CHD, we applied a 3-step strategy. First, we investigated the observational association between PAI-1 and CHD incidence using a systematic review based on a literature search for PAI-1 and CHD studies. Second, we explored the causal association between PAI-1 and CHD using a Mendelian randomization approach using summary statistics from large genome-wide association studies. Finally, we explored the causal effect of PAI-1 on cardiovascular risk factors including metabolic and subclinical atherosclerosis measures. In the systematic meta-analysis, the highest quantile of blood PAI-1 level was associated with higher CHD risk comparing with the lowest quantile (odds ratio=2.17; 95% CI: 1.53, 3.07) in an age- and sex-adjusted model. The effect size was reduced in studies using a multivariable-adjusted model (odds ratio=1.46; 95% CI: 1.13, 1.88). The Mendelian randomization analyses suggested a causal effect of increased PAI-1 level on CHD risk (odds ratio=1.22 per unit increase of log-transformed PAI-1; 95% CI: 1.01, 1.47). In addition, we also detected a causal effect of PAI-1 on elevating blood glucose and high-density lipoprotein cholesterol. Conclusions--Our study indicates a causal effect of elevated PAI-1 level on CHD risk, which may be mediated by glucose dysfunction

Influence of annealing on anisotropic crystalline structure of HDPE cast films

High density polyethylene (HDPE) films were produced using cast film extrusion process with different draw ratios, ranging from 16.9 to 148.8. Morphology, crystallinty and orientation state of crystalline and amorphous phases of the cast films were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and polarized Fourier transform infrared spectroscopy (FTIR) analyses, respectively. The anisotropic crystalline structures of row-nucleated lamellar morphology were observed for the films produced with high draw ratios. The crystalline phase axes orientation functions were found to be significantly dependent on the applied draw ratios. As expected, annealing increased the crystallinity and melting point temperature (Tm) of the cast films and on the other hand, it also enhanced the crystalline phase orientation. However, the results revealed that annealing also promoted non-twisted lamellar structures, since it increased fc values (c-axis orientation function) and decreased fa values (a-axis orientation function) simultaneously. Additionally, it was found that the annealing induced enhancement in c-axis orientation function was more significant for the cast films with lower draw ratios, therefore, it was dependent on the draw ratio

A Process-Oriented Cooperation Model for Distributed Civil Engineering Construction Works

The planning processes in Civil Engineering have specific aspects compared to the design-, construction- and maintenance processes in other industry domains: In opposition to industrial production processes, Civil Engineering always deals with unique structures. Planning is characterized by a high degree of specialization and a great division of work. Planning participants operate in legally independent and temporarily and physically distributed organizations. They have to co-operate and communicate in a heterogeneous planning environment. In order to develop appropriate methods and tools for the process modeling in Civil Engineering, the specialization and the distribution are important aspects that have to be considered. This paper presents a new approach to better coordinate the planning processes based on a generic process model, which uses semantic information within the theoretical background of Coloured Petri Nets. Planning information is represented in metainformation and is linked to the process model, so that it can be accessed to support decisions. The approach uses process model patterns which are predefined for each construction element. They match a general formalism and are compatible to each other. The process model can thus be adapted to the proceeding planning process and meets the requirements of the dynamic change. The contribution gives an overview on the approach to handle the distributed process modeling in Civil Engineering for cooperation purposes and shows the pilot-implementation

Utilization of Agrowaste Polymers in PVC/NBR Alloys: Tensile, Thermal, and Morphological Properties

Poly(vinyl chloride)/nitrile butadiene rubber (PVC/NBR) alloys were melt-mixed using a Brabender Plasticorder at 180∘C and 50 rpm rotor speed. Alloys obtained by melt mixing from PVC and NBR were formulated with wood-flour- (WF-) based olive residue, a natural byproduct from olive oil extraction industry. WF was progressively increased from 0 to 30 phr. The effects of WF loadings on the tensile properties of the fabricated samples were inspected. The torque rheometry, which is an indirect indication of the melt strength, is reported. The pattern of water uptake for the composites was checked as a function WF loading. The fracture mode and the quality of bonding of the alloy with and without filler are studied using electron scanning microscope (SEM)

Process modelling in civil engineering based on hierarchical Petri nets

Process modeling is a central aspect for the support of the network-based coordination of planning processes in civil engineering. Hereby, the planning processes are characterized by some significant aspects, especially the great complexity and the dynamical behavior. To master both, the complexity and the refinement of planning processes, appropriate hierarchical structured process models are necessary. This contribution provides a Petri Net based approach for hierarchical process modelling. The focus is on the formalism to ensure the structural and behavioural correctness of the hierarchical process models and a prototypic software implementation for hierarchical process modelling in civil engineering

Processes Modelling in Civil Engineering based on Hierarchical Petri Nets

ABSTRACT: Process modeling is a central aspect for the support of the network-based coordination of planning processes in civil engineering. Hereby, the planning processes are characterized by some significant aspects, especially the great complexity and the dynamical behavior. To master both, the complexity and the refinement of planning processes, appropriate hierarchical structured process models are necessary. This contribution provides a Petri Net based approach for hierarchical process modelling. The focus is on the formalism to ensure the structural and behavioural correctness of the hierarchical process models and a prototypic software implementation for hierarchical process modelling in civil engineering.

Carboxylated nitrile butadiene rubber/hybrid filler composites

The surface properties of the OSW and NLS are measured with the dynamic contact-angle technique. The x-ray photoelectron spectroscopy (XPS) of the OSW reveals that the OSW possesses various reactive functional groups namely hydroxyl groups (OH). Hybrid filler from NLS and OSW were incorporated into carboxylated nitrile rubber (XNBR) to produce XNBR hybrid composites. The reaction of OH groups from the OSW with COOH of the XNBR is checked by attenuated total reflectance spectra (ATR-IR) of the composites. The degree of curing ΔM (maximum torque-minimum torque) as a function of hybrid filler as derived from moving die rheometer (MDR) is reported. The stress-strain behavior of the hybrid composites as well as the dynamic mechanical thermal analysis (DMTA) is studied. Bonding quality and dispersion of the hybrid filler with and in XNBR are examined using scanning-transmission electron microscopy (STEM in SEM)