Is there any chance for polypropylene/clay nanocomposites in injection molding?

editoria

Energy Efficiency and Renewable Solar Energy Integration in Heritage Historic Buildings

AbstractWhen facing a retrofitting project which tries to improve the energy performance of a cultural heritage building it is necessary to weigh carefully different aspects such as: energy efficiency, modernization and comfort. These energy improvements are desirable, but are not always possible without compromises. The situation may become slightly problematic when solar energy systems should be installed in historic buildings. The first step to overcoming barriers successfully, is to better understand the processes for both, historic preservation and solar PV project implementation, and to foster working with professionals in each sector to receive appropriate support and guidance. Establishing an assessment criterion for each step was the top priority of the research project presented here to assist in achieving a successful result

Making an impact with nanocomposites

Nanoclays can improve the performance of injection-molded polypropylene components likely to be subjected to impact in servic

Low birth weight and longitudinal trends of cardiovascular risk factor variables from childhood to adolescence: the bogalusa heart study

BACKGROUND: Several studies have linked low birth weight to adverse levels of cardiovascular risk factors and related diseases. However, information is sparse at a community level in the U.S. general population regarding the effects of low birth weight on the longitudinal trends in cardiovascular risk factor variables measured concurrently from childhood to adolescence. METHODS: Longitudinal analysis was performed retrospectively on data collected from the Bogalusa Heart Study cohort (n = 1141; 57% white, 43% black) followed from childhood to adolescence by repeated surveys between 1973 and 1996. Subjects were categorized into low birth weight (below the race-specific 10(th )percentile; n = 123) and control (between race-specific 50–75(th )percentile; n = 296) groups. RESULTS: Low birth weight group vs control group had lower mean HDL cholesterol (p = 0.05) and higher LDL cholesterol (p = 0.05) during childhood (ages 4–11 years); higher glucose (p = 0.02) during adolescence. Yearly rates of change from childhood to adolescence in systolic blood pressure (p = 0.02), LDL cholesterol (p = 0.05), and glucose (p = 0.07) were faster, and body mass index (p = 0.03) slower among the low birth weight group. In a multivariate analysis, low birth weight was related independently and adversely to longitudinal trends in systolic blood pressure (p = 0.004), triglycerides (p = 0.03), and glucose (p = 0.07), regardless of race or gender. These adverse associations became amplified with age. CONCLUSIONS: Low birth weight is characterized by adverse developmental trends in metabolic and hemodynamic variables during childhood and adolescence; and thus, it may be an early risk factor in this regard

Solar Radiation and Daylighting Assessment Using the Sky-view Factor (SVF) Analysis as Method to Evaluate Urban Planning Densification Policies Impacts

Abstract This study identifies and proposes simple methods to assess solar radiation, daylighting availability and Sky-View Factor (SVF) modification, in complex urban environment. Numerical methods and 3D simulation software are combined with photo processing methods using digital cameras with special mirrors to project the hemispherical environment onto a circular image. This methodology has been applied to a real case study in Switzerland that is undergoing a very fast urban densification process, where urban planning strategies will determine significantly the possibility to relish solar irradiation in buildings. This paper analyzed the particularities of different urban scenarios considering the effects of urban densification planning strategies on existing buildings, in particular historical protected buildings

Fracture toughness of injection moulded organoclay reinforced polypropylene composites

The fracture behavior of polypropylene reinforced with different amounts of PP/50% organoclay masterbatch was studied. Test pieces were prepared using a two-gated hot runner injection mould. Morphology of final pieces was analyzed by polarized optical microscopy, Xray diffraction and transmission electron microscopy. Fracture toughness was evaluated under quasi-static conditions at different positions in the molded pieces. The brittle mode of failure of PP became more ductile with increasing the amount of clay. However, the midthickness region (core) of “ductile” samples underwent brittle fracture while the surface layers (skin) behave in a ductile way, exhibiting elongation, necking and ductile tearing, probably due to differences in thickness and crystalline structure found in skin layers of composite pieces. Different Fracture Mechanics approaches were applied to characterize the fracture behavior: fracture toughness initiation value was assessed by means of the stress intensity factor at 5% non-linearity, KIq, and fracture toughness propagation value was obtained by means of the propagation strain energy release rate, Gcp. It was found that fracture initiation neither depends on clay content nor on test piece location. On the other hand, clay reinforcement increased fracture propagation values away from weld line region. This toughening effect was found to be dependent on the clay content and reinforcement orientation induced by the processing technique

The energy performance evaluation of buildings in an evolving built environment: an operative methodology

Abstract The paper is based on a case study in Switzerland, where the Cantonal Director Plan, expected for the next years, will change the urban density. The plan allows raising from three and four floors the height of the existing buildings now separated by streets that are quite narrow, to get over up to eight floors, without modifying the width of street. A case study located in Paradiso municipality, part of Lugano's city (CH) is used to understand and quantify the impact of the future buildings on the energy performance of historical heritage buildings. The building adopted as case study is protected as cultural monument by the new Master Plan and listed in the sectorial regulations for the landscape. However, this building as others in the area is strongly influenced by the new changes in act, due to the New Master Plan, in term of solar availability and thus energy demand. The actual urban density scenario is compared to the future one to evaluate through dynamic energy simulation the change affecting the building considering the energy and economic aspects

Surface property effects of compounding a nanoclay masterbatch in PP injection moulding

Indicado para o prémio de melhor artigo mais inovador.The interest on the use of nanofillers in injection mouldings has been going on for more than a decade but a real breakthrough has not been achieved yet, especially in that mechanical properties are concerned. The nucleating effect of nanoclays in semicrystalline polymers suggests that surface effects may result interesting especially during processing. This paper includes some information on the surface properties of an injection moulding grade of polypropylene mixed with a commercial masterbatch of PP and 50% of organoclay. They were moulded as plates for testing in a prototype device for determining the coefficient of friction in as-moulding conditions. The surface was also characterised by depth sensing indentation tests. The through thickness microstructures of the mouldings were assessed by optical microscopy and differential scanning calorimetry, while surface morphology was assessed by X-ray diffraction. It was observed that independently of MB content, its addition caused a slight increase in elastic modulus and hardness in the skin layer.The friction properties directly associable to the product performance showed a slight improvement in terms of the dynamic friction coefficient. Conversely the static friction coefficient that is relevant in processing was no affected by the presence of the nanoclay

Microestructura y desempeño de compuestos de PP/nanoarcilla producidos por técnicas de inyección no convencionales

Fundação para a Ciência e a Tecnologia (FCT)CONyCET (Argentina

Impact behavior of injected PP/nanoclay parts

This work attempts to contribute to bridge the gap between scientific challenges and industrial stakes regarding PP/nanoclay composites. Pieces of nanocomposites were obtained by direct injection of commercial PP mixed with a commercial MB of PP with 50% of organoclay, with a double-gated hot runner mould, which produced mouldings with a weld line. The moulding microstructure was assessed by POM and XRD, while the distribution and exfoliation grade of clay was evaluated by TEM and XRD. The typical skin-core structure was found, with a skin thickness wider in bulk than in weld line zones. Regarding clay platelets mostly intercalated structures were seen. The impact properties at room temperature were assessed by means of tensile and biaxial tests. Properties were monitored at different sites of the mouldings. At the weld line zone less energy was consumed under tensile conditions and exhibited higher apparent impact toughness under biaxial conditions than the bulk zone. Visual inspection of biaxially impacted samples showed that the orientation of polymer molecules and clay platelets induced by melt flow prevailed, and the weld line was not the determinant of the toughness of the mouldings. An optimum in impact performance was found for moulding with 3% of clay, since at larger clay contents platelets agglomerated and acted as stress raisers