bluuebunny/crossref_metadata_2025 huggingface dataset:
Using the Adolescent Time Inventory—Time Attitudes (ATI-TA) to assess time attitudes in Italian adolescents and young adults: Psychometric properties and validity
Authors: Donati Maria Anna , Boncompagni Jessica , Scabia Aurora , Morsanyi Kinga , Primi Caterina
Published: September 2018

Time attitudes (TA) are evaluative feelings toward the past, present and future. Given the role of TA in psychological and behavioral outcomes, the aim of this study was to analyze the adequacy of the Adolescent Time Inventory—Time Attitudes (ATI-TA) scale among adolescents and young adults in Italy. The scale was administered to 638 students in order to test its psychometric properties and validity. The analyses confirmed the adequacy of the six-factor model and the reliability of the subscales. Additionally, the measurement invariance of the scale across genders and age groups (between adolescents up to the age of 18, and young adults above 18) was demonstrated. Specifically, gender invariance reached the level of equivalence of error variances/covariances, and the same level was partially reached for invariance across age groups. Evidence of the validity of the scale was also provided by obtaining significant correlations between the subscales, and self-esteem and strategic learning. Taken together, these results support the suitability of the ATI-TA to be used for research and clinical purposes.
Modelling the Gas-loss Creep Mechanism in EVA Foam from Running Shoes
Authors: Mills N.J. , Rodriguez-Perez M.A.
Published: September 2018

Compressive creep experiments were performed on an EVA foam from a running shoe midsole of density 275 kg m-3. Analysis revealed a 50% air loss from the cells on a time scale of 10 hours, and a significant polymer contribution to the creep response. The recovery process after creep is slow and incomplete, perhaps due permanent deformation or polymer recrystallisation. SEM shows that surface cells are ‘permanently’ compressed. Modelling was performed of gas diffusion perpendicular to the stress axis, to predict the creep curves, and along the stress axis to predict the development of a compressed, gas-depleted surface layer. The latter considers the interactions of cell strain, diffusivity, stress sharing between the polymer and cell gas, and strain rate. The number of gas-depleted cells is predicted to increase with the square root of the creep time.
A Viscoelastic-Plastic Behaviour Analysis of Expanded Polystyrene under Compressive Loading: Experiments and Modelling
Authors: Imad Abdellatif
Published: September 2018

Generally, when soil has poor properties (unstable or compressible soils) it is possible to use EPS foam in road construction, because this material has low density. In this case, it is necessary to investigate the mechanical properties of EPS. In this work, an experimental study and modelling investigation were performed in order to determine the EPS mechanical behaviour under compressive loading.

The experimental results show that the global compression behaviour of EPS is characterised by three stages. The linear elastic stage is defined by an initial tangent modulus E* followed by a non-linear elastic part. The second stage, which is described by a plateau, is characterised by a stress threshold σs*. Finally, the densification stage corresponds to large compressive strains when the material of the cell walls is entirely compressed.

Globally, the apparent density of EPS plays an important role. In fact, when the density increases Young's modulus and threshold stress increase, but the densification strain decreases.

A phenomenological mechanical model is verified in order to simulate the EPS viscoelastic-plastic behaviour under compressive loading. This model, which is based on a super-position of viscoelastic and elastic-plastic behaviour, introduces six parameters determined by an identification technique. The results obtained in terms of the stress-strain curves are in a good agreement with the experimental data.

Using “Castem 2000” finite element software, the numerical simulations were achieved in order to describe the mechanical behaviour of the EPS material. This shows that it is possible to use numerical simulation in order to compute EPS structure used in road laying.
Gas Solubility in and Foamability of Various Forms of Syndiotactic Polystyrene
Authors: Handa Y. Paul , Zhang Zhiyi , Nawaby Victoria , Tan Julie
Published: September 2018

A high pressure microbalance was used to measure solubility of CO2 at 35°C and pressures to 55 atm in amorphous, meso, and α-crystalline forms of syndiotactic polystyrene, sPS. Diffusion coefficient of CO2 in the various samples were derived from sorption kinetics. When normalized with respect to 100% amorphous content, the solubility and diffusivity of CO2 was found to be highest in the semi-crystalline α-form, followed by the meso and the amorphous forms. This rather unusual observation was attributed to the existence of microvoids in α-sPS and meso-sPS, and due to the finite solubility of gas in the rigid amorphous phase associated with these two forms. All three forms of sPS were foamed at various temperatures in the range 50 to 295°C to give microcellular structures. The cell walls in foams obtained from amorphous sPS showed unusual, starburst type structure. The density of meso-sPS foams first decreased and then increased with foaming temperature due to the transformation of the mesophase to the α-phase with increasing temperature. The microvoids in α-sPS and meso-sPS are conjectured to serve as the nucleating sites rather than the often suggested phenomenon of heterogeneous nucleation induced by the crystallites.
Morphology and Surface Area of Cellular Structured Resorcinol/Formaldehyde Microspheres: Effect of Ageing Conditions
Authors: Lee Hae-Joon , Lee Jun-Young , Lee Kyung-Nam , Kim Joong-In , Kim Jung-Hyun
Published: September 2018

Cellular structured resorcinol/formaldehyde (R/F) microspheres were synthesized via the sol-emulsion-gel reaction and followed by supercritical drying with CO2. The materials were characterized by thermogravimetry, FT-IR spectroscopy, nitrogen physisorption technique and scanning electron microscopy. Variation of ageing conditions leaded to different micro and macro-structure, which affected bulk density, pore size distribution, specific surface area, and morphology of cellular structured R/F microspheres. The resultant R/F microspheres have average pore sizes in the range of less than 100 nm. Increasing the ageing time leaded to decreased surface area of cellular structured R/F microspheres. As the ageing temperature increased, the bulk density increased and the surface area decreased. The pore morphology depended on the ageing temperature and it was evidenced by nitrogen physisorption experiments.
Experimental Analysis of Decohesive Phenomenon in Expanded Polystyrene under Bending and Tensile Loading Conditions
Authors: Imad Abdellatif
Published: September 2018

In this paper, the decohesive phenomenon of expanded polystyrene (EPS) is analysed using bending and tensile tests. Globally, the typical stress-strain curve is characterised by a wide linear or nonlinear elastic part, the plastic phase being almost neglected. The mechanical properties, such as the elastic modulus E* and the stress threshold σth*, increase with the EPS apparent density ρ*. The empirical equations have been proposed from experimental data fitting curve. The failure strain called εf, corresponding to the point where the final breakage occurs, decreases when the density value increases. Globally, these observations indicate a brittle behaviour of the EPS material under bending and tensile loading. On the other the hand, scanning electron microscopy (SEM) has been used in order to analyse the EPS fracture surfaces. The trans-beads (TB) fracture mode, where the crack grows through the beads, has sometimes been observed for the high diameters beads. But, according to all observations, the inter-beads (IB) mode generally seems to be the major mode of fracture. Therefore, this indicates that the EPS mechanical strength under bending and tensile loading essentially depends on the beads fusion quality.
Water-Blown Expandable Polystyrene. Improvement of the Compatibility of the Water Carrier with the Polystyrene Matrix by in Situ Grafting
Authors: Pallay Jan , Berghmans Hugo
Published: September 2018

The compatibility of starch with the polystyrene matrix in the synthesis of water-blown expandable polystyrene (WEPS) was improved by making use of maleic anhydride. The foam morphology on the contrary is significantly changed after pre-expansion as the content of maleic anhydride is increased. It has been found that starch is grafted during the polymerization with styrene-maleic anhydride copolymer. Partial immscibility of polystyrene matrix and styrene-maleic anhydride grafts formed at higher concentrations of maleic anhydride causes the agglomeration of starch. Consequently, water, as the blowing agent, cannot be finely dispersed in the matrix, which is the reason of the irregular foam morphology. Different methods for the improvement of the compatibilization are discussed.
Studies of Mechanical Properties and Melting Behaviour of Foamed and Crosslinked LDPE/PP Blends
Authors: Kotzev George
Published: September 2018

Foamed crosslinked specimens of LDPE/PP blends produced by RIM process were examined. A crosslinking system containing 2,5-dimethyl-2,5-di(tert.-butylperoxy)hexane as an initiator and hydroquinone as a coagent was used. Azodicarbonamide was applied as a foaming agent. The crosslinking degree was evaluated by insoluble portion of the blends. An improvement of the mechanical properties due to crosslinking mainly in the LDPE phase as well as crosslinking between polyethylene and polypropylene on their interface was observed. Melting behaviour of the blends studied by DSC shows that both the initiator and the coagent cause opposite effects on temperatures and enthalpies of melting.
Elongational Mixing in Foam Extrusion
Authors: Rauwendaal Chris
Published: September 2018

This paper describes the development of elongational mixing technology from the early inception of the basic ideas behind the technology, the first commercial applications, subsequent developments, to the current status. Future developments currently underway will be described with a discussion on how these developments will likely impact the polymer processing industry.
Effect of Wood Flour Fillers on Density and Mechanical Properties of Polyurethane Foams
Authors: Krishnamurthi B. , Bharadwaj-Somaskandan S. , Sergeeva T. , Shutov F.
Published: September 2018

A comparison analysis has been undertaken to study the effect of different wood fillers on density and mechanical properties of two different types of commercial polyurethane (PUR) foams: low-density flexible foams and high-density rigid foams. The micro-fillers used were based on wood flour particles of size 70-250 microns (wood waste of furniture industry). The relationships between the filler size and content, density and various mechanical properties - compression test, compression force deflection test and modulus of elasticity have been studied. It was found that micro-fillers provide various effects depending on flexibility and density of PUR foams. For low-density flexible PUR foams, the density and mechanical properties increased for both types of fillers. However, for high-density rigid PUR foams these effects were just the opposite: the density and compression strengths decreased for both types of fillers. Explanation of the observed effects should take into consideration the chemical nature and physical structure of flexible and rigid PUR binders based on various types of polyol-isocyanate systems, as well as chemical and physical affiliation of cellulose based fillers with the matrices.
Effect of Weld Lines on the Injection Moulding of Structural Foams. II Mechanical Properties
Authors: Leduc Simon , Rodrigue Denis
Published: September 2018

The effect of weld lines on the mechanical properties of structural high density polyethylene foams was studied. Injection moulding was used to produce foams using azodicarbonamide in single and double gated moulds where shot size, injection speed, and flow direction were changed. The mechanical response of the foams was characterized in tensile and shear tests. Density reduction, decreasing injection speed, and the presence of the weld line were found to reduce both tensile and shear moduli, as well as tensile strength, break strain and toughness. The lost of mechanical properties can be related to lower skin thickness and incomplete bonding at the weld line. Simple correlations are also presented to predict moduli and strength of these foams.
Supercritical Fluids in Thermoplastics Foaming: Facts or Fallacies?
Authors: Gendron Richard , Champagne Michel F. , Reigniër Joël
Published: September 2018

The past two decades have seen extensive interests and efforts for developing processes based on supercritical fluids (SCF). Microcellular foaming is one of these processes that take advantage of the unique properties of supercritical fluids when they are used as physical foaming agents (PFA). In this technology, the emphasis has been mostly focused on inert gases such as carbon dioxide and nitrogen that both inherently provides very high cell densities and very small cell sizes. Incidentally the benign carbon dioxide is frequently considered as the panacea of PFA, in response notably to the environmental pressures related to the destruction of the ozone layer. Hydrofluorocarbons (HFCs) have also been identified as potential alternative agents for extruded polystyrene foam. Unfortunately, HFCs remain difficult to process at the high concentrations required to yield low-density foams.

Surprisingly, the processing difficulties occur when the pressures required for dissolving high HFCs concentrations reach the range located immediately above the critical pressure of the PFA used. PS/HFC systems have been well documented in terms of abnormal behaviors occurring as the foaming agent gets into the supercritical conditions, and similar observations have also been made for other SCF used for thermoplastic foaming. These observations are reported here, and attempts are made to link the supercritical nature of the fluid to the PFA heterogeneities suspected under these conditions.
On the Processing and Compressive Properties of Cellular Foams of Cyanate Ester
Authors: John Bibin , Nair C.P. Reghunadhan , Ninan K.N.
Published: September 2018

Cellular foams based on the cyanate ester, viz., (2,2-bis (4-cyanatophenyl) propane) have been processed. Azodicarbonamide (ADC) was used as the foaming agent. Cyanate ester foams with different densities were processed by varying the concentration of the foaming agent. The effect of foaming agent concentration on the density and compressive properties of the resultant foams has been investigated. The density of the foams was found to be inversely proportional to the concentration of foaming agent up to 2 parts per hundred parts of resin (phr). The increase in density beyond a foaming agent concentration of 2 phr has been attributed to the accelerated curing of cyanate ester, catalysed by the decomposition products of ADC. The compressive strength and modulus of the foams were found to be directly proportional to the density. The specific compressive properties also followed the same trend. Cyanate ester cellular foams exhibited better compressive properties in comparison to similar foams of other thermosets. However, the compressive properties of these cellular foams were inferior to those of the corresponding syntactic foams of comparable density.
Foaming Behaviour and Compressive Properties of Microcellular Nanostructured Polystyrene
Authors: Ruiz Jose Antonio Reglero , Viot Philippe , Dumon Michel
Published: September 2018

A batch foaming process has been employed to obtain microcellular materials from polystyrene plus a SBM copolymer (polystyrene-co-1,4-polybutadiene-co-poly(methyl methacrylate). In the first part of the process, raw materials were mixed and extruded in a proportion 90:10 to obtain the precursor materials, leading to a nanostructured assembly in which SBM self-organizes in the polystyrene matrix. In a second stage, foaming was carried out by means of supercritical CO2 in a single step-process. Foamed samples were produced using a technique based on the saturation of the polymer under scCO2, and final properties were controlled by varying the temperature. The swelling in scCO2 was performed at 300 bar during 16 h, and subsequently releasing the gas with a fixed depressurization rate of 60 bar/min. Temperature was varied from 30 °C to 80 °C, leading to densities from 1.0 g/cm3 to 0.5 g/cm3 and cell sizes from 2 micron to 100 micron. In this part of the work, a comparison between foaming behaviour of neat PS and a nanostructured PS+SBM blend is reported, investigating the role of the nanostructured phase as nucleating agents for microcellular foaming. Finally, low rate compression tests were carried out, analyzing the dependence of mechanical parameters such as elastic modulus, yield stress and densification strain with density.
Effect of Weld Lines on Injection Moulded Fibreglass Reinforced Structural Foams. 1 - Morphology, Shear and Tensile Properties
Authors: Bégin Mathieu , Rodrigue Denis
Published: September 2018

In this work, the effect of weld lines and density reduction on the morphology and mechanical properties of injection moulded fibreglass reinforced polypropylene structural foams is reported. In this first part, cell size, cell density, skin thickness as well as tensile and shear mechanical properties are reported. As expected, all mechanical properties decreased with density reduction. On the other hand, the presence of a weld line produced a more complex behaviour: lower tensile properties with higher torsion modulus. These results are shown to be related to a change in fibre orientation along the sample length which is the main factor controlling the mechanical response of these composite foams.
The Foaming Process and the Damping Capacity and Sound Insulation of Bell Structures
Authors: Shimbo Minoru , Koshida Shirei , Misawa Akihiro
Published: September 2018

The forming process and the characteristics of bell structures produced using batch-type foaming with a supercritical-fluid blowing agent were examined. Various forming methods were tried for the production of bell structures. Impact and acoustic tests of the structures were conducted, followed by an evaluation of shock absorption and sound insulation. Bell structures, including various kinds of ball, were successfully produced by means of batch foaming. It was verified that these bell structures exhibit the required shock absorption and sound insulation performance.
Development of Mechanically Stable Polymer-Based Silica Aerogel
Authors: In Eunji , Naguib Hani E.
Published: September 2018

Silica aerogels have attracted attention for many applications due to their unique properties such as low density (0.003 g/cm), mesoporosity (pore size 2–50 nm), high thermal insulation and high surface area (500–1200 m2/g). However, their fragility and environmental sensitivity restricts the use of monolithic silica aerogel. In this paper, silica aerogel that is crosslinked with diisocyanate is introduced and the effects of polymer concentration on aerogel properties, especially mechanical strength are discussed. Fracture of silica aerogel mainly occurs at the interface of secondary particles that are formed during aging. It is believed that if the surface of silica aerogel is covalently bonded to nanocast polymer coating, the interparticle necks become wider and can reinforce the structure of the aerogel. In this study, several characterizations are performed to investigate the properties of the aerogel. First, bulk density is measured to visualize the change in density with increase in crosslinker concentration. Brunauer Emmett and Teller (BET) illustrated the pore size, bulk density and surface area. The critical temperature up to which polymer crosslinked aerogel decompose was investigated by Thermogravimetric Analysis (TGA). The phase change in the aerogel was studied with Differential Scanning Calorimetry (DSC) testing. Using Scanning Electron Microscope (SEM), the nanoscale pore size and pore distribution throughout the aerogel surface were investigated. Furthermore, compression tests were performed to study the effect of crosslinking polymer on mechanical strength over non-crosslinked framework.
Microwave Enhanced Foaming of Carbon Black Filled Polypropylene
Authors: Prociak Aleksander , Sterzynski Tomasz , Michalowski Slawomir , Andrzejewski Jacek
Published: September 2018

Microwave heating has a number of advantages in comparison to the conventional method due to the ability to heat a part of composite material directly through specific interaction of electromagnetic radiation with selected types of materials. Most thermoplastics are relatively transparent for microwave irradiation and they do not absorb microwaves to a sufficient extent to be heated. Enhanced microwave heating can result from the use of fillers such as carbon black.

Different types of carbon black were used to increase the susceptibility of polypropylene (PP) for microwave processing. Measurements were carried out on PP filled with carbon black of different grades. Relative temperature rises and heat efficiency versus the content of carbon black in PP were analyzed. The temperature changes of different mass samples of these materials under microwave irradiation with various power were also investigated. Moreover, polypropylene composites with additive of chemical blowing agents were blown under microwave irradiation and the influence of foaming conditions on cell structure and selected properties of porous products were estimated.
The Effect of Polymer Molecular Weight and UV Radiation on Physical Properties and Bioactivities of PCL Films
Authors: Yeh Chih-Chang , Chen Cheng-Nan , Li Yun-Ting , Chang Chao-Wei , Cheng Ming-Yan , Chang Hsin-I
Published: September 2018

Biodegradable polymers, such as polycaprolactone (PCL), have been well studied in the application of tissue engineering and drug delivery systems due to their favourable biocompatibility profiles. However, little research has discussed the influence of the molecular weight of these polymers on cell behaviours. Here, PCL films were synthesized using polymers with various molecular weight and the physical characteristics of these films and their effect on cell growth were evaluated. Results showed that the tensile strength and elongation rate of PCL films increased from 1.82 MPa and 95.3% to 2.01 MPa and 741.6% when the molecular weight (Mn) of polymers increased from 40,000 to 80,000. A significant difference in polymer crystallinity was also observed between these formulations. Moreover, we found that prolonged exposure to UV radiation of these films could lead to the breakdown of polymer chains and consequently increased the crystallinity of PCL films with a corresponding reduction in the tensile strength. Using Hs68 human foreskin fibroblasts, PCL films prepared using high molecular weight polymers (CAPA 6800) displayed a higher cell proliferation rate compared to ones prepared using low molecular weight polymers (CAPA 6400 and 6500). In contrast, a higher cell proliferation rate was observed for PCL films made of low molecular weight polymers, especially CAPA 6500, when H9c2 rat heart myoblasts were used. In conclusion, polymer molecular weight can alter the
Block Copolymer-Assisted Microcellular Supercritical CO2 Foaming of Polymers and Blends
Authors: Dumon Michel , Ruiz José Antonio Reglero , Sanz Javier Pinto , Perez Miguel Angel Rodriguez , Tallon J-M. , Pedros M. , Cloutet E. , Viot P.
Published: September 2018

The behaviour in supercritical CO2 of block copolymers containing styrenic, butadiene, and methacrylic or perfluroalkyl blocks is studied in view of a specific swelling and foaming by a gas dissolution process. These block copolymers are considered as neat materials or as additives in blends e.g in polystyrene (PS) or polymethylmethacrylate (PMMA) matrices.

In both cases (neat or blend) the copolymers may exhibit a structuration at a micro or nano level. The phase separated (nano) structures depend on the block type and the concentration of copolymers in the polymer matrix, so that micelles, vesicles, lamellas, or warm-like structures are generated.

Furthermore when one block is chosen as a highly CO2-philic moiety, the nanostructures are able to act as CO2 reservoirs. The result is the possibility to control microcellular foaming, or sometimes nanocellular foaming, of commodity amorphous polymers such as PMMA and PS. Besides, at room temperature, the blocks can be either glassy or rubbery in order to freeze the growth and coalescence of cells during foaming.

Different cellular polymers were elaborated by varying either the copolymer type or the foaming conditions (saturation pressure, temperature, depressurization rate). Cell sizes are accessible in a range from 0.2 to 200 μm, and densities from 0.40 to 1 g/cm3.

It is also shown that nanostructuring polymers are also efficient to produce polymer foams with oriented / structured voids.

This new approach could be used to produce nanocellular or ultra microcellular polymer foams in a simple process, using blending and extrusion.
Overmoulding of Plane Structural Foamed Parts with a Second Thermoplastic Component
Authors: Mueller Johannes , Spoerrer Andreas , Altstaedt Volker
Published: September 2018

Over the last few years some highly-efficient manufacturing processes in the field of foam injection moulding occurred based on new developments in the machine, the mould and the material technology. The manufacturing of car interior parts with a soft touch surface for example became possible in a one-step injection moulding process, in which an injection moulded carrier made of a fibre reinforced thermoplastics is overmoulded with a foamed thermoplastic elastomer (TPE). The TPEcomponent with compact skin layers and a foamed core generates a soft touch effect, reduces the part weight and observes the quality standards of the automobile manufacturers. Furthermore this technique offers a much higher economic efficiency compared to conventional manufacturing processes.

To lower the part weight even further it is aspired to produce the thermoplastic carrier in a physical or chemical foam injection moulding process. With special mould technologies and the right process management it is already possible to foam light plane parts with a high specific flexural stiffness. As the main function of the carrier is the stiffening of the part an interesting aspect is to combine a stiff foamed carrier with a soft TPE-component by an overmoulding injection moulding process.

This paper is going to show the possibility to overmould a plane foam injection moulded part with a second thermoplastic component, e.g. a TPE. The aim is to reach ideal dimensional stability and mechanical properties by the right adjustment of the manufacturing process.
Nanoclay-Flexible Polyurethane Nanocomposites Formulated by Recycled Polyether Polyols
Authors: Nikje Mir Mohammad Alavi , Diarjani Elham , Haghshenas Moslem
Published: September 2018

Flexible polyurethane nanocomposites (PUNCs) containing recycled polyether polyols received from chemical recycling of original corresponding foams were synthesized by the incorporation of organically functionalized Cloisite 30B montmorillonite (MMT). Different amounts of MMT (1-3%w) were added to the polyol mixture prior to introducing the isocyanate portion. Recycled polyol was ranged between 10 to 30% of total polyol and MMT was maximum 3%. Thermal, morphological and mechanical properties of prepared PUNCs were studied and the results demonstrated the improvement of properties.
Foaming of Microcellular PP-MWCNT Nanocomposite in a Sub-Critical CO2Process
Authors: Dolomanova Viktoriya , Kumar Vipin , Pyrz Ryszard , Madaleno Liliana A.O. , Jensen Lars R. , Rauhe Jens Chr. M.
Published: September 2018

The present work covers the processing route and investigation of PP-MWCNT nanocomposite foams. CO2is used as a blowing agent in a batch foaming process with a saturation pressure range of 3-7 MPa. Carbon nanotubes act as nucleating agents during the foaming process, which is supported by SEM image analysis and DSC study. Relative density measurements have demonstrated that even though MWCNT promote nucleation of a large amount of cells, the densities of PP-MWCNT nanocomposite foams do not differ significantly from pure PP samples.
Parameter Estimation of a Hyperelastic Constitutive Model for the Description of Polyurethane Foam in Large Deformation
Authors: Ju M.L. , Mezghani S. , Jmal H. , Dupuis R. , Aubry E.
Published: September 2018

Polyurethane foam is widely used in such areas as the automotive industry and sport, and in the field of packaging because of its low stiffness, high compressibility and its ability to absorb strain energy. The quasi-static behaviours of polyurethane foam are highly nonlinear and elastic. This paper demonstrates that the nonlinear elastic mechanical behaviour of compressible polyurethane foam during the loading and unloading quasi-static compression tests can be described by applying Ogden's modified model. The experimental data from a uniaxial compression of three types of polyurethane foam in three different strain rates are used for parameter identification. A nonlinear optimization method helps to ensure that the parameters are satisfied with stability conditions. Thanks to the optimized parameter results, the numerical simulations agree with the experimental data. Finally, the errors between the model results and the experimental results are analyzed and the unloading phases are discussed in detail.
Lightweight Potential of Fiber-Reinforced Foams
Authors: Roch Alexander , Menrath A. , Huber T. , Henning F. , Elsner P.
Published: September 2018

This paper analyses the lightweight potential of long-fiber-reinforced and local continuous-fiber-reinforced foam injection molded components. Using the LFT-D foam process [7, 13] and breathing mold technology [11, 12], long-glass-fiber-reinforced polypropylene foams were manufactured with a constant weight per unit area and varying density reductions. As the area moment of inertia increases with the wall thickness to the third power, in these investigations small density reductions were sufficient to increase the flexural rigidity by several hundred% compared to a compact reference sample. The fiber length advantage generated by the direct process (injection molding compounding) also meant that even at higher density reductions the ductility was not reduced by the foaming.

In order to achieve even better mechanical properties, foam injection molding can be combined with local continuous-fiber reinforcement. To demonstrate the potential, sandwich integral foam components with local continuous-fiber-reinforced facing were produced in-situ in an injection mold and characterized. Fully-consolidated tape blanks and self-reinforced PP fabrics were positioned on both sides of the cavity and heated. Afterwards a gas-loaded melt was injected between them. A short embossing stroke generated sufficient interfacial adhesion between the facing layers and the core material, and the foaming process was initiated by the pressure drop resulting from the precision opening of the injection compression mold.
Effect of Chain Extension on the Rheological Property and Thermal Behaviour of Poly(lactic acid) Foams
Authors: Liu Wei , Li Hangquan , Wang Xiangdong , Du Zhongjie , Zhang Chen
Published: September 2018

Epoxy-based chain extended high-melt-strength poly (lactic acid) (PLA) was prepared. Rheological properties and the thermal behaviours of the chain extended PLA were studied. The rheological properties indicated that the melt elasticity and melt strength of the chain extended PLA samples were gradually improved by increasing the content of chain extender (CE). Moreover, the thermal results showed that the crystallinity and the spheruilite morphology of PLA were greatly influenced due to the introduction of CE. The effect of CE contents on foam morphology was also studied. Adding CE resulted in higher expansion ratio and smaller cell size of PLA foams.
Acoustic Properties of Waste Particle Mixed Polyurethane Composites
Authors: Küçük Haluk
Published: September 2018

A variety of particles were mixed with polyurethane-based matrix to develop functional composites. Adding marble, steel, prina (olive oil extraction) and sand particles into PU foam increases sound absorption characteristics of the material. Best results were obtained with marble and steel particles. Marble particles improved high frequency characteristics better than steel particles. Increasing the amount of prina particles enhanced mid-to-high frequency sound absorption properties. Acoustic properties of sand mixed composites were increased to its optimal rates by adding 25% particles into the polyurethane matrix.
Reactive Modification of Poly(ethylene terephthalate) and its Foaming Behavior
Authors: Liu Haiming , Wang Xiangdong , Liu Wei , Liu Bengang , Zhou Hongfu , Wang Wenzhao
Published: September 2018

A methodology for the preparation of chain extended poly (ethylene terephthalate) (PET) and its foams by autoclave batching foaming method was proposed. First, PET was mixed with tetraglycidyl diamino diphenyl methane (TGDDM) as chain extender to generate the branching/crosslinking molecular structure and improve the viscoelasticity of PET. Then, PET foams were prepared using supercritical CO2 as physical blowing agent. The molecular structures of various PET samples were characterized by the nuclear magnetic resonance, gelation degree and crosslinking density test. The results showed that with the introduction of TGDDM, the branching/crosslinking structure of PET appeared. The influences of various molecular structures on the thermal property and rheology of PET were also studied. The results showed that the crystallization temperature, crystallization rate, and crystallinity of various PET samples decreased with the content of TGDDM, but the modified PET had higher melt elasticity than that of pure PET. PET foam with the addition of 0.4% TGDDM had finer cellular morphology and the highest expansion ratio.
Preparation and Characterization of Magnetic Rigid Polyurethane Foam Reinforced with Dipodal Silane Iron Oxide Nanoparticles Fe3O4@APTS/GPTS
Authors: Nikje Mir Mohammad Alavi , Akbar Raheleh , Ghavidel Razieh , Vakili Maryam
Published: September 2018

In this study, a new class of magnetic rigid polyurethane foams (PUFs) has been fabricated by one-shot process. Dipodal silane-coated magnetic nanoparticles (DScMNPs) was used as the magnetic nanoparticle and synthesized by functionalization of iron oxide nanoparticles by the prepared dipodal silane based on 3-aminopropyltriethoxysilane (APTS) and γ-glycidoxypropyltrimetoxysilane (GPTS) via sol-gel method. The synthesized DScMNPs were used up to 8.0% in the rigid polyurethane foam formulation and prepared foams were characterized. The chemical structure of DScMNPs was confirmed by proton nuclear magnetic resonance spectroscopy (1H NMR), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM), respectively. Morphological, thermal and mechanical properties of the PU nanocomposites were studied by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Vibrating sample magnetometery (VSM) was also showed that the synthesized PU nanocomposites are super paramagnetic.
Foamed Polyurethane Composites with Different Types of Ash – Morphological, Mechanical and Thermal Behavior Assessments
Authors: Hejna Aleksander , Kopczyńska Milena , Kozłowska Urszula , Klein Marek , Kosmela Paulina , Piszczyk Łukasz
Published: September 2018

Incorporation of two types of ash particles into flexible polyurethane foams has been investigated, wood ash from gasification process and fly ash resulting from coal burning in power plant. Samples were modified with 5, 10 and 15 wt% of fillers. Structure, mechanical and thermal properties of obtained foams were investigated. Incorporation of both types of ash particles resulted in materials showing satisfactory mechanical properties, simultaneously decreasing their density. Addition of fly ash inhibited noticeably thermal degradation of material, because of the thermal insulation effect of gas trapped in the spherical ash particles. Results of research show that fly ash can be successfully used as a modifier of thermal properties in polyurethane foams, enhancing the economical aspect of the production through the decrease of material's density and incorporation of low cost filler.
The Polyurethane Foams Based on Melamine-formaldehyde-cyclohexanone Resins
Authors: Głowacz-Czerwonka Dorota
Published: September 2018

The conditions and methods for obtaining polyurethane foams based on melamine-formaldehyde-cyclohexanone resins are presented These foams were obtained from melamine solution in reactive solvents based on cyclohexanone and 4,4′-diphenylmethane diisocyanate. Some properties of obtained polyurethane foams were examined, e.g. apparent density, water absorbing capacity, dimensional stability, thermal conductivity, thermal stability, flammability and compression strength. Also a thermal analysis using the differential thermal analysis and differential scanning calorimetry methods was carried out. Polyurethane foams with increased thermal stability were obtained.
Effect of Crosslinking Agent and Branching Agent on Morphological and Physical Properties of Poly(Butylene succinate) Foams
Authors: Boonprasertpoh Aekartit , Pentrakoon Duanghathai , Junkasem Jirawut
Published: September 2018

To enhance a viscosity of poly(butylene succinate) (PBS), a crosslinking agent (i.e. dicumyl peroxide, DCP) or branching agent (i.e. Desmodur®N3300, N3300) was incorporated with various amount ranging from 0 to 4 phr via an internal mixer. The thermal transition, rheological properties (e.g. storage modulus, loss modulus, and complex viscosity) and gel content of the compound were determined via differential scanning calorimeter, rheometer, and gel content measurement, respectively. The results revealed that less degree of crystallinity, higher viscosity and more crosslinked structure were detected as increasing amount of DCP and N3300. Subsequently, a compression moulding technique was used to prepare PBS foam with a chemical blowing agent, i.e. azodicarbonamide (ADC). Scanning Electron Microscopy was acquired to examine cell size, cell size distribution, cell structure, and cell density. Besides, physical properties, e.g. foam density and physical appearance, were investigated. The results indicate that the degree of crystallinity, viscosity, and crosslinked structure affect the morphological and physical properties of PBS foams, i.e. greater viscosity and crosslinked structure causing obstacle for cell growth, and less degree of crystallinity allowing easier cell nucleation and cell growth.
Rotomolding of Foamed and Unfoamed GTR-LLDPE Blends: Mechanical, Morphological and Physical Properties
Authors: Dou Yao , Rodrigue Denis
Published: September 2018

In this work, a simple method is presented to produce ground tire rubber (GTR) -linear low density polyethylene (LLDPE) compounds and foams via rotational molding. In particular, different GTR concentrations (0 to 50% wt.) were dry-blended with different chemical blowing agent (CBA) content (0 to 1% wt.). From the samples produced, a complete set of characterization was performed in terms of mechanical properties (tensile, flexural and impact), density and morphological properties. The results show that increasing GTR content or CBA content not only decreased both tensile and flexural moduli, but decreased ultimate strength and strain at break. As expected, increasing blowing agent content decreased density. Besides, with respect to impact strength, the value of all samples decreased with the addition of GTR or CBA except for 0.2% wt. CBA of GTR-LLDPE composite foams, which nearly remain at the same level.
Chemical Blowing Agents in the Rubber Industry. Past – Present – and Future?
Authors: Stehr J.
Published: September 2018

Whether it be foamed aluminium in the A-pillar of a passenger car, Ytong autoclaved aerated concrete, Elastolit PU rigid foam or Semperform EPDM window profile – whatever the class of materials, there will inevitably be foamed versions. Some of these are new while others have been established for decades, and they are used in a wide range of industrial and consumer-oriented applications. Defined foam structures have therefore become an essential tool in modern materials development. This article outlines the technical aspects of chemical blowing agents and the special mechanisms by which they act, which lead to the targeted production of different elastomeric foams. In addition, it reports on the status of the current REACH discussion concerning the blowing agent azodicarbonamide.
Annealing effects of high sensitive thin strain gauges consisting of nickel carbon nanocomposites
Authors: Karapepas Christos , Nestler Daisy , Wett Daniel , Wagner Guntram
Published: September 2018

Hybrid laminates consisting of fiber-reinforced thermoplastic films and metallic thin sheets are successively replacing thermoset-based systems due to their obvious advantages of higher formability and the aptitude for mass production. In order to monitor the material under operating condition, hybrid laminates need to be equipped with smart sensor units. Therefore, the aim of the present work is to evaluate the temperature stability of the Ni-C thin film strain gauge sensors. The analyses of the deposited Ni-C films manufactured by means of a magnetron sputtering process were carried out by means of Raman spectroscopy and X-ray diffraction to investigate the phase development after a heat treatment at different temperatures and holding times. In addition, the four-terminal sensing was utilized to study the change of temperature coefficients of resistance after a single annealing treatment.
Acceptability of Naloxone Dispensing Among Pharmacists
Authors: Do Vivian , Behar Emily , Turner Caitlin , Geier Michelle , Coffin Phillip
Published: September 2018

Background:

The San Francisco Department of Public Health initiated naloxone prescribing at 6 safety net clinics. We evaluated this intervention, demonstrating that naloxone prescribing from primary care clinics is feasible and acceptable.

Objective:

To evaluate acceptability of naloxone dispensing to patients prescribed opioids among pharmacists serving clinics participating in a naloxone intervention.

Methods:

We surveyed 58 pharmacists from November 2013 through January 2015 at pharmacies that serviced San Francisco safety net clinics. Surveys collected information on demographics, experiences in dispensing naloxone, and interest in prescriptive authority. We conducted descriptive analyses and assessed bivariate relationships.

Results:

Most respondents were staff (56.9%) or supervising pharmacists (34.5%). Most (92.9%) were aware their pharmacy stocked naloxone and 86.8% felt it should be prescribed to some or all patients on long-term opioids. Most (82.1%) dispensed naloxone at least once in the past 12 months. More than half were comfortable providing naloxone education. Nearly half (43.4%) indicated they would want authority to furnish without a prescription. Over half (55.2%) reported no problems dispensing. The common problem was insufficient naloxone knowledge. Only 12% reported more than one problem in dispensing naloxone, which was associated with being uncomfortable with educating patients ( P = .03).

Conclusion:

Naloxone dispensing was acceptable among pharmacists. Their most cited problem was insufficient naloxone education. This may be resolved with improved instructional materials, incentives for patient education, or mandatory training.
New evidence on the earliest human presence in the urban area of Genoa (Liguria, Italy): A multi-proxy study of a mid-Holocene deposit at the mouth of the Bisagno river
Authors: Arobba Daniele , Caramiello Rosanna , Firpo Marco , Mercalli Luca , Morandi Lionello F , Rossi Stefano
Published: September 2018

The article presents the results of a multi-proxy study investigating an alluvial deposit located in the coastal plain of Genoa (Liguria, Northwest Italy). A very deep core was sampled from 15 to 25 m below ground level to analyse sedimentological properties, pollen assemblages, non-pollen palynomorphs, plant macrofossils and micro-charcoal. The deposit, spanning from the second half of the 5th Millennium to the end of the 7th Millennium cal. BC, was characterized by an alternation of silty and peaty layers, and proved to be rich in plant remains. Pollen data allowed the confirmation of a gradual increase in Fagus sylvatica to the detriment of Abies alba during the mid-Holocene of the region, and showed the presence of brackish lagoons, as well as the progressively stronger incidence of anthropogenic taxa, indicating the use of the plain for agricultural purposes. The study of non-pollen palynomorphs led to the taxonomic identification of some previously unidentified types, and pointed to the occurrence of marshy environments, which were probably grazed on by domestic herbivores. Macrofossil analysis provided the first record of Triticum new glume wheat type in Liguria. Moreover, the finding of a grain of Triticum dicoccum dated to the second half of the 6th Millennium cal. BC allowed us to pre-date by seven centuries the agriculture in the region. To date, this represents the oldest evidence of human activity in the urban area of Genoa.
Personality, Culture and Career Assessment
Authors: Priyadharshini S. K. , Ganesh L. S. , Kondaveeti Balaraju
Published: September 2018

This article reviews the literature on indigenisation of personality measures, including adaptations of existing, well-established Western ones, and justifies in detail the need in India. It is evident that despite over 200 ‘indigenous’ instruments mentioned in the National Library of Educational and Psychological Tests, apparently none has gained widespread awareness even among practitioners, not to mention anything about their use. These instruments seem to lack adequate, scientific evidence of their reliability, validity and/or documentation. Also, they do not appear to be featured in the literature. The indigenisation efforts and developments in other Asian countries are discussed. The cross-cultural applications of Western tools are deliberated upon. To capture the real essence of local culture and cultural understanding, we propose the need for a combined etic–emic approach to indigenisation, and briefly discuss other approaches as a way to appreciate both, the universality and the cultural sensitivity reflecting personality in the sample. The article ends with a suggestion to develop, validate, test and use indigenised personality measures by spreading awareness of their value in various socio-culturally distinct contexts like India.
Mixed states in bipolar disorder: modelling, measuring and managing
Authors: Parker Gordon , Ricciardi Tahlia
Published: September 2018

Objective:

To consider whether consensus exists in recommendations for managing bipolar mixed states published in recent reviews and treatment guidelines, and to summarise what might be their best management.

Conclusion:

Limitations to and changes in the definition of mixed states compromise diagnosis and management. The striking comparison between DSM-IV and DSM-5 criteria sets risks under-diagnosis and over-diagnosis. Current reviews and guidelines offer limited evidence to guide treatment; however, management should involve addressing the contribution of any antidepressant medication, and the introduction of a second-generation antipsychotic medication to stabilise the condition.