Structure-property relationships of nylon 6, MXD6, their blends and nanocomposites

This research project aimed to develop an understanding of the structure-property relationships of nanocomposite materials (injection moulded and fibres) based on nylon 6, MXD6 and their blends, with a layered silicate in combination with polyhedral oligomeric silsesquioxane nanoparticles and SEBS rubber particles.

Dielectric properties of conducting polymer

The dielectric properties of conducting polymer composites containing polypyrrole (PPy) crushed films, PPy powder, polyaniline (PAn) base and acid powders as the dispersants and silicone rubber and vinyl ester as matrix materials have been investigated in the frequency range 2-18 GHz. The dielectric parameters such as the real part, epsiprime, and imaginary part, epsiPrime, of the permittivity and loss tangent, tandelta, increase with increasing conductivity and concentration of the dispersant. The geometrical shape of the dispersant governs the ability of conductive network formation which is indicated by a large drop in the resistivity of the composite. Also, dispersant/matrix interactions and physical properties of the matrix influence the agglomeration of the dispersant phase which, in turn, affects the dielectric properties of the composites. Flakes of PPy obtained by crushing highly conductive films and large PAn powder aggregates were unable to form a conducting network. The composites without a network of dispersant exhibit low dielectric parameters. On the other hand, high values of tan delta ranging from 0.7–1.1 were achieved for the PPy powder (15 parts)/silicone rubber composites where a conducting network was observed.

Comparing different economic linkages among commodity futures

Gasoline (GA) and kerosene (KO) are extracted from crude oil (CO), such that the three fuel commodities share a chemical link. On the other hand, GA also shares an industrial link with natural rubber (NR) and palladium (PA) as complementary commodities that are heavily consumed by the automobile industry. We contrast the information content embedded in the two economic linkages. Focusing on TOCOM futures contracts written on the five commodities and centering on GA, we confirm that incremental information provided by either CO, KO or NR, PA over a buy-and-hold strategy and a naive forecast, are both statistically and economically significant. While the chemical link forecast is more profitable, a double-link forecast generated from a VECM with two cointegrating vectors (KO-GA and GANR prices) outperforms both single-link forecasts based on risk-adjusted profit net of transaction costs. Further comparisons against the profitability of commodity-based momentum strategies documented in Erb and Harvey (2006) and Miffre and Rallis (2007) show that the double-link forecast holds its own against the most profitable of the 75 momentum strategies considered. This strongly suggests that not only are there incremental profits to be gained from harnessing and combining economic links among commodity futures, the resultant incremental profits are economically significant against other proven commodity-based trading strategies in the existing literature.

The effects of testing procedure on critical fall height determination for third-generation synthetic turf

Test procedures and their accuracy in determining critical fall height (CFH) on sporting grounds are paramount to player safety. The procedure currently adopted for synthetic turf in Australian football [1] consists of four consecutive drops at various drop heights at three test locations on the sample. The quantity and packing of the infill in third-generation turf and the pooling effect of the rubber particles with consecutive drops suggests that the current standard protocol may need re-assessment. Therefore, the purpose of this pilot study was to investigate whether current methods of testing for CFH are appropriate for third-generation synthetic turf or whether an alternative or adapted method needs to be developed. CFH was measured, using a HISUN Uniaxe-II Impact Tester, on 12 combinations of synthetic turf samples (four different products with three shock pad options). Three conditions were investigated on each sample; the existing protocol; an alternative 12 single-drop protocol and four single drops from the CFH determined from the existing protocol. A significant difference was found for both absolute and percentage difference between the existing and 12 single-drop protocol, with p = 0.001 and t = 4.33 and p < 0.001 and t = 6.03, respectively. There was also a significant difference between the CFH reached with and without a shock pad for both the existing protocol and the 12 single-drop protocol. The results of this pilot study demonstrate that differences do occur with alterations to the existing protocol and highlight the need for a more detailed characterisation of testing methods on third-generation synthetic turf and the response of surfaces to them.

The science of our own fiction : affective experiments enacted through creative research

This paper will explore the ways in which art may be understood as an ongoing experiment that interacts with the plasticity of the body to prompt change and affect the body-environment relationship. The arts offer an approach to research that recognizes the importance of the affect in studies of perception and action, self-organization and selection. An affective approach to experimentation would connect cognitive activity to the material processes of the environment in a science of our own fiction. This connection becomes the basis of affective experiments, which aim to yield new insights by merging the creative researcher with self-affecting-experimenter. To this end, I will discuss the scientific objectives of the “rubber hand”, and the ‘mirror-box” experiments are contrasted with work by artists-turned-architects Arakawa and Gins and three of my creative projects to suggest how creative research might enact embodied change. Throughout the paper I will argue that cognitive processes such as attention, selection, decision and judgment are ripe for re-entry and experimentation through an embodied approach to acquiring knowledge that is particular to the arts.

Primary prevention of latex related sensitisation and occupational asthma : a systematic review

Eight primary prevention intervention studies on natural rubber latex (NRL) published since 1990 were identified and reviewed. This is the largest evidence base of primary prevention studies for any occupational asthmagen. Review of this small and largely observational evidence base supports the following evidence statement: Substitution of powdered latex gloves with low protein powder‐free NRL gloves or latex‐free gloves greatly reduces NRL aeroallergens, NRL sensitisation, and NRL‐asthma in healthcare workers. Evidence in support of this statement is ranked SIGN level 2+, referring to well conducted case‐control or cohort studies with a low risk of confounding, bias, or chance and a moderate probability that the relationship is causal. Substitution of powdered latex gloves with low protein powder‐free NRL gloves or latex‐free gloves promises benefits to both workers' health and cost and human resource savings for employers. This message should be broadly disseminated beyond the hospital sector to include other healthcare settings (such as aged care facilities) as well as food service and other industries where latex gloves might be used.

Carbon nanotube based elastomer composites-an approach towards multifunctional materials

The current study focuses on giving a basic understanding of tubular graphene sheets or carbon nanotubes (CNTs) and points towards their role in fabricating elastomer composites. Since the properties and the performance of CNT reinforced elastomer composites predominantly depend on the rate of dispersion of fillers in the matrix, the physical and chemical interaction of polymer chains with the nanotubes, crosslinking chemistry of rubbers and the orientation of the tubes within the matrix, here, a thorough study of these topics is carried out. For this, various techniques of composite manufacturing such as pulverization, heterocoagulation, freeze drying, etc. are discussed by emphasizing the dispersion and alignment of CNTs in elastomers. The importance of the functionalization technique as well as the confinement effect of nanotubes in elastomer media is derived. In a word, this article is aimed exclusively at addressing the prevailing problems related to the CNT dispersion in various rubber matrices, the solutions to produce advanced high-performance elastomeric composites and various fields of applications of such composites, especially electronics. Special attention has also been given to the non-linear viscoelasticity effects of elastomers such as the Payne effect, Mullin's effect and hysteresis in regulating the composite properties. Moreover, the current challenges and opportunities for efficiently translating the extraordinary electrical properties of CNTs to rubbery matrices are also dealt with.

Fabrication of conductive elastic nanocomposites via framing intact interconnected graphene networks

Electrically conductive elastic nanocomposites with well-organized graphene architectures offer significant improvement in various properties. However, achieving desirable graphene architectures in cross-linked rubber is challenging due to high viscosity and cross-linked nature of rubber matrices. Here, three dimensional (3D) interconnected graphene networks in natural rubber (NR) matrix are framed with self-assembly integrating latex compounding technology by employing electrostatic adsorption between poly(diallyldimethylammonium chloride) modified graphene (positively charged) and NR latex particles (negatively charged) as the driving force. The 3D graphene structure endows the resulted nanocomposites with excellent electrical conductivity of 7.31. S/m with a graphene content of 4.16. vol.%, extremely low percolation threshold of 0.21. vol.% and also analogous reinforcement in mechanical properties. The developed strategy will provide a practical approach for developing elastic nanocomposites with multi-functional properties. © 2014 Elsevier Ltd.

Does dynamic vulcanization induce phase separation?

Immiscible and miscible blends of poly(vinylidene fluoride) (PVDF) and acrylic rubber (ACM) were subjected to dynamic vulcanization to investigate the effect of crosslinking on phase separation. As a result of different processability, mixing torque behavior of miscible and immiscible blends was significantly different from one another. Scanning electron microscopy (SEM) was used to investigate the morphology of the system. After dynamic vulcanization, submicron ACM droplets were observed in the samples near the binodal curve of the system under mixing conditions. Small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) analysis were used to investigate the effect of dynamic vulcanization on the lamellar structure of the system. It was shown that for samples near the boundary of phase separation, increasing the crosslink density led to a decrease in the lamellar long period (L) as a sign of increment of crosslink density induced phase decomposition. Effects of shear rate on the final morphology of the system were investigated by changing the mixing temperature and by comparing the results of dynamic vulcanization at one phase and two phase regions.

Variation of phloem turgor pressure in Hevea brasiliensis: An implication for latex yield and tapping system optimization

Phloem turgor pressure (PTP) is the initial driving force for latex flow after a rubber tree is tapped and therefore plays an important role in rubber tree latex production. Variation in PTP with rubber tree clone, age, yield potential and commonly used Ethrel (an ethylene releaser) stimulation have, however, not been comprehensively studied to date. The aim of this study was to investigate these relations and examine whether PTP can be used as an index for rubber tree clone assessment and tapping system optimization. The results showed that: (1) the daily change of PTP in the foliation season suggests that a high PTP can ensure a high latex yield and tapping could be moved forward to midnight or earlier in the night; (2) the decrease of PTP from the basal to distal stem indicates the benefit of a controlled upward tapping system; (3) the logarithmic increase in PTP with rubber tree planting age and age-based mean girth suggests that the preferred age for the commencement of rubber tree tapping is eight years; (4) the change of PTP with regenerated bark age suggests that the regenerated bark could be exploited again after the second year; (5) PTP is positively related to the yield potential of rubber tree clones; (6) although Ethrel stimulation could not significantly increase the initial PTP of a rubber tree, it delays the recovery of PTP after tapping. Therefore, PTP is an indicator of rubber tree latex yield and can be used for tapping system optimization. © 2014 Elsevier B.V.

Context sensitivity in action decreases along the autism spectrum: a predictive processing perspective

Recent predictive processing accounts of perception and action point towards a key challenge for the nervous system in dynamically optimizing the balance between incoming sensory information and existing expectations regarding the state of the environment. Here, we report differences in the influence of the preceding sensory context on motor function, varying with respect to both clinical and subclinical features of autism spectrum disorder (ASD). Reach-to-grasp movements were recorded subsequent to an inactive period in which illusory ownership of a prosthetic limb was induced. We analysed the sub-components of reach trajectories derived using a minimum-jerk fitting procedure. Non-clinical adults low in autistic features showed disrupted movement execution following the illusion compared to a control condition. By contrast, individuals higher in autistic features (both those with ASD and non-clinical individuals high in autistic traits) showed reduced sensitivity to the presence of the illusion in their reaching movements while still exhibiting the typical perceptual effects of the illusion. Clinical individuals were distinct from non-clinical individuals scoring high in autistic features, however, in the early stages of movement. These results suggest that the influence of high-level representations of the environment differs between individuals, contributing to clinical and subclinical differences in motor performance that manifest in a contextual manner. As high-level representations of context help to explain fluctuations in sensory input over relatively longer time scales, more circumscribed sensitivity to prior or contextual information in autistic sensory processing could contribute more generally to reduced social comprehension, sensory impairments and a stronger desire for predictability and routine.

Different thermal analysis technique application in determination of fold surface-free energy

In this work, the crystallization rates and spherulitic growth rate of miscible blends of poly(vinylidene fluoride) (PVDF) and acrylic rubber (ACM) were determined using differential scanning calorimetry (DSC), real-time FTIR, and optical microscopy. FTIR results suggest that blending does not induce the creation of polymorphic crystalline forms of PVDF. SAXS data demonstrate the formation of interlamellar structure after blending. The fold surface-free energy (σ e) was analyzed and compared using different thermal analysis techniques. The isothermal crystallization curves obtained using real-time FTIR and DSC explored in two different methods: t 1/2 or Avrami equation. While the Avrami equation is more widespread and precise, both analytical methods gave similar free energy of folding values. However, it was found that the direct optical method of measuring spherulitic growth rate yields σ e values 30-50 % lower than those obtained from the overall crystallization rate data. Conversely, the σ e values were found to increase with increasing amorphous ACM phase content regardless of the analytical methods.

Copolimeros de propileno-etileno com baixos teores de etileno : estrutura, morfologia e propriedades

A estrutura básica predomínante encontrada em todos os copolímeros foi a de longos blocos de polipropileno cristalizáveis, separados por unidades isoladas de etileno, que atuaram como defeitos cristalínos, reduzindo o grau de cristalínidade, além da perfeição e da espessura dos cristais. O gradual aumento do teor de etileno nas amostras origínais, até aproximadamente5 moI % provocou redução progressiva no comprimento dos blocos de propileno em ambas as frações cristalizável e elastomérica. Acima daquela concentração, o etileno mostrou por principal efeito a elevação do teor de borracha de etileno-propileno(EPR), refletíndo-seem pronunciado aumento da resistência ao impacto dos copolímeros, com pouca alteração do comprimento das seqüências propiJênicas nas frações cristaJizáveJe elastomérica. A estrutura e a morfologia da borracha EPR gerada foram analisadas, observando-se sua excepcional dispersão na fase contínua cristalína. Análise das curvas de fusão por DSC, utilizando-se conceitos cínéticos, demonstrou a existência de uma energia de ativação aparente de fusão, associada à introdução de unidades etilênicas nas cadeias, e relacionada ao processo de fusão dos cristais poliméricos. A redução de cristalínidade das amostras e o aumento de mobilidade de cadeia da fase amorfa para teores crescentes de etileno resultaram em redução da rigidez dos copolímeros. Propriedades ópticas, como "haze" e brilho mostraram-se dependentesdo balanço entre o teor de cristais e o teor de borracha. Um balanço global das propriedades analisadas sugere uma composição ótima para aplicações típicas de copolímeros de propileno-etileno aquela com teores de etileno entre 4 e 6 moI % (aproximadamente 3 -4 % em massa).