Experimentally driven atomistic model of 1,2 Polybutadiene

We present an efficient method of combining wide angle neutron scattering data with detailed atomistic models, allowing us to perform a quantitative and qualitative mapping of the organisation of the chain conformation in both glass and liquid phases. The structural refinement method presented in this work is based on the exploitation of the intrachain features of the diffraction pattern and its intimate linkage with atomistic models by the use of internal coordinates for bond lengths, valence angles and torsion rotations. Atomic connectivity is defined through these coordinates that are in turn assigned by pre-defined probability distributions, thus allowing for the models in question to be built stochastically. Incremental variation of these coordinates allows for the construction of models that minimise the differences between the observed and calculated structure factors. We present a series of neutron scattering data of 1,2 polybutadiene at the region 120-400K. Analysis of the experimental data yield bond lengths for C-C and C=C of 1.54Å and 1.35Å respectively. Valence angles of the backbone were found to be at 112° and the torsion distributions are characterised by five rotational states, a three-fold trans-skew± for the backbone and gauche± for the vinyl group. Rotational states of the vinyl group were found to be equally populated, indicating a largely atactic chan. The two backbone torsion angles exhibit different behaviour with respect to temperature of their trans population, with one of them adopting an almost all trans sequence. Consequently the resulting configuration leads to a rather persistent chain, something indicated by the value of the characteristic ratio extrapolated from the model. We compare our results with theoretical predictions, computer simulations, RIS models and previously reported experimental results

The use of scattering data in the study of the molecular organisation of polymers in the non-crystalline state

This research was funded by the Polytechnic of Leiria and FCT (Portugal) through UC4EP PTDC/CTM-POL/7133/2014) and UID/Multi/04044/2019, the University of Reading and EPSRC (UK).Scattering data for polymers in the non-crystalline state, i.e., the glassy state or the molten state, may appear to contain little information. In this work, we review recent developments in the use of scattering data to evaluate in a quantitative manner the molecular organization of such polymer systems. The focus is on the local structure of chain segments, on the details of the chain conformation and on the imprint the inherent chemical connectivity has on this structure. We show the value of tightly coupling the scattering data to atomistic-level computer models. We show how quantitative information about the details of the chain conformation can be obtained directly using a model built from definitions of relatively few parameters. We show how scattering data may be supplemented with data from specific deuteration sites and used to obtain information hidden in the data. Finally, we show how we can exploit the reverse Monte Carlo approach to use the data to drive the convergence of the scattering calculated from a 3d atomistic-level model with the experimental data. We highlight the importance of the quality of the scattering data and the value in using broad Q scattering data obtained using neutrons. We illustrate these various methods with results drawn from a diverse range of polymers.info:eu-repo/semantics/publishedVersio

Biomaterials for In Situ Tissue Regeneration: A Review

Funding: This research was funded by FCT (Portugal), grant number POCI-01-0145-FEDER-031146.This review focuses on a somewhat unexplored strand of regenerative medicine, that is in situ tissue engineering. In this approach manufactured scaffolds are implanted in the injured region for regeneration within the patient. The scaffold is designed to attract cells to the required volume of regeneration to subsequently proliferate, differentiate, and as a consequence develop tissue within the scaffold which in time will degrade leaving just the regenerated tissue. This review highlights the wealth of information available from studies of ex-situ tissue engineering about the selection of materials for scaffolds. It is clear that there are great opportunities for the use of additive manufacturing to prepare complex personalized scaffolds and we speculate that by building on this knowledge and technology, the development of in situ tissue engineering could rapidly increase. Ex-situ tissue engineering is handicapped by the need to develop the tissue in a bioreactor where the conditions, however optimized, may not be optimum for accelerated growth and maintenance of the cell function. We identify that in both methodologies the prospect of tissue regeneration has created much promise but delivered little outside the scope of laboratory-based experiments. We propose that the design of the scaffolds and the materials selected remain at the heart of developments in this field and there is a clear need for predictive modelling which can be used in the design and optimization of materials and scaffolds.info:eu-repo/semantics/publishedVersio

Biopolymers based on rosin

This work form part of the Green Thermosets project PTDZ/0001/2015 funded by the Foundation of Science and Technology (FCT) in Portugal. We acknowledge most helpful discussions with our Algerian partners, Dr Amine Harrane of the university of Oran and his research group in this project. The authors thank Respol for permission to reproduce Table 1 in this paper.Rosin is a material, which can be obtained from pine resin using a green technology with no waste output. It is a mixture of terpenes with a functionality that make them a rich chemical resource. Rosin is a material which has been available for hundreds of years and has developed many niche applications some old, some new. The authors review the potential of this material for preparing sustainable biopolymers and composites by identifying the reaction paths. The authors conclude that foams and composites may be the most effective route to high volume applications based on rosin.info:eu-repo/semantics/publishedVersio

Prevalence and risk factors of sarcopenia among adults living in nursing homes

Objectives: Sarcopenia is a progressive loss of skeletal muscle and muscle function, with significant healthand disability consequences for older adults. We aimed to evaluate the prevalence and risk factors ofsarcopenia among older residential aged care adults using the European Working Group on Sarcopeniain Older People (EWGSOP) criteria.Study design: A cross-sectional study design that assessed older people (n = 102, mean age 84.5 ± 8.2 years)residing in 11 long-term nursing homes in Australia.Main outcome measurements: Sarcopenia was diagnosed from assessments of skeletal mass index bybioelectrical impedance analysis, muscle strength by handheld dynamometer, and physical performanceby the 2.4 m habitual walking speed test. Secondary variables where collected to inform a risk factoranalysis.Results: Forty one (40.2%) participants were diagnosed as sarcopenic, 38 (95%) of whom were categorizedas having severe sarcopenia. Univariate logistic regression found that body mass index (BMI) (Oddsratio (OR) = 0.86; 95% confidence interval (CI) 0.78–0.94), low physical performance (OR = 0.83; 95% CI0.69–1.00), nutritional status (OR = 0.19; 95% CI 0.05–0.68) and sitting time (OR = 1.18; 95% CI 1.00–1.39)were predictive of sarcopenia. With multivariate logistic regression, only low BMI (OR = 0.80; 95% CI0.65–0.97) remained predictive.Conclusions: The prevalence of sarcopenia among older residential aged care adults is very high. Inaddition, low BMI is a predictive of sarcopenia

Microwave Treatment of Polyacrylonitrile Powder Method Development and Effects of Surface Modification Porosity for Supercapacitor Devices or other Mobile Applications

Acknowledgment: The work at CDRSP was supported by the FCT (Portugal) through Strategic Project - UI 4044.The aim of this article is to develop a method in order to investigate the surface modifications of degraded polyacrylonitrile powders under microwave treatment in air. Microwave treatment of polyacrylonitrile powders in air recorded two stages of degradation firstly an exothermic reaction that started in the range of (86-117)°C. Secondly the Thermal runway here the weight loss reached a peak value between 80-90 percent with the small quantity of 0.25g polyacrylonitrile and in the ashes with a bigger quantity 1g of polyacrylonitrile. Scanning electron microscopy analysis technique revealed the morphological characteristics and the porosity of the carbon compound that may play an important role in the construction of high porosity area and so in electrochemical supercapacitor devices with high performances.info:eu-repo/semantics/publishedVersio

Towards a Conceptual Notion for a Universal Printing Machine

The idea of Universal Printing Machine is advanced. It is designed to serve as a theoretical model for 3D printing. Suitable mathematical structures are proposed as a framework for the Universal Printer.Acknowledgement: The Authors are grateful to Saba Abdulghani Oliveira da Silva for enlightening discussions on the subject. This work is supported by the Fundação para a Ciência e a Tecnologia (FCT) and Centro2020 through the Project references: UID/Multi/04044/2013 and PAMI - ROTEIRO/0328/2013 (Nº 022158) and also by CDRSP and ESTG from the Polytechnic Institute of Leiria.info:eu-repo/semantics/publishedVersio

The coconut tree: A source of sustainable polymeric materials

This work is supported by the Fundação para a Ciência e a Tecnologia (FCT) and Centro2020 through the Project references: UID/Multi/04044/2013; PAMI - ROTEIRO/0328/2013 (Nº 022158) and MATIS (CENTRO-01-0145-FEDER-000014 - 3362).Coconut is a versatile tree belonging to the palm family (Botanic term Arecaceae, coconut palms, Cocos nucifera) in which each part is used for numerous applications. It is grown in the tropic and subtropic regions of the world. There is a tradition and culture associated with the coconut tree due to its enormous value as a food commodity, the use of its branches and wood for daily needs. Coconut is typically cultivated in the coastal regions of the countries due to its preferred moistened soil and salty nature. As well as a source of food, coconut fibres are widely used due to its high strength material properties for many domestic applications. It is clear that the coconut tree can contribute materials without compromising on the supply of food in contrast to other sources of sustainable materials.info:eu-repo/semantics/publishedVersio

Highly Anisotropic Polymer Composites Based on Carbon Nanotubes

Properties of polymers can be optimized through processing methods or by the addition of nanofillers. Carbon nanotubes (CNTs) have gained attention due to their promising behavior. Carbon nanotubes are essentially a sheet of graphene wrapped into a cylindrical shape with either a single or multiple walls. Tube diameters are approximately nanometres, but they can be micrometres in length. Due to the unique properties of nanotubes, they offer promise in composite materials with current research dedicated to embedding them in a polymer matrix. If improvements are to be made, the nanotubes need to be in an aligned configuration. This presents challenges due to the strong intermolecular forces that cause nanotube agglomeration leading to poor quality dispersion and random CNT orientations. Thus, there are two particular challenges to the formation of polymer composites based on CNTs: dispersion and alignment, and these are the focus of this chapter. We consider recent developments in the synthesis of carbon nanotubes and their properties. Next, we detail the challenges of dispersion and alignment that are presented in the preparation of polymer/CNT composites. Finally, we review the literature to identify progress made in preparing high performance polymer/CNT composites and their properties and present one particular solution

Carbon nanotubes in electrospun polyethylene oxide nanofibres: a potential route to conducting nanofibres

Polyethylene oxide solution containing multi-walled carbon nanotubes have been electrospun onto a rotating collector to produce highly aligned arrays of electrospun nanofibers ranging in diameters from (200 – 360) nanometres. The addition of a surfactant (Triton X-100)is highly effective in dispersing carbon nanotube within an aqueous solution of polyethylene oxide and the resulting mixture can be electrospun without excessive clumping to produce nanofibers containing high loadings of nanotubes; in this case up to 5% wt thereby providing an effective route to electrically conductive nanofibres