Recyclable structural composites for marine renewable energy

The InterReg SeaBioComp project will develop and deliver demonstrators using innovative bio-based thermoplastic composite materials with mechanical properties comparable to conventional oil-based composites, durability tailored to the specific application (2 to >20 years), recycling potential, reduced CO2 emissions and reduced microplastic and ecotoxic impact in the marine environment. The University of Plymouth is investigating to use of manufacture by monomer infusion under flexible tooling (MIFT) with in situ polymerisation to produce natural, or glass, fibre reinforced structural composites. Following an extensive literature survey, the monomer selection has suggested two potential matrix materials: poly(methyl methacrylate) (PMMA) and poly(L-lactide) (PLA). The conference paper will present the progress in measurement of the composite mechanical properties and correlation to models predicting the material performance

Curing resin infused composites in the autoclave

There is increasing interest across the range of composites manufacturing processes for cost reduction with a current focus on out-of-autoclave (OOA) processes. However, for the highest performance composites, the maximum fibre volume fraction is limited by the compressibility characteristics of the reinforcement. For any specific reinforcement, vacuum-only processes cannot achieve fibre contents as high when additional external pressure is applied. Compression moulding in a hydraulic press creates limited compaction perpendicular to the line of action of the press. The autoclave is good for complex three-dimensional components. Autoclave processes normally use pre-impregnated reinforcements with a premium price for the impregnation process and the associated quality issues. The use of dry reinforcements infused with liquid resins should lead to significant cost reductions. This paper considers the optimisation of autoclave cure for resin-infused composites and extends an earlier feasibility study for composite plates referenced to equivalent systems manufactured by hand-lamination, or by resin infusion without autoclave cure. Consolidation at 5.9 bar lead to an additional 8.4% (thickness method) or 8.6% (burnoff) fibre volume fraction. In turn, the flexural modulus was increased by 39% and the flexural strength was increased by 20% relative to vacuum-only cured composites

Maximum Entropy for Gravitational Wave Data Analysis: Inferring the Physical Parameters of Core-Collapse Supernovae

The gravitational wave signal arising from the collapsing iron core of a Type II supernova progenitor star carries with it the imprint of the progenitor's mass, rotation rate, degree of differential rotation, and the bounce depth. Here, we show how to infer the gravitational radiation waveform of a core collapse event from noisy observations in a network of two or more LIGO-like gravitational wave detectors and, from the recovered signal, constrain these source properties. Using these techniques, predictions from recent core collapse modeling efforts, and the LIGO performance during its S4 science run, we also show that gravitational wave observations by LIGO might have been sufficient to provide reasonable estimates of the progenitor mass, angular momentum and differential angular momentum, and depth of the core at bounce, for a rotating core collapse event at a distance of a few kpc.Comment: 44 pages, 12 figures; accepted version scheduled to appear in Ap J 1 April 200

Preface

The marine environment is challenging for traditional engineering materials due to the corrosion of metals or the bio-deterioration of natural materials. Consequently, the use of fiber-reinforced polymer matrix composites in the seas and oceans has grown in diversity of components, the size of structures and production numbers. Composites consistently demonstrate good performance, with many technologies and developments only realized because of their use. This chapter introduces the book, signposts to the topics covered, and briefly considers some of the recent innovations not otherwise included in the text

On the static and dynamic properties of flax and Cordenka epoxy composites

Fibre reinforced composites have excellent specific properties and are widely sought after by engineers seeking to reduce mass. However, end of life disposal is a significant problem and so research into more sustainable natural fibre composites is extremely topical. This paper examines the applicability of natural fibre composites for high performance structural applications. Woven flax and regenerated cellulose (Cordenka) textiles were pre-impregnated with commercially available epoxy resins and consolidated into test laminates in an autoclave to determine their static (compressive, tensile, flexural) and dynamic (energy absorption) properties. The range of compressive strengths was 77.5–299.6 MPa. Tensile strengths ranged from 63 to 92.6 MPa and interlaminar shear strength (ILSS) from 10.7 to 23.3 MPa. Specific energy absorption (SEA) varied between 21.2–34.2 kJ/kg. Biotex flax combined with MTM49 resin matched the SEA of T300 carbon fibre using the same resin system and layup. This work has demonstrated that natural fibre composites have significant scope for use in structural applications but additional work is required on fibre to matrix bonding in order to maximise their properties whilst remaining an environmentally credible option

Development of Smartphone-based ECL Sensor for Dopamine Detection: Practical Approaches

In this work, a compact, mobile phone-based ECL sensor apparatus was developed using the phone cameras, screen-printed electrodes (SPE), and mobile app for dopamine detection. Methods of DC voltage application for ECL reaction were comprehensively studied from the mobile phone itself or external power. Under optimized sensing conditions, with disposable carbon SPE and 20 mM coreactant tri-n-propylamine (TPrA), acceptable repeatability and reproducibility were achieved in terms of relative standard deviation (RSD) of intra- and interassays, which were 6.7 and 5.5%, respectively. The biochemical compound dopamine was measured due to its ECL quenching characteristics and its clinical importance. The quenching mechanism of Ru(bpy)32+/TPrA by dopamine was investigated based on the estimation of the constants of the Stern-Volmer equations. The linear range for detectable dopamine concentration was from 1.0 to 50 μM (R2 = 0.982). As the developed mobile phone-based ECL sensor is simple, small and assembled from low-cost components, it offers new opportunities for the development of inexpensive analytical methods and compact sensors

Thermoplastic matrix systems for large marine structures

Almost all large fibre composite structures used in the marine environment use a thermoset resin matrix. These materials have excellent durability in the sea, but are difficult to dispose of at end-of-life. After a rigorous selection process, methyl methacrylate and lactide monomers have been identified as potential thermoplastic matrix systems which can be manufactured using in situ polymerisation during monomer infusion under flexible tooling. The presentation will address manufacturing issues (acrylic is a “drop in” for polyester resin, but lactide requires heating systems), and end of life (acrylic is lower in the recycling hierarchy). This work was conducted within the SeaBioComp project which has received funding from Interreg 2 Seas Mers Zeeën programme 2014–2020 co-funded by the European Regional Development Fund under subsidy contract No. 2S06-006

A base-free synthetic route to anti-bimetallic lanthanide pentalene complexes

We report the synthesis and structural characterisation of three homobimetallic complexes featuring divalent lanthanide metals (Ln = Yb, Eu and Sm) bridged by the silylated pentalene ligand [1,4-{SiiPr3}2C8H4]2− (= Pn†). Magnetic measurements and cyclic voltammetry have been used to investigate the extent of intermetallic communication in these systems, in the context of molecular models for organolanthanide based conducting materials

Monomer Selection for In Situ Polymerization Infusion Manufacture of Natural-Fiber Reinforced Thermoplastic-Matrix Marine Composites

Awareness of environmental issues has led to increasing interest from composite researchers in using “greener” materials to replace synthetic fiber reinforcements and petrochemical polymer matrices. Natural fiber bio-based thermoplastic composites could be an appropriate choice with advantages including reducing environmental impacts, using renewable resources and being recyclable. The choice of polymer matrix will significantly affect the cost, manufacturing process, mechanical properties and durability of the composite system. The criteria for appropriate monomers are based on the processing temperature and viscosity, polymer mechanical properties, recyclability, etc. This review considers the selection of thermoplastic monomers suitable for in situ polymerization during resin, now monomer, infusion under flexible tooling (RIFT, now MIFT), with a primary focus on marine composite applications. Given the systems currently available, methyl methacrylate (MMA) may be the most suitable monomer, especially for marine composites. MMA has low process temperatures, a long open window for infusion, and low moisture absorption. However, end-of-life recovery may be limited to matrix depolymerization. Bio-based MMA is likely to become commercially available in a few years. Polylactide (PLA) is an alternative infusible monomer, but the relatively high processing temperature may require expensive consumable materials and could compromise natural fiber properties