Tunable and processable shape memory composites based on degradable polymers

The authors acknowledge the funding provided by NSFC-DG-RTD Joint Scheme (Project No. 51361130034) and the RAPIDOS project under the European Union's 7th Framework Programme (Project No.604517)

Responses of Vascular Endothelial Cells to Photoembossed Topographies on Poly(Methyl Methacrylate) Films.

Failures of vascular grafts are normally caused by the lack of a durable and adherent endothelium covering the graft which leads to thrombus and neointima formation. A promising approach to overcome these issues is to create a functional, quiescent monolayer of endothelial cells on the surface of implants. The present study reports for the first time on the use of photoembossing as a technique to create polymer films with different topographical features for improved cell interaction in biomedical applications. For this, a photopolymer is created by mixing poly(methyl methacrylate) (PMMA) and trimethylolpropane ethoxylate triacrylate (TPETA) at a 1:1 ratio. This photopolymer demonstrated an improvement in biocompatibility over PMMA which is already known to be biocompatible and has been extensively used in the biomedical field. Additionally, photoembossed films showed significantly improved cell attachment and proliferation compared to their non-embossed counterparts. Surface texturing consisted of grooves of different pitches (6, 10, and 20 µm) and heights (1 µm and 2.5 µm). The 20 µm pitch photoembossed films significantly accelerated cell migration in a wound-healing assay, while films with a 6 µm pitch inhibited cells from detaching. Additionally, the relief structure obtained by photoembossing also changed the surface wettability of the substrates. Photoembossed PMMA-TPETA systems benefited from this change as it improved their water contact angle to around 70°, making it well suited for cell adhesion.This project was supported in part by MRC/EPSRC grant G0502256-77947. Lin Qiu was supported by a joint PhD studentship from Queen Mary University of London and the China Scholarship Council (CSC) between 2010 and 2014

Sustainable and self-regulating out-of-oven manufacturing of FRPs with integrated multifunctional capabilities

With the ever increasing demand for energy reduction to stimulate sustainable development, new energy efficient manufacturing processes for advanced fibre-reinforced plastics (FRPs) are of great interest to overcome limitations of conventional autoclave or oven based manufacturing processes such as high energy consumption and size restrictions. Herein, a highly energy efficient and safe out-of-oven curing method is presented by integrating a pyroresistive surface layer with intrinsic self-regulating heating capabilities, into a composite laminate. This surface layer consists of a nanocomposite film based on graphene nanoplatelets (GNPs) and high density polyethylene (HDPE) and possesses self-regulating Joule heating capabilities, which can be used to cure epoxy based composites at a desired temperature without the risk of over-heating. Moreover, the thermoplastic nature of the surface layer enables easy fabrication with good flexibility for complex shapes. Compared to state-of-the-art out-of-autoclave oven curing, the proposed out-of-oven Joule heating approach consumed only 1% of the energy required for curing, with no effect on mechanical performance and glass transition temperature (Tg) of the final composite. Moreover, the integration of the self-regulating heating layer offers additional functionalities to the cured composites, like strain or damage sensing as well as the potential of de-icing without affecting the internal structure and performance of the laminate. The presented smart heating layer provides a novel solution for sustainable manufacturing as well as real-time structural health monitoring (SHM) throughout the components’ life for multifunctional composite applications in the field of renewable wind energy and aerospace

PA6 nanofibre production: A comparison between rotary jet spinning and electrospinning

© 2018 by the authors. Polymer nanofibres are created from many different techniques, with varying rates of production. Rotary jet spinning is a relatively new technique for making nanofibres from both polymer solutions and melt. With electrospinning being by far the most widespread processing method for polymer nanofibres, we performed a direct comparison of polyamide 6 (PA6) nanofibre production between these two methods. It was found that electrospinning produced slightly smaller-diameter fibres, which scaled with a decrease in solution viscosity. In comparison, rotary jet spun fibres could be produced from a reduced range of polymer concentrations and exhibited therefore slightly larger diameters with greater variation. Crystallinity of the fibres was also compared between the two techniques and the bulk polymer, which showed a decrease in crystallinity compared to bulk PA6

Synergistic effects of spray-coated hybrid carbon nanoparticles for enhanced electrical and thermal surface conductivity of CFRP laminates

This research has received funding from NanoSynth Project funded by the Technology Strategy Board (TSB) through the Technology Inspired Innovation – H2020 LEIT Nanotechnologies Competition, No. 101257. Y.L. would also like to acknowledge the financial support through the China Scholarship Council (CSC) scheme

Glass-like transparent high strength polyethylene films by tuning drawing temperature

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service toour customers we are providing this early version of the manuscript. The manuscript will undergocopyediting, typesetting, and review of the resulting proof before it is published in its final formY. Lin greatly acknowledges financial support by the China Scholarship Council (CSC)

Transparent, Lightweight, and High Strength Polyethylene Films by a Scalable Continuous Extrusion and Solid-State Drawing Process

The continuous production of transparent high strength ultra-drawn high-density polyethylene films or tapes is explored using a cast film extrusion and solid-state drawing line. Two methodologies are explored to achieve such high strength transparent polyethylene films; i) the use of suitable additives like 2-(2H-benzotriazol-2-yl)-4,6-ditertpentylphenol (BZT) and ii) solid-state drawing at an optimal temperature of 105 °C (without additives). Both methodologies result in highly oriented films of high transparency (≈91%) in the far field. Maximum attainable modulus (≈33 GPa) and tensile strength (≈900 MPa) of both types of solid-state drawn films are similar and are an order of magnitude higher than traditional transparent plastics such as polycarbonate (PC) and poly(methyl methacrylate). Special emphasis is devoted to the effect of draw down and pre-orientation in the as-extruded films prior to solid-state drawing. It is shown that pre-orientation is beneficial in improving mechanical properties of the films at equal draw ratios. However, pre-orientation lowers the maximum attainable draw ratio and as such the ultimate modulus and tensile strength of the films. Potential applications of these high strength transparent flexible films lie in composite laminates, automotive or aircraft glazing, high impact windows, safety glass, and displays