Study on properties of composites reinforced by heat treated glass fibres simulating thermal recycling conditions

In the present study, commercial chopped glass fibres were heat treated at 300°C, 450°C, 500°C and 600°C to imitate a composite thermal recycling process. The heat treated fibres were extrusion compounded and injection moulded with polypropylene to form composites. The heat treatment increased the susceptibility of the fibres to length degradation during the melt processing particularly at higher conditioning temperatures. Comparison with the Cox model revealed that the stiffness of the composite was affected by the reduced fibre length. The reduced fibre length did not significantly contribute to the reduction of the tensile strength and the impact strength. These properties were deteriorated by other factors such as the strength degradation of the glass fibres and the reduced fibre matrix interaction. Thus a post treatment which recovers the fibre strength and optimizes the fibre-matrix interface will be essential to produce thermally recycled glass fibre composites with high mechanical properties

Regeneration of thermally recycled glass fibre for cost effective composite recycling : the effect of fibre regeneration and matrix modification

The recycling of glass fibre composites has become an important issue because of social-ecological, financial and legislative reasons. One main obstacle for the recycling of glass fibre composites is the low value of the recycled fibres. The present study investigates methods to maximize the reinforcement potential of thermally recycled glass fibres. Glass fibres were exposed to thermal recycling temperatures and processed into injection moulded polypropylene composites. Microbond tests were performed to characterize the adhesion between the fibres and the polypropylene matrix. Similar to other studies, the composite performance dropped when the fibres were exposed to high temperatures. It was found that the regeneration of the interfacial shear strength using maleic anhydride grafted polypropylene improves the composites performance but a post treatment of the fibres with γ-aminopropyltriethoxysilane was more effective. It was concluded that the application of γ-aminopropyltriethoxysilane might have improved the strength of the fibres

Regeneration of thermally recycled glass fibre for cost-effective composite recycling : Performance of composites based on PP and Recovered glass fibre

Due to economic and technical reasons, no recycling process for glass fibre composites has been commercialized on a large scale. Thermal recycling processes are promising in terms of potential for commercialization but the reinforcement potential of thermally recycled fibres is too low for the application in composites. In the present study, glass fibres were exposed to elevated temperatures prior to composite processing to imitate a thermal recycling process. The exposure of the fibres to elevated temperatures prior to composite processing caused a significant reduction of the mechanical properties of the composites. The heat treated fibres were regenerated with a post treatment. The regeneration of the glass fibres recovered the mechanical properties of the composites almost completely. Thus, this study shows that composites based on thermally recycled glass fibres have the potential to compete with composites based on ‘new’ glass fibres

A study of the thermal degradation of glass fibre sizings at composite processing temperatures

Although not fully understood, it is well recognized that optimal working of glass fibre sizings is necessary to maximize the performance of glass fibre reinforced polymer composites. It is important that the organic components in such sizings continue to function after exposure to the high temperatures often experienced during composite processing. This study presents the results on the thermal stability of polypropylene and epoxy compatible glass fibre sizings obtained using TGA, microbond adhesion measurement and composite mechanical testing. Test results indicate that the performance of commercial polypropylene compatible glass fibre sizings can be significantly compromised by thermo-oxidative degradation at normal composite processing temperatures. A significant reduction in composite performance is directly related to a loss of fibre-matrix adhesion caused by thermal degradation of some of the principal sizing components

Recover : regenerating the strength and value of thermally recycled glass fibres

Results are presented from the ReCoVeR project on the regeneration of the strength of thermally conditioned glass fibres. Thermal recycling of end-of-life glass fibre reinforced composites or composite manufacturing waste delivers fibres with virtually no residual strength or value. Composites produced from such fibres also have extremely poor mechanical performance. Data is presented showing that a short hot sodium hydroxide solution treatment of such recycled fibres can more than triple their strength and restore their ability to act as an effective reinforcement in second life composite materials. The implications of these results for real materials reuse of recycled glass fibres as replacement for pristine reinforcement fibres are discussed

Recover : Regenerating the strength of glass fibres thermally recycled from end-of-life

Global production of composite materials in 2015 will significantly exceed 10 million tons. Glass fibre reinforced composites account for more than 90% of all the fibre-reinforced composites currently produced. Development of economically viable processes for recycling end-of-life glass fibre composites would have major beneficial economic and environmental impacts for the glass fibre composites industry. This paper reports a study on regenerating the performance of thermally recycled glass fibres. The effectiveness of the ReCoVeR treatments on the single fibre strength of glass fibres thermally treated to imitate the conditions of composite recycling technology is presented. The regenerated strength levels of these ReCoVeRed fibres must be further protected and maintained by the use of fibre sizing technology similar to standard glass fibre products. Consequently the effect on fibre strength of the combination of the ReCoVeR treatment with a standard silane coating was also studied. Significant increase of fibre strength was obtained through the regeneration treatments, achieving greater than triple the fibre strength in comparison with the thermally treated glass fibre. Furthermore the same treatments have also been applied to glass fibres recovered from model composites using laboratory thermal recycling. Fibre strengths have been achieved which makes reusing these fibres as a composite reinforcement a viable option. Results on the mechanical performance of composites containing ReCoVeRed glass fibres are presented and discussed in support of this assertion

The ReCoVer Project : regeneration of thermally recycled glass fibre for cost-effective composite recycling

Global production of composite materials in 2015 will significantly exceed 10 million tons. Glass fibre reinforced composites account for more than 90 % of all the fibre-reinforced composites currently produced. Development of economically viable processes for recycling end-of-life glass fibre composites would have major economic and environmental impacts. This paper introduces and reviews the initial results of the ReCoVeR projects on enabling cost-effective performance regeneration of glass-fibres from thermal recycling of end-of-life automotive and wind energy composites. ReCoVeR technology targets treating glass fibre thermally reclaimed from GRP waste in order to regenerate a performance level which is equivalent to new fibres. Composite materials reinforced with ReCoVeR glass fibres can currently attain over 80 % of the reinforcement performance of composites produced with pristine glass fibres

Towards a new generation of glass fiber products based on regenerated fiber thermally recycled from end-of-life GRP and GRP manufacturing waste

The recovery and reuse of glass fiber from waste glass fiber and end-of-life GRP in an environmentally friendly, cost-effective manner is one of the most important challenges facing the composites industry. The annual global consumption of reinforcement grade E-glass fiber (GF) now exceeds 5 million tons. Associated with this global GF consumption was the production of 0.5-1 million tons of GF manufacturing waste most of which is landfilled. Furthermore, approximately 70% of reinforcement GF is used to manufacture thermoset based composites (GRP) which also produces approximately 15% manufacturing waste. Consequently it can be shown that there is actually sufficient GF available in current manufacturing waste and end-of-life GRP to meet approximately 50% of the global demand for GF reinforcements. Although a number of processes for recycling GRP are available or under development, the most likely methods to be cost-effective are based on thermal recycling where temperatures in the range 450-600 °C are used to remove the polymer matrix and allow extraction of the glass fiber reinforcement. One of the key barriers to reuse of such thermally recycled glass fibers (RGF) in second-life composite materials is their drastically reduced strength. A breakthrough in the regeneration of RGF performance has the potential to totally transform the economics of recycling GRP waste and end-of-life composites. In this presentation we will review the outputs from two EPSRC funded research projects focussed on the cost effective recycling of end-of-life glass fiber composites from automotive (TARF-LCV: Towards Affordable, Closed-Loop Recyclable Future Low Carbon Vehicle Structures) and wind energy applications (ReCoVeR: Regenerated Composite Value Reinforcement). The mission of the ReCoVeR team is to research and grow the knowledge to enable the development of cost-effective, drop-in, glass fiber and composite products based on recycled glass fibers with regenerated mechanical performance. The Research Goals for the project are threefold - • Generate fundamental understanding of the changes in glass fibers caused by thermo-mechanical conditioning • Develop cost effective treatments to regenerate the performance of thermo-mechanically recycled glass fibers • Produce examples of glass fiber and composite products using regenerated glass fibers The presentation will provide an overview of the research results from all three areas of the project

Results from a real-time dosimetry study during left atrial ablations performed with ultra-low dose radiation settings

Background: Three-dimensional mapping systems and the use of ultra-low dose radiation protocols have supported minimization of radiation dose during left atrial ablation procedures. By using optimal shielding, scattered radiation reaching the operator can be further reduced. This prospective study was designed to determine the remaining operator radiation exposure during left atrial catheter ablations using real-time dosimetry. Methods: Radiation dose was recorded using real-time digital dosimetry badges outside the lead apron during 201 consecutive left atrial fibrillation ablation procedures. All procedures were performed using the same X‑ray system (Siemens Healthineers Artis dBc; Siemens Healthcare AG, Erlangen, Germany) programmed with ultra-low dose radiation settings including a low frame rate (two frames per second), maximum copper filtration, and an optimized detector dose. To reduce scattered radiation to the operators, table-suspended lead curtains, ceiling-suspended leaded plastic shields, and radiation-absorbing shields on the patient were positioned in an overlapping configuration. Results: The 201 procedures included 139 (69%) pulmonary vein isolations (PVI) (20 cryoballoon ablations, 119 radiofrequency ablations, with 35 cases receiving additional ablation of the cavotricuspid isthmus) and 62 (31%) PVI plus further left atrial substrate ablation. Mean radiation dose measured as dose area product for all procedures was 128.09 ± 187.87 cGy ∙ cm2 with a mean fluoroscopy duration of 9.4 ± 8.7 min. Real-time dosimetry showed very low average operator doses of 0.52 ± 0.10 µSv. A subanalysis of 51 (25%) procedures showed that the radiation burden for the operator was highest during pulmonary vein angiography. Conclusion: The use of ultra-low dose radiation protocols in combination with optimized shielding results in extremely low scattered radiation reaching the operator.Hintergrund: Der Einsatz von dreidimensionalen Mapping-Systemen und von Niedrigdosiseinstellungen der Röntgenanlage führte zu einer Minimierung der Strahlenbelastung bei linksatrialen Ablationen. Optimierte Abschirmung kann die Streustrahlung als Strahlenbelastung des Untersuchers weiter reduzieren. In dieser prospektiven Studie wurde untersucht, welcher Strahlenbelastung der Untersucher unter Anwendung dieser Maßnahmen während linksatrialer Ablationen noch ausgesetzt ist. Methoden: Die Strahlenbelastung wurde mittels Echtzeitdosimetrie an der Außenseite der Bleischürze während 201 konsekutiven linksatrialen Ablationen gemessen. Alle Prozeduren wurden mit demselben Röntgensystem (Siemens Healthineers Artis dBc; Siemens Healthcare AG, Erlangen, Deutschland) und mit strahlensparenden Einstellungen durchgeführt, unter anderem mit einer niedrigen Bildrate von 2 Bildern/s, maximaler Kupferfilterung und angepasster Detektoreingangsdosis. Um Streustrahlung zu reduzieren, wurden die Seitenlamellen, die mobile Acrylscheibe und die strahlenabsorbierenden Schilde auf dem Patienten überlappend angeordnet. Ergebnisse: Die 201 Prozeduren umfassten 139 (69%) Pulmonalvenenisolationen (PVI; 20 Kryoballonablationen, 119 Radiofrequenzablationen, in 35 Fällen mit zusätzlicher Ablation des kavotrikuspidalen Isthmus) und 62 (31%) PVI mit zusätzlicher linksatrialer Substratmodifikation. Die Strahlendosis als Dosis-Flächen-Produkt (DAP) betrug durchschnittlich 128,09± 187,87 cGy ⋅cm2 bei einer Fluoroskopiedauer von imMittel 9,4± 8,7min. Die per Echtzeitdosimetrie erhobene mittlere Strahlendosis des Untersuchers zeigte sich mit 0,52± 0,10 μSv als sehr gering. Eine Subanalyse bei 51 (25 %) Prozeduren zeigte, dass die Strahlendosis des Untersuchers während der Pulmonalvenenangiographie am höchsten war. Schlussfolgerung: Die Kombination von Niedrigdosiseinstellungen und optimierter Abschirmung führt zu einer extremniedrigen Streustrahlung als Strahlenbelastung des Untersuchers

Recover : regenerating the strength and value of glass fibres thermally recycled from end-of-life GRP composites

The recovery and reuse of end-of-life GRP in an environmentally friendly, cost-effective manner is one of the most important challenges facing the polymer composites industry. A number of processes for recycling GRP are available or under development. However, nearly all options deliver recycled glass fibres which are not cost-performance competitive due to the huge drop in performance of recycled glass fibre compared to its original state. A breakthrough in the regeneration of recycled glass fibre performance has the potential to totally transform the economics of recycling such GRP composites. This presentation will review the status of the ReCoVeR project which is focussed on the enabling cost-effective regeneration of the performance and value of glass fibres obtained from thermal recycling of end-of-life GRP and GRP manufacturing waste. Highlights of our latest results will be presented with emphasis on our breakthrough treatments to regenerate the properties of thermally conditioned glass fibres