Sustainable waste recycling solution for the glass fibre reinforced polymer composite materials industry

In this paper the adequacy and the benefit of incorporating glass fibre reinforced polymer (GFRP) waste materials into polyester based mortars, as sand aggregates and filler replacements, are assessed. Different weight contents of mechanically recycled GFRP wastes with two particle size grades are included in the formulation of new materials. In all formulations, a polyester resin matrix was modified with a silane coupling agent in order to improve binder-aggregates interfaces. The added value of the recycling solution was assessed by means of both flexural and compressive strengths of GFRP admixed mortars with regard to those of the unmodified polymer mortars. Planning of experiments and data treatment were performed by means of full factorial design and through appropriate statistical tools based on analyses of variance (ANOVA). Results show that the partial replacement of sand aggregates by either type of GFRP recyclates improves the mechanical performance of resultant polymer mortars. In the case of trial formulations modified with the coarser waste mix, the best results are achieved with 8% waste weight content, while for fine waste based polymer mortars, 4% in weight of waste content leads to the higher increases on mechanical strengths. This study clearly identifies a promising waste management solution for GFRP waste materials by developing a cost-effective end-use application for the recyclates, thus contributing to a more sustainable fibre-reinforced polymer composites industry.

Molecular mobility of n-ethylene glycol dimethacrylate glass formers upon free radical polymerization

Quando um l��quido evita a cristaliza����o durante o arrefecimento, diz-se que entra no estado sobrearrefecido. Se a temperatura continuar a diminuir, o consequente aumento da viscosidade reflecte-se na mobilidade molecular de tal maneira que os tempos caracter��sticos se tornam da mesma ordem de grandeza que os tempos acess��veis experimentalmente. Se o arrefecimento continuar, o l��quido altamente viscoso acaba por vitrificar, i.e. entra no estado v��treo onde apenas os movimentos locais s��o permitidos. Os mon��meros da fam��lia n -etileno glicol dimetacrilato ( n -EGDMA, para n = 1 at�� 4, que constituem o objecto deste estudo, facilmente evitam a cristaliza����o, sendo pois bons candidatos para estudar a mobilidade molecular nos estados sobrearrefecido e v��treo. A Espectroscopia de Relaxa����o Diel��ctrica (DRS) foi a t��cnica escolhida para obter informa����o detalhada sobre a sua din��mica molecular (Cap��tulos 1 e 2). A primeira parte deste trabalho consistiu na caracteriza����o diel��ctrica dos processos de relaxa����o existentes acima e abaixo da temperatura de transi����o v��trea (g T ), a qual aumenta com o aumento do peso molecular (w M ), sendo este resultado confirmado por Calorimetria Diferencial de Varrimento (DSC). No que respeita ao processo cooperativo a , associado �� transi����o v��trea, e ao processo secund��rio b, observa-se uma depend��ncia com w M , enquanto que o outro processo secund��rio, g , aparenta ser independente deste factor (Cap��tulo 3). Nos cap��tulos seguintes, foram levadas a cabo diferentes estrat��gias com o objectivo de clarificar os mecanismos que est��o na origem destas duas relaxa����es secund��rias (b e g ), assim como conhecer a sua respectiva rela����o com a relaxa����o principal (a ). Do estudo, em tempo real, da polimeriza����o isot��rmica via radicais livres do TrEGDMA por Calorimetria de Varrimento Diferencial com Modula����o de Temperatura (TMDSC), levado a cabo a temperaturas abaixo da g T do pol��mero final, concluem-se entre outros, dois importantes aspectos: i) que a vitrifica����o do pol��mero em forma����o conduz a graus de convers��o relativamente baixos, e ii) que o mon��mero que est�� por reagir �� expulso da rede polim��rica que se forma, dando lugar a uma clara separa����o de fases (Cap��tulo 4). Com base nesta informa����o, o passo seguinte foi estudar separadamente a polimeriza����o isot��rmica do di-, tri- e tetra-EGDMA, dando especial aten����o ��s altera����es de mobilidade do mon��mero ainda por reagir. Com as restri����es impostas pela forma����o de liga����es qu��micas, as relaxa����es a e b detectadas no mon��mero tendem a desaparecer no novo pol��mero formado, enquanto que a relaxa����o g se mant��m quase inalterada. Os diferentes comportamentos que aparecem durante a polimeriza����o permitiram a atribui����o da origem molecular dos processos secund��rios: o processo g foi associado ao movimento twisting das unidades etileno glicol, enquanto que a rota����o dos grupos carboxilo foi relacionada com a relaxa����o b (Cap��tulo 5). No que respeita ao pr��prio pol��mero, um processo de relaxa����o adicional foi detectado, pol b , no poly-DEGDMA, poly-TrEGDMA e poly-TeEGDMA, com caracter��sticas similares ao encontrado nos poli(metacrilato de n -alquilo). Este processo foi confirmado e bem caracterizado aquando do estudo da copolimeriza����o do TrEGDMA com acrilato de metilo (MA) para diferentes composi����es (Cap��tulo 6). Para finalizar, o EGDMA, o elemento mais pequeno da fam��lia de mon��meros estudada, al��m de vitrificar apresenta uma marcada tend��ncia para cristalizar quer a partir do estado l��quido ou do estado v��treo. Durante a cristaliza����o, a forma����o de uma fase r��gida afecta principalmente o processo a , cuja intensidade diminui sem no entanto se observarem modifica����es significativas na depend��ncia do tempo de relaxa����o caracter��stico com a temperatura. Por outro lado, o processo secund��rio b torna-se melhor definido e mais estreito, o que pode ser interpretado em termos de uma maior homogeneidade dos micro-ambientes associados aos movimentos locais(Cap��tulo 7).

Drilling delamination outcomes on glass and sisal reinforced plastics

Nowadays, fibre reinforced plastics are used in a wide variety of applications. Apart from the most known reinforcement fibres, like glass or carbon, natural fibres can be seen as an economical alternative. However, some mistrust is yet limiting the use of such materials, being one of the main reasons the inconsistency normally found in their mechanical properties. It should be noticed that these materials are more used for their low density than for their high stiffness. In this work, two different types of reinforced plates were compared: glass reinforced epoxy plate and sisal reinforced epoxy plate. For material characterization purposes, tensile and flexural tests were carried out. Main properties of both materials, like elastic modulus, tensile strength or flexural modulus, are presented and compared with reference values. Afterwards, plates were drilled under two different feed rates: low and high, with two diverse tools: twist and brad type drill, while cutting speed was kept constant. Thrust forces during drilling were monitored. Then, delamination area around the hole was assessed by using digital images that were processed using a computational platform previously developed. Finally, drilled plates were mechanically tested for bearing and open-hole resistance. Results were compared and correlated with the measured delamination. Conclusions contribute to the understanding of natural fibres reinforced plastics as a substitute to glass fibres reinforced plastics, helping on cost reductions without compromising reliability, as well as the consequence of delamination on mechanical resistance of this type of composites.

Uranium glass in museum collections

Disserta����o apresentada na Faculdade de Ci��ncias e Tecnologia da Universidade Nova de Lisboa para obten����o do grau de Mestre em Conserva����o e Restauro ��rea de especializa����o ��� Vidro

Synthesis of Sub-5 NM Co-Doped SnO2 nanoparticles and their structural microstructural, optical and photocatalytic properties

A swift chemical route to synthesize Co-doped SnO2 nanopowders is described. Pure and highly stable Sn1-xCoxO2-delta (0 <= x <= 0.15) crystalline nanoparticles were synthesized, with mean grain sizes <5 nm and the dopant element homogeneously distributed in the SnO2 matrix. The UV-visible diffuse reflectance spectra of the Sn1-xCoxO2-delta samples reveal red shifts, the optical bandgap energies decreasing with increasing Co concentration. The samples' Urbach energies were calculated and correlated with their bandgap energies. The photocatalytic activity of the Sn1-xCoxO2-delta samples was investigated for the 4-hydroxylbenzoic acid (4-HBA) degradation process. A complete photodegradation of a 10 ppm 4-HBA solution was achieved using 0.02% (w/w) of Sn0.95Co0.05O2-delta nanoparticles in 60 min of irradiation. (C) 2014 Elsevier B.V. All rights reserved.

Increasing the wear resistance of molds for injection of glass fiber reinforced plastics

Abrasion by glass fibers during injection molding of fiber reinforced plastics raises new challenges to the wear performance of the molds. In the last few decades, a large number of PVD and CVD coatings have been developed with the aim of minimizing abrasion problems. In this work, two different coatings were tested in order to increase the wear resistance of the surface of a mold used for glass fiber reinforced plastics: TiAlSiN and CrN/CrCN/DLC. TiAlSiN was deposited as a graded monolayer coating while CrN/CrCN/DLC was a nanostructured coating consisting of three distinct layers. Both coatings were produced by PVD unbalanced magnetron sputtering and were characterized using scanning electron microscopy (SEM) provided with energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), micro hardness (MH) and scratch test analysis. Coating morphology, thickness, roughness, chemical composition and structure, hardness and adhesion to the substrate were investigated. Wear resistance was characterized through industrial tests with coated samples and an uncoated reference sample inserted in a feed channel of a plastic injection mold working with 30 wt.% glass fiber reinforced polypropylene. Results after 45,000 injection cycles indicate that the wear resistance of the mold was increased by a factor of 25 and 58, by the TiAlSiN and CrN/CrCN/DLC coatings, respectively, over the uncoated mold steel.

Influence of the deposition pressure on the properties of transparent and conductive ZnO: Ga thin-film produced by r.f. sputtering at room temperature

Thin Solid Films, vol. 427, n�� 1-2

Experimental study on polyester based concretes filled with glass fibre reinforced plastic recyclates ��� a contribution to composite materials sustainability

The development and applications of thermoset polymeric composites, namely fibre reinforced plastics (FRP), have shifted in the last decades more and more into the mass market [1]. Despite of all advantages associated to FRP based products, the increasing production and consume also lead to an increasing amount of FRP wastes, either end-of-lifecycle products, or scrap and by-products generated by the manufacturing process itself. Whereas thermoplastic FRPs can be easily recycled, by remelting and remoulding, recyclability of thermosetting FRPs constitutes a more difficult task due to cross-linked nature of resin matrix. To date, most of the thermoset based FRP waste is being incinerated or landfilled, leading to negative environmental impacts and supplementary added costs to FRP producers and suppliers. This actual framework is putting increasing pressure on the industry to address the options available for FRP waste management, being an important driver for applied research undertaken cost efficient recycling methods. [1-2]. In spite of this, research on recycling solutions for thermoset composites is still at an elementary stage. Thermal and/or chemical recycling processes, with partial fibre recovering, have been investigated mostly for carbon fibre reinforced plastics (CFRP) due to inherent value of carbon fibre reinforcement; whereas for glass fibre reinforced plastics (GFRP), mechanical recycling, by means of milling and grinding processes, has been considered a more viable recycling method [1-2]. Though, at the moment, few solutions in the reuse of mechanically-recycled GFRP composites into valueadded products are being explored. Aiming filling this gap, in this study, a new waste management solution for thermoset GFRP based products was assessed. The mechanical recycling approach, with reduction of GFRP waste to powdered and fibrous materials was applied, and the potential added value of obtained recyclates was experimentally investigated as raw material for polyester based mortars. The use of a cementless concrete as host material for GFRP recyclates, instead of a conventional Portland cement based concrete, presents an important asset in avoiding the eventual incompatibility problems arisen from alkalis silica reaction between glass fibres and cementious binder matrix. Additionally, due to hermetic nature of resin binder, polymer based concretes present greater ability for incorporating recycled waste products [3]. Under this scope, different GFRP waste admixed polymer mortar (PM) formulations were analyzed varying the size grading and content of GFRP powder and fibre mix waste. Added value of potential recycling solution was assessed by means of flexural and compressive loading capacities of modified mortars with regard to waste-free polymer mortars.

Occupational risk in a glass manufacturing industry unit

Risk assessment is one of the main pillars of the framework directive and other directives in respect of health and safety. It is also the basis of an effective management of safety and health as it is essential to reduce work-related accidents and occupational diseases. To survey the hazards eventually present in the workplaces the usual procedures are i) gathering information about tasks/activities, employees, equipment, legislation and standards; ii) observation of the tasks and; iii) quantification of respective risks through the most adequate risk assessment among the methodologies available. From this preliminary evaluation of a welding plant and, from the different measurable parameters, noise was considered the most critical. This paper focus not only the usual way of risk assessment for noise but also another approach that may allow us to identify the technique with which a weld is being performed.

Sensitive bi-enzymatic biosensor based on polyphenoloxidases���gold nanoparticles���chitosan hybrid film���graphene doped carbon paste electrode for carbamates detection

A bi-enzymatic biosensor (LACC���TYR���AuNPs���CS/GPE) for carbamates was prepared in a single step by electrodeposition of a hybrid film onto a graphene doped carbon paste electrode (GPE). Graphene and the gold nanoparticles (AuNPs) were morphologically characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, dynamic light scattering and laser Doppler velocimetry. The electrodeposited hybrid film was composed of laccase (LACC), tyrosinase (TYR) and AuNPs entrapped in a chitosan (CS) polymeric matrix. Experimental parameters, namely graphene redox state, AuNPs:CS ratio, enzymes concentration, pH and inhibition time were evaluated. LACC���TYR���AuNPs���CS/GPE exhibited an improved Michaelis���Menten kinetic constant (26.9 �� 0.5 M) when compared with LACC���AuNPs���CS/GPE (37.8 �� 0.2 M) and TYR���AuNPs���CS/GPE (52.3 �� 0.4 M). Using 4-aminophenol as substrate at pH 5.5, the device presented wide linear ranges, low detection limits (1.68��10��� 9 �� 1.18��10��� 10 ��� 2.15��10��� 7 �� 3.41��10��� 9 M), high accuracy, sensitivity (1.13��106 �� 8.11��104 ��� 2.19��108 �� 2.51��107 %inhibition M��� 1), repeatability (1.2���5.8% RSD), reproducibility (3.2���6.5% RSD) and stability (ca. twenty days) to determine carbaryl, formetanate hydrochloride, propoxur and ziram in citrus fruits based on their inhibitory capacity on the polyphenoloxidases activity. Recoveries at two fortified levels ranged from 93.8 �� 0.3% (lemon) to 97.8 �� 0.3% (orange). Glucose, citric acid and ascorbic acid do not interfere significantly in the electroanalysis. The proposed electroanalytical procedure can be a promising tool for food safety control.

A case study undertaken recycling & reuse of glass fiber reinforced thermoset polumer wastes of composite materials industry

Glass fibre-reinforced plastics (GFRP) have been considered inherently difficult to recycle due to both: crosslinked nature of thermoset resins, which cannot be remoulded, and complex composition of the composite itself. Presently, most of the GFRP waste is landfilled leading to negative environmental impacts and supplementary added costs. With an increasing awareness of environmental matters and the subsequent desire to save resources, recycling would convert an expensive waste disposal into a profitable reusable material. In this study, efforts were made in order to recycle grinded GFRP waste, proceeding from pultrusion production scrap, into new and sustainable composite materials. For this purpose, GFRP waste recyclates, were incorporated into polyester based mortars as fine aggregate and filler replacements at different load contents and particle size distributions. Potential recycling solution was assessed by mechanical behaviour of resultant GFRP waste modified polymer mortars. Results revealed that GFRP waste filled polymer mortars present improved flexural and compressive behaviour over unmodified polyester based mortars, thus indicating the feasibility of the GFRP industrial waste reuse into concrete-polymer composite materials.

Glass in Cultural Heritage ��� An Introduction

Proceedings of the Chemistry and Conservation Science

Real f��brica de vidros de Coina ��� Chemical analysis of archaeological glass fragments

Actas do 17�� Congresso da Associa����o Internacional para a Hist��ria do Vidro

Uranium glass in museum collections

Journal of Cultural Heritage, n�� 9 (2008), p. 64-68

The potential of molecular imprinting as a biosensing devices for monitoring the CEA cancer biomarker

6th Graduate Student Symposium on Molecular Imprinting