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Due to their excellent mechanical properties and easy application Carbon Fibre Reinforced Polymers (CFRP) are being successfully used to repair and renewing old and damaged civil engineering infrastructures. In particular, the method of strengthening concrete members with externally bonding of CFRP laminates has become increasingly popular. In fact, extensive research has shown that this technique can lead to a substantial improvement in the flexural and shear strength capacities of the member repaired. In such applications, materials involved will be exposed to outdoor environmental conditions, including humidity, water from rain, saline-water, ground water and high alkalinity solutions due to chemical composition of the concrete itself, as well as solar ultraviolet radiation. Thus, it is of great relevancy to study the durability of the materials involved, namely epoxy adhesives and CFRP laminates, as well as, the integrity of the entire system, when subjected to those environmental factors. This work is part of a much larger research study that is being made to predict the long-term behaviour of several commercial CFRP laminate/adhesive systems used in the rehabilitation of concrete structures. In the whole project it is recognized that the durability of these solutions depends, not only on the durability of the composite materials but also on the performance of the systems used to bond them to the concrete. The present document provides details about the part of the investigation concerning the durability of CFRP laminates. This paper describes the study carried out to investigate the environmental and accelerated ageing effects on three types of commercially available CFRP laminates. The changes in CFRP laminates properties after exposure up to 18 months under different environmental conditions - immersion in demineralised water, saline and alkaline solutions at room temperature, 40 ºC and 60 ºC, as well as under constant humidity condensation atmosphere at 40 ºC – are reported and discussed. The results of tests performed in accelerated weathering chambers – with ultraviolet radiation – are also included. Results obtained offer valuable information about the progression of material degradation under different ageing conditions (some of them accelerated), which can be used, not only to characterize the behaviour of CFRP laminates, but also for a better understanding of the degradation mechanisms involved, which is a base for the design of service life-prediction models.

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Four different PVC formulations, designed for outdoor applications, in the form of calen dered films, were submitted to artificial accelerated ageing under different radiation sources, with and without water spray, and also to natural exposure. The influence of the different photo-oxidation conditions was evaluated by means of surface analysis using X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy. The photo-oxidation of PVC is well monitored by FTIR measurements by following the formation of oxidation products of the carbonyl type, which are due to radical attack on the double bonds in the molecular structure of PVC, and enhanced by radiation and temperature. Results show that relative rates of PVC degradation reactions are different under different photo-oxidative conditions. XPS results show that, in technical PVC formulations, the fraction of chloride ions trapped in the inorganic filler is a better parameter to measure the PVC degradation (measured by the yellowing index variation) than the total remaining (or lost) chlorine in the surface. When the ageing method includes water jets, the top superficial layers made from the inorganic filler and the organic products from the PVC degradation are removed and leave behind a much more homogeneous layer which is more resistant to ageing than the ‘‘as processed’’ one that contains defects introduced by the calendering process. XPS also makes clear that zinc–calcium additive is a better thermal stabilizer than dibutyltin-maleate, and the presence of tinuvin P retards the PVC degradation. The best simulation of the natural weathering of such PVC materials under laboratory conditions needs to consider, besides the light, the intervention of water jets and/or humidity as well as the existence of light and dark periods.

In the present work, four different PVC formulations, designed for outdoor applications, were submitted to artificialaccelerated ageing under xenon light, without and with spray of water, and to natural exposure. The influence of the combined action of water and radiation was evaluated by means of surface analysis using XPS, SEM and colourimetry, permitting comparison of the results obtained under different exposure conditions. Results show that a long preliminary period of irradiation ( 2000 h) before the exposure to water increases the resistance of PVC surfaces to weather conditions. The role of that initial irradiation period is to create an erodable layer made of shrunk ‘‘PVC’’ that had lost most of its chlorine atoms and, thence, creating a network of cracks. That layer loses easily adhesion to deeper layers due to erosive action of water spray. The more perfect uncovered surface is better at resisting the effect of radiation.

Results of an experimental research into the physical, chemical, mechanical, and aesthetical changes suffered by pultruded glass-fiber-reinforced polyester profiles during their testing for accelerated aging under the action of moisture, temperature, and ultra violet (UV) radiation are presented. The profiles were submitted to the influence of four different exposure environments: (i) in an immersion chamber, (ii) in a condensation chamber, (iii) in a QUV accelerated weathering apparatus, and (iv) in a xenon-arc accelerated weathering apparatus. The results obtained were analyzed regarding the changes in their weight, sorption ability, tensile and flexural strength characteristics, color, and gloss; the chemical changes were investigated by means of Fourier-transform infrared spectroscopy. Considerable chromatic changes were observed, especially owing to the UV radiation. Although some reduction in the mechanical properties was observed, particularly in the immersion and condensation chambers, the durability tests proved a generally good behavior of this material under the aggressive conditions considered.

Some artificial accelerated methods are currently used and accepted in the prediction of polymer lifetimes. However, in order to evaluate the durability of these materials, it is indispensable to reproduce the natural weathering phenomena as closely as possible. To attain this target, it is fundamental to understand the role of the atmospheric agents in the photo-degradation. The importance of radiation and temperature in the degradation of polymers is universally recognised. However, there is a trend to underestimate other environmental agents, such as humidity and rain, which play an important part in the evolution of degradation in certain compounded polymers. The objective of this paper is to show the fundamental role of water in the mechanism of degradation of TiO2 pigmented PVC formulations, and compare the results from different exposure methods, considering the influence of this degradation agent.

The state of the art in predicting weatherability lags far behind the need for such predictions. The exact prediction of the useful lifetime of a given polymer in a specific geographic location is still the dream of both specifiers and manufacturers. As a result, the estimation of durability of these materials remains one of the most challenging issues in weathering studies.

In the present work, a new technique was developed to determine the interfacial properties of two opaque glass fibre/polypropylene (GF/PP) systems via fragmentation tests on single filament model composites. Fragmentation tests usually require the fibre inside the composites to be completely aligned in the loading direction. Since PP matrices are non-transparent, it is not possible to guarantee a priori this condition. Hence, a novel technique was developed to determine the inclination of the filaments embedded in the composites. The fibre–polymer systems were also evaluated by comparing their interfacial properties with the overall mechanical properties determined on pultruded GF/PP composites. The present work shows that the knowledge of the interfacial properties is important, not only to compare alternative fibre/matrix systems, but also to assess whether the level of adhesion in these systems is adequate to fabricate composites with good mechanical properties.

The low cost and the good performance of poly(vinyl chloride) products make this polymer very suitable for applications in buildings, mainly in exterior applications, like window profiles, cladding structures and siding. However, the ultimate user acceptance of PVC products for outdoor building applications will depend on their ability to resist the deterioration of their mechanical and aesthetic properties over long periods of exposure. In order to assure the weatherability of these materials, the PVC resin needs to be compounded and processed properly, using suitable additives, leading to a complex material, whose behaviour and properties are quite different from the PVC resin by itself. The outdoor degradation of such products is complex and not completely understood for most of the technical formulations, so the study of the photodegradation of such products still remains a matter of interest. In the present work, we have used various analytical techniques to evaluate the variations of the physical,chemical and mechanical properties of extruded PVC samples, resulting from the degradation by light.

Na eficiente and cost-effective dry coating process was developed to deposit polymer powders on continuous fibers and produce thermoplastic matrix towpregs to be processed into composites. The technological solutions used in the coating line construction and the influence of the precessing parameters on manufactured glass fibre reinforced polypropylene (GF/PP) towpregs are detailed in this paper.Composites were produced from characterized GF/PP towpregs using hot plate compression moulding. The mechanical properties determined on the composites are compared with theoretical values predicted by the Classical Laminate Theory using the experimentally determined raw material contentes and tensile properties.

This communication presents preliminary results of a research project on the effects of different environmental agents on the physical, chemical, aesthetical and mechanical properties of glass fibre reinforced polymer pultruded (GFRP) profiles made of either polyester or vinylester resin. In order to study the potential degradation of the two types of profiles in typical environments of civil engineering applications, test specimens are being subjected to the following exposure conditions: (i) immersion in demineralised water, at 23 ºC, 40 ºC and 60 ºC; (ii) immersion in salt-water, at the same temperatures; (iii) continuous condensation at 40 ºC; (iv) salt fog chamber; (v) thermal cycles, from -5ºC to 40ºC; (vi) accelerated weathering fluorescent ultraviolet light apparatus. Additionally, test specimens were placed in the roof of LNEC thereby being subjected to a natural degradation in a controlled environment. At predefined time intervals, batches of test specimens placed in the above mentioned exposure environments are being removed for physic-chemical and mechanical characterization, in order to assess their behaviour. / Nesta comunicação são apresentados os resultados preliminares de um projecto de investigação em que estão a ser avaliados os efeitos da degradação ambiental nas características físico-químicas de perfis pultrudidos de plástico reforçado com fibra de vidro com dois tipos de matriz – uma de poliéster e outra de viniléster. Com o objectivo de estudar os eventuais efeitos de degradação nos dois tipos de perfis, quando expostos a condições típicas das aplicações em engenharia civil, foram efectuadas as seguintes exposições em provetes retirados dos perfis: (i) imersão em água desmineralizada, a 23 ºC, 40 ºC e 60 ºC; (ii) imersão numa solução salina, às mesmas temperaturas; (iii) condensação em contínuo a 40 ºC; (iv) câmara de nevoeiro salino; (v) ciclos térmicos, entre -5 ºC e 40 ºC; (vi) envelhecimento artificial acelerado com lâmpadas fluorescentes de radiação ultravioleta. Para além disso, foram expostos provetes no telhado do edifício principal do LNEC, onde ficaram sujeitos a envelhecimento natural. Em intervalos predefinidos, foram efectuados ensaios de caracterização físico-química e mecânica dos materiais, para monitorizar o seu desempenho ao longo do tempo.

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The main purpose of this paper is to present the results of a study intended to assess the durability of stabilized PVC-U for outdoor applications, in form of calendered films and extruded plates. The samples were subject to different ageing conditions and their degradation state were evaluated, using techniques of molecular analysis, namely Fourier transformed infrared spectroscopy (FTIR), as well techniques for evaluation of macroscopic properties, as colorimetry and tensiles tests. The development of formulations, the ageing and the subsequent characterisation were done in LNEC. Therefore, after a brief introduction, this paper presents the experimental part of the study, as regards the composition of samples and the experimental methods of deterioration and characterisation. Subsequently, the results of the study, their interpretation and the final conclusions are also presented.

The main purpose of this paper is to present the results of a study intended to assess the durability of stabilized PVC-U for outdoor applications, in form of calendered films and extruded plates. The samples were subject to different ageing conditions and their degradation state were evaluated, using techniques of molecular analysis, namely Fourier transformed infrared spectroscopy (FTIR), as well techniques for evaluation of macroscopic properties, as colorimetry and tensiles tests. The development of formulations, the ageing and the subsequent characterisation were done in LNEC. Therefore, after a brief introduction, this paper presents the experimental part of the study, as regards the composition of samples and the experimental methods of deterioration and characterisation. Subsequently, the results of the study, their interpretation and the final conclusions are also presented.

The outdoor degradation of poly(vinyl chloride) (PVC) products is complex and not completely understood for most of the technical formulations. Furthermore, it is known that the behaviour of such materials is dependent of the photo-oxidation conditions, namely source of radiation, temperature, presence of water and humidity. In the present work, we have used X-ray photoelectron spectroscopy (XPS) to evaluate the influence of different photo-oxidation conditions on the surface degradation of stabilized PVC, low thickness calendered samples (~ 150 ?m). The main objective is the study of the influence of the weathering conditions on the degradation level of stabilized PVC products for outdoor applications trying to go deeper in the understanding of the mechanism of both the degradation and the stabilization of the surface under different environmental conditions, different polymer formulations and different processing methods (extrusion or calendering). Comparisons are made with previous results obtained using colourimetry and infrared spectroscopy. The role of PVC formulation and of radiation source and water were studied using artificial weathering. Results were compared with degradation induced by natural weathering in Lisbon.

The main purpose of this paper is to present the results obtained, during the years 2001 and 2002, from a study developed in LNEC. The object of this study was to assess the synergetic effect of three of the most significant deteriorating climatic agents (radiation, temperature and water) on the evolution of the properties of hard PVC stabilised with titanium dioxide, for outdoor applications. For the purpose, several samples were subject to natural and artificial weathering. Moreover, their physical and mechanical properties were characterised by techniques of analysis and assessment of the surface aspect (colour and brightness), of assessment of the molecular properties by infrared microscopy (MICROFTIR), as well as of determination of the tensile mechanical properties and assessment of the Charpy impact resistance. The paper was both orally presented and by poster at the panel meeting “Ageing, Irradiation, Stabilisation” of the Congress MoDeSt 2002. Therefore, this publication includes the text of the paper, the poster, as well as the slides from the oral communication. The development of the formulations, the ageing and the subsequent characterisation by colorimetry, brightness, Charpy impact and tension, were done in LNEC. The characterisation by infrared microscopy was performed in the Laboratoire de Photochimie Moleculaire et Macromoleculaire of the University Blaise-Pascal, Clermont-Ferrand, France.

The main purpose of this paper is to present the results obtained, during the year 2003, from a study developed in LNEC. The object of this study was to assess the synergetic effect of two deteriorating climatic agents (radiation and water) on the evolution of the properties of extruded plates made of hard PVC stabilised with titanium dioxide, for outdoor applications. For the purpose, several samples were subject to natural and artificial weathering, their deterioration condition having been characterised by means of techniques of analysis of colorimetry and infrared spectroscopy (FTIR). Initially, only the presentation of a poster titled “Artificial and Natural Weathering of Polyvinyl chloride for Outdoor Applications: the Influence of the Radiation and Water on the Evolution of the PVC Properties” was scheduled. Nevertheless, upon request from the secretariat of the Congress, the author also presented an oral paper on the same subject, but including experimental results obtained during the year 2004, which were not mentioned in the poster. Similarly, these results, which were obtained by means of surface analysis techniques by Scanning Electron Microscopy (SEM) and by X photoelectron spectroscopy (XPS), were not included in the paper submitted to the Congress. Therefore, this publication includes the text of the paper referring to the poster, which was initially predicted, as well as the slides of the oral communication presented. It also contains a few results obtained in 2004. The development of the formulations, as well as the ageing and the subsequent characterisation by colorimetry, by infrared spectroscopy and by scanning electron microscopy were performed in LNEC. The characterisation by X photoelectron spectroscopy was conducted at the Molecular Chemistry-Physics Centre of the Instituto Superior Técnico (Higher Technical Institute).

The main purpose of this paper is to present the results of a study intended to assess the deterioration condition of extruded hard PVC plates, for outdoor applications. The plates were subject to different ageing conditions, using techniques of surface analysis, namely scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The development of formulations, the ageing and the subsequent characterisation by scanning electron microscopy were done in LNEC. The characterisation by X-ray photoelectron spectroscopy was done at the Centre for Molecular Chemistry-Physics of Instituto Superior Técnico (Higher Technical Institute of Lisbon). Therefore, after a brief introduction, this paper presents the experimental part of the study, as regards the composition of samples and the experimental methods of deterioration and characterisation. Subsequently, the results of the study, their interpretation and the final conclusions are also presented.

Procurou-se com a presente comunicação, apresentar uma metodologia de validação de um programa informático, desenvolvido no NMPC do LNEC especificamente para a calibração de um calorimetro diferencial de varrimento (DSC) e para calcular a incerteza associada à determinação da entalpia de fusão. Assim, após uma breve introdução, a presente comunicação expõe a formulação essencial que serviu de suporte ao desenvolvimento do programa informático referido, descreve os elementos que constituem o procedimento de validação do mesmo, apresenta o processo de estimativa da incerteza de medição e os resultados da análise efectuada.

No presente relatório apresentam-se os dados meteorológicos do ano de 2019 recolhidos na estaçãometeorológica existente no Núcleo de Materiais Orgânicos do Departamento de Materiais do LNEC, em Lisboa

No presente relatório apresentam-se os dados meteorológicos do ano de 2020 recolhidos na estaçãometeorológica existente no Núcleo de Materiais Orgânicos do Departamento de Materiais do LNEC, em Lisboa

No presente relatório descrevem-se os procedimentos adotados pelo LNEC, no âmbito do estudo a efetuar para a concessão de um Documento de Aplicação (DA), relativo a revestimentos por pintura elastoméricos para rebocos de cimento e para betão aplicados em paredes exteriores de edifícios. Consideram-se as condições de exposição atmosférica no exterior sem a influência de ações químicas severas. Indicam-se, também, as ações a desenvolver periodicamente para comprovar que continuam reunidas as condições que terão permitido a concessão do DA.

No presente relatório descrevem-se os procedimentos adotados pelo LNEC para a concessão de um Documento de Aplicação (DA) relativo a revestimentos por pintura de base aquosa para aplicação em paredes e tetos de interiores de habitações, sobre superfícies de estuque de gesso, de gesso cartonado, de reboco de cimento ou de betão. Indicam-se, também, as ações a desenvolver periodicamente para comprovar que continuam reunidas as condições que permitiram a concessão do DA.

No presente relatório apresentam-se os dados meteorológicos do ano de 2016 recolhidos na estação meteorológica existente no Núcleo de Materiais Orgânicos do Departamento de Materiais do LNEC, em Lisboa

No presente relatório descrevem-se os procedimentos adotados pelo LNEC no âmbito do estudo a efetuar para a concessão de um Documento de Aplicação (DA) relativo a revestimentos por pintura para rebocos de cimento e de betão aplicados em superfícies exteriores (tintas não elastoméricas). Consideram-se as condições de exposição atmosférica no exterior, sem influência de ações químicas severas. Indicam-se, também, as ações a desenvolver periodicamente para comprovar que continuam reunidas as condições que terão permitido a concessão do DA. Este relatório constitui uma revisão do relatório do LNEC nº 252/2013-DM/NMO.

No presente relatório apresentam-se os dados meteorológicos do ano de 2014 recolhidos na estação meteorológica existente no Núcleo de Materiais Orgânicos dom Departamento de Materiais do LNEC, em Lisboa

No presente relatório apresentam-se os dados meteorológicos do ano de 2013, recolhidos na estação meteorológica existente no Núcleo de Materiais Orgânicos do Departamento de Materiais do LNEC, em Lisboa.

No presente relatório descrevem-se os procedimentos adoptados pelo LNEC no âmbito dos estudos para concessão de um Documento de Aplicação (DA) a produtos de pintura para proteção de superfícies madeira, em condições de exposição atmosférica no exterior. Indicam-se também as ações a desenvolver periodicamente para comprovar que continuam reunidas as condições para a concessão do DA.

Nesta publicação apresenta-se o critério presentemente seguido pelo LNEC para concessão de homologação com certificação, bem como posterior controlo periódico da qualidade a sistemas de tubagem de poli(cloreto de vinilo) não plastificado (PVC-U) destinados à extração de água em profundidade. Após uma breve introdução e a definição do objetivo, indicam-se: - Os requisitos para o sistema da qualidade seguido pelo fabricante; - as caraterísticas e as especificações para a matéria-prima constituinte dos tubos e acessórios; - as caraterísticas e as especificações para os produtos finais, designadamente os tubos e as suas uniões; - a classificação das condições de serviço; - as recomendações para a utilização dos produtos, relativamente ao seu transporte e manuseamento, armazenagem e instalação; - os requisitos do LNEC para o autocontrolo do fabricante; - os requisitos de amostragem do LNEC durante as auditorias técnicas ou campanhas de recolha realizadas ao fabricante pelos técnicos do LNEC, no âmbito da concessão e manutenção da homologação.

Os resultados experimentais, obtidos através da medição de propriedades dos materiais e produtos, requerem tratamento específico e adequado, de forma a garantir a sua qualidade. É por isso muitas vezes necessário recorrer a métodos estatísticos para fazer a análise do tipo de distribuição dos resultados, proceder à deteção de valores suspeitos num conjunto de observações e à eventual rejeição de resultados anómalos. Este tipo de tratamento estatístico é principalmente adequado a ensaios de intercomparação, quer do foro metrológico (comparação de valores de padrões ou materiais de referência, mediante medição efetuada por operadores de diferentes laboratórios metrológicos, com incerteza variável), quer do âmbito dos laboratórios de ensaio. Os ensaios de Comparação Interlaboratorial realizados por laboratórios de ensaio, constituem uma ferramenta de garantia da Qualidade e são utilizados para a validação de métodos de ensaio (incerteza e robustez) e como um meio para a determinação das características de desempenho dos laboratórios, nomeadamente da reprodutibilidade e da repetibilidade. Nesta publicação faz-se uma descrição dos vários parâmetros que devem ser determinados em ensaios interlaboratoriais do tipo “Intercomparações com valor de consenso” e respetivos métodos de cálculo. A estatística aqui apresentada pode, numa boa parte dos casos, ser também aplicada à análise de resultados de medições experimentais correntes.

The main purpose of this Paper is to present a state of the art about weathering and polymer degradation. This review was presented during a training course promoted by the 5th European Weathering Symposium EWS (XXVIIth Colloquium of Danubian Countries on Natural and Artificial Ageing of Polymers), which was held in Lisbon on September 21 - 23, 2011, organised on behalf of CEEES (Confederation of European Environmental Engineering Societies) by the German Management Society for Environmental Engineering GUS (Gesellschaft für Umweltsimulation e.V.) and supported by SOPSAR (Sociedade Portuguesa de Simulação Ambiental e de Avaliação de Riscos), APIP (Associação Portuguesa da Indústria de Plásticos) and LNEC (Laboratório Nacional de Engenharia Civil). The main topics of this review are the weathering of polymers and composites, the determination, simulation and effects of relevant climatic quantities, innovative polymer additives, new test procedures and devices, instrumental methods of analysis to evaluate polymer degradation, recent developments in polymeric materials and composites designed for outdoor applications and methods for service-life prediction.

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