High-energy impact testing of agglomerated cork at extremely low and high temperatures

Agglomerated cork, made from the scraps of wine stoppers, has been finding a wide set of applications due to its excellent thermal and acoustic insulation properties. The random orientation of grains makes the material nearly isotropic, while its dominant viscoelastic behaviour and nearly zero Poisson's ratio make the material also very interesting in applications where dimensional stability is highly demanded. With proven properties, agglomerated cork has been widely used for manufacturing of architectural facades, in civil construction, aerospace engineering and even home appliances production. For outdoor applications, the performance of cork material under different working temperatures is a vital point to be considered. This paper assesses the capability of five different types of cork agglomerates to withstand 500 J impact energy under different temperature conditions. Keeping 11.2 kg impact mass and velocity of 9.2 m/s, impact tests were performed for a wide range of temperatures starting from sub-zero temperature (−30°C) up to 100°C in order to cover a full span of working circumstances. Results show significant variations of amount of absorbed energy depending on testing temperature, calling the attention of designers and product developers for important aspects to be considered upon the application of this material under extreme weather conditions.publishe

Biodiversity and ecosystem services in the Campo Rupestre: a road map for the sustainability of the hottest Brazilian biodiversity hotspot

Global sustainability rests on a myriad of benefits provided by natural ecosystems that support human livelihoods and well-being, from biodiversity persistence to climate regulation. The undeniable importance of conserving tropical forests has drawn most of the conservation spotlight towards it. However, open ecosystems such as the Brazilian Campo Rupestre (rupestrian grassland), have been historically overlooked despite their high diversity and key associated ecosystem services. We highlight major current threats to the persistence of the Campo Rupestre emphasizing its ecological, social, cultural, geo-environmental, and economic importance. We call attention to the importance of the Campo Rupestre as a reservoir of biodiversity and ecosystem services and offer priority actions that resulted from discussions involving scientists, industry representatives, environmental managers, and other members of civil society. Proposed actions include efforts related to ecological restoration, sustainable ecotourism, protection of traditional ecological knowledge, identification of emerging research questions, and development of tailored public policies. Such issues are integrated into a framework that collectively represents a road map to safeguard the Campo Rupestre from further degradation and steer its historical overexploitation towards sustainable management. Safeguarding the future of non-forest biomes like this poses a challenge to current paradigms of nature conservation. By establishing priorities and guidelines, we propose an actionable plan, which we hope can support informed decision-making policy towards a sustainable use of the Campo Rupestre.Long Term Ecological Research PELD-CRSC-17Conselho Nacional de Pesquisas CNPq/MCTIFundação de Amparo à Pesquisa do Estado de São Paulo 2013/50155-0, 2010/51307-0, 2019/07773-

Static and dynamic mechanical response of different cork agglomerates

Cork is a natural cellular material capable of withstanding considerable amounts of energy and exhibiting a viscoelastic return to its original shape. This feature is particularly interesting to resist to successive impacts. In this study, the behavior of different types of agglomerated cork (AC) and expanded cork (EC) is investigated under static and dynamic loadings. Double impact was carried out on the samples using a hemispheric actuator. The peak acceleration data for all compounds were further analyzed. Static compression tests gave an interesting insight into the stress–strain curve of agglomerates and Poisson’s ratio variation during deformation. Results demonstrate a clear influence of agglomerated density and grain size on the resulting mechanical properties and point out a tremendous potential for this sustainable material to be tailored to fit diverse crashworthiness applications

Comparing the mechanical performance of synthetic and natural cellular materials

his work compares the mechanical performance of agglomerated cork against synthetic materials typ- ically used as impact energy absorbers. Particularly, the study will focus on the expanded polystyrene (EPS) and expanded polypropylene (EPP). Firstly, quasi-static compression tests are performed in order to assess the energy storage capacity and to characterize the stress–strain behavior cellular materials under study. Secondly, guided drop tests are performed to study the response of these materials when subjected to multiple dynamic loading (two impacts). Thirdly, finite element analysis (FEA) is carried out in order to simulate the compressive behav- ior of the studied materials under dynamic loading. Results show that agglomerated cork is an excellent alternative to the synthetic materials. Not only for being a natural and sustainable material but also for withstanding considerable impact energies. In addi- tion, its capacity to keep some of its initial properties after loading (regarding mechanical properties and dimensions) makes this material highly desirable for multiple-impact applications