Search results for "renewable resource"
showing 10 items of 50 documents
Thermal and structural properties of a hemp–lime biocomposite
2013
Abstract The need to reduce greenhouse gases emission produced by the building sector leads to the research of renewable and less impacting materials that can replace traditional ones. This subject has encouraged new researches on biocomposite concretes with the aim to exploit renewable resources like vegetal fibres intended as materials whose production processes are generally characterized by low costs and energy demand. This biocomposite is obviously much lighter than concrete and, therefore, can be suitably used in such cases where a structure cannot be overloaded, for instance in the realization of a green covering on top of a preexistent building. In this work, a first analysis of the…
Modern Electrochemical Aspects for the Synthesis of Value‐Added Organic Products
2017
The use of electricity instead of stoichiometric amounts of oxidizers or reducing agents in synthesis is very appealing for economic and ecological reasons, and represents a major driving force for research efforts in this area. To use electron transfer at the electrode for a successful transformation in organic synthesis, the intermediate radical (cation/anion) has to be stabilized. Its combination with other approaches in organic chemistry or concepts of contemporary synthesis allows the establishment of powerful synthetic methods. The aim in the 21st Century will be to use as little fossil carbon as possible and, for this reason, the use of renewable sources is becoming increasingly impo…
A Simple Analytical Model for Remote Assessment of the Dynamics of Biomass Accumulation
2011
Efficient means for assessment of the dynamics and the state of the stocks of renewable assets such as wood biomass are important for sustainable supplies satisfying current needs. So far attention has been paid mainly to the economic aspects of forest management while ecological problems are rising with the expected transfer from fossil to renewable resources supplies of which from forest being essential for traditional consumers of wood and for emerging biorefineries. Production of biomass is more reliant on assets other than money the land (territory) available and suitable for the purpose being the first in the number. Studies of the ecological impacts (the “footprint”) of sustainable u…
Undecylenic acid: A tunable bio-based synthon for materials applications
2016
International audience; An undecylenic acid-based monoglyceride prepared from glycidol and undecylenic acid is used as suitable and tunable synthon for polymerization applications. Epoxidation and acrylation reactions lead to photopolymerizable monomers while transesterification with dimethyl carbonate, metathesis and aminolysis reactions provide access to polyhydroxyurethane-based materials. The successive intermediates were synthesized according to a green chemistry approach implicating solvent-less and catalyzed reactions, and were at each step fully characterized by infrared, 1H and 13C{1H} NMR spectroscopy, elemental analysis and mass spectrometry. Analyses of the resulting polymer mat…
Partially Renewable Resources
2014
In recent years, in the field of project scheduling the concept of partially renewable resources has been introduced. Theoretically, it is a generalization of both renewable and non-renewable resources. From an applied point of view, partially renewable resources allow us to model a large variety of situations that do not fit into classical models, but can be found in real problems in timetabling and labor scheduling. In this chapter we define this type of resource, describe an integer linear formulation and present some examples of conditions appearing in real problems which can be modeled using partially renewable resources. Then we introduce some preprocessing procedures to identify infe…
Highly selective generation of vanillin by anodic degradation of lignin: a combined approach of electrochemistry and product isolation by adsorption
2015
The oxidative degradation of lignin into a variety of valuable products has been under investigation since the first half of the last century. Especially, the chance to claim this cheap, abundant and renewable source for the production of the important aroma chemical vanillin (1) was one of the major driving forces of lignin research. So far most of the developed methods fail in technical application since no viable concept for work-up is included. This work represents a combined approach of electrochemical conversion of Kraft lignin and product recovery by adsorption on a strongly basic anion exchange resin. Electrolysis conditions are optimized regarding reaction temperatures below 100 °C…
Mitigating forest biodiversity and ecosystem service losses in the era of bio-based economy
2018
Abstract Forests play a crucial role in the transition towards a bioeconomy by providing biomass to substitute for fossil-based materials and energy. However, a policy-policy conflict exists between the desire to increase the utilization of bio based renewable resources and the desire to protect and conserve biodiversity. Increasing forest harvest levels to meet the needs of the bioeconomy may conflict with biodiversity protection and ecosystem services provided by forests. Through an optimization framework, we examined trade-offs between increasing the extraction of timber resources, and the impacts on biodiversity and non-wood ecosystem services, and investigated possibilities to reconcil…
Facile and efficient chemical functionalization of aliphatic polyesters by cross metathesis
2016
International audience; An effective preparation of new tailor-made macromolecular materials via a combination of two (atom-efficient) catalytic transformations is reported. First, new aliphatic polyesters with alternated composition have been prepared using a salen aluminum catalyst system. Next, the pendant vinyl moieties in those copolymers have been selectively transformed into various functional groups by metathesis in the presence of homogeneous Grubbs catalysts. The latter metathesis reaction has been optimized in terms of catalytic activity and selectivity, to define the conditions for an effective and safe procedure that does not affect the macromolecular architecture. All polymer …
Multicatalytic Transformation of (Meth)acrylic Acids: a One-Pot Approach to Biobased Poly(meth)acrylates
2021
International audience; Shifting from petrochemical feedstocks to renewable resources can address some of the environmental issues associated with petrochemical extraction and make plastics production sustainable. Therefore, there is a growing interest in selective methods for transforming abundant renewable feedstocks into monomers suitable for polymer production. Reported herein are one-pot catalytic systems, that are active,<br>productive, and selective under mild conditions for the synthesis of copolymers from renewable materials. Each system allows for anhydride formation, alcohol acylation and/or acid esterification, as well as polymerization of the formed (meth)- acrylates, providi…
Un procedimiento de fuerte reducción de las dimensiones del RCPS/π
2009
Recently, in the field of project scheduling problems the concept of partially renewable resources has been introduced. Theoretically, it is a generalization of both renewable and non-renewable resources. From an applied point of view, partially renewable resources allow us to model a large variety of situations that do not fit into classical models, but can be found in real problems in timetabling and labour scheduling. When modelling real problems, the problem of project scheduling with partially renewable resources, as many other combinatorial problems, gets such large dimensions that it is quite difficult to apply solution procedures. In this paper, we describe some powerful preprocessi…