1,721,118 research outputs found
Green synthesis of flexible polyurethane foams from liquefied lignin
No full textThe present paper reports the innovative, sustainable, and green synthesis of soft foams from Kraft lignin. This research activity was performed in the EC project FORBIOPLAST grant agreement No. 212239 focused on the use and valorisation of forest resources which include lignin as by-products of wood industries and of bioethanol production. In order to produce flexible foams two types of chain extender were used in combination with liquefied lignin: polypropilenglycol triol and castor oil. The samples were produced with the "one shot" technique and the only blowing agent used was water. All samples were produced with a ratio NCO/OH less than one, because it is well known that it significantly reduces the degree of crosslink, resulting in higher flexibility of the material. Samples were produced in free and controlled rise expansion. The properties of these foams can be modulated by industrial producer, by the individuation of the most efficient chain extenders, thus introducing flexible chains in the macromolecular structure that can reduce the glass transition temperature of the materials and generate foams with higher flexibility. The quality of the foams are compatible with application in packaging, such as packaging of furniture, and for the interior part of car seats
Flammability of fiber-based composites
No full textIn recent years, the development of composites for enhancement of flame retardant properties has occurred. Studies on this have largely been focused on utilization of jute fabric as structure reinforcement along with biopolymer, such as polylactic acid, as a matrix. These composite matrices are most commonly fabricated using a solution casting technique. The presence of biopolymer within the composite structure plays a decisive role in optimization of the overall performance of bio-nanocomposites. Keeping the focus on biopolymer as a key component, this chapter reveals the current state and future prospective of bio-based nanocomposite structures, along with field applications and unsolved problems
New eco-composites based on polyhydroxyalkanoates (PHA) for marine applications
Full text linkBio-based polymers have attracted increasing attention over the last two decades, predominantly due to their environmental friendly nature and no dependence on petroleum resources. This type of polymers has got a growing consideration which has been so far focused specifically on starch based products, PLA (Polylactic acid), PHA (Polyhydroxylalkanoates) in particular PHB (Polyhydroxyl butyrate), cellulose derived plastics, etc. The production of these materials is based on renewable agricultural and biomass feedstocks. The degradability of bio-based materials not just in compost but also in different natural environments is an important property for sustainability and reduction of plastic pollution. In this work, blends of PHA and PHB with Posidonia Oceanica fibres were investigated to assess the feasibility of producing materials biodegradable in marine environment, varying the fiber percentage from 10 to 30 wt%. The chemical composition of the Posidonia O. fiber is similar to that of other lignocellulosic materials. It consists mainly of cellulose, hemicellulose, and lignin. Thermal, rheological, mechanical and morphological characterization of the developed PHA/PHB-fibre blends has been conducted in order to investigate the effect of the fibres on their processability and tensile properties.
Biodegradability of the produced composites has been investigated in sea water in view of their use in marine environment
Engineered Matrices Based on Gellan Gum and Biocompatible Synthetic Polymers for the Release of Molecules with Antioxidant Activity
Full text linkOver the past few decades, microbial polysaccharides hydrogels have been used in the field of tissue regeneration due to their ability to mimic the physical-chemical and mechanical characteristics of the extracellular matrix. Gellan gum, an anionic heteropolysaccharide that can form hydrogel in presence of di or trivalent cations, has interesting properties in terms of biodegradability, biocompatibility and the ability to integrate with surrounding tissues. However, it also has some limitations such as the lack of specific sites within the polysaccharide chains for cell recognition and adhesion, high hygroscopicity and limited mechanical properties. Gellan gum has also been proposed for application in the field of controlled release of bioactive molecules; the bio-inert nature of gellan gum makes it suitable for the encapsulation of biomolecules, drugs, enzymes and nutraceutical formulations. Furthermore, the anionic nature of this polysaccharide makes it suitable as a pH sensitive drug delivery system. This work deals with the production and characterization of hydrogels based on gellan gum and polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) for the creation of matrices, containing curcumin as an antioxidant agent, having a micro-engineered surface obtained using micro-molded silicone molds. The properties of gellan hydrogels mixed with PVA or PVP containing curcumin, before and after crosslinking with Ca2+ ions, were investigated. The highest curcumin solubility was observed in PVP solution (0.0156 mg/mL) as compared to PVA solution (0.0074 mg/mL). The contribution of gellan hydrogels mixed with PVA or PVP to the antioxidant capacity of curcumin, expressed as % inhibition, was 22% and 25%, respectively
Structural and spectroscopic features of naphthol green B integrated for improved light harvesting capability of organic/inorganic hybrid solar cells
No full textRegarding the intensified interest in photovoltaic devices for a wide range of applications, here, we exploited a promising naphthol green organic dye for designing efficient organic/inorganic heterojunction for solar cell applications. The crystal and molecular structures of the spin-coated NGB thin films were inspected using XRD and FTIR techniques, respectively. A nanostructured polycrystalline film was obtained with a crystallite size of ∼76.2 nm with a stable molecular configuration. The optical properties of the films were analyzed using spectrophotometrically measured transmission and reflection. The prepared films showed high absorption over the UV–Vis–NIR regimes with a relatively small energy gap of ∼1.42 eV and a low refractive index of ∼1.48 which increased its suitability for photosensing applicability. The photovoltaic performance of the fabricated Ag/NGB/p-Si/Al heterojunction was evaluated in detail yielding promising photovoltaic characteristics with Voc ∼0.77 V, Jsc ∼18.64 mA/cm2, and PCE ∼6.49 %
Thermoplastic Blends Based on Poly(Butylene Succinate-co-Adipate) and Different Collagen Hydrolysates from Tanning Industry—II: Aerobic Biodegradation in Composting Medium
No full textTwo diferent raw hydrolyzed collagens (HCs), by-products of the Tannery industry, were investigated in blends with a
bioplastic, as poly(butylene succinate-co-adipate) (PBSA), for the production of thermoplastic items for possible applications in agriculture. Chemical characterization of selected PBSA/HC blends and phytotoxicity assays on garden cress seeds
(Lepidium sativum L.), used as spy species, were carried out; in addition, biodegradation and disintegration of specimens
were assessed under controlled composting conditions at diferent temperature (58 and 25 °C). Although one of the HC
investigated released sodium chloride in the aqueous extract, all PBSA/HC blends, up to 20 wt.% HC, resulted no-phytotoxic
and showed considerable amounts of macro- and micro- nutrients for plants (mainly nitrogen). Regardless the amount added,
HCs enhanced the biodegradation rate of PBSA/HC blends in compost at 58 °C compared to pure PBSA; lowering the
temperature at 25 °C, as expected, biodegradation rate slightly lowered using the same compost. Most disintegration tests,
performed on dog bone samples, corroborated the results of the biodegradation tests, thus suggesting that plastic mixtures
could reasonably end their life cycle in a composting facility without decreasing the quality and the safety of the resulting
compost. The outcomes achieved encourage the use of raw collagen hydrolysates from tanning industry in the production of
PBSA-based thermoplastic blends to produce compostable items (mulching flms and/or plant pots) for more sustainable uses
in agriculture and/or plant nurseries. In addition, the use of these low-cost by-products can lower the cost of fnal product
and give it fertilizing properties for plants given the presence of organic nitrogen in the hydrolysates
- …
