Carmen-Alice Teacă

Effect of cellulose reinforcement on the properties of organic acid modified starch microparticles/plasticized starch bio-composite films

The present paper describes the preparation and characterization of polysaccharides-based bio-composite films obtained by the incorporation of 10, 20 and 30 wt% birch cellulose (BC) within a glycerol plasticized matrix constituted by the corn starch (S) and chemical modified starch microparticles (MS). The obtained materials (coded as MS/S, respectively MS/S/BC) were further characterized. FTIR spectroscopy and X-ray diffraction were used to evidence structural and crystallinity changes in starch based films. Morphological, thermal, mechanical, and water resistance properties were also investigated. Addition of cellulose alongside modified starch microparticles determined a slightly improvement of the starch-based films water resistance. Some reduction of water uptake for any given time was observed mainly for samples containing 30% BC. Some compatibility occurred between MS and BC fillers, as evidenced by mechanical properties. Tensile strength increased from 5.9 to 15.1 MPa when BC content varied from 0 to 30%, while elongation at break decreased significantly.

Antioxidant and chemical properties of Inula helenium root extracts

AbstractThe objective of the paper was to investigate the chemical composition of Inula helenium roots extracts and to evaluate the antioxidant potential conferred by the chemical constituents. GC/MS and HPLC/MS techniques were used to characterize two extracts separated from Inula helenium roots by extraction with chloroform and ethyl acetate, respectively. Volatile compounds have been identified by GC from their mass spectra and retention time values, while HPLC identification of phenolic compounds was realized by comparing their retention times, UV and MS spectra with those of standards or literature data. Measurements of antioxidant activity of Inula helenium root extracts showed a variation between them, which can be correlated with the flavonoid and total phenolic contents. Both Inula helenium root extracts contain phenolic acids (caffeic, chlorogenic, dicaffeoyl quinic, hydroxibenzoic), terpenes (alantolactone) and different flavonoids (epicatechin, catechin gallate, ferulic acid-4-O-glucoside, dihydroquercetin pentosyl rutinoside, kaempherol-7-O-dipentoside, quercetin-3-O-β-glucopyranoside). In addition, the study provides preliminary data on the anti-inflammatory activity of Inula helenium root extracts, this being evaluated using the fresh egg albumin as phlogistic agent, and aspirin as reference compound. Root extracts of I. helenium did not exert any significant anti-inflammatory effect on egg albumin-induced rat paw edema.

Polypropylene-based composites reinforced by toluene diisocyanate modified wood

Composites made of polypropylene, a mixture of polypropylene and poly(lactic acid) and spruce wood fibres both non-modified and modified with toluene 2,4-diisocyanate – were prepared by melt blending. The chemical modifications of wood fibres with toluene 2,4-diisocyanate were evidenced by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Wood fibre reinforced polypropylene/poly(lactic acid) composites prepared with addition of maleic anhydride polypropylene as coupling agent were further investigated for structural and morphology properties before and under controlled accelerated weathering conditions by attenuated total reflectance Fourier transform infrared spectroscopy, mechanical testing and scanning electron microscopy analysis. Some specific indexes (carbonyl and vinyl) were also calculated.

Physico-chemical properties investigation of softwood surface after treatment with organic anhydride

AbstractWood originating from a softwood species was subjected to chemical treatment by reaction with succinic anhydride in N, N-dimethylformamide at different concentration values. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis were used to study changes that occurred on a softwood surface. The extent of chemical treatment on softwood was evaluated by determining the weight percent gain values. Thermal properties of modified softwood and the water absorption were also evaluated. The chemical treatment with succinic anhydride influenced the thermal stability of the softwood samples with increasing anhydride concentration levels.

Photochemical Behavior of Wood Based Materials

Wood, as a natural composite material used mainly in exterior construction and building applications, requires long-term durability under exposure to environmental factors including solar UV radiation, temperature, humidity and pollutants. The outdoor service life of wood and wood based materials, namely wood–thermoplastic polymer composites, is strongly related to their deterioration under weathering conditions. Wood is extremely sensitive to UV radiation in the range from 300 to 400 nm. Photo-chemical degradation of wood causes significant structural and color changes, lignin component being the most susceptible to de-polymerization reactions by which phenoxy radicals are generated as intermediates and further oxidized into colored chromophores (quinones). Effective treatments, e.g. UV photo-stabilizers, or surface coatings of wood products, e.g. paints, varnishes, stains or water repellents, may provide significant wood protection against weathering in long-term outdoor applications.

Multicomponent Polymer Composite/Nanocomposite Systems Using Polymer Matrices from Sustainable Renewable Sources

Green composites are increasingly promoted for sustainable development considering the growing awareness of environmental and waste management issues. Recent advances in natural fiber development, and nanocomposites research area generate significant opportunities for obtaining materials from renewable resources with improved properties and suitable for different applications. Green composites are made from both renewable resource-based polymers (biopolymers) and bio-fillers (including nano-type fillers), with a positive environmental impact. Green composites based on biopolymer matrix (plasticized starch) have been obtained by combination with various bio-fillers (beech wood sawdust, fir tree needles, beech wood lignin). Their structure and properties were further investigated through Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), and TG/DTG/DTA simultaneous thermal analysis methods, as well as by water uptake and opacity measurements. The results are presented in this chapter.

Epoxidized Vegetable Oils for Thermosetting Resins and Their Potential Applications

In the recent decades, bio-based polymers have gained increasing interest, especially for composite materials. These polymers and their respective monomers are derived from renewable resources, being thermoplastics or thermosetting resins which are biodegradable or non-biodegradable. Thermosettings are strong, rigid polymer materials and cannot be easily processed by melting after their hardening. At present, thermosetting resins are obtained using highly toxic and volatile petrochemicals, which require human and environmental safety monitoring. Considering the wide range of diverse renewable monomers available, vegetable oils (VOs) are especially well-suited when it comes to the synthesis of thermosetting resins due to their carbon-carbon double bonds, highly desirable for this type of application as these unsaturated bonds can be chemically modified in order to increase reactivity toward further polymerization. Thus, epoxidation, which consists of introducing a single oxygen atom to each non-saturated bond to yield in an epoxidic cycle, is a simple, effective method to modify these VOs. The resulted thermosetting resins exhibit improved toughness and environmental-friendly behavior. VOs, especially soybean oil which is abundant and cheap, are typically mixtures of unsaturated fatty acids with numerous bonds that can be easily converted into the more reactive oxirane rings through the reaction with peracids or peroxides. The present chapter focuses on composites obtained from epoxidized vegetable oils (EVOs) and epoxy resins and their properties in correlation with their envisaged applications.