Controlled biodegradability of functionalized thermoplastic starch based materials

The present work focuses on the preparation and characterization of biodegradable materials based on plasticized and chemically modified starch. During the experiments, the morphology, properties and biodegradability of the starch materials were influenced by the functionalization (acetylation, propionation) of the starch, different processing procedures and the use of plasticizers. The starch materials were prepared by either solution casting or melt mixing or by the combination of the two procedures, which strongly affected the degree of the material plasticization, its homogeneity, and the final morphology. FTIR spectroscopy qualitatively proved the esterification of starch by the intensity of signals associated with esters groups. The thermogravimetric analysis confirmed a gradual reduction in the water content proportional to the acetylation of starches, as well as noticeable changes in their thermal properties at the higher degree of substitution (DS). Signal intensities and weight losses derived from FTIR and TGA, respectively, were well correlated with DS. The morphological changes of the polysaccharide materials were visualized by microscopy techniques. The biodegradation rate of prepared materials was expressed as the percentage of carbon mineralization and was significantly retarded as a function of the starch acetylation. A remarkable effect of the material processing, the presence of plasticizers, and the propionation of the starch on biodegradation has been found. © 2019 Elsevier LtdTechnology Agency of the Czech Republic [TE01020118]; Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Program I [LO1507]; UTB internal grant [IGA/FT/2017/003

Influence of ionic liquid-modified LDH on microwave-assisted polymerization of ε-caprolactone

International audienceThe study reported herein describes multifunctional effect of layered double hydroxide (LDH) modified with phosphonium-based ionic liquids (IL) containing phosphinate, carboxylate and phosphate anions on progress of ring-opening polymerization of ε-caprolactone under microwave irradiation. The extent of IL-modification had a crucial effect on the exfoliation of LDH. The non-modified LDH was able to catalyse the ring-opening polymerization of ε-caprolactone with polymer yield 89% but provided only micro-composite material. On the contrary, LDH with intercalated IL-anions promoted exfoliation of LDH after only 3 min of microwave irradiation. The developed process is fast, environmentally-friendly (solvent-free) and adaptable to various polymer matrices, since a broad variety of IL-anions might be applied

Ionic Liquids as Delaminating Agents of Layered Double Hydroxide during In-Situ Synthesis of Poly (Butylene Adipate-<i>co</i>-Terephthalate) Nanocomposites

Currently, highly demanded biodegradable or bio-sourced plastics exhibit inherent drawbacks due to their limited processability and end-use properties (barrier, mechanical, etc.). To overcome all of these shortcomings, the incorporation of lamellar inorganic particles, such as layered double hydroxides (LDH) seems to be appropriate. However, LDH delamination and homogenous dispersion in a polymer matrix without use of harmful solvents, remains a challenging issue, which explains why LDH-based polymer nanocomposites have not been scaled-up yet. In this work, LDH with intercalated ionic liquid (IL) anions were synthesized by a direct co-precipitation method in the presence of phosphonium IL and subsequently used as functional nanofillers for in-situ preparation of poly (butylene adipate-co-terephthalate) (PBAT) nanocomposites. The intercalated IL-anions promoted LDH swelling in monomers and LDH delamination during the course of in-situ polycondensation, which led to the production of PBAT/LDH nanocomposites with intercalated and exfoliated morphology containing well-dispersed LDH nanoplatelets. The prepared nanocomposite films showed improved water vapor permeability and mechanical properties and slightly increased crystallization degree and therefore can be considered excellent candidates for food packaging applications

Hydrothermal stability of geopolymers prepared in 4SiO(2).Al2O3.Na2O.18H(2)O system

The present paper deals with the structural stability of inorganic amorphous aluminosilicate geopolymer during long-term period. The geopolymer systems have been prepared by mixing calcinated kaolines and sodium activators. Structural behavior, during ambient ageing and thermal treatment (at 100 degrees C for 1 - 4 weeks) have been monitored by XRD, solid state NMR spectroscopy, and measurement of compression strength. Growth of crystalline zeolite phases were observed after thermal treatment. These structural changes are accompanied with fluctuations of geopolymer bodies compressive strengths.Czech Ministry of Education, Youth and Sports [6046137302]; Grant Agency of Czech Republic [210/10/0938