2026-04-13T02:55:26Zhttps://recercat.cat/oai/request
oai:recercat.cat:2117/229932026-02-05T02:22:16Zcom_2072_1033col_2072_452950
RECERCAT author Planellas Oates, Marc author Sacristan, Matias author Rey, Lorena author Olmo Osuna, Cristian author Aymami Bofarull, Juan author Casas Becerra, María Teresa author Valle Mendoza, Luis Javier del author Franco García, María Lourdes author Puiggalí Bellalta, Jordi 2014-07 Ultrasound technology was proved as an efficient processing technique to obtain micro-molded specimens of polylactide (PLA) and polybutylene succinate (PBS), which were selected as examples of biodegradable polyesters widely employed in commodity and specialty applications. Operational parameters such as amplitude, molding force and processing time were successfully optimized to prepare samples with a decrease in the number average molecular weight lower than 6%. Ultrasonic waves also seemed an ideal energy source to provide effective disaggregation of clay silicate layers, and therefore exfoliated nanocomposites. X-ray diffraction patterns of nanocomposites prepared by direct micro-molding of PLA or PBS powder mixtures with natural montmorillonite or different organo-modified clays showed the disappearance of the 0 0 1 silicate reflection for specimens having up to 6 wt.% clay content. All electron micrographs revealed relatively homogeneous dispersion and sheet nanostructures oriented in the direction of the melt flow. Incorporation of clay particles during processing had practically no influence on PLA characteristics but enhanced PBS degradation when an organo-modifier was employed. This was in agreement with thermal stability data deduced from thermogravimetric analysis. Cold crystallization experiments directly performed on micro-molded PLA specimens pointed to a complex influence of clay particles reflected by the increase or decrease of the overall non-isothermal crystallization rate when compared to the neat polymer. In all cases, the addition of clay led to a clear decrease in the Avrami exponent.Peer ReviewedPostprint (published version) http://creativecommons.org/licenses/by-nc-nd/3.0/es/ Restricted access - publisher's policy Attribution-NonCommercial-NoDerivs 3.0 Spain Àrees temàtiques de la UPC::Enginyeria química Polymers Nanocomposites (Materials) Cold crystallization Exfoliated structures Micro-molding Nanocomposites Polybutylene succinate Polylactide Polímers Nanocompòsits (Materials) Micro-molding with ultrasonic vibration energy: New method to disperse nanoclays in polymer matrices Article