NEW MATERIALS BASED ON POLYLACTIC ACID WITH CONTROLLED FLEXIBILITY – FLEX4PLA

Funding: Romanian Ministry of Education and Research, CNCS – UEFISCDI

Programme: PNCDI III – Human resources – Research projects to stimulate young independent teams 2019, PN-III-P1-1.1-TE-2019-1333

Research domain: PE5_7 – Biomaterials, biomaterials synthesis; PE5_1 – Structural properties of materials

Project title: NEW MATERIALS BASED ON POLYLACTIC ACID WITH CONTROLLED FLEXIBILITY – FLEX4PLA

Financing contract: no. 67/2020

Total funding: 431.900,00 RON

Project duration: 24 months

Period of project implementation: 15.09.2020-14.09.2022

Contractor: National Institute for Research & Development in Chemistry and Petrochemistry – ICECHIM, Bucharest

Project Manager: PhD eng Adriana Nicoleta Frone

E-Mail address: ,

HUMAN RESOURCE ALLOCATION

Frone Adriana Nicoleta, CS 1, Project Leader

Corobea Mihai Cosmin, CS 1, Young Researcher

Panaitescu Denis Mihaela, CS 1, Researcher

Teodorescu George-Mihail, ACS, Master’s Student

Iordache Tanta Verona, CS 1, Young Researcher

Florea Ana-Mihaela, CS 3, Post-doc

Raduly Monica Florentina, CS 3, Young Researcher

Afilipoaei Andreea, ACS, PhD Student

Cărăulașu Monica, ACS, Master’s Student

PROJECT SUMMARY

The present project fits into the stream of study and characterization of biobased materials, considering the need to improve their properties from a technological point of view to allow their wider use in final products. Currently, biopolymers have found applications in fields starting from packaging to automotive but an almost unexploited market segment is represented by materials intended for children goods. Most of the global produced toys and other goods for children are made with conventional plastics derived from non-renewable petrochemicals containing dangerous chemical additives to ensure flexibility, natural feel and easy coloring. Thus, the FLEX4PLA project aims the research and design of new biomaterials in which both polymers and additives are being derived from renewable resources. The approach of FLEX4PLA consists in the synthesis of new bioelastomers compatible with PLA from biobased resources and the design of a new technological route to ensure nanodispersion and an engineered interface in PLA/bioelastomers nanomaterials. The new nanomaterials will exhibit the good elasticity of the bioelastomer and the excellent processability of PLA and no more that 10% decrease in strength compared to neat PLA. Tensile properties, impact tests, melt flow index, fracture behavior and morphology will be performed in order to characterize the new biomaterials with the aim of correlating the composition to processability and thus establishing the final properties.

NOVELTY AND ORIGINALITY

FLEX4PLA project will innovate by using new synthesized biobased bioelastomers coupled with NC with controlled surface properties as toughening modifiers and compatibilizer for PLA.

OBJECTIVES

The specific objectives of this project are:

  • Setting-up the best conditions for the development of bioelastomer component;
  • Designing nanocelulose with controlled hydrophobicity (high and medium level);
  • Optimizing the components ratio and technology for PLA/bioelastomer/NC bionanocomposites; sweeping the composition for the best toughness and elongation at break;
  • Setting-up the technological conditions for the development of nanocomposite biomaterials model;
  • Dissemination of the project results and Protection of Intellectual Property Rights.

ESTIMATED RESULTS

The specific objectives of this project are:

  • Setting-up the best conditions for the development of bioelastomer component;
  • Designing nanocelulose with controlled hydrophobicity (high and medium level);
  • Optimizing the components ratio and technology for PLA/bioelastomer/NC bionanocomposites; sweeping the composition for the best toughness and elongation at break;
  • Setting-up the technological conditions for the development of nanocomposite biomaterials model;
  • Dissemination of the project results and Protection of Intellectual Property Rights.

PHASES

PHASE I

Title: Setting up the preliminary conditions for synthesis of bioelastomers; Structure and composition analysis; NC functionalization

Period: 15.09.2020 – 31.12.2020

Summary of the activity report

During the 1st phase of FLEX4PLA project, a selection of the raw materials that will be employed for the polycondensation reactions has been made on the basis of the eco-friendly character of the material sources. Sebacic acid was chosen for the preliminary synthesis of the bioelastomers and the synthesis conditions were established. Also during this first stage of this project, several functionalization reactions were performed in order to decrease the hydrophilic characteristics of the nanocellulose. In this regard, two organosilane-type coupling agents and a carboxylic acid were tested. The efficiency of the functionalization reactions was highlighted by specific morpho-structural analyzes (atomic force microscopy – AFM, infrared spectroscopic analysis – FTIR, static contact angle) and thermogravimetric analysis – TGA. The results of the FTIR analysis indicated the presence in the nanocellulose structure of the specific functional groups belonging to the employed functionalization agents. Moreover, the AFM results showed different morphologies of nanocellulose depending of the functionalization agent type. As expected, the modification of the nanocellulose surface with silane coupling agents led to increased of both static contact angles values (from 29 °- control sample to 89 °) and thermal stability.

DISSEMINATION

Conferences:

1. Radu, E.-R.; Panaitescu, D.M.; Gabor, A.R.; Nicolae, C.A.; Frone, A.N. Bio-Based Polyester/Cellulose Films for Engineering Applications. The 16th International Symposium “Priorities of Chemistry for a Sustainable Development” PRIOCHEM, Bucharest, Romania, 28–30 October 2020 (Oral presentation). Proceedings 2020, 57, 36, ISSN 2504 – 3900;

PHASE II

Title: Setting up conditions for the synthesis of bioelastomers; Structure and composition analysis; Development of the new PLA/bioelastomer/NC bionanocomposites

Period: 01.01.2021 – 31.12.2021

Summary of the activity report

In this second phase of FLEX4PLA project, several bioelastomers with different molecular weights were synthesized by polycondensation reactions of varying molar ratios of monomers. The obtained bioelastomers were subjected to detailed morpho-structural (FTIR, AFM), thermal (TGA, DSC) and rheological (MFI, torque) characterizations. Following the obtained results, the bioelastomers with the best thermal performances as well as a low viscosity were selected. The selected bioelastomers were tested as plasticizers in the PLA matrix (2.5 – 20 wt%) using the melt blending process. Thus, various weight ratios between the components of the mixtures were used, and the processing parameters were varied in order to select the best processing conditions (methodology for obtaining PLA/bioelastomers mixtures). The PLA/bioelastomer mixtures that led to the best results in terms of low melt viscosity, low glass transition temperature but also displayed optimal ratio between thermal stability/mechanical strength were subsequently used for the preparation of the PLA/bioelastomer/NC bionanocomposites. In order to obtain an improved dispersion of both bioelastomers and NC in the PLA matrix, a series of masterbatches consisting of bioelastomers, PHB and NC (methodology for obtaining PLA/bioelastomers/NC masterbatches) were obtained. The bionanocomposites were obtained both by direct melt mixing of the components and by diluting the masterbatches in the PLA matrix using various melt processing techniques (extrusion and injection). The bionanocomposites structure/properties relationship was established based on static (tensile elongation and tensile strength) and dynamic mechanical properties, impact strength, small-scale mechanical properties (nanoindentation) and thermal behavior (TGA and DSC analysis). Morphological analysis (AFM and SEM) are currently underway to evaluate the dispersion of NC and bioelastomer particles in the PLA matrix and the best method for obtaining bionanocomposites as well as their optimal composition is to be selected. Some of the experimental work carried out during this stage was disseminated by sending an article for publication in a journal with an impact factor> 4, by publishing an article in a specialized journal with an impact factor> 9 and by participating at 3 conferences.

DISSEMINATION

Papers:

1. A. N. Frone; M. Ghiurea; C. A. Nicolae; A. R. Gabor; S. Badila, D. M. Panaitescu, Effect of cellulose fibers from different sources in poly(lactic acid)/poly(3-hydroxybutyrate) biocomposites, Journal of Materials Research and Technology, 2021, under review

2. I. Chiulan, D. M. Panaitescu, E.-R. Radu, S. Vizireanu, V. Sătulu, B. Biţă, R. A. Gabor, C. A. Nicolae, M. Raduly, V. Rădiţoiu, Influence of TEMPO oxidation on the properties of ethylene glycol methyl ether acrylate grafted cellulose sponges, Carbohydrate Polymers, 2021, 272, 118458, https://doi.org/10.1016/j.carbpol.2021.118458

Conferences:

1. S. Badila, E.-R. Radu, M. S. Popa, D. M. Panaitescu, M. F. Raduly, A. R. Gabor, C.-A. Nicolae, A. N. Frone*, Properties of PLA films with natural agents for children’s toys, 7th Portuguese Young Chemists Meeting (7PYCHEM), 19-21 May 2021, online (poster);

2. A. N. Frone, E.-R. Radu, S. Badila, G.-M. Teodorescu, M. F. Raduly, C.-A. Nicolae, A. R. Gabor, D. M. Panaitescu, Modification of renewable PLA by melt blending with natural additives, 2nd Bucharest Polymer Conference,9-11 June 2021, online (poster);

3. M. S. Popa, E. R. Radu, D. M. Panaitescu, R. A. Gabor, C. A. Nicolae, M. F. Raduly, A. N. Frone*, The potential of biopolyesters as plasticizers for polylactide, PRIOCHEM XVIIth Edition, 27-29 October 2021, Bucharest, online (oral presentation).