LbL DEPOSITION OF HALOGEN FREE FLAME RETARDANTS BASED ON PHYTIC ACID. COST ACTION MP1105 FINAL CONFERENCE April 27-28, 2016, Poznan, Poland

Transcription

1 LbL DEPOSITION OF HALOGEN FREE FLAME RETARDANTS BASED ON PHYTIC ACID COST ACTION MP1105 FINAL CONFERENCE April 27-28, 2016, Poznan, Poland

2 Research main objectives: 1. Development of environmentally friendly FR from renewable resources by introducing LbL method of surface modification 2. Detailed characterisation of burning mechanism of LbL deposited fabrics which will clarify the effectiveness of applied method

3 MATERIALS: Cotton fabrics (100 %) - chemically bleached, desized 100% cotton fabric, 177 g/m 2 BPEI branched polyethylenimine (Sigma-Aldrich Chemie GmbH, Germany) PA sodium phytate (Carbosynth Ltd, UK) Deionized (DI) water

4 PA SODIUM PHYTATE: polyanion (-) phytic acid and its salt in a form of phytin - principal phosphorus store in plant (bran, seeds, vetch) phytic acid - easily bonds to metals and other organic compounds (possible replacement for ammonium polyphosphates) inhibits enzymes necessary for digesting proteins and starch, which makes minerals and phosphorus inaccessible to human organism - a detrimental impact to human health a preservative E391 in food industry (in Japan) mass production from soybeans, rice etc.

5 PA SODIUM PHYTATE Myo-inositol hexaphosphate

6 BPEI - BRANCHED POLYETHYLENIMINE polycation (+) on charged surfaces to provide a biocompatible coating on surfaces nitrogen source application: detergents, adhesives, water treatment, printing inks, dyes, cosmetics, and paper industry, adhesion promoter, lamination primer, fixative agent, flocculant, cationic dispersant, stability enhancer, surface activator, chelating agent, scavenger for aldehydes and oxides

7 BPEI - BRANCHED POLYETHYLENIMINE

8 Hypotheses: 1. PA is an effective alternative flame retardant, because it is a natural source of phosphorus in plants, easily binds metals (iron, copper) and can be deposited onto a cellulose fabric via LbL method 2. BPEI (branched polyethylenimine) is biocompatible polyelectrolyte rich in nitrogen, and in combination with PA acts as an effective N-P flame retardant 3. Kaolin is an aluminosilicate effective as a flame retardant even in low concentrations 4. Copper (II) sulfate (CuSO 4 ) enhances the effectiveness of an alternative N-P flame retardant while achieving antimicrobial protection 5. Optimization of LbL parameters (type of electrolyte, number of layers, ph of electrolyte solution, concentration of solution) enables equal efficiency to the commercially available flame retardans.

9 SCHEMES OF THE LAYER-BY-LAYER DEPOSITION METHOD (LBL) C O T T O N 1 BILAYER Cotton: 1- immersion into polycationic C O T T O N solution (BPEI) 2- washing in deionized water 3 - immersing into polyanionic solution (PA) 4 - washing in deionized water.. 5 x 10 x. Drying at 50 C

10 EXPERIMENT + LOI RESULTS Sample BPEI (wt %) PA (wt %) Number of bilayers LOI (%) (BPEI/PA) 0 - cotton n/a n/a n/a 18, , , , , , , , , ,0

11 CHARACTERISATION: Burning behaviour Limiting Oxygen Index device (Dynisco): EN ISO PA good replacement for ammonium polyphosphate the best LOI values (29 %) were obtained by treating cotton samples with concentrated solution of PA (50 wt %)

12 CHARACTERISATION: Morphology: Tescan MIRA\\LMU FE-SEM Scanning Electron Microscope (BSE detector, 3.5 kv) SC7620 Sputter Coater equipped with gold/palladium target (Quorum Technologies) Elemental analysis: EDX detector (Bruker)

13 CHARACTERISATION: Thermal stability: TGA thermogravimetric analyser (PerkinElmer Pyris 1): temperature range 50 C to 700 C heating rate 40 C/min purge gas air (flow rate: 30 ml/min)

14 DERIVATIVE TG CURVES OF UNTREATED AND LBL DEPOSITED COTTON (PA 5 %) Trend of linear decrease of temperature peaks with the increase in: - no of bilayers - PA contest Cotton 1 bilayer 5 bilayers 10 bilayers

15 DERIVATIVE TG CURVES OF UNTREATED AND LBL DEPOSITED COTTON (PA 10 %) Trend: the increase of PA concentration influences on decrease in flammability of cotton Cotton 1 bilayer 5 bilayers 10 bilayers

16 CHAR RESIDUE AFTER TG (PA 50 %, 1 BILAYER) EDX spectrum Presence of carbon, oxygen, phosphorus, sodium and others in traces (aluminum, magnesium, calcium - impurities of the technical grade sodium phytate)

17 EDX results: high contest of sodium suggests that the aqueous solution is saturated with sodium phytate, which deposites on the surface of fabric instead of negatively charged PA meaning that Layer-by-Layer deposition is not applicable for highly concentrated polyelectrolyte solutions EDX analysis did not show any traces of nitrogen suggesting that NO x gas compounds evolved during the combustion

18 CHAR RESIDUE AFTER TG (PA 50 %, 1 BILAYER) SEM image of the char residue after heating in TGA The intumescent N-P flame retardant effect on cotton fabric with something like bubbles coming from NO x gas compounds evolved during the combustion

19 CONCLUSIONS: PA (Sodium phytate) possible replacement for ammonium polyphosphates PA + branched polyethylenimine = alternative N-P flame retardant Sodium phytate is effective at hight concentration (< 50 wt %) at highly concentrated polyelectrolyte solutions Layer-by-Layer deposition is not applicable.

20 CONCLUSIONS: Increase in number of bilayers (1, 5, 10) at the same PA concentration linear but modest increase in the LOI values TG temperature peaks of decomposition decrease lineary with the increase in: PA contest (5, 10, 50 wt %) number of bilayers (1, 5, 10).

21 RESEARCH CONTRIBUTION: 1. Determination of the burning mechanism of the LbL treated textile materials and its comparison with the burning mechanism of textile materials treated with commercial organophosphorus flame retardants 2. The development of environmentally friendly treatment of textile material for the purpose of flame retardancy 3. Replacing conventional, environmentally unfavorable FR treatment by applying LbL deposition 4. Maintaining good functionality, thermal and mechanical properties of newly developed products 5. Development of innovative materials of dual effectiveness (FR and antimicrobial).

22 APPLICABILITY: LbL deposition is one of the innovative textile finishing process intended for manufacturing products of highprotective properties e.g. decorative textiles, textile wallpapers, which must meet strict standards of flame retardancy and will not be subjected to intensive wash.

23 CONTACTS: Prof. Sandra Bischof, PhD, Eva Magovac, BSc, University of Zagreb Faculty of Textile Technology The work has been supported by the Croatian Science Foundation under the project 9967 Advanced textile materials by targeted surface modification, ADVANCETEX.