Development of Biodegradable Polyurethane Footwear Soling Materials

Transcription

1 Development of Biodegradable Polyurethane Footwear Soling Materials G. Saraswathy, Scientist, CSIR- CLRI, India

2 Council of Scientific and Industrial Research (CSIR) MISSION To provide scientific industrial R&D that maximises the economic, environmental and societal benefits for the people of India.

3 CSIR-Central Leather Research Institute (Council of Scientific and Industrial Research)

4 Recent Head Lines Coffee industry responsible for significant plastic litter Food packaging industry can do a lot better Plastic bottles litter the solar system Super markets hand out 8 billion plastic bags- UK Footwear industry.! Social Responsibility- Challenges of Footwear Industries

5 Wastes generated by the footwear manufacturing - % of world areas North and Central America 5% South America 7% Rest of the world 3% Western Europe 10% astern Europe 3% China 47% Middle East 3% Asia (excl. China) 22%

6 General Solutions for Waste Management 4R s Reduce Reuse Wear them around / Sell them / Donate them Recycle Collecting from post-consumers (Nike) Separated by materials - Upper fabric - Midsole foam - Outsole rubber Floors of Basket ball court/ Playground surfacing/ Running tracks Energy recovery Heat/ Power

7 Rejuvenate Rejuvenation using landfill biodegradable additives to make plastics fade away. Shoe soles - Land fill -??? Footwear Soling Materials Percentage (%) Leather 8 Polyurethane (PU) 8 Thermoplastic Rubber (TPR) 14 Ethylene Vinyl Acetate (EVA) 9 Poly (Vinyl Chloride) (PVC) 20 Rubber 40 Others 1 Ref: Staikos T, Rahimifard, S. A decision-making model for waste management in the footwear industry. Intl J Production Res 2007; 45 (18):

8 Biodegradable Shoes / Simple Shoes The shoe raw materials and packaging come from Vegetable origin polymers Fossil organic matter Natural fibre Recycled cardboard Pigments 1. The upper is pieced together from leather and synthetic leather waste from the factory floor using zig-zag stitching. 2. The mid-sole - scrap-ground foam from factory production. 3. The outsole uses environmentally-preferred rubber and Nike Grind material 4. Packaged in a fully recycled cardboard shoe box.

9 But we are talking about.

10 What is Biodegradability? Biodegradability is characteristic of natural substances and materials being assimilated by micro-organisms, and thus introduced into the natural cycles. Biodegradability testing determines the potential rate of degradation by biological processes in the environment.

11 Need of Biodegradable Shoe Soling material Though polyurethane is used only 8% of the global production of shoes and this figure continuous to rise for its unique mechanical properties. Therefore footwear/ polymer industries have started to develop low cost PU to replace the conventional polymer soles. The polymeric shoe soles create an enormous amount of waste that is currently being disposed as landfill.

12 Objective of the project To prepare and characterize biodegradable polymer composites based on PU. To determine the physical, mechanical and degradation properties of prepared polyurethane materials for application as shoe soling material.

13 Experimental Procedure Materials: Polyol: Polycaprolactone diol (PCL diol). Diisocyanates: 4,4 -methylenediphenyl diisocyanate (MDI), Hexamethylene 2 O C Synthesis of Segmented PU Prepolymer Method N R N C O H O R' O H diisocyanate (HMDI), Toluene diisocyanate (TDI), and Isophorone diisocyanate (IPDI). Chain Extender: Ethylene diamine (ED),1,4-Butane diol (BD), N-Methyl H O O H diethanol amine (MIDE), Triethanol amine (TEA). OCN R N C O R' O C N R NCO Catalyst: Dibutyltin dilaurate (DBTDL). prepolymer Solvents: Dimethyl formamide (DMF). Nanoparticles: Nanoclay and Titanium dioxide. reaction with diol H O R' O H Thermoplastic polyurethane (CPU) prepared using PCL as one of the polyol, from Sigma. O R" O O C H N H O N C O R" O polyurethane

14 PREPARATION OF PU SHEET BY CASTING After completion of two step synthesis of segmented polyurethanes, the polymer solution was poured into glass dishes and dried at 60 C for 24 h and then stored in desiccator until use.

15 Types of PUs synthesized in the laboratory

16 Preparation of PU Composites Properties of Nanoclay (MMT) Chemical Name: Hydrated sodium calcium aluminum silicate Nominal Chemical Composition (%): Al= 9.98, Si= 20.78, H= 4.10 and 0=65.12 Powder as fine as 20 nanometers Molecular Weight (g/mol.): Average Density (g/cm 3 ): 2.35 Crystal System: Monoclinic Abundantly available Eco-friendly and cost effective Properties of TiO 2 Nanopowder Appearance: White solid Average Density (g/cm 3 ): 4.23 Contents: Rutile wt %; Anatase wt % Partical Size: nm SSA: m 2 /g Crystal system: Tetragonal Occurs in nature

17 List of PU composites developed in the laboratory Sl. No Sample Code Description 1. CPU Control 15 % CPU (15 g of CPU in 100 ml of DMF) 2. CPU- NC 1% 15 % CPU : NC 1 % (15 g of CPU : 0.1 g NC in 100 ml of DMF) 3. CPU- NC 2% 15 % CPU : NC 2 % (15 g of CPU : 0.2 g NC in 100 ml of DMF) 4. CPU- NC 4% 15 % CPU : NC 4 % (15 g of CPU : 0.4 g NC in 100 ml of DMF) 5. CPU- NC 6% 15 % CPU : NC 6 % (15 g of CPU : 0.6 g NC in 100 ml of DMF) 6. CPU- TD 1% 15 % CPU : TD 1 % (15 g of CPU : 0.1 g NC in 100 ml of DMF) 7. CPU- TD 2% 15 % CPU : TD 2 % (15 g of CPU : 0.2 g NC in 100 ml of DMF) 8. CPU- TD 4% 15 % CPU : TD 4 % (15 g of CPU : 0.4 g NC in 100 ml of DMF) 9. CPU- TD 6% 15 % CPU : TD 6 % (15 g of CPU : 0.6 g NC in 100 ml of DMF)

18 SEM Pictures The outer surface morphology and corresponding cross section at 1000 magnification of Samples A) SPU, B) SPU 2% NC, C) SPU 2% TD, D) CPU 2% NC and E) CPU 2% TD.

19 Biodegradability Test by Soil Burial Method The soil burial test was carried out in two different soils (red and normal soil) of same locations at garden (CLRI campus). The percentage weight loss of the test films was calculated by using the relationship: where Wi = initial weight Weight loss (%) = ((Wi Wf) / Wi) x 100 Wf = final weight of the test sample. Sample A- PU based on MDI:PCL:BD Sample B - PU based on MDI:PCL:MIDE Sample C- CPU from Sigma

20 Biodegradability Test Results Weight Loss (%) % Weight Loss days 45 days 60 days 90 days 2 0 A B C Sample Code A SPU (MDI:PCL:BD), B SPU (MDI:PCL:MIDE), C - CPU (430218)

21 Loss of Tensile Strength 18 Tensile strength, MPa days 45 days 60 days 90 days 0 A B C Sample code A SPU (MDI:PCL:BD), B SPU (MDI:PCL:MIDE), C - CPU (430218)

22 Physico-Mechanical Properties of PU sheets as Soling Materials Hardness Density Tensile strength Tear strength Abrasion resistance

23 Results Hardness & Density Hardness, Shore A Density, g/cc NC TD

24 Tensile & Tear strength Tensile Strength, MPa Max. load/t, N/mm NC TD

25 Abrasion Resistance Sample code Abrasion Resistance (Volume loss) in mm 3 CPU Control CPU NC 1% CPU NC 2% CPU NC 4% CPU NC 6% CPU TD 1% CPU TD 2% CPU TD 4% CPU TD 6% Volume Loss, cu.mm

26 Hydrolysis Sample code Thickness (mm) Tensile strength (MPa) Elongation at break (%) Reduction in Tensile strength after hydrolysis (%) Change in Elongation after hydrolysis (%) SPU Control SPU Hydrolysed CPU Control CPU Hydrolysed

27 Summary & Conclusion Biodegradable PUs having material properties required for soling material were prepared. The standard stoichiometric ratio of 2:1:1 was optimized for synthesis of biodegradable PU using HMDI: PCL: BD composition. In order to improve the mechanical properties, nanoparticles were added to commercial and synthesized polyurethanes in various concentrations. The concentration of nanoparticles was optimized. Other ingredients which are normally used in the preparation of PU soles were not used in the preparation of PU nanocomposites. The PU sheets developed with 2% concentration of nanoclay (NC) and Titanium dioxide (TD) had shown better mechanical properties than the other PU sheets. The mechanical properties of composites are found to meet the standard specifications for soling materials.

28 Acknowledgement Organizers UITIC - CLIA DST, Govt. of India The Director, CSIR-CLRI

29 THANK YOU FOR YOUR KIND ATTENDTION