Handling of production waste and health hazards from composites

Transcription

1 Handling of production waste and health hazards from composites Per Reinholdsson, Exova Materials Technology SICOMPs 27h Conference on Manufacturing and Design of Composites 2016 Linköping,

2 2 Recycling of CFRP reference:

3 3 Statistics about CFRP Source: Arne Lewis, Boeing Exemples of commercial capacity CFK Valley Recycling (Stade, Germany) ELG Carbon Fibre (Coseley U.K.) LLC (MIT LLC, Fletcher, N.C)

4 4 CFRP life loop Examples from CFK Valley Recycling (Stade, Germany)

5 5 Airborne dust from CFRP Measurements of emissions of airborne dust from CFRP in different operations have been performed, e.g.: Cutting and lay-up of carbon fibre fabrics, demoulding and cleaning tools for autoclave curing Various types of machining (milling, grinding, cutting, drilling etc.) End of life-handling of CFRP - Post crash handling/handling of burned CFRP - Recycling Handling of carbon / carbon composite brake system Handling of future materials as carbon nanotubes

6 6 How do CFRP decompose? Mechanical decomposition What happens to the composite during heat exposure? The size and the morphology of the dust (from fibres and/or particles) depends on the 1. type of mechanical force and the energy during decomposition 2. depends on the fiber properties, e.g. the rate of crystallinity 3. reflects the composite proporties

7 7 Carbon / carbon composite brake system Replacement, renovation, maintenance and disposal

8 8 Health hazards Exposure to fibers / particles may cause: Irritation to skin, eyes and respiratory ways Skin: itching, rash, allergic reactions Respiratory: irritation, inflammatory reactions, fibrosis, lung cancer, etc. The maximum average concentration/day: Thermoset dust 3 mg/m 3 Synthetic, inorganic, non-crystalline fibers 1.0 fiber/cc Synthetic, inorganic, crystalline fibers 0.2 fiber/cc Type of carbon nano tubes Recommended limits (Level limit value) References MWCNT 2,5 µg/m 3 Nanocyl, 2009 MWCNT 50 µg/m 3 Bayer, 2010 MWCNT 7 µg/m 3 Schulte et al., 2010 Carbon nano tubes 0,01 fiber/cm 3 Institute for Occupational safety and Health of German Social Accident Insurance (IFA), 2009

9 9 Instrument for measuring airborne dust and fibers EPS 3090 GRIMM 1.108, 2 st DustTrak DRX P-Trak FAM-1: Measures fibers from 100 to 4500 nm in diameter (in cooperation with IVL). FAM-1 Filter samples for analysis: All fiber sizes. Grimm: Measures particles in 14 interval from 230 nm to more than nm (in cooperation with IVL). MMmm DustTrac DRX: Meusures particles in four fractions: PM10, Respirable, PM2,5, PM1 plus the total dust concentration (Exova s instrument). EPS 3090: Measures particles from 6 nm to 500 nm in 32 size fractions (in cooperation with IVL). P-Trak: Measures particles from 20 nm to 1000 nm (0,2-1 micron) from 0 too particles/cc (Exova s instrument).

10 10 Conclusions Emission of dust from machining of CFRP in aircraft applications 1. Without strategies to reduce the concentration of airborne dust from machining processes (milling, grinding, cutting, drilling etc.) the total dust concentration sometimes exceeded the limits 2. The respirable fractions were low in all cases (0,1 mg/m 3 was a typical value) 3. The dust fraction from carbon fibre was in the bronchial fraction, i.e., no fibre dust in the respirable fraction 4. Most of the dust came from the epoxy-matrix. A typical value was that the dust from the grinding of CFRP was consisting of 70 % epoxy particles and 30 % dust from the carbon fibres. 5. Even when the concentration of the dust was below the limit, the working environment was unpleasantly dusty, for example when the total dust concentration 0,5 mg/m 3 was emitted both during cutting in carbon fibre fabrics and drilling in CFRP 6. The size and the morphology of the dust particles / fibres depended on aspects as the type and speed of the machining process, the micro geometry of the machining tools including the (knife) edge drop area where the dust is released and the composite properties 7. The question is always: Is the used protecting strategies enough or not?

11 11 Conclusions Special cases Handling and machining of burned/crashed CFRP High temperatures can scale off the carbon fibres as a leek and produce respirable fractions Cutting in burned CFRP emitted high concentrations of airborne dust in nano fractions Dust from crashed/burned CFRP were contaminated with toxic substances Handling with carbon / carbon composite brake system Emitted dust was wet and had a tendency to get absorbed at surfaces Some of the dust fractions were in nano sizes Observed risk moments was e.g. handling of the brake system without gloves and using compressed air to cool the brakes Mixing, grinding and simulation of careless handling of carbon nanotubes The detected concentration of airborne fibre dust were in all cases below the limits but exceeded the recommended level limit value The careless handling of the carbon nanotubes emitted higher dust values and a leakage from the fume hood to the area outside the fume hood was observed

12 12 Prevention of exposure to airborne dust Effective ventilation in the working area is important the room, the fume hood, a local extractor connected to the machining tools If there is a risk to get exposed to airborne dust protect the eyes, skin and airways (dust-repellent clothes and e.g., protective (full) face mask with particle filter class P3 or compressed air line breathing apparatus). Gas filter class A2 should be used against exposure to steam / gas / aerosol from e.g. epoxy from work with lay up of carbon fibre fabrics and demoulding or cleaning tools for autoclave curing, All surfaces - vertical and horizontal from working areas where dust is emitted must be cleaned regularly Protective clothing, work equipment, etc. will be contaminated by dust why they need to be cleaned regularly and kept in special areas. Separate locker rooms for private and work clothes is recommended Use glove box when working with e.g. carbon nano fibres. If an accident occurs the area should have negative pressure or vacuum (it can be done by closing the supply of the air flow). Use a vacuum cleaner equipped with HEPA-filter. Then clean all the surfaces as much as possible. Discuss the working environment at your workplace - any concern from the staff can often be eliminated by mapping the working environment with direct reading instruments and perhaps make simple changes in the cleaning routines or move dusty work to a workspace where ventilation is more effective

13 13 Thank you! Per Reinholdsson Polymer & Composites Exova Materials Technology Box 1340 SE Linköping, Sweden telephone: mobile: fax: