Rapid Assessment of Electronic Product Enclosure Plastics for Manufacturing Support and End-of. of-life Management. Gary Stevens

Transcription

1 Rapid Assessment of Electronic Product Enclosure Plastics for Manufacturing Support and End-of of-life Management Gary Stevens IeMRC Conference Loughborough, 20 September 2006

2 Presentation Outline Introduction Project Objectives Instrument Development Summary of Previous Work on Insulating Paper Enclosure Scoping Study Spectroscopy of Base Polymer Materials Spectroscopy and Analysis of Processed and Weathered Thermoplastics Further Work

3 Regulatory Background - WEEE WEEE Directive UK implementation 1 January 2007 network of designated collection facilities (registered) Declarations of compliance expected 30 April designated waste streams - Large Household appliances (other than appliances containing refrigeration subject to the Ozone-Depleting regulations; b) Appliances in Cat 1 containing Ozone Depleting substances; c) TV s s and Monitors; d) Fluorescent Tubes e) All other WEEE. 4kg per person target too easy 14 kg achieved in Sweden RoHS Directive established in UK July 2006, in advance of WEEE legislation EuP Directive 2005/32/EC on the Eco 2005/32/EC on the Eco-design Requirements for Energy-using Products working plan expected July 2007 Chemicals Directive REACH negotiations ongoing

4 Market Background and EEP Plastics Plastics widely used in electrical/electronics industry End of life polymer management is poor Many contain hazardous chemicals Product life <1yr to >15yrs Waste product in UK is >1million tonnes/yr Current recycling/reuse methods inefficient Generally low value of plastics recyclates Need to retrieve more value from these materials at end-of of-life Development of tools for rapid identification, condition assessment and qualification is required

5 Typical Resin Proportions in Electrical and Electronic Devices (MBA Polymers report, USA, 1999)

6 UK Electronics Supply Chain (EIGT 2015 report, DTI, 2004)

7 UK Electronics Value Chain (EIGT 2015 report, DTI, 2004)

8 Electronic Thermoplastics Supply Chain (Dillon et al, University of Massachusetts, 2000)

9 Current Methods of Processing End-of of-life Electrical and Electronic Equipment (Waste Watch: Plastics in the UK Economy, 2003)

10 Polymer Degradation Mechanisms (Sharp Ltd.)

11 Rapid Assessment Wide Wavelength Spectroscopy Provides rapid identification, condition assessment and qualification of recyclate materials Portable, robust on-line measurement capability Fibre-optics based visible-near infrared spectroscopy is suitable Multivariate statistical analysis (MVSA) for rapid on- line material property evaluation

12 Spectroscopy and MVSA Visible spectral range (electronic transitions): information relating to colour variation Near-infrared (NIR) spectral range (overtones and combinations of molecular vibrations) : information relating to presence of specific functional groups MVSA: Unscrambles all spectral information; regression of spectral data against known materials parameters.

13 Visible-Near Infrared Portable Spectroscopy Combination of colour and chemical type information is an advantage These methods have been successfully tested in the field for site analysis of the aged condition of insulating paper on power transformer coils (TRANSPEC TM ), including accurate prediction of water and oil content Spectral range nm Fibre-optic probes designed for sampling in the field Non-destructive and fast technique

14 Measurement Technique: TRANSPEC TM

15 TRANSCHEM TM Control Software

16 Portable TRANSPEC TM System for Site Measurements

17 In-situ Measurements on Transformer Coils with One of Our Portable TRANSPEC TM Systems

18 Transformer Insulating Paper Results: DP - Calibration Samples Predicted Y Elements: 33 Slope: Offset: Correlation: RMSEC: SEC: Bias: 3.190e SEP:<30 DP units RESULT7, (Y-var, PC): (DP,8) Measured Y

19 1 0.9 Measuring Water in Kraft Paper 8-96% w/w water content Increasing water content absorbance wavelength/nm

20 Spectra of Water-adsorbed adsorbed Kraft Paper % water content Increasing water content absorbance wavelength/nm Note: no change

21 PLS Model HS New Kraft 0.3 to 7% wt , p, p,,( (p, g ), ) Regression Coefficients Improved model Predicted Y Elements: 26 Slope: Offset: Correlation: RMSEC: SEC: Bias: 2.507e X-variables 0 Measured Y SEP: 0.13%

22 Significant Recent Result: Transformer Phase On-Coil DP Prediction predicted viscometric DP sample

23 Study Objectives for Enclosure Plastics Consultation with industry: identify and access virgin and processed enclosure polymers Investigate ability to discriminate virgin/unprocessed polymers and additives particularly FRs Application to materials in manufactured enclosures Ability to discriminate between processed/aged polymers from their source virgin materials Change in material properties resulting from simple and multiple pass injection moulding Effect of environmental ageing on discrimination Enhanced instrument development.

24 Basis for New TRANSPEC TM System

25 Scoping Study of Enclosures Electronic housings within the University were inspected spectroscopicly Principal Components Analysis (PCA) Colours varying from light to dark grey Discrimination of materials by source was made possible

26 PCA, Plastic Enclosure Materials: PC2 v PC3 floppy disks CRTs keyboards HP dj 950 PCs flat screens HP lj 1200

27 Investigation of Base Polymers Spectroscopic assignments relating to molecular groups: identification of copolymer molecular group concentration Powders, pellets and plaque samples Effect of size, shape and surface roughness on measurements Identification of polymer grades

28 Base Polymer Repeat Units of Enclosure Thermoplastic Materials Polyacrylonitrile Polybutadiene (cis- in this example) ABS (Acrylonitrile- Butadiene- Styrene) Polystyrene Polycarbonate (of bisphenol A) (PC)

29 Spectroscopic Assignment of Vibrational Overtones and Combinations UV-vis-NIR spectra of base polymers PC PS PAN PB 3ν(CH) 2ν(CH) 2ν(CH)+δ(CH) ν(ch)+δ(=ch) absorbance (offset) ν(ch)+ν(c N) ν(ch)+ν(c=c) ν(ch)+δ(ch) ν(ch)+ν(cc) ν(C=O) wavelength/nm

30 2.5 Visible-NIR Spectra of Plastic Materials Absorbance ABS sheet (red colour) polycarbonate/abs sheet (purple colour) polycarbonate sheet (unpigmented) pure polycarbonate pellets pure polystyrene pellets wavelength/nm

31 Br Flame Retardant & Copolymer Content ABS content: accurate to ~1% over 0-100% 0 content FR content: accurate to <0.2% over 0-7% 0 content

32 Processing and Environmental Ageing of Thermoplastic Copolymers ABS and PC/ABS selected as most common enclosure materials for processing 10-pass injection moulding used as mechanical processing scheme for both plastics UV 500 hr weathering scheme for both plastics Intermediate property evaluation between passes/exposure times: Melt flow rate (MFR) Tensile modulus Stress and elongation measurements

33 PC1 and PC2 (accounting for 91% of variance) colour-coded coded by polymer, ageing processes and flame retardant content 10 8 PC ABS2_extruded ABS2_UVaged ABS_virgin ABS_FR PCABS_extruded PC_FR PCABS_UVaged PCABS_virgin PCABS_FR -4 PC1 3 grades of virgin ABS

34 PC2 and PC3 (encompassing 14% of the spectral variance) colour coding by polymer, ageing and flame retardant presence 4 3 PC ABS2_extruded ABS2_UVaged ABS_virgin ABS_FR PCABS_extruded PC_FR PCABS_UVaged PCABS_virgin PCABS_FR -6 PC2

35 Predicted versus Actual and regression coefficient UV exposure for UV-Aged PC/ABS Predicted Y Elements: Slope: Offset: Correlation: RMSEC: SEC: Bias: e X-loadings Measured Y PCABS_PCR_02, (Y-var, PC): (UVexposure,3) X-variables PCABS_PCR_02, PC(X-expl,Y-expl): 1(74%,45%) 2(23%,48%) 3(2%,0%) Error of prediction: ~32 hours (2σ)

36 Predicted versus Actual Tensile Modulus for UV-Aged PC/ABS, colour coded by UV exposure time Predicted Y Elements: Slope: Offset: Correlation: RMSEC: SEC: Bias: Regression Coefficients (B) Measured Y PCABS_PCR_02, (Y-var, PC): (TensileMod,3) X-Variables PCABS_PCR_02, (Y-var, PC): (TensileMod,3) B0 = Error of prediction: ~26 MPa (2σ)

37 Predicted versus Actual and regression coefficient MFR for mechanically and UV-Aged PC/ABS Error of prediction: ~0.7 g/10 min. (2σ)

38 Summary for ABS and PC/ABS Plastic type and grade can be identified Polymer type concentration of blends can be determined FR content can be determined to better than 0.2% b.w.. : visible region is particularly useful here Polymer property variation can be determined to good accuracy Amount of UV exposure can be determined most of which occurs in the first 100 hrs and affects the surface area only MFR (a bulk property) is not affected by UV weathering Tensile strength is affected by UV and process ageing Mechanical processing has a much more marked effect on PC/ABS compared with ABS

39 Further Work Further population of data sets: More weathering studies Additional injection moulding and reprocessing effects Additional property data Different flame retardant types and concentrations Investigation of carbon-black black filled polymers using high intensity NIR, mid-infrared, infrared, Raman and Photoacoustic spectroscopy Enhancing spectroscopic systems and probes (under development) Investigate the use of imaging spectroscopy for online identification/separation DTI Technology Programme