BACKGROUNDHalogenated flame retardants have been commercially utilized in the plastics industry since the early 1970’s. They are highly effective in decreasing flammability. When developed, very little information was known regarding the environmental persistence and toxicity of brominated additives. These compounds were elected for study by the National Institute of Environmental Health Sciences in 1995 for hazard evaluation1. Since then, extensive research has been conducted

Development of a Wire and Cable Extrusion Line for Processing Polyolefins Containing Novel* Flame Retardants

Andrew Fothergill, Liam Driscoll, Sethumadhavan Ravichandran,Prof. Stephen Johnston, Prof. Jayant Kumar, Prof. Ramaswamy Nagarajan

University of Massachusetts Lowell

Special Thanks To: The International Wire and Cable Symposium, Professor Stephen Driscoll, and Mayur Kumbhani

ABSTRACT

Due to concerted environmental regulations, some of the halogenated flame retardants such as decabromodiphenyl ether are being phased out. The focus of this project is to complete an investigation into the effectiveness of a bio-derived non-halogenated flame retardant material. Ultimately, the proprietary flame retardant could be compounded into a polyethylene resin to accommodate wire and cable grade products. The successful qualification of the flame retardant will serve as an alternative to current halogenated additives. Extensive testing has shown the ability to reduce the rate of thermal degradation, and has indicated the ability to be melt processed with the base resin. Processability was found to be effected only slightly by increasing loading levels as well.

current grades is now well-known to cause bodily harm through various degenerative diseases4,5 including cancers3. Dioxins and furans are both carcinogenic in very low amounts, and remedial measures and cost-effective reduction to exposure is nearly non-existent. Influenced by sustainability trends, specific studies to understand the root contaminants were initiated. Two specific chemicals were identified to have an impact on the wire and cable industry: polybrominated diphenyl ethers and polybrominated biphenyls. On July 1, 2006, the European Union enacted the RoHS Directive, which initiated the phase-out of poly(vinyl chloride) and halogenated flame retardants6. The directive only restricts the use of these substances. However, companies are phasing out these chemicals to ensure sustainability, safety, and recyclability7. This presents a market potential for non-halogenated flame retardants. This research is focused on exploring the use of a novel alternative material.

REFERENCES1. United States of America. Department of Health and Human Services. National Toxicology Program. Report on

Carcinogens. 11th ed. Vol. 70. Print. Ser. 25.

2. International Chemical Secrateriat. Bromine and Chlorine - Human Health and Environmental Concerns. ChemSec. Clean Production Action, Nov. 2009. Web. 28 Oct. 2010. <http://www.chemsec.org/rohs/reports-and-documents>.

3. Report on Carcinogens, Eleventh Edition; U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program.

4. Lebel, G. “Organochlorine Exposure and the Risk of Endometriosis.” Fertility and Sterility, vol. 69 (1998): 221-228.

5. Bertazzi P.A. et al. “The Seveso studies on early and long term effects of dioxin exposure: a review.” Environmental Health Perspectives, vol. 106 (suppl 2, 1998): 625-631.

6. "What Is the RoHS Directive?" EBFRIP - European Brominated Flame Retardants Industry Panel. European Brominated Flame Retardant Industry Panel, 2008. Web. 25 Oct. 2010. <http://www.ebfrip.org/main-nav/european-regulatory-centre/rohs-directive-restriction-of-the-use-of-certain-hazardous-substances-in-electrical-and-electronic-equipment/what-is-the-rohs-directive>.

7. International Chemical Secretariat. Electronics Without Brominated Flame Retardants and PVC. May 2010. Web. 29 Oct. 2010. <http://www.chemsec.org/rohs/reports-and-documents>.3

8. TN 48, “Polymer Heats of Fusion”, TA Instruments, New Castle, DE

9. TA123, “Determination of Polymer Crystallinity by DSC”, TA Instruments, New Castle, DE.

* “Non-Halogenated Flame retardant materials” J. Kumar, R. Nagarajan, S. Ravichandran et al. Patent Pending

regarding the ability of halogenated organics to act as precursors to dioxin and furan generation2. This includes brominated and chlorinated flame retardants. The toxicity of

Figure 4: DSC Comparison Base vs. PVP

Figure 3: DSC Comparison Base vs. Novel

Reduction of crystallinity by 20% for Novel FR Reduction of crystallinity by 30% for PVP FR Minimal variation noticed in TM for blend

Figure 2: TGA Comparison Base vs. PVP

Figure 1: TGA Comparison Base vs. Novel

Novel FR shows a 9% maximum reduction in mass loss rate at 5% loading PVP FR shows minimal effect for various loadings

of additive on degradation characteristics The Novel FR produced twice the amount of

char at 2%

DSC results show a reduced crystalline phase due to the addition of FR

Low loading levels for Novel FR additive

reduced dynamic viscosity up to 15% 15% Novel FR increased viscosity by 20% compared to 51% for the 15% PVP FR PVP FR showed a 20-51% increase in

dynamic viscosity relative to the base resin

All samples passed the UL94-HB test Flame retarded samples swelled upon

burning, which reduced the drip count Results inconclusive as to which loading

level provided best flame retardancy

Figure 5: Dynamic viscosity results

FUTURE WORK Blend higher loadings of FR by mass Potentially blend with nanoclays Scale-up to extrusion/injection molding Additional industry standard testing X-Ray crystallography for crystal size and type

CONCLUSIONS Thermal degradation of the polymer-FR blends

fall within the range of 375oC- 500oC Novel FR had a lower mass loss rate than PVP FR DSC results indicate ability to extrude blend at

similar conditions to base resin• Matching exothermal peaks at 110oC and

endothermal peaks at 125oC• Inhibited crystallinity for both blends

Processability not compromised at low loading levels of Novel FR, slightly effected at 15%

10% loading level underperformed in UL94-HB test due to possible phase separation

Table 2: UL94-HB Burn Test Results

Table 1: Percent Crystallinity from DSC

MATERIALS Medium Density Polyethylene [MDPE]

• Manufacturer: Dow Chemical Company• Grade: DHDB-6549 NT

Flame Retardants [FR]• Bio-derived and non-halogenated

proprietary additive• Poly(4-vinylphenol) [PVP]

COMPOUNDING Blend MDPE with non-halogenated flame

retardants at 5%, 10%, and 15% FR by mass Procedure

• MDPE processed at 185oC – 5 minutesPVP processed at 165oC – 5 minutes

• FR added to melt and blended for 5 additional minutes

CHARACTERIZATION Thermogravimetric analysis [TGA]

• Degradation of samples through thermal exposure to 1000oC

Differential scanning calorimeter [DSC]• Cycle: Heat – Cool – Heat • Rate: 10oC/min

Rheological analysis• Study the non-Newtonian characteristics

based on storage/loss modulus and viscosity Flammability - UL 94-HB

• Determine the burn rate of the base resin and blends

• Burn less than 1.5” per minute to pass

RHEOLOGICAL PROPERTIES

THERMAL PROPERTIES BURN CHARACTERISTICS

Base Resin(Flaming Drips)

5% Novel FR(Hanging Glob)

5% PVP FR(Drip Forming)

THERMAL PROPERTIES