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POLYETHYLENE, RAJA ZARITIH SOFEA BT RAJA AZIZAN - Coggle Diagram
POLYETHYLENE
INTRODUCTION
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- Obtained by polymerizing ethylene gas
- Most widely used grade of PE are LDPE and HDPE
- A new LDPE grade is LLDPE which produced like high density polymer at low pressure
PHYSICAL PROPERTIES
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- LDPE exhibits high flexibility
- Melting point range 120oC to180oC
CHEMICAL PROPERTIES
- Excellent chemical resistence
- Burn slow with a blue flame & gives off and odour of paraffin
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POLYMERIZATION
- Most common and useful reaction for making polymers is free radical polymerization
- Used to make polymers from vinyl monomers that is, from small molecules containing carbon double bonds.
REACTION MECHANISM
Polymerized by a radical mechanism with the addition of an organic peroxide radical initiator / Zielger Nata catalys
Step 1: Chain initiation
- The chain is initiated by free radical, Ra produced by reaction between some of the ethene & oxygen initiator.
Step 2: Chain propagation
- Each time a free radical hits an ethene molecule a new longer free radical is formed.
Step 3: Chain termination
- 2 radical hit each other producing final molecule. Process stops because no new free radicals.
- random process, polyethene will be made up of chains of all sorts of different lengths.
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SAFETY MEASURE
POTENTIAL HEALTH EFFECT
1) EYES
- Dust may cause mechanical irritation to eye
- Heated polyethylene can cause serious thermal burns
2) INHALATION
- Nuisance dust can be irritating to upper respiratory tract
- Irritating vapor may form when polyethylene is processed at high tempretature.
POTENTIAL HAZARDS
i) Steamers
- Can create feed and product quality problems
ii) Fine & Dust
- Regrind dry colorants and additives in powder form can bring in hazardous dust particles
iii) Static electricity
- Ungrounded metal piece of conveying equipment can present significant hazard
EXPOSURE CONTROL
- Engineering control. Local exhaust ventilation of process equipment is recommended for control
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- Personal protection. Wear safety glasses with side shields
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WASTE MANAGEMENT
- Waste generated during start up, breakdown or machinery problems
- Using a contract recycler to turn the waste film back into pellets for re-use
- PE film manufacturers recycle this waste
CONCLUSION
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4) PE is not considered biodegradable, as it take decade until efficiently degraded
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