Paraffin Films

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Paraffin Films

Siswand Ali

Mohamed Ali Rauff


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Scope

Composition and chemistry of polymer

Industrial manufacturing process methods

Physical properties due to polymer structure

Possible uses


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Composition

Blend of Olefin-type materials

Olefin is made from propylene and ethylene

gases Olefin can be formed into thic fiber and shares

identical properties to that of Parafilm

added wa!"lie material coats on paraffin filmaccounts for high temperature resistance


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In the Industry

Possible se#eral methods

)apour *eposition

$ubular Blowing Method

Cast Film Method )main

Reactants used

+aseous Radical Initiator( typically o'one

,thylene +as

Pro lene as


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)apour *eposition

One of the most useful methods for obtainingan organic thin film with a desired molecularorientation

Reactants

n"paraffins with C ranging from -."/.

,#aporated at pressure of about - ! 0."1 $orrdeposited onto a slide glass substrate

$emperature of the substrate and e#aporationcontainer could be ad2usted between " 031 and-..oC


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)apour *eposition

- Possible Orientations%

4ormal 5molecular chain a!is is perpendicular toglass substrate6

7ateral 5molecular chain a!is is parallel to glasssubstrate6

Molecular orientation is controlled by

*eposition rate

Substrate temperature

Substrate morphology


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)apour *eposition

For paraffin thin film on a glass substrate

4ormal orientation obtained by light supercooling

7ateral orientation obtained by high supercooling

Supercooling is defined as difference betweenmelting temperature of sample and substrate

temperature 7ateral orientation in the thin film could be

changed to normal orientation by annealing #"main


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)apour *eposition

)apour deposition as 8 elementary steps

,#aporation process from e#aporation source

Adsorption process onto substrate

4ucleation process on the substrate

For e!ample( molecules adsorbed on the substrate

can tra#el along the substrate surface with #ariousmolecular motions and orientation

Some molecules can re"e#aporate fromsubstrate and molecules diffusing on substrate

surface meet one another to form clusters and


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For production of stretch wraps used to wrappallets and those used to wrap food

Reactants used Polyethylene or copolymer of ethylene with one or

more co"monomers selected from C/ to C0. 9olefins such as butane and he!ene

Small weight percentage or Sorbitan Monooleate asantiha'ing agent


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0&- parts Sorbitan Monooleate and 3:&: partsof 77*P, powder 5;": wt < polymeri'ed i"butene( .&30= S+ density( .&= melt inde!6 were

thoroughly mi!ed in ribbon blender ande!truded into pellets

$hen blown into using a *a#is Screw ,!truder

ha#ing fluted head screw connected to a die *ie temperature was maintained at about

/1.>F( while a#erage barrel temperature wasabout /8.>F


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,!trusion process has a series of e#ents thataffects consistency and stability of the e!trudeand therefore film

Feeding( melting( mi!ing( metering andfiltration

*ie?s annular shape produces a tube ofpolymer which is inflated by air pressure

Inflation of tube stretches film and pro#idesorientation of polymer


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Formation ofpolypropylene( - steptubular orientation

process

Film must first becooled to allow

crystallisation due tohigh melt strength ofpolypropylene

Film is reheated to

melting temperature


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General ExtruderConsiderations May need to handle a wide range of

polyethylene characteristics e&g& #arying molarmass distributions

@se of additi#es such as antio!idants(lubricants may be needed to ensure goodperformance

Able to supply sufficient heat to melt polymerand can con#ey molten polymer to the die fore!trusion

Single or *ouble"Screw will depend on how


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crew !esignConsiderations Screw typically di#ided into three 'ones% feed

'one( compression 'one and metering 'one

"eed #onecon#eys the polymer pellets( filler andadditi#es into e!truder

Compression #one:polymer is melted( mi!ed withother components and compressed into continuousstream of molten compounds

$etering #one ensures a uniform flow rate tocon#ey the polymer to the die


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crew !esignConsiderations Screw typically di#ided into three 'ones% feed

'one( compression 'one and metering 'one

"eed #onecon#eys the polymer pellets( filler andadditi#es into e!truder

Compression #one:polymer is melted( mi!ed withother components and compressed into continuousstream of molten compounds

$etering #one ensures a uniform flow rate tocon#ey the polymer to the die


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crew !esignConsiderations Polyethylenes are semicrystalline polymers

and therefore can ha#e broad melting range

,specially when they are copolymers or ha#erandom branching

Melting or compression 'ones of screw shouldbe broad


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crew !esign

Considerations


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%low &atio and "rost-'ine

Molten film e!its the annular die as a tube ofpolymer

$ube is pinchedsealed as it passes betweenpinch rollers

$ube is e!panded using air

$ube only e!pands significantly when thepolymer is molten

Blow ratio is ratio of final tube diameter to

diameter of annulus in the die


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%low &atio and "rost-'ine

Rate at which polymer e!its from the die

Air pressure blown into the tube

Flow of e!ternal chilled air determine blow ratio

$his ratio( together with width of the slot in thedie( determines film thicness and trans#erse

orientation of film


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Properties

*uctility

Malleability

aterproofness

4onto!icity

$ranslucency

Cohesi#eness


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Properties

*uctility and malleability refers to property ofmaterial to deform under tensile orcompressi#e stress respecti#ely

For paraffin films( since the polymer consists ofmostly straight chain carbon bacbone withminimal side groups or branching

,!pected to be fle!ible and therefore ductileand malleable


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(ses

7ab uses Seal test tubes

Beaers

Shape of storage container

Bandage in medical first aid

rapping flowers to retain moisture 5eepfresh longer( pre#ent fungal growth6

rapping for food( cargo


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Paraffin Films

Documents

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