kimia polimer_chalid 2013.usai utsppt

7/29/2019 Kimia Polimer_Chalid 2013.Usai UTSppt

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KIMIA POLIMER

M. Chalid

DEPARTEMEN TEKNIK METALURGI DAN MATERIAL

FAKULTAS TEKNIK UNIVERSITAS INDONESIA


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ENMT 6 0 0009 - KIMIA POLIMER - M. CHALID

DEPARTEMEN METALURGI DAN MATERIAL FAKULTAS TEKNIK UNIVERSITAS INDONESIA

Buku Acuan Mata Kuliah Kimia PolimerDra. Sari Katili, MS.

Dr. Mochamad Chalid, S.Si, M.Sc.Eng.

Polymer Chemistry: An Introduction, G. Challa.


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Definisi Polimer

Polimer berasal dari katapoly(banyak) dan meros/mer(bagian/unit)

Molekul raksasa yang terdiri dari

ribuan bahkan jutaan unit

pengulangan (mer) dalam satu

molekul polimer

Berdasarkan atom penyusun rantai

utama, terdapat polimer organik

(C,N,O) dan anorganik (non C,N,O)

Apa i tu pol imer?

Polietilenaterepthalat (PET)

Silikon

Polimer anorganik Polimer organik


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f i lmblowing with

potato starchpo ly -

ethylene

po ly -

styrene

potato

starch3-d puzzle from p otato starch

ASAL MATERIAL PLASTIK DAN POLIMER

A

L

A

M

B

U

A

T

A

N

Petro-pol imer

Bio-pol imer

Apa i tu pol imer?

SEMI-BUATAN: modifikasi polimer alam dan polimer buatan
http://localhost/var/www/Movie%20Bank%20of%20Lecturing/Injection%20Molding/Understanding%20Plastic%20Materials_Definition%20of%20Plastics.mp4http://localhost/var/www/Movie%20Bank%20of%20Lecturing/Injection%20Molding/Understanding%20Plastic%20Materials_Definition%20of%20Plastics.mp4http://www.google.com/imgres?imgurl=http://kelarutan.files.wordpress.com/2009/12/biji-plastik.jpg&imgrefurl=http://kelarutan.wordpress.com/2009/12/23/plastik-organik/&usg=__UXQc9W67Bm7dpYHjTJtjpLwEhdg=&h=480&w=491&sz=108&hl=en&start=8&sig2=6ecX1SgLYVKsIAQPm_ZA-Q&zoom=1&um=1&itbs=1&tbnid=yGpZCVP1jUhO3M:&tbnh=127&tbnw=130&prev=/images%3Fq%3Dbiji%2Bpolimer%26um%3D1%26hl%3Den%26rls%3Dcom.microsoft:en-us:IE-SearchBox%26rlz%3D1I7SKPB_en%26tbs%3Disch:1&ei=Lzd7TOzADoqXccjIqeUFhttp://www.google.com/imgres?imgurl=http://allabout10.co.cc/wp-content/uploads/2010/01/54582_kilang_minyak.jpg&imgrefurl=http://allabout10.co.cc/2010/01/29/10-negara-penghasil-cadangan-minyak-terbesar-di-dunia/&usg=__ys04rbKKfQ23mHEG_gnKGpiZZno=&h=300&w=400&sz=84&hl=en&start=7&sig2=UG3XrxWaSQ1zEsw5PSOiFg&zoom=1&um=1&itbs=1&tbnid=2_LjEw_UHAMqNM:&tbnh=93&tbnw=124&prev=/images%3Fq%3Dkilang%2Bminyak%26um%3D1%26hl%3Den%26rls%3Dcom.microsoft:en-us:IE-SearchBox%26rlz%3D1I7SKPB_en%26tbs%3Disch:1&ei=7Dd7TK2tC8rzcYWY8PEFhttp://www.google.com/imgres?imgurl=http://imghost.indiamart.com/data/4/G/MY-216591/Vinyl-Co-polymer-Resin_250x250.jpg&imgrefurl=http://www.waxexporter.com/industrial-resin.html&usg=__hIVLdjorrbFy_J-ExIpkmC1FGfY=&h=240&w=240&sz=13&hl=en&start=3&sig2=EXiRSbvrvkaqRXBZlIuZUA&zoom=1&um=1&itbs=1&tbnid=hVqhIQxDCmgjUM:&tbnh=110&tbnw=110&prev=/images%3Fq%3Dresin%2Bpolymer%26um%3D1%26hl%3Den%26sa%3DN%26rls%3Dcom.microsoft:en-us:IE-SearchBox%26rlz%3D1I7SKPB_en%26tbs%3Disch:1&ei=nzd7TJuQCYfJcYyUgPUFhttp://www.google.com/imgres?imgurl=http://www.craftywoodpicker.com/products/API/Resin/resin.jpg&imgrefurl=http://www.craftywoodpicker.com/default.asp%3FCWPmenu%3Dmaterials&usg=__nKfL3YLrJczYhAtMFaET4wnR_p0=&h=210&w=280&sz=26&hl=en&start=12&sig2=F0nFYRdLGnA4VStYCQMD0Q&zoom=1&um=1&itbs=1&tbnid=ukvN8Exx6nDQuM:&tbnh=86&tbnw=114&prev=/images%3Fq%3Dresin%2Bpolymer%26um%3D1%26hl%3Den%26sa%3DN%26rls%3Dcom.microsoft:en-us:IE-SearchBox%26rlz%3D1I7SKPB_en%26tbs%3Disch:1&ei=pjZ7TJDuK8idceKIkeMF


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Jenis kopolimer (a) monomer selang seling,(b) monomer acak, (c) kopolImer blok, and(d) kopolimer cangkok. Perbedaan ukurandan warna sebagai perbedaan jenismonomer.

Kopolimer (>1 Jenis Monomer)

Terpolimer (> 2 jenis monomer)

Jenis Monomer Penyusun Polimer

Homopolimer (hanya 1 Jenis Monomer)

Apa i tu pol imer?


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Karakteristik polimertermoplastik.

Termasuk polimertermoplastik.

Various structures of polymer molecules: (b) branched

Karakteristik polimerelastomer/karet.

Karakteristik polimertermoset

Konfigurasi Struktur Rantai Polimer

Apa i tu pol imer?


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Polimer padat dipanaskan: Suhu pemanasan rantai molekul bergetar (vibrasi)

antar rantai saling menjauh ruang kosong (free volume) selanjutnya ??

1. Pada rantai lurus: mobilitas molekul polimer, hingga suatu saat (Tg dan Tm) semua

molekul polimer mobil dan material berubah wujud menjadi cair(leleh)

2. Pada rantai bercabang: mobilitas molekul polimer , hingga suatu saat (Tg dan Tm)

semua molekul polimer mobil dan material berubah wujud menjadi cair(leleh)

3. Pada rantai hubung silang: mobilitas molekul polimer, namun dibatasi oleh hubung

silang. Sehingga material hanya mengalami pelunakan dan tidak meleleh (Tg)

4. Pada rantai jaringan: mobilitas molekul polimer , namun dibatasi oleh hubung silang

yang telah terbentuk. Pada saat bersamaan, pemanasan lebih lanjut (Tc) mengakibatkan

pembentukkan hubung silang baru, sehingga material semakin keras dan tidak melunak,

apalagi meleleh.

Struktur 1 dan 2 adalah TERMOPLASTIK, 3 adalah KARET dan 4 adalah TERMOSET

Polimer termoplastik leleh didinginkan: vibrasi rantai molekul polimer pelipatan atau

pembelitan rantai molekul (tergantung struktur molekul dan kecepatan pendinginan) ruang

kosong (free volume) mobilitas molekul polimer, hingga suatu saat material menjadi

padat. BAGAIMANA dengan karet & termoset ??

Prilaku rantai polimer terhadap termal

Apa i tu pol imer?


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Penataan substituen

pada polimer

bercabang, sepertipolipropilena (PP)

dan polistirena (PS)

Taksisitas Rantai Polimer

Cabang tertata pada

satu bidang

Cabang tertata

secara selang seling

Cabang tertata

secara acak

Apa i tu pol imer?

polistirena (PS)


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MonomerPolimer(Resin)

Resin +Additives(Plastik)

ProdukSemi Jadi

ProdukSiap Pakai

Application Waste

Siklus Polimer

Apa i tu pol imer?
http://www.google.com/imgres?imgurl=http://allabout10.co.cc/wp-content/uploads/2010/01/54582_kilang_minyak.jpg&imgrefurl=http://allabout10.co.cc/2010/01/29/10-negara-penghasil-cadangan-minyak-terbesar-di-dunia/&usg=__ys04rbKKfQ23mHEG_gnKGpiZZno=&h=300&w=400&sz=84&hl=en&start=7&sig2=UG3XrxWaSQ1zEsw5PSOiFg&zoom=1&um=1&itbs=1&tbnid=2_LjEw_UHAMqNM:&tbnh=93&tbnw=124&prev=/images?q=kilang+minyak&um=1&hl=en&rls=com.microsoft:en-us:IE-SearchBox&rlz=1I7SKPB_en&tbs=isch:1&ei=7Dd7TK2tC8rzcYWY8PEF


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Requirements for a monomer

A monomer must be AT LEAST DIFUNCTIONAL

A monomer must be sufficiently REACTIVE

A monomer must be VERY PURE

THERMODINAMICS must allow a monomer to

polymerize


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Functionality of monomers: . must be at least difunctional

Functionality of monomer molecule is the number of chemical bonds it

can form with other molecules under the prevailing reaction condition

For polymerization, requires a minimum functionality of 2 of the

monomers (difunctional)

Example:

Polyesterification is possible by taking a diol and a diacid

A hydroxy acid is also difunctional, but contains both types of

complementary functional groups in one molecul


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Difunctional: . more examples.

Diols Diamines Diisocyanates Reactive ring

Dicarboxylic acids Hydroxy acids

Amino acids Reactive double bond


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Trifunctional Glycerol with three OH-groups

Phenol with two reactive ortho

positions and one reactive

para position

Tetrafunctional Isoprene

Butadiene

They have a possibility for making crosslinking to

build an elastomer and a thermoset

Functionality of monomers: . must be at least difunctional


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Reactivity of monomers: .. must be sufficiently reactive

Slowly reacting monomer would be unattractive,

because high degrees of polymerization would require

unacceptably long reaction time

Catalyst accelerate chain growth process

Increasing temp Side reatcion like chain scission by

thermal degradation

Steric hindrance around functional group should beavoided


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Purity of monomers: must be very pure

Monofunctional impurities may cause premature

stopping of chain growth

Sometimes desired to avoid the formation of too high a

molar mass polymer from very pure monomers.


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Thermodynamics of polymerization: must

allow to polymerize

and are n- and (n+1)-mers carrying radical endgroups and M is a monomer molecule

Further polymerization is only possible as long as the

Gibbs free energy G of the system decrease

If G>0, depolimerization will occure

G=0, denotes a situation of chemical quilibrium


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At constant absolute temperature T we further know that

It follows that the equiluilibrium occurs at a critcal

absolute temperature:

Exothermic polymerization, i.e. H 0, polymerization would be possible at each T

For S< 0, polymerization is possibble if T|S| < |H| For S< 0, polymerization is not possible if T|S| > |H|

For S< 0, polymerization exhibi tsa so called ceiling

temperature Tc= H/ S


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Endothermic polymerization, i.e. H 0, polymerization is possibble if TS > H

For S> 0, polymerization is not possible if TS < H

For S> 0, polymerization exhibits a so called floor

temperature Tf= H/ S

Entropy decreases (S< 0) upon polymerization.

Most polymerization must be exothermic (H< 0) and

should be performed below the ceilling temperature.

If the temperature rises above the ceilling temperature,

then depolymerization starts from reactive chain ends.


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When a polymer is to be processed afterwards of used

at a temperature above the ceiling temperature, then it

might be necessary to stabilize its end groups

A polymer with stabilized end group can still

depolymerization if chain scission by thermal degradation

above the ceiling temperature creates new reactive chain

ends

This problem might be restricted by incorporating a

comonomer


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The values of the critical temperatures Tc and Tf are

governed by thermodynamics of the chemical equilibriumitself.


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Florys Principle of Equal Reactivity

The reactivites of all like functional groups are equal to each

other, irrespective of the size of the polymer molecules to

which they belong

Reactivity of Polymer Molecules


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Influence of Viscosity on Reactivity

In former times, one expected that long molecule should

be less reactive than a short one because of its lower

mobility and diffusion rate.

Theoretical basis for vanishing mobility effect by Flory

and G.V. Schulte

They made use the concept of frequent collision during

one encounter of two reactants


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Owing a truly lower relative mobility of macromolecules,

any pair encountering functional groups attached

todifferent macromolecules in a more viscous medium

will remain together for longer period

The number of collision during each encounter will

increase


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This effect compensates longer period of time elapsing

before the functional groups encounter another reactive

partner at new positions in the reaction medium

Only the distribution over time of the collisions is

changed by a possibly lower mobility


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A more quantitative description of the aboce ideas can be

given in terms of a kinetic scheme including a difusion step

of reactans:


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The Functional Group Approach

All like functional groups behaved similarly and could be

regarded as the reactants

The polymer chain segments between or beside these

groups were considered as kind of solvent


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From kinetic analysis is should then appear whether k and

k remain really constant in the course of polymerizationwith increasing viscosity


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Transesterifications may also occur during the above

condensation polymerization

This reaction cannot be analysed in terms of functional

groups as their number does not change


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Its interesting to describe it in terms of molecules :

The average chain length remains the same, but the chainlength distribution alters.

It is not a polymerization but a redistribution.

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