ALAMAT REDAKSIPusat Penelitian Fisika - LIPI

Jalan Sangkuriang / Cisitu No.211152DKomplek LIPI Bandung 40135Telepon (022) 2503052, 2504826, 2504833, Fax (022) 2503052

e-mail: www.jurnal.lipi.go.id/situs/mpi

?rtajaCa/i

POLIMER INDONESIAIndonesian Po (ymer Ioumai

Vol. 17, No.1, 2014ISSN 1410-7864

REDAKTURPELAKSANAEXECUTIVE EDITORIAL

Dra. Sri Pujiastuti, Dra. Rina Ramayanti,Dra, Mirah Yulaili, Yualina Riastuti Partiwi, Indriyanti, M.Sc

Penerbit : Perhimpunan Polimer Indonesia (HPI)Terbit pertama kali : Januari 1998. Frekwensi terbit : Enam BulananAlamat Redaksi/Editorial Address' Pusat Penelitian Fisika - LIPI

JI. Sangkuriang/Cisitu No. 211l54D Kompleks LIPI, Bandung 40135Telepon : (022) 2503052, 2504826, 2504833, Fax: (022) 2503050

e-mail: www.jumal.lipi.go.id/situs/mpi

MITRA BESTARIREVIEWER

Dr. Rike Yudianti, LIPJDr. Sudaryanto, BATAN

Dr. Edy Giri Rachrnan Putra, BATANDr. Myrta Karina, LIPJ

Ir. Wiwik Pujiastuti, M.Sc, Kemenperin

STAF EDITOREDITORIAL STAFF

Dr. Asep Riswoko, BPPTDr. Emil Budiarto, VI

Dr. Eniya Listiani Dewi, BPPTDr. Darmawan Darwis, BATAN

WAKILKETUACo-CHAIRMAN

Dr. Agus Haryono, LIPJ

KETUACHAIRMAN

Drs. Sudirman, M.Sc. APU, BATAN

DEWAN REDAKSIEDITORIAL BOARD

PENANGGUNGJAWABMANAGING EDITOR

Ketua Umum Perhimpunan Polimer Indonesia (HPI)

DEWANPENGARAHSTEERING BOARD

Dr. Suharto, Dr. M. Sugandi Ratulangi, Dr. Ir. A. Zainal Abidin,Dr. Wiwik S. Subowo, Dr. Sunit Hendrana, Dra. Nursyamsu Bahar, M.Sc.,

Dr. Rochrnadi, Ir. Lies A. Wisojodharmo, Dr. Cynthia L. Radiman, Prof. Basuki Wirjosentono, Ph.D

DEWAN PENASEHAT INTERNASIONALINTERNATIONAL ADVISORY BOARD

Prof. Hiroyuki Nishide, Waseda University, JapanProf. Dr. Takashi Nishino, Faculty of Engineering - Kobe University, Japan

Prof. John Forsythe, Monash University, Australia

DEWAN PENASEHAT NASIONALNATIONAL ADVISORY BOARD

Prof. Dr. N. M: Surdia, M.Sc., Dr. Roestamsyah,Prof. Dr. Tjia May On, Prof. Dr. Suminar S. Achmadi

MAJALAH POLIMER INDONESIAIndonesian Polymer Journal

Vol. 17, No.1, 2014

ISSN 1410-7864

Dewan Redaksi

Komentar, kritik dan saran yang membangun atas penerbitan jurnal ini, baikterhadap substansi maupun redaksi, sangat karni hargai

Semogajurnal edisi kali ini dapatmemberikanmanfaat bagi peneliti, pelaku industridan juga litbang serta perguruan tinggi di Indonesia terkait sintensis, modifikasi, prosesdan karakterisasi bahan polimer.

Selain artikel terkait sintesis dan modifikasi untuk proses dan aplikasi polimer,karakterisasi khusus dananalisis kegagalan bahanpolimer sangat penting dilakukan untukdapat mempredisikan sifat-sifat bahan polimer tersebut.

Peningkatan sifatmekanik untukberbagaiaplikasijuga telah ditunjukkan daribahankomposit polimer dengan memanfaatkan serat alami seperti bambu serta tandan kosongkelapa (empty fruit bunch).

Dalam proses pengolahan bahan polimer, penambahan senyawa aditifhidrazinsangat dibutuhkan dalam menentukan viskositas konstan karet sebelum prosespengunyahan (mastication) pengolahan karet mentah. Sedangkan penggunaan perekatdari kopolimer resin akrilik yang meliputi kekentalannya, suhu serta waktu pemanasandalarn proses penempelan serat nylon 66 terhadap bahan kain kapas telah meningkatkanketahanan gosok, kekakuan, kekuatan sobek, kekuatan tarik dan mulur kain.

Penggunaan polimer untuk kebutuhan penyediaan sumber energi menjadiperhatian yangpenting akhir-akhir ini.Untukitu, sintesispolimerpoliimida yangmemilikigugus akhir maleat dari maleimid dan bismaleimid dan karakterisasinya telah berhasildilakukan untuk digunakan sebagai bahan membran elektrolit pada sel bahan bakarpenukar proton.

Dalam Volume 17,No. 1ditampilkan 1buah artikel terkait dengan sintesispolimer,2 buah artikel tentang modifikasi serat alam menjadi bahan komposit dan 2 buah artikelmengenai proses peningkatan kualitas bahan polimer untuk proses lanjutan serta aplikasipengunaannya, serta 1buah artikelkhusus terkaitkarakterisasisertaanalisisbahan polimer.

KATA PENGANTAR

VoL17,No.1, 2014ISSN: 1410-7864Majalah Polimer Indonesia

_R __

11

lndeks Pengarang 41

lndeks Kata Kunci 40

Synthesis and Characterization of Polyimide End Group Maleic asMembraneofElectrolyte in Proton Exchange Membrane Fuel CellSudirman, E. Budianto, E. L. Dewi, R. Yudianti and JOinting 33

Pembuatan Kain Berbulu dengan Metode Mekanik Elektro Statik ,Kuntari Adi Suhardjo 20

Failure Analysis on Polyoxymethylene Product Using Scanning ElectronMicroscope, Thermal and Processing AnalysisR. Wijaya, A. Rifathin and B. Afrinaldi 16

Effect of Ultrasonic at ion Process from Unbleached Empty Fruit Bunch PulpReinforcing with PolyvinylAlcoholWida B. Kusumaningrum, lsmadi and Sasa Sofyan Munawar 11

Mechanical Properties of Recycled Polypropylene and Bamboos FibersCompositesKurnia Wiji Prasetiyo, LilikAstari and M Yusram Massijaya 6

Application ofHydrazine Compound to Produce Constant ViscosityRubberAfrizal Vachlepi, Didin Suwardin, Mili Purbaya and Sherly Hanifarianty . 1

Daftar lsi 11

Kata Pengantar

(j)aftar lsi

ISSN : 1410-7864Indonesian CPofymerJourna{

Vol. 17, No.1, 2014MAJALAH POLIMER INDONESIA

16

of 175 °C and 162-173 °C respectively. POM issemi crystalline polymer with 75-85 %degree ofcrystallinity.

As engineeringplastics, PolyOxyMethylene(POM) has two types, homopolymer andcopolymerwhich differ slightly in itsmelting point

INTRODUCTION

Kala Kunci: Analisis retak, Polioksimetilen,Derajat kristalinitas,Termal

ANALISIS RETAKPOLIOKSIMETILEN MENGGUNAKAN SCANNING ELECTRONMICROSCOPE, ANALISIS TERMAL DAN PROSES. Analisis retak dilakukan menggunakanScanning Electron Microscope (SEM) danDifferential Scanning Calorimetry (DSC). Perbandingankarakteristik bahan antara sampel NG dan standar dilakukan. Analisis SEM menunjukkan bahwapermukaanretakan pada sampelNG cenderung lebihmudah patahdibandingkanretakan pada sampelstandar.Retakan diduga berasal dari vicinity gate location. Derajat kristalinitas patahan NG adalah59,6% lebih rendah dibandingkandengan sampel standard 65,8 %. Tidak ada perbedaan yangjauhantara suhu leleh (164°C) dengan suhu kristalisasi (146 0C).Perubahan danjalur patahan disekitargate location berpotensi menyebabkan retakan selama proses. Berdasarkan hasil SEM dan DSC,retakan diduga berasal dari setting proses yang tidak tepat yang menghasilkan derajat kristalinitasyang rendah danJrozen-in stress. Beban luar yang diterima juga merupakan salah satu penyebabterjadinya retakan.

ABSTRAK

Keywords: Failure, Polyoxymethylene,Crystallinitydegree, Thermal

FAILURE ANALYSISON POLYOXYMETHYLENE PRODUCT USING SCANNINGELECTRON MICROSCOPE, THERMAL ANDPROCESSING ANALYSIS.Failure analysisofPolyOxyMethylene(POM) product were carried out using Scanning Electron Microscope (SEM),DifferentialScanningCalorymetry(DSC) and parameter process related factors. Comparationof thefailuremode and material propertiesbetween theNG and Proven sampleswere taken. SEM analysisshowed that failure surface tent to have more brittle fracture compared with the proven samplefailure.The origin of crackwaspredicted from the vicinityof gate location.Degreeof crystallinityoffailure part was 59.6%, which was lower than the proven products (65.8%). Melting (Tm) andCrystallizationTemperature(Tc)showedno significantdifferences, 164°Cand 146°Cformeltingandcrystallizationtemperature respectively. Whiteningand molded streamflowwere shown around thegate locationwhich potentially causedmolded in stress and crack propagation during application inchemicalenvironment. External load also found in the vicinityof crack. Based on the SEM,DSC andprocess related factor analysis, the failure of product was supposed due to the combination ofimproper setting process which resulted in lower degree of crystallinity and frozen-in stress aroundthe gate and external load received have triggered the crack on product.

ABSTRACT

Accepted: 13December 2013Revised: 13November 2013Received: 19July 2013

R.Wijaya, A.Rifathin and B.AfrinaldiCenterfor Polymer Technology(STP)- BPPT

Kawasan Puspiptek; Serpong 15314, TangerangSelatan

FAILURE ANALYSISON POLYOXYMETHYLENEPRODUCT USING SCANNING ELECTRON MICROSCOPE,

THERMAL AND PROCESSING ANALYSIS

Vol.17,No.1, 2014, hal: 16-19ISSN: 1410-7864Majalak Polimer Indonesia

17

approximately 10mg,placed intoalumina crucible.The alumina crucible was then placed in ThermalGravimetry Analysis (TGA) instrumentation. Thetest is conducted under temperature program asfollow: Firstly the sample was heated up fromtemperature of 50 to 600 DC under nitrogen gas.The temperature was held at 600 DC for 5minutesnitrogen gas environtment. The temperature wasthen continuing heated up until 900 DC underoxygen gas. The rate of heating was 10 DC perminute, and the nitrogen/oxygen gas flow ratewas50 mL per minute. After measurement wascompletely finished the TGA-thermograms wereanalyzed.

DSC821-Mettler Toledo was used tomeasure the thermal properties of the samples suchas melting point, glass transition temperature,thermal history, degree and the growth' ofcrystallinity. The test was conducted according toASTM D 3418-2003. Sample was cut andweighed approximately 20 mg, placed into Alcrucible. The Al-cruble was then placed in DSCsample chamber. The test is conducted undernitrogen gas environment with temperatureprogram of "heating-cooling-heating" as follow:the temperature program was started from 30 to200 "C, then cooled down to -100 °C and finallyheated up to 200 °C. The rate of heating was10 -c per minute, and the nitrogen gas flow ratewas 50 mL per minute. After the test wascompletely finished the DSC-thermograms wereanalyzed.

Figure 2. FTIR test results of NG and provensamples

i I~' -,-

._

The failure POM product was received asfailured-part applied in motor cycle.

To identify the main material, possibledegradation and semi quantitatively analysis thematerial composition, we used FT-IR-BrukerTensor 27, ATR method. Placed the sample onATR crystal. Touched the sample surface perfectlyon the crystall by setting down the stainless steeltip. Samples analysis were carried out by OPUSsoftware (Figure 2).

To measure the material composition.The test was carried out in accordance to ASTM1131-1998. Sample was cut and weighed

EXPERIMENTAL METHOD

Figure 1. Frozen-in orientation (top) and poten­tial shrinkage near to the gate (bottom)

t Edge p.le

\\~I\ I '>:~I/ :/'_____

POM are generally processed in injectionmolding with special runner system. Hot runnertypes are commonly applied in POM. Wrongselection of runner type could result in loss ofpressure during process. Toovercome the pressurereduction, operators usually increase thetemperature. Unfortunately this could severe thematerial to degradation.

The melt entering the cavity will formorientation during fillingphase.And melt adjacentto themoldwill freeze:firstandleadtohigh interfacialshear stress between the melt and the solid layer.This frozen-in orientation will continue to developduring holding pressure in order to compensate forvolume shrinkage, particularlynear the gate regionof the part (Figure 1). However, fast cycle timeduring production is required. Those processparameters influentthemicrostructureofpartwhichalso affect the properties and performances.

In this paper, we analyzed the effect ofsettingprocess to thermal properties as contributionofpotential causes of failureby observing the crackpattern on the failed surface.

Failure Analysis on PolyOxyMethylene Product Using Scanning Electron Microscope, Thermal and ProcessingAnalysis (R. Wijaya)

Figure 4. DSC test results ofNG (a) and proven(b) samples on cooling phase after first heating

'---';"::;';';;"j,

_______ _.'._H.__ ,'_"' __ . .. ,_.__ _._ __ ,_.._' ..~: I" to ~,(;~.

!....~

..,..~--.....--.......~-----"":;-;.;~=.~~-·-=·,·~--""""u=·~=,:=,;~~.:;;::~:.;\.~- ~-::::;i:'!~;~~_,.:...

_-6l"l.'Ii\ ,)'U~'.ll':<;;:.~

\\.

:.;.~/ \! \

:1 (a)--_ .._----,._-------,

:___ ._" .1

Figure 3. DSC test results ofNG (a) and proven(b) samples on heating phase

--_ .•._---------.. '" ,., ""

..._.",,';j:

~'"':'...:...:"._-;=-~--.._--- ...~--.-.-~.-.-.-------."-.'--.-----.--..-.~ ._..._( -.•_ ..- ,:.!:-<"",~,-,

18

Degree of crystalinity of the NG sampleshowa littlebit lower (Figure3),whilecrystalizationrate is higher and the crystal distribution (whichindicates the size of crystaline) is lower than theproven one. (Figure 4)

Figure 5 shows crack that occured near tothe gate. Smoothlbrittle pattern of crack found onthe crack surfaceofNG sample. On the otherhand,the fracturepattern of proven sample showedmoreductile (see Figure 6).

Crack supposed initially occured from theouter to the inner surfaces and was caused by theextemalload.Thiswas shownwithwhiteningcircle­like defect on outer surface (see Figure 4).

Lower degree of crystallinitywhich is foundon the NG sample is usually related to high the

Test Methods Proven sample NG sampleFTIR, polymer type Polyoxymethylene PolyoxymethyleneTGA, % polymer 100 99.99DSCHeating phaseMelting point (OC) 164.51 164.06Delta H (Jig) 156.1098 149.6349Crystallinity (%) 65.8 59.6

Cooling phaseTemp ofCrytalline 145.80 146.45CCC)Crystalline rate 0.31 0.29(min)Crystalline distr 0.38 0.32(min)

Table 1. Comparative test results of NG and provensamples.

.No significance differences on spectra ofNG and proven samples. Both show the POMmaterialaccording to OPUS software analysis.Nodegradation is indicated both samples. Table 1shows the results of FT-IR, TGAand DSC.

RESULTS AND DISCUSSION

ScanningElectronMicroscopy JEOL JSM-6510LA was applied to observe the fracturesurface in order to see the crack initiation andpropagation.

Inorder to analyze the root causes of failure,the comparative method between the failure andthe new proven product are carried out on the testresults.

VoL17,No.1, 2014, hal: 16 -19ISSN: 1410-7864Majalah Polimer Indonesia

19

REFERENCES

[1]. DuPont, 2008, Problems with Hot Runners.[2]. DuPont, DuPont™ Delrin® acetal resin

Molding Guide:Technical Information.[3]. ARCHODOULAKI VM, LUFTL S,

KOCH T, SEIDLER S, Property changesin polyoxymethylene (POM) resulting fromprocessing, ageing and recycling, Pol DegradStab, 92 (2007) 2181-2189

[4]. MALLOY RA., Plastic Part Design forInjection Molding: An Introduction, HanserGardner Publications Inc. (1994)

The authors are grateful to The Center forPolymer Technology for supporting this project.

ACKNOWLEDGMENTS

Extemalload on the surfaceofhighly frozen­in stress part due to improper setting process tendto form brittle on the surface and layer betweenthe surface. The inner core part resulted in crackbeginning from the outer surface part andpropagate toward the entire part of thickness

CONCLUSION

Figure 7.Delamination form on the fracture sur­face, supposed due to layer formation betweenthe skin and the core.

Figure 6. Different pattern surface fracture

Proven sample.NGsample.

Figure 5. Crack around the gate (bottom) and(top) ofNG sample.

cooling rate. The setting process also tend toincrease the frozen-in stress orientation on thesurface near to the gate (see Figure 2). Thissupposed cause two layers formation, surface partwith highly frozen-in stress orientation (smooth!brittle surface-pattern crack); delamination formedand ductile fracture mode in the inner core part.This is in accordance to the information receivedabout the cycling time reduction duringproduction(Figure 7).

Frozen-in stress in microstructure and theexternal load applied from outer surface hasresulted in initial crack and propagate to entirethickness product.

Failure Analysis on PolyOxyMethylene Product Using Scanning Electron Microscope, Thermal and ProcessingAnalysis (R. Wijaya)