Proses pengolahan kembali zat kelelahan (asam laktat) menjadi cadangan tenaga di dalam hati umumnya terjadi di malam hari antara jam 24.00 sampai dengan jam 02.00. Oleh sebab itu, seyogyanya kita memberikan kesempatan kepada tubuh agar beristirahat terutama pada saat waktu tersebut.

Mengantuk juga dapat menunjukkan bahwa otak sedang kekurangan oksigen. Oksigen dibutuhkan oleh sel-sel otak untuk melakukan aktifitas rutin sehari-hari. Apabila oksigen yang beredar di darah kurang mencukupi kebutuhan metabolisme dasar, maka otakpun akan kekurangan oksigen. Gejala yang ditunjukkan adalah mengantuk.

Kadar gula di dalam darah secara normal adalah di atas 80 mg/dl. kekurangan gula di dalam darah bila kadarnya kurang dari 80 mg/dl maka akan menimbulkan gejala mengantuk. Sebab untuk melakukan aktivitas secara normal, maka otak hanya mengandalkan pengiriman gula dari aliran darah. Otak tidak mempunyai kemampuan untuk menyimpan gula sebagai cadangan energy. Akibatnya, apabila kadar gula darah turun di bawah 80 mg/dl, maka tubuh akan memberikan sinyal berupa rasa mengantuk.

Selanjutnya lensa mata yang mengalami myopia (mata minus), apabila tidak dikoreksi sesuai kebutuhan mata, maka akan menyebabkan mata mudah lelah dan memudahkan mengantuk saat kita sedang membaca.

Kekurangan zat besi di dalam konsumsi makanan kita akan menyebabkan gangguan pembentukan sel darah merah (eritrosit, hemoglobin). Akibatnya tubuh mengalami anemia. Salah satu fungsi hemoglobin adalah mengangkut oksigen ke seluruh tubuh. Apabila alat pengangkutnya kurang maka oksigen yang beredar termasuk yang ke otak akan berkurang. Dengan demikian kekurangan zat besi akan menyebabkan mudah mengantuk.

Kekurangan Biotin juga dapat menyebabkan mengantuk. Biotin adalah vitamin B yang diperlukan untuk metabolisme lemak dan karbohidrat.
Biotin ditemukan dalam berbagai makanan dan sumber yang mengandung banyak biotin adalah hati, ginjal, pankreas, telur, susu, ikan dan kacang-kacangan.

Kekurangan vitamin ini sangat tidak mungkin terjadi pada orang-orang yang asupan makanannya seimbang. Tetapi mengkonsumsi telur mentah selama beberapa minggu dapat menyebabkan kekurangan biotin karena telur mentah mengandung suatu bahan yang mengikat biotin dalam tubuh sehingga mencegah penyerapannya.

Kekurangan vitamin ini dapat terjadi pada orang-orang yang menerima pemberian makanan secara intravena (infus) dalam waktu yang lama tanpa biotin tambahan.

Dengan demikian, tampak jelas penyebab mengantuk adalah bermacam-macam. Kita bisa mengevaluasi kembali kira-kira apa yang mungkin menyebabkan mengantuk yang sedang dialami saat ini. Walaupun sudah makan makanan yang bergizi dan berolah raga secara teratur, bisa saja mudah mengantuk, kalau salah satu kemungkinan penyebab mengantuk di atas belum dikoreksi dengan baik.

source by :

DR. MUCHLIS ACHSAN UDJI SOFRO

“hati-hati dg hati!” , kata nenek kita..

mata gw mungkin ngga’ bisa ngeliat tapi hati gw bisa ngerasain apa aja sampai ke hal2 yg blm gw sndiri blm tau dari firasat..

firasat yang selama ni gw ga percaya ternyata ngga bs gw sepele’in , cz ini juga anugrah dari Tuhan buat kita-kita agar kita bisa waspada tanpa berpikir negatif sekalipun !

” Teman” apa sebenarnya definisi dari pertemanan? ^^

kita bergaul dengan teman, kita berkomunikasi dengan mereka yang umumnya kita pake ‘mulut’ n’ kadang body language jg… apa gunannya sebenarnya kita bicara kepada mereka dear????

“Teman” apa sebenarnya otak dari pertemanan dear friends? ^^

saling berbagi, baik ataupun buruk, cakep maupun jelek, kaya ataupun miskin, sehat ataupun sakit, susah maupun senang, sadar ataupun saat ga waras !!

note :”Teman minum anggur” adalah teman yg ga patut ditauladani.. =D

siapa saja sebenarnya teman kita? apakah teman yang kita anggap sebagai teman baik bahkan sahabat sejati itu benar2 seperti yg kita pikir dan percayai? siapa yg njamin, namanya manusia bisa saja berubah 180 deg dalam suatu limit waktu, siapa nyankaaaaa gt ungkapan kita setelah tau dia begitu ..hmm baik maupun ngga baik perubahannya?!

cewe itu peka perasaanya makanya mereka cepat menerima firasat dari reseptor2 hatinya itu yang lalu diteruskan ke bagian emosi, yg kesanya cenderung emosional, dibandingan cowo yg terkenal dengan otak super number one nya itu,mengapa Tuhan menciptakan cowo ma cewe berbeda?….mengapa Tuhan juga menciptakan sifat, ciri dan kepribadian setiap manusia berbeda? apa maksudnya smua ini? apakah dengan perbedaan ini, kita justru sering crush dan akibatnya serinng ada pertentangan antara umat T.T..

pernahkah teman memikirkan hal ini?(*_*)

. . . . . .

. . . . . . . . . . ……

Tuhan pasti punya rencana yang sempurna dan pelajaran buat kita, Tuhan cinta pada manusia yang berfikir, Dia juga cinta pada manusia yang peka perasaanya~

perbedaan diantara kita itu adalah agar kita dapat belajar satu sama lain, baik dan buruk dari diri kita maupun baik dan buruk dari orang lain, jadi kita HARAM memandang rendah , dan cepat menilai orang dengan muka sebelah , karena meski mata mereka ngga bisa ngeliat apa yg kita lakuin ke mereka tapi hati mereka bisa apalagi cewe, ” hAti-hAti dengan cewe’ ^^ ” sekali terlukai, susah sembuhnya meskipun dia uda berusaha cuek n’ memanage perasaanya ^^

Teman kita berteman dengan orang lain itu tidak lain kita sebenarnya berteman dengan HaTi mereka, agar kita ngga samoai menyakitin hati mereka maka parameter kita adalah Hati kita sendiri-sendiri, kita umpamakan kita sebagai mereka , nah karena kita juga ga similar ma mereka, maka kita ga boleh / makruh hukumnya buat langsung me-judge seperti layaknya diri kita , perlu adanya suatu parameter kalibrasi yg bisa menyetarakan tingkat ke-erroran analisa kita kepada mereka, jadi disini disela atau mungkin pikiran kita andaikata bekerja sendirian tanpa perasaan mungkin otak kita lelah memikirkan rangkaian rumus persamaan buat mengatasi parameter 2 tadi, jadi disini perasaan bisa memberikan the Power of Rule of tumb , jadi secara alamiah , bantuan dari Sang Pencipta datang lewat perasaan ini, dengan catatan perasaan ini bukan emosi yg ngga beralasan n’ ga logis..

jadi marilah mulai saat ini kita Jaga Hati kita dari effect negative dari dalam ataupun luar lingkungan kita, kita terima yang baik dan sisihkan yg buruk disuatu tempat yg orang lain ga bisa nemuin supaya mereka jg ngga bakalan bs make’ yg buruk itu..

Trus bagaimana mengatasiny jika ada teman kita yang kepribadianya sering berubah sebagai fungsi kondisi n’ style ?^^

dimensi membutakan mata memekakkan telinga, lalu diri menjadi hampa..

saat paradigma dunia tak lagi digunakan untuk menerka~~

sadarku akan hadirmu, mematahkan sendi-sendi yang biasanya tegak berdiri

…..

sujudkupun takkan memuaskan inginku ..

tuk’ hanturkan sembah sedalam kalbu..

adapun kusembahkan syukur padamu ya Allah

untuk nama, harta, dan keluarga yang mencinta …

dan perjalanan yang sejauh ini tertempa——-Alhamdulillah ~ pilihan dan kesempatan yang membuat hamba mengerti lebih baik makna  diri~~

semuanya lebih berarti akan mudah dihayati

*Alhamdulillah~Alhamdulillah~Alhamdulillah*

ika ingin terbang, ato kl masi jauh buat skarang aj, ika ingin memanjat(kalo ini hobby mah..)

sumpah gw bingung 7 keliling muter2 kemana2 ni pikiran gw belakangan ini ( lama kalee, maka dari itulah saudara2 ku sakalian blog ini kaga pernah gw update, gomen ne!  dui bu qi) ^^

btw, udah bacakan kutipan syair diatas (lo salah kl ngira tu rangkaian kata gw yg bikin, gw ma cuman copas aj dari favourite song gw sejak pertama ngrasain kehidupan perkuliahan disurabaya (ITS) ^^ ) but anyway lagu ini bagi gw penuh makna n’ ngasi motivasi joss bnged dah buat jiwa – jiwa yg lg puyeng kayak gw ini 0_O hehe..

sebenarny gw ni ngrasa mulai mendeteksi ada dua kepribadian didiri gw, suatu saat bisa extrovert eh pada saat yg dibutuhin malah mendadak jadi introvert..

payahh arghhhh!!! sampe sampe mo curhat di blog aj malas dung dung doeng ==”

salah apa gw ini ya Tuhan? sadarkanlah trus bangkitkanlah jangan biarkan hambamu ini keterusan jadi pemalas, oh NO!!

ya ya ya gw dapet jawabanya dari sini, saat ini gw kejangkit penyakit kronis yg namanya malas yang bikin gw smakin lemah aj hari ke hari, so dari sini gmn menanggulanginya? butuh surgery kah? complete med check? gw butuh obat segera ni , kalo bs saat ini jg hbs gw publish ni tulisan (*Aminnn); ngarep mode : on cz peliharaan gw butuh dikasi makan segera sebelum loyoo smua ne huhu ( *ngarep lg smg bs mberesin dampak negatif dari penyakit ini T.T segera! )

temans maapkan ika ya selama ini ( khususnya selama di chengkung ini ika emg dodol ga pernah nyadarin kl smua itu butuh usaha yg sungguh2  sepenuh hati) ika jujur kurang sepenuh hati kemaren (9 bulan ini) ; [busyet dah 9 bulan kemana aj gw arghhh!! ] yg jelas mulai saat ini ika ga mo ngulangin kesalahan yg sama seperti 9 bulan belakangan , ika akan sepenuh hati sembari mengobati penyakit kronis ika ini, ^^

ika ingat ni pesen pak mario (mungkin kawans jg bisa ngambil manfaat dari sini ^^) :

dipikir2 emg bener si gitu rule of thumbnya, tapi dipikir2 lagi susah ngendaliin gangguan dari lingkungan di dunia yg dah ga steril ini(*maksud kaga nyinggung sapa2 ni^^cm pake istilah) meskipun kita udah sungguh2 niat dengan iman kita, so berhati2lah hidup dilingkungan anda,,,,

nah ika mo crita lagi ni mumpung inget, soal lingkungan ni, (pake gw lg ya biar enak)

…

lingkungan gw sekarang adalah laboratorium, kelas buat kuliah, perpustakaan dan dormitory oh lupa satu lagi adalah tempat makan favourite gw (KFC)…

yang mo gw bahas disini adalah yg part pertama (laboratorium)

gw skarang idup di  opteoelectric polymer laboratory under Prof. Liu (Bapak ke-4 gw )

dilab ini member terdiri dari 3 orang Phd student (2native + 1 bule iran), master student thun ke dua 4 orang (3 native cewe, 1 orang indo namanya dolok steven butar-butar), master tahun ke 1 ada 4 orang juga (2 cewe (native), 1 cowo (native) dan gw),  baru2 ini ada post doc dari korea tapi dia native india satu orang namanya Bala diary ..

kesan pertama gw masuk lab ini, yg ada dalam otak gw dulu sebelum liat TKP, “wah ni mesti belajar dari awal gw, buat nguasain ilmu disini( standart orang baru lah^^) , trus saat pertama kali gw nemuin Professor, gw merasa welcomed banged cz mulut ini belum apa2 uda buru masuk dalam suatu acara meeting mingguan gt..hihi

hari ke hari kelewati~ santai2 (kmbali lg ni crita gw yg hati gw kurang penuh=p) bukanya banyak belajar malah , bnyak trip ,oh dear.., sebenarnya theme thesis gw termasuk earlier dari kawans seangkatan gw disini, tapi dodolny gw yg blm ngerti apa2 soal new thing ini , ga malah ganbatte eh escape ke hal2 yg ga jelas as example : sleeping ==”

and feel so difficult to stop it T.T…

alhasil synthesis gw jg geje, and sekarang jelas 2 gw ganti judul hmmmzzz, tolong gw kudu belajar dari awal lg , oh MG help me…

semoga project gw yang ini mulus lancar jaya and hasilnya bagus bisa  nyenengin si Professor (it’s my recent dream^^)

ga lupa juga semoga nilai2 kuliah gw semester ini Better than ever Aminn^^

paparan diatas adalah generalny seperti itu…

soal gosip miring yg geje, humas antar lab member, ppi dll disini gw bakal ungkap sekelumit klimaksny aj yg bikin gw emosi smpe skarang gw nulis ini:

1. Di lab, gw termasuk international student yg bs dibilang masi bego bahasa native (mandarin/chinese), gw no commet soal mereka nggosip soal gw ( gw akan trima positivenya aj ), tapi yg bikin gw males kenapa para senior juarang banged ngajarin gw eh tp sering bnged ngajarin sesama native >:) invy dung >,<
2. ni soal sepele sebenarnya tapi paling bikin gw sebel. Di lab gw seperti dah gw sebutin diatas ada member bule dari iran kita biasa manggil ONTA iran, ( ni gw ga pake emosi nulisnya ) saat awal meeting lab gw nilai dia ma orangnya aktif n’ kritis alias  bnyak nanya (biasalah orang barat gt kn , besar mulut wajar ), ok no prob. lanjut~ dia pernah ngajarin gw pas awal2 (ni gara2 si rex yg recomend dia buat ngajarin gw ==” gw kaga tau ma okok aj  gmn lg). nah segi positifnya tu dia fluently in english ( ngajar inggris jg gt soalny jadi ngomongnya kayak native ) , trus ramah (gara2 bnyak ngoceh kemana2 ) itu positivenya, mo tau negatifnya ? bnyakkkkkk, sbg manusia yg baek kita ga boleh ngomongin negatif orang secara langsung jadi disini gw curhat soal apa aj yg bikin annoying gr2 dia, pertama dia bauuuu! kedua sok tau, ngira kita ga denger pas dia ngomong( cz ngomongnya mesti ndeketin gt, risih dong gw, sampah gw bs denger jarak 5 meter jg dasar bedes! dari sini temens gw ngira gw ada apa2nya sama dia , apalagi makin sedap kl ada yg ngomporin y?(*maybe aj kl ada, ga nuduh gw..) tp semenjak kerjanya not properly, maybe every member in my lab knew about it! cm gw aj yg cupu, maklum kn orang baru==” , jadi butuh bimbingan yg benar ni huhu.. akirnya gw bebas dari dia, pembimbing gw ganti orang yg lebih expert in his major LC and i hope my thesys will gonna be better in result InsyaAllah.., eh tp masi ada satu dua orang yg masi nanyain gini ke gw ” ka ga ke lab, dicari Onta lo?!” >:) paling sebal kalo denger ni kalimat==” bikin malas ke lab!!!!!  makanya selalu gw jawab gini ” what the hell!! throw him in the damn! ” agak kasar si omongan gw, tp ya gt kl gw dah ga tahan mo marah alias emosi gw dah overload! (too much =p )

that’s all for this session, maybe i will continue write it anytime if  i’m not busy..

thanks for your attention friends (^_^), i love you all, thanks for being my friend

Some liric addopted from tembang syahdu too phat feat dian sastro

Dian Sastro:
Disaat waktu berhenti… kosong
Dimensi membutakan mata, memekakkan telinga
Lalu diri menjadi hampa
Saat paradigma dunia tidak lagi digunakan untuk menerka*
Sadarku akan hadirmu, mematahkan sendi2 yang biasanya tegak berdiri

Yassin:
Ult li albi bissaraha (I’m opening up my heart with honesty)
Hayya nab’idil karaha (Let’s avoid the hated and hatred)
Syakkireena a’ kulli ni’ma (Let’s remain thankful with what we have)
Ba’ ideena anil fattana (Let’s avoid all lies and sins)

Malique:
Merenungi luar jendela, mengagumi kebesaran yang Maha Esa
Ku menilai kehidupan dari sudut berbeza
Tak memadai hanya kecapi rasa selesa
Maukan harta yang mampu beli 1 semesta
Berpesta ke pagi botol bergelimpangan
Kekasih muda bukan setakat berpegang tangan
Harta dan jamuan nafsu tidak berkekalan
Bila menjelang tua bukan itu jadi bekalan
Dan jangan puisi ini disalah tafsir pula
Bukan berkhutbah cuma betuli diri jua
Ingin hidup sempurna aset nilai berjuta,
Saling tukar wanita, senyum dan mati tua
Bakat dikurnia jangan disalah guna
Jangan kufur nikmat yang diberi percuma
Guna kelebihan untuk hikmah bersama
Jagalah nama hidup penuh pementasan dan drama
Ada berisi ada yang kurus, ada melencong ada yang lurus bukan semuanya tulus
Ada sempuna ada kurang upaya ada yang jadi buta hanya bila sudah kaya
Sebesar rumah bermula dengan sekecil bata, boleh hilang dalam sekelip mata
Ucaplah alhamdulillah bukannya sukar, kerna semua yang kaya atau besar
Tetap Allahuakbar!

Joe Flizzow:
Jadikanlah ku tentera Fisabilillah yang tertera di kalimah harap memanduilah
Entah apabila persimpangan tiba, hidup penuh rintangan harus kuhadapinya
Harapku tidak lupa diri bila gembira, dan cuma mula mencari kau disaat hiba
Ku cuma manusia penuh dengan kesilapan tapi bisa membezakan cahaya dan kegelapan
Tabah bila dihalangan duri onak dan cobaan
Teguh bila dicobakan keruh kuasa dan perempuan
Sentiasa legar diminda, dikejar dan dipinta dari zaman bermula hingga ke akhirnya
Ku mengerti siapa ku tanpamu disisi dan apa guna posisi juga posesi
Sementara ini cuma hanya puisi, nukilan tulisan dan bisikan isi hati
Mencari ketenangan, menjiwai peranan menepati pesanan janji jua saranan
Alhamdulillah atas kurniaan rezeki, moga tidak leka dalam perjalanan ini

Yassin:
Ult li albi bissaraha (I’m opening up my heart with honesty)
Hayya nab’idil karaha (Let’s avoid the hated and hatred)
Syakkireena a’ kulli ni’ma (Let’s remain thankful with what we have)
Ba’ ideena anil fattana (Let’s avoid all lies and sins)

Ahli Fiqir:
Aku yang memandang di dalam lubuk hati, mencari-cari zat rahsia yang katanya tersembunyi
Aku yang melihat alam meliputi wujud menyertai lalu ku pindahkan alam ke dalam mata hati
Aku hakiki, aku mengerti segala yang terjadi di langit dan di bumi
Gunanya tiada fantasi, pelik dan benar, qada’ dan qadar kau berilah ku kekuatan
Agar dapat ku hindarkan segala kesesatan
Usah kau biar nafsuku terliur dari pandangan majazi ini,
Aku yang hodoh lagi hina amat benar merindui
Moga cahaya lelapku tak membutakan mataku, semoga segala puji tak ku meninggi diri
Moga segala janji dapat jua ku penuhi, moga dapatku hadapi tikaman dari belakang
Lidah setajam pisau, ku tidak akan risau dengan cabaran, dugaan sepanjang perjalanan
Ku pasrah ku akur 7, 8, 6 Alhamdulillah Syukur…

Yassin:
Ult li albi bissaraha (I’m opening up my heart with honesty)
Hayya nab’idil karaha (Let’s avoid the hated and hatred)
Syakkireena a’ kulli ni’ma (Let’s remain thankful with what we have)
Ba’ ideena anil fattana (Let’s avoid all lies and sins)
Laihi ya ruhi yadada ya laihi
Yalaihi ya yaruhi ya yadada yalaihi…

Dian Sastro:
Sujudku pun takkan memuaskan inginku
‘Tuk hanturkan* sembah sedalam kalbu
Adapun kusembahkan syukur padamu ya Allah
Untuk nama, harta dan keluarga yang mencinta
Dan perjalanan yang sejauh ini tertempa
Alhamdulillah pilihan dan kesempatan
Yang membuat hamba mengerti lebih baik makna diri
Semua lebih berarti akan mudah dihayati
Alhamdulillah, Alhamdulillah, Alhamdulillah…

liric source: Alhamdulillah

1. gw sadari gw kurang berdoa ma Tuhan (ya Allah astagfirllah, maapin hambamu yg lalai ini , smg hamba bs memanfaatkan waktu yg tersisa ini Aminn^^)
2. sedekah, gw akuin kurang sedekah akir2 ini, sebenernya no excuse si mo beasiswa blm turun lah, mo blm ngambil atm apa lagi dasar pemalas =p
3. silaturahmi keluarga ma sahabat ^^
nah bisa lah yg ini diperbaikin , oh my friends i'm coming^^…maapin ika yg cuek slama ini ^^
4. Do it Now, dont wait until tomorrow, what u can do today, realize we are a human so we can't do it perfectly but at least we can try then let God do the rest , right^^
5. using TIME properly !!!
ini dia masalah terbesar gw, masih susah nepatin yg ini, baik atas kendali gw ato tidak=p
okay ini maybe sementara, instrospeksi diri gw malam ini, smg bs bermanfaat jg ^^

best regards n' cheers
-IKAsss-

M. HUSSAINSchool of Physics and Materials Engineering, Monash University, Clayton, Vic-3180, AustraliaR. J. VARLEYCSIRO, Division of Molecular Science, Clayton, Vic-3168, AustraliaM. MATHUS, P. BURCHILLDSTO, Army Research Laboratory, PO Box 4331, Melbourne 3001, AustraliaG. P. SIMONSchool of Physics and Materials Engineering, Monash University, Clayton, Vic-3180, Australia

the content is : ….

Epoxy resins have been used extensively for surface coating, adhesives, paintingmaterials, semiconductors, insulating materials for electrical devices and as filler or fiber-reinforced composites in aerospace, automobiles and marine vessels because of their low cost, easy processing, good mechanical properties and environmental stability.However,many industries such as aerospace, automotive and marine, are increasingly realizing that the flammability of epoxy resins is pre-venting their further use in a number of applications where fire performance is critical. As a result, considerable attention is now being given to synthesizing new epoxy resins with high thermal and fire performance properties for high performance applications. Several approaches have been reported for improving the flame and thermal resistance of epoxymaterials, such as by incorporating aluminum oxide tri-hydrate, bromine compounds in conjunctionwith antimony oxide, silicon and boron. The major problems occurred with these system is the generation of toxic and corrosive gases that occur during combustion. Another problem is the high levels of additive required, often around 30–50% depending upon the application. While this may well impart the required level of fire retardancy to the materials, if does so at a high cost to the mechanical performance of the materials. To overcome these problems, non-halogenated, flame-retardant reactive additives are required to increase the flame retardance time without affecting the physical and mechanical properties of the composites. Physical or chemical incorporation of phosphorus-containing compounds onto the epoxy backbone has been shown to lead to an improvement in the thermal and fire resistance properties of a materials by quenching flammable particles and reducing the energy of the flame in the gas phase

In recent times a general strategy to increase the flame retardancy of epoxy materials, has focused on the introduction of organo-phosphorus compounds containing significant quantities of phenyl groups into the epoxy back-bone. This has been done by blending either reacting an organo-phosphorous compounds with an epoxy resin or using an organo-phosphorus compound as a curing agent [10–12]. Significant improvement in fire retardance has been demonstrated in these types of epoxy materials. In the present article we have reported the reaction behavior of epoxy diglycidyl ether of bisphenol-A (DGEBA) with 9,10-dihydro-9-oxa- 10-phosphaphenanthrene10-oxide (DOPO) and cured with mixture of 3,5-diethyltoluene-2,4-diamine and 3,5-diethyltoluene-2,6-diamine (Ethacure-100). Thermal and fire retardant behavior of this system as characterized by cone calorimetry is reported for the first time as a function of phosphate content. 250 g of DGEBA, commercially known as DER-331 Dow epoxy resin was placed into a three-necked round bottomflask and heated to 130 ◦Cby placing in an oil bath connected with a temperature controller. 66 g of DOPO from Tokyo Kasei Kogyo Co., Ltd, Japan was then added and mixed with a mechanical stirrer, keeping the temperature constant at 130 ◦C untilDOPO was dissolved and the mixture was clear. The temperature was then raised to 180 ◦C and stirring was continued for a further 5 h. 45 g of the amine Ethacure-100 (Albemarle, USA) was added and stirred until mixing was complete. The phosphorus-containing epoxy resin and amine system was then pre-cured at 120 ◦C for 4 h and then post cured at 200 ◦C for 2 h. Differential scanning calorimetry (DSC), Fourier transformer infrared (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H-NMR) techniques were used to confirm chemical reaction of DOPO. Samples were prepared to investigate the thermal and flame retardant properties by thermo-gravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA) and cone calorimetry.

TGA analysis of cured DGEBA and phosphorous containing DGEBA provided valuable information concerning their thermal stability and thermal degradation. TGA thermographs of cured resin and phosphorus-containing resins under air at the heating rate of 10 ◦C/min are shown in Fig. 1. The temperature at which onset of degradation occurred for the 1% phosphorus-containing epoxy was found around 425–430 ◦C and gradually decreased with increasing phosphorous content. Note that the degradation temperature of the phosphorous-containing epoxy is itself already lower than that of neat epoxy DGEBA (450–470 ◦C). However, it is interesting that the weightlosses of phosphorous-containing epoxy at higher tem-perature (600 ◦C) are much less than that of DGEBA alone.The initial decrease inweight loss of phosphorus containing epoxy is due to the initial decomposition of the P-O-C bonds of the phosphorus containing epoxy resin [13, 14]. However, decomposition at higher temperature yields phosphorus-rich residues (char) which form and prevent further decomposition of resins. The char is quite thermally stable, protecting the resins from further degradative oxidation and leading to higher char yields. This mechanism plays an important role in designing new fire resistant epoxy materials. Fig. 2 shows the linear relationship of char yield with phos- phorous content. It is clear that increasing the phosphorous content in epoxy increases the char yield, and thus also the thermal stability at higher temperatures. DMTA analysis provides more information on thermal and relaxational behavior of the fire retardant materials. Fig. 3 shows the tan δ peak of phosphorus containing resins compared with DGEBA. The glass transition temperature (Tg) decreased with increasing the phosphorus content, while the height of loss tangent increases with phosphorus content. However, the storage modulus was found to be similar in all samples. Similar behavior was observed by Lin [10] who proposed that even though the functionality of the resin system was reduced by reaction with DOPO andthus a lower modulus could be expected, the increased modulus was likely due to the bulky nature of DOPO moiety which is attached to the network. The lower crosslink density is confirmed by the greater height of the delta relaxation observed in Fig. 3, which is indicative of a greater relaxation strength. In addition the higher crosslink density phosphorus-free epoxy system is also broader, indicative of the greater structural in homogeneity of a highly crosslinked system. Cone calorimetry can produce an evaluation of the fire-retardant behavior of the resinswith respect to peak and average heat release rates (RHR), specific extinction area and the smoke production rates (CO2 and CO). The RHR is a measure of the heat release perunit surface area of burning materials. Fig. 4 shows the RHR variation with time at heat flux 50 kW/m2 which indicates that there is substantial improvement in the maximum rate of heat release, as well as the average heat release, when 3% of phosphorus is incorporated into the backbone of the polymer network. The maximum RHR of DGEBA was observed after 150 s of burning, while for the phosphorus-modified resin system, the maximum RHR was 165 s. The greatest effect upon fire performance, however, was the large decrease observed in the maximum and average rate of RHR. This can be attributed to char formation acting as a thermal insulator preventing the transfer of combustion products to the surface of the material. In the case of DGEBA, char yield is less than phosphorus-containing resins and thus shows higher a RHR. The result suggests that the presence of organo-phosphorus group enhances char formation. The effect of the phosphorus on the flame test by cone calorimetry has been summarized in Table I. The effect of phosphorus on the flame retardancy in epoxy resin systems such is a burgeoning area of interest, as improved fire retardancy becomes increasingly important in newmaterials development. As such it is equally important to be able to characterize the fire performance of materials from a rigorous scientific standpoint. While thermogravimetric analysis is often reported its relevance to the fire environment is limited. The cone calorimetry test is becoming increasingly important, as it is one of the few techniques that are able to do this. The results presented here are one of the first reported cone calorimeter studies of the fire performance of phosphorus-modified epoxy resins, with further investigations into this system in progress.

not3 : Received 24 July and accepted 21 November 2002

]]> http://ikaasss.wordpress.com/2010/01/23/development-and-characterization-of-a-%ef%ac%81re-retardant-epoxy-resin-using-an-organo-phosphorus-compound/feed/ 0 22.997681 120.221896 22.997681 120.221896 ikaasss 1 2 3 4 5 http://ikaasss.wordpress.com/2010/01/23/ir-spectroscopy-tutorial-how-to-analyze-ir-spectra-for-beginner/ http://ikaasss.wordpress.com/2010/01/23/ir-spectroscopy-tutorial-how-to-analyze-ir-spectra-for-beginner/#comments Sat, 23 Jan 2010 21:33:11 +0000 ikaasss http://ikaasss.wordpress.com/?p=119 ]]> If you have followed this tutorial group-by-group, you will realize that in even rather simple, mono-functional molecules there are so many IR bands that it is not feasible to assign every band in an IR spectrum. Instead, look for tell-tale bands — the region from 4000-1300 cm^-1 is particularly useful for determining the presence of specific functional groups. You can rely on the IR correlation charts (linked in the left frame), but we recommend (in fact, in organic chem 1 lab, we require) that you memorize the distinctive bands of the common functional bands:

3500-3300 cm-1	N–H stretch	1&Mac251;, 2&Mac251; amines
3500-3200 cm-1	O–H stretch	alcohols, a broad, strong band
3100-3000 cm-1	C–H stretch	alkenes
3000-2850 cm-1	C–H stretch	alkanes
1760-1665 cm-1	C=O stretch	ketones, aldehydes, esters
1680-1640 cm-1	C=C stretch	alkenes

Begin by looking in the region from 4000-1300. Look at the C–H stretching bands around 3000:

	Indicates:
Are any or all to the right of 3000?	alkyl groups (present in most organic molecules)
Are any or all to the left of 3000?	a C=C bond or aromatic group in the molecule

Look for a carbonyl in the region 1760-1690. If there is such a band:

	Indicates:
Is an O–H band also present?	a carboxylic acid group
Is a C–O band also present?	an ester
Is an aldehydic C–H band also present?	an aldehyde
Is an N–H band also present?	an amide
Are none of the above present?	a ketone

(also check the exact position of the carbonyl band for clues as to the type of carbonyl compound it is)

Look for a broad O–H band in the region 3500-3200 cm^-1. If there is such a band:

	Indicates:
Is an O–H band present?	an alcohol or phenol

Look for a single or double sharp N–H band in the region 3400-3250 cm^-1. If there is such a band:

	Indicates:
Are there two bands?	a primary amine
Is there only one band?	a secondary amine

Other structural features to check for:

	Indicates:
Are there C–O stretches?	an ether (or an ester if there is a carbonyl band too)
Is there a C=C stretching band?	an alkene
Are there aromatic stretching bands?	an aromatic
Is there a C≡C band?	an alkyne
Are there -NO2 bands?	a nitro compound

If there is an absence of major functional group bands in the region 4000-1300 cm^-1 (other than C–H stretches), the compound is probably a strict hydrocarbon.

Also check the region from 900-650 cm^-1. Aromatics, alkyl halides, carboxylic acids, amines, and amides show moderate or strong absorption bands (bending vibrations) in this region.

As a beginning student, you should not try to assign or interpret every peak in the spectrum. Concentrate on learning the major bands and recognizing their presence and absence in any given spectrum.

In the organic chem teaching labs, you usually know what compound you started with and what compound you are trying to make. For instance, if you are oxidizing an alcohol to a ketone, your product should show a carbonyl band but no hydroxyl band. If no carbonyl band is present, the experiment was not successful. If both carbonyl and hydroxyl bands are present, the product is not pure.

example for Study case :

IR Spectroscopy Tutorial: Amines

The N–H stretches of amines are in the region 3300-3000 cm^-1. These bands are weaker and sharper than those of the alcohol O–H stretches which appear in the same region. In primary amines (RNH₂), there are two bands in this region, the asymmetrical N–H stretch and the symmetrical N–H stretch.

Secondary amines (R₂NH) show only a single weak band in the 3300-3000 cm^-1 region, since they have only one N–H bond. Tertiary amines (R₃N) do not show any band in this region since they do not have an N–H bond.

(A shoulder band usually appears on the lower wavenumber side in primary and secondary liquid amines arising from the overtone of the N–H bending band: this can confuse interpretation. Note the spectrum of aniline, below.)

The N–H bending vibration of primary amines is observed in the region 1650-1580 cm^-1. Usually, secondary amines do not show a band in this region and tertiary amines never show a band in this region. (This band can be very sharp and close enough to the carbonyl region to cause students to interpret it as a carbonyl band.)

Another band attributed to amines is observed in the region 910-665 cm^-1. This strong, broad band is due to N–H wag and observed only for primary and secondary amines.

The C–N stretching vibration of aliphatic amines is observed as medium or weak bands in the region 1250-1020 cm^-1. In aromatic amines, the band is usually strong and in the region 1335-1250 cm^-1.

Summary:

• N–H stretch 3400-3250 cm^-1
  • 1° amine: two bands from 3400-3300 and 3330-3250 cm^-1
  • 2° amine: one band from 3350-3310 cm^-1
  • 3° amine: no bands in this region
• N–H bend (primary amines only) from 1650-1580 cm^-1
• C–N stretch (aromatic amines) from 1335-1250 cm^-1
• C–N stretch (aliphatic amines) from 1250–1020 cm^-1
• N–H wag (primary and secondary amines only) from 910-665 cm^-1

The spectrum of aniline is shown below. This primary amine shows two N–H stretches (3442, 3360); note the shoulder band, which is an overtone of the N–H bending vibration. The C–N stretch appears at 1281 rather than at lower wavenumbers because aniline is an aromatic compound. Also note the N–H bend at 1619.

The spectrum of diethylamine is below. Note that this secondary amine shows only one N–H stretch (3288). The C–N stretch is at 1143, in the range for non-aromatic amines (1250-1020). Diethylamine also shows an N–H wag (733).

Triethylamine is a tertiary amine and does not have an N–H stretch, nor an N–H wag. The C–N stretch is at 1214 cm^-1 (non-aromatic).

Phosphorous analogs of amines are called phosphines. The chemistry of phosphines and the related phosphite esters is dominated by their strong nucleophilicity and reducing character. The nucleophilicity of trivalent phosphorus results in rapid formation of phosphonium salts when such compounds are treated with reactive alkyl halides. For example, although resonance delocalization of the nitrogen electron pair in triphenylamine, (C₆H₅)₃N, renders it relatively unreactive in S_N2 reactions, the corresponding phosphorus compound, triphenylphosphine, undergoes a rapid and exothermic reaction to give a phosphonium salt, as shown below in the first equation. Phosphite esters react in the same manner, but the resulting phosphonium salts (shaded box) are often unstable, and on heating yield dialkyl phosphonate esters by way of a second S_N2 reaction (equation 2 below).

Oxidation States of Phosphorus Compounds

The difference in oxidation states between nitrogen and phosphorus is less pronounced than between oxygen and sulfur. Organophosphorus compounds having phosphorus oxidation states ranging from –3 to +5, as shown in the following table, are well known (some simple inorganic compounds are displayed in green). As in the case of sulfur, the P=O double bonds drawn in some of the formulas do not consist of the customary sigma & pi-orbitals found in carbon double bonds. Phosphorus is a third row element, and has five empty 2d-orbitals that may be used for p-d bonding in a fashion similar to p-p (π) bonding. In this way phosphorus may expand an argon-like valence shell octet by two electrons (e.g. phosphine oxides).

Phosphorus Compounds as Reducing Agents

Trivalent phosphorus is easily oxidized. In contrast with ammonia and amines, phosphine and its mono and dialkyl derivatives are pyrophoric, bursting into flame on contact with the oxygen in air. The affinity of trivalent phosphorus for oxygen (and sulfur) has been put to use in many reaction systems, three of which are shown here. The triphenylphosphine oxide produced in reactions 1 & 3 is a very stable polar compound, and in most cases it is easily removed from the other products. Reaction 2 is a general formulation of the useful Corey-Winter procedure for converting vicinal glycols to alkenes.

Triphenylphosphine is also oxidized by halogens, and with bromine yields dibromotriphenylphosphorane, a crystalline salt-like compound, useful for converting alcohols to alkyl bromides. As in a number of earlier examples, the formation of triphenylphosphine oxide in the irreversible S_N2 step provides a thermodynamic driving force for the reaction.

Most people would certainly consider natural foods as good for them, enhancing their health and even helping them to lose weight. But there are usually exceptions to most rules. It is not so well known that some foods can actually hinder the thyroid function due to pacific plant compounds in these foods known as goitrogens. There are two in particular you need to know about because they are used very extensively in the food industry, they are peanuts and soy. Soy in one form or another is found in so many manufactured foods these days. You will also find peanuts and peanut oil in a lot of products too. Then add to this the fact that most people eat too many foods that contain sugar and refined carbohydrates that also have a detrimental effect on the thyroid function too, mainly due to the fact that these foods lack the very nutrients needed to convert one thyroid hormone into another more active form. Then there are the chemical pollutants, pesticides, mercury, chlorine, and fluoride that all have a harsh affect on the thyroid gland.

Other big enemies to the thyroid glands normal function

The processed vegetable oils freely found on the supermarket shelves and in just about every manufactured food available. The majority of the oils are made from soybeans or partly from soybeans. These highly processed oils are heated to extreme temperatures, changing the molecular structure of the oil, causing serious free-radical damage to every cell in the body, including the thyroid cells.

It is almost impossible to buy processed packaged foods of the shelf that doesn’t contain to some degree soybean oil. Unfortunately, most often just labeled as vegetable oil, hydrogenated fat, partially hydrogenated fat, margarine or shortening. It is important to become an avid label reader of the ingredient list found on all processed food products.

These cheap processed oils interfere with your thyroid function by

a) blocking thyroid hormone secretion

b) hindering its general circulation

c) altering the cells response to the hormone

Anything that interferes with the function and production of the thyroid hormone will interfere with cholesterol and hormone levels.

If you eat a lot of soybean products because you are a vegetarian consider cutting down and adding more variety of beans and lentils to your diet. The important thing to consider if you are a vegetarian always mix beans or lentils with grains this will give you the amino acids you need for a protein. So you would for example have brown rice with a bean chili or a lentil casserole with millet.

The other thing to consider about soybean products is that most of the soybeans on the world market are genetically modified and soybean products are also quite hard to digest. I suggest buying organic tofu to eat it occasionally. The process of fermenting soybeans to make tofu helps in digestion and being organic it will not be genetically modified.

From now on read label carefully and avoid those foods that will hinder your thyroid function and ultimately your weight-loss, general health and energy levels.