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Lecture Notes_01_12_11_CHM4272

Lecture Notes_01_12_11_CHM4272 - Cum £1111'3701757 C_en 3...

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Unformatted text preview: Cum £1111 '3701757; C_)_en,: 3%] Weak-sch? / Dom \Z- Lecxhfiw “SS” 6“" ~ 1'-‘~\§ gr“ Leaf Ran 2:31 IFYUS‘L) finch CBNI Ev“ .Tcfl C\L3; h «reué CHE}, \‘3r1 Ann-wk ) Mo\{(-,__\¢, W4‘Sh‘t Avtlh)” me‘gr* bah/nu); I £w~dav~4~r¥h52 X“ \e-w m4wy4": ~ L~=\15w}’\n {($440 thg._«{ YAVrm~;L 7H. §v_ah~A~}v’2 3; How mgflflru _. ‘|5\5V“-J( Sigi'itr2f‘) EikaQ-; ffi' ehtk {a Mk J Mp4“? VQ‘STCll\ $61!)..1x7 Ca(3)(1-tr; \ziwpkfi‘ 3f ch*(lt§<aa, br‘ 5*(( - 514w)?“ g-ai-ynL-Fv I 5&0; cL". OpugJCr') C AR -\' $1] C‘r mpg: YWAB ‘Effhvk-JH ‘5'?“ F.) E7m€~.f\€‘t.t1 ~ YJ\)C_G(Lani_-11fl) J a" d\.-?hm{t)/l Fig. 2.11 BU STEP POLYMERIZATlON ‘ Figure 2—] l shows pints of X,, vs the stoicbiometric imbalance for several values of p in accordance with Eq. 273-17 The stoichiomctric imbalance is expressed both ‘iS‘thL‘ ratio r and also as the mole percent exceSs of the B—-B reactant over the h—A reactant. The various plots Show how r and p must be controlled \o particular degree of polyincrimtionr However. one does I freedom of choice of the r and p values in a polymerization Complete control of the stoichiometrtc ratio is not always possible1 since reasons of economy and difficulties in the purilication of reactants may prevent one from obtaiinini: r values very close to 1.000. Similarly, many polymerizatioiis are carried out to less than 10023}.- completion as to obtain a not usually have complete N O 3 Number- average degree of polymerization, in 7D 50 40 50 —Jl t ._.; 2 3 4 Mat: percent excess 6 78 O 5 l I 5 2 Male percanl excess B far l'tt‘l = N J.— _A _..__L —._._._—L— l 000 O 9901 05804 O 9709 0 96l5 Steicniomeirm Fflllo‘f . , r Dependence of the number-average degree of polymerization I} on the stoichiomelric ratio r or different extents of reaction p in the polymerization of Ar A With I378 MOLECUU (i.e., 10p <1 L000} for reasonsr each of the last few percent of re so percent of reaction. Thus it d_£ required to go from p 2 0“}? (A the same as that to reach p f ('1. Consider a few examples to stoichiomelric imbalances of (Ll llll. respectively) at 100% rcrtcli The degree of polymerization (I: and to 49 and 40 at 9892. reactn always be carried out to at iCLtSI ‘ least approximately SU--l()0 is us sions and the appropriate stoichi of polymerization The exact cot particular degree of pnlytnerixati also calculate the effect of lossu: through voltttilization‘ or side re stniehiometric ratio in a polynieri experimentally employed r value plots in Fig; 2-1] shows that th greater at higher degrees of poly to synthesize the higher-moleeul TYPE 2. The control of the deg equrmolar mixture AiA and E functional reactant. for example that apply to a Type 1 polymeriz redefined as NA r : — N], + 2N5- where NW is the number of 1} rr front of N3 is required since on excess B—B molecule in limitin 2786 do not apply to Type 2 sh arc prescnt. Other situations ill’i Sec. l—lfla. 'r‘rPE 3. Polymerizatinns of A" automatically take place with it ertzation Eqs. 2-84 and 2785 app that is subsequently unstable low of the polymer molecules can re usually accomplished by using a same equations apply with r red N A r = ‘— Na + ZNHv K Kl .. a 2 3w. .1. 5 II n E .omEo><Ew_o>> “*2sz I x KEflN n .5 . lmlmmwlll n :2 .umfiu>< “36:2 2 ZN I mmwfifiom Haw mask Ewmug 515302 .N muswfi ...
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