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Table 5 

29Si NMR Chemical Shifts - Silicone Materials

Chemical Shift            

Region (ppm)              Silicon Species                                                                                  

+10 to +4                     Polymer termination sites (SiO(CH3)3)       M

-5 to –15                      Polymer Termination Sites (SiO(CH3)2OH)        MOH

-10 to –20                    Motionally restricted silicone polymer. Cross-linked and hydrogen- bonded –(O-Si(CH3)2-O-)n as well as D units                                         within 5 monomer units of polymer termination

-21                               D Units - motionally unrestricted silicone –(O-Si(CH3)2-O-)n

-75 to –85                    Q1        Si(OSi)(OH)3    Silicate Center (M(OH)3)

-85 to –94                    Q2        Si(OSi)2(OH)2   Silicate Center (D(OH)2)

-94 to –104                  Q3        Si(OSi)3(OH)     Silicate Center (TOH)

-104 to –120                Q4        Si(OSi)4             Silicate Center   (Q)

                                                                                                                                                                                                                                               

 

Explanation of Terms in Table 5:

Silicate Content   (% of Si atoms present in silicate filler)

Q4 (% of Si atoms present in Q4 structures in silicate – Si(Osi)4)

Qn  (% of Si atoms in Qn structures in silicate (Q1, Q2, Q3))

Q4/Qn Ratio  (Allows relative change in silanol (Si-OH) distribution to be observed.)

Percent Polymer  (% of silicon atoms in D and MOH polymer units)