Polymethyl methacrylate, spectrum

In the syndiotactic sequence the two methylene protons adjacent to an M—C—X group are in the same environment and are chemically equivalent, whereas in the isotactic sequence they are chemically nonequivalent and give rise to an AB spectrum. An example of the spectrum of a vinyl polymer, polymethyl methacrylate, is shown in Fig. 13.6. Note that the CH2 resonance around 2.1 ppm is a singlet in a but an AB quartet in b. 

Figure 5. The 0-ls XPS spectrum (---------) from clean polymethyl methacrylate.

Figure 21 HPLC/MS spectrum index plot of pMMA/BA copolymers. Mass spectra extracted from the total ion chromatogram show the progression from polymethyl methacrylate homopolymer (A) to polybutyl methacrylate homopolymer (F) in 20% butyl acrylate increments. 

Before each quasi in situ Fe Mossbauer measurement, a sample was loaded in a specially designed quartz reactor similar to that described in [16], which enabled the measurements of a sample under various atmospheres without exposing to air. The quartz reactor has two stopcocks at the ends and a side cell made of polymethyl methacrylate (PMMA). First, the sample placed in the quartz reactor was reduced under 300 °C for 2 h. After cooling to room temperature in He flow, both stopcocks were closed to seal the reactor filled with He gas. Then, the sample was moved into the side cell and a Mossbauer spectrum of the sample was measured. Mossbauer spectra were also collected for the catalysts after they were treated in the mixture containing 2 vol% CO, I vol% O2, and 0—40 vol% H2 in He in simulation to the reaction conditions. 

The surface morphology of whiskers can be characterized and analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Elgures 3.19 and 3.20 show SEM images and EDS spectrum of potassium titanate whiskers treated with polymethyl methacrylate (PMMA). According to the SEM results, the surface of unmodified whiskers is smooth without attachments, while the surface of modified whiskers is rough with attachments. The EDS spectrum of modified whiskers shows the characteristic peak of carbon (C). Both SEM and EDS results prove that the whisker surface is cladded with PMMA molecules.35... 

Some plastics, such as polymethyl methacrylate, decompose under thermal exposure into their monomers. Other plastics, such as polypropylene, generally form an entire spectrum of decomposition products. 

In Fig. k is shown the 90 MHz C-13 spectrum of free radical polymethyl methacrylate, the same as that in Fig. la. A superconducting instrument was employed, operating at 360 MHz for protons. Spectrum (a) shows all the resonances because of the large (ca. l60 ppm) range of chemical shifts, the spectrum is necessarily rather compressed. Tne u-methyl resonance (ca. 17-22 ppm, referred to tetramethylsilane as zero) is split into triads with pentad fine structure not discernible on this scale. 

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