Pure PMMA

The PMMA pellets were milled to a size of 0.5-1.5 mm. Table 24.1 shows the results of three runs in the fluidized bed with new material, one with tinted product from automobile rear lights. 

Raising the temperature increases the amount of gas. At temperatures beyond 550°C, the gas fraction increases rapidly, reaching 42 wt% at 590°C. The gas consists of methane, ethene, propene, carbon monoxide and carbon dioxide (Table 24.2). 

Only small amounts of carbon black are formed. The main component in the liquid is methylmethacrylate (MMA). At a pyrolysis temperature of 450°C it is 98.6%, and at 490°C it is 98.3% pure. Even coloured waste PMMA materials such as rear lights gave 

The detailed pyrolysis products are listed in Table 24.3. The influence of temperature on MMA is small between 450 and 500°C, but is drastically increased in the temperatme range 500-600°C. The MMA concentration decreases from 97 to 54%. 

4-Cyclohexane dicer-boxylic acid dimethyl ester 0.14 0.25 0.29 0.14 

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More recently, test products were created of a blend of PMMA with a phenyl-substituted methacrylate these products have a glass-transition temperature of around 125°C, a significantly reduced water absorption compared to pure PMMA of about 0.32%, but also a higher birefringence (a stress-optic coefficient of 5.2 X 10 , compared with 0.3 X 10 for PMMA and 6.8 x 10 for BPA-PC). 

Films containing about 10% CIRh(PPh3)3 in PMMA were prepared and subjected to oxygen index, TGA, and DSC measurements. The oxygen index, bottom ignition (1 1), increases from about 14 for pure PMMA to about 20 for the rhodium compound in PMMA. TGA analysis indicates that about 25% of the sample is non-volatile at 600°C and the glass transition temperature increases by about 15°C by DSC. 

All carbon resonances of pure PMMA, PS(OH), and their blends showed single-exponential decays in both Ti and Tjp. The Tj and Tjp values for the main resonance lines are shown in Figs. 13 and 14, respectively. For each of PMMA and PS(OH) containing different amounts of hydroxyl, the protons attached to different carbons have similar relaxation times, which indicates that the spin diffusion equalizes the relaxation rates of all protons. In addition, the Tj and Tip values for PS(OH) show a gradual decrease and increase, respectively, as the hydroxyl content in PS(OH) is increased. The difference in either Tj or Tj between PMMA and PS(OH) is substantial, encouraging the gathering of information about the phase structure of their blends by NMR relaxation time analysis. 

Fig. 13. Spin-lattice relaxation times of PS(OH) and PS(OH)/PMMA as functions of the hydroxyl content in PS(OH). for different protons attached to different carbons in pure PS(OH). A and O for different protons in PS(OH) and PMMA in the blends, respectively. Thin horizontal line for pure PMMA as a reference [111]...

Products with improved properties use instead pure PMMA a terpolymer from 1,3-butadiene, styrene, and methyl methacrylate (8). Actually, the proposed blend consists of up to 6 components of copolymers of different composition and particle diameters. 

The viscoelastic response of a series of CMIMx copolymers has been determined as a function of temperature [79]. The loss modulus, El, at 1 Hz, of a series of copolymers with molar content of maleimide units varying from 5 to 25% is plotted in Fig. 127 for comparison the curve for pure PMMA is also drawn. 

At first, the bulkiness of the CMI group creates sites with a lower local density, in which ester group 7r-flips with a smaller activation energy occur. This effect gradually disappears for MMA units located farther away from the CMI group along the chain, in such a way that the pure PMMA behaviour is recovered for MMA units separated from CMI cycle by five or more C - C bonds. 

Thus, assuming that the contribution of the MMA unit to J" is the same in MGIM36 as in pure PMMA, the contribution to /" of the MMA units contained in MGIM36 is given by 0.64 / (PMMA) and, consequently, the effect of... 

Type (1 ) A single phase which has the morphological features of pure PMMA with no indication of a second, dispersed phase. Samples of this type showed SEM photomicrographs identical to pure PMMA as shown in Figure 2. 

Putz et al. 2004 08) SWCNT Laser Ablation NASA Johnson Space Center Purified In situ polymerization CNT Loading levels 0.0001 to 0.014 wt% Bulk Composites Addition of 0.014 wt% SWCNT increased low temperature modulus by 10% beyond that of pure PMMA. ... 

The above cited authors further modified the procedure (57) by applying ultrasonication during the whole polymerization time the resulting pure PMMA and composite particles are presented in Figure 8.10. Figure 8.10(a) represents PMMA microparticles prepared under mechanical stirring. As can be seen, the particles pose uniform size distribution, with a slightly smaller diameter ( 6 pm) than in the previous paper (48). The other two pictures present... 

Fig. 25. a) ESR spectrum observed from pure PTFE after UV illumination at 77 K. b) ESR spectrum observed from pure PMMA after UV illumination at 77 K. c) Superposed spectrum the two spectra, a and "b ... 

A decay curve of PMMA radicals formed from the PTFE mechano-radical was obtained and is shown in Fig. 26 with those of pure PTFE radical and pure PMMA radfcal, which were produced by y-irradiation. The decay curve of the PMMA p-o-duced from the mediano-rathcal is apparently different from the rest of the two curves. This type of PMMA radical begins to decay in the lower temperature range, where the pure PTFE radical decays considerably but the pure PMMA does not. 

The parameters of the pyrolysis experiments are shown in Table 24.4. In the experiments, the pyrolysis temperature was 450°C which was found in previous experiment with pure PMMA to be the optimal temperature. Total mass balances are calculated to the organic content even for the filled PMMA to allow a comparison. The losses (1-2%) calculated to 100% were determined on all product fractions proportionately. The following results should be noted. 

The monomer recovery is the highest by feeding pure PMMA pellets (98.4 wt%) in the laboratory plant. But highly filled PMMA yielded monomer concentrations of 83-90 wt%. A short residence time is preferred. The good results of the laboratory-scale experiments were confirmed by the experiments in the technical-scale plant yielding 97% MMA for pure PMMA pellets and 83.5% for silica-filled PMMA. 

Table 24.4 Process conditions and product fractions for the pyrolysis of filled and pure PMMA in laboratory and mini pilot plants of fluidized beds at 450°C...

It was fonnd that the pyrolysis of the ATH-filled PMMA yielded only 58% MMA monomer instead of 97% fonnd with a pure PMMA feed. Hydrolysis products from MMA such as methacrylic acid, methanol and isobutyric acid were found to be the other main by-prodncts from the thermal decomposition of this composite material. Pyrolysis-GC-MS experiments showed that the yield of the monomer MMA can be increased to 65 wt% by lowering the process temperature to 400°C. Water released during pyrolysis of ATH and the chemical starter/stabilizer in the composite material were found to be responsible for the low monomer yield. The high amount of the alnmininm components in this material has almost no catalytic influence on the hydrolysis reaction because the same result was found if steam was used as fluidizing medinm instead of nitrogen. 

Fluorinated PMMA Pure PMMA Ethyl acetate Chang et al. (2007)" ... 

It is important that no THG intensity change was observed in the pure PMMA sample. Moreover, the THG efficiency of the pure PMMA sample was about 300 times smaller than that of the 10% DRl-PMMA sample with the same thickness. This proves the rationality of our ignoring the f f the polymer matrix in our theoretical model. 

Figure 422. Graph showing the improvement of wettability of PMMA after coating it with Ti02 by Mechanofusion. (Courtesy of Hosokawa Micron Corp., Osaka, Japan.) Pure PMMA is hydrophobic. As compared with simple mixing, product containing 10% Ti02 exhibits five times better wettability after Mechanofusion than PMMA powder simply mixed with 30% Ti02 ( in the graph)...

Fig. 1. C CPMAS spectra at room temperature for pure PVPh, pure PMMA... 

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