For polystyrene

Fig. XI-5. Adsorption isotherm from Ref. 61 for polystyrene on chrome in cyclohexane at the polymer theta condition. The polymer molecular weights x 10 are (-0) 11, (O) 67, (( )) 242, (( )) 762, and (O) 1340. Note that all the isotherms have a high-affinity form except for the two lowest molecular weights.

Samples of analyte are dissolved in a suitable solvent and placed on the IR card. After the solvent evaporates, the sample s spectrum is obtained. Because the thickness of the PE or PTEE film is not uniform, the primary use for IR cards has been for qualitative analysis. Zhao and Malinowski showed how a quantitative analysis for polystyrene could be performed by adding an internal standard of KSCN to the sample. Polystyrene was monitored at 1494 cm- and KSCN at 2064 cm-. Standard solutions were prepared by placing weighed portions of polystyrene in a 10-mL volumetric flask and diluting to volume with a solution of 10 g/L KSCN in... 

Figure 1.2 shows sections of polymer chains of these three types the substituent R equals phenyl for polystyrene and methyl for polypropylene. The general term for this stereoregularity is tacticity, a term derived from the Greek word meaning to put in order. ... 

Since the compliance is essentially the inverse of the modulus, it is not surprising that the same four regions of mechanical behavior show up again here. The data for polystyrene is more fully developed, so we shall examine if. 

Figure 3.12 Log-log plots of compliance versus time for polystyrene at 100 C and cis-polyisoprene at -30°C. (Data of D. J. Plazek and V. M. O Rourke and of N. Nemoto, M. Moriwaki, H. Odani, and M. Kurata from Ref. 4.)...

Figure 3.12 shows that, at long times, the creep compliance is directly proportional to time for the polymers shown. For polystyrene (M = 600,000) at 100°C, the following values describe the linear portion of the datat ... 

Use Eq. (3.69) to evaluate the viscosity of the polymer at this temperature. For polystyrene M. = 30,000. Use the viscosity value calculated above and the entanglement correction procedure introduced in Example 3.7 to... 

Use values of the constants for polystyrene from Table 4.4 to calculate the shift factors needed to connect those segments in Fig. 4.17 measured at 96.3 and 108.7°C, with the isotherm measured at Tg = 100.0°C. Are the values reasonable ... 

Combination and disproportionation are competitive processes and do not occur to the same extent for all polymers. For example, at 60°C termination is virtually 100% by combination for polyacrylonitrile and 100% by disproportionation for poly (vinyl acetate). For polystyrene and poly (methyl methacrylate), both reactions contribute to termination, although each in different proportions. Each of the rate constants for termination individually follows the Arrhenius equation, so the relative amounts of termination by the two modes is given by... 

Figure 6.8 Effect of chain transfer to solvent according to Eq. (6.89) for polystyrene at 100°C. Solvents used were ethyl benzene ( ), isopropylbenzene (o), toluene (- ), and benzene (°). [Data from R. A. Gregg and F. R. Mayo, Discuss. Faraday Soc. 2 328 (1947).]...

From the ratio of activities and measured values of n, the average number of initiator fragments per polymer can be determined. Carry out a similar argument for the ratio of activities for polystyrene and evaluate the average number of initiator fragments per molecule for each polymer from the following datat ... 

By combining Eqs. (8.42), (8.49), and (8.60), show that Vi°(52 - 5i) = (l/2)RTj., where T. is the critical temperature for phase separation. For polystyrene with M = 3 X 10, Shultz and Floryf observed T. values of 68 and 84°C, respectively, for cyclohexanone and cyclohexanol. Values of Vi° for these solvents are abut 108 and 106 cm mol", respectively, and 5i values are listed in Table 8.2. Use each of these T. values to form separate estimates of 62 for polystyrene and compare the calculated values with each other and with the value for 62 from Table 8.2. Briefly comment on the agreement or lack thereof for the calculated and accepted 5 s in terms of the assumptions inherent in this method. Criticize or defend the following proposition for systems where use of the above relationship is justified Polymer will be miscible in all proportions in low molecular weight solvents from which they differ in 5 value by about 3 or less. 

Shultz and Floryf measured the critical temperature for precipitation for polystyrene fractions of different molecular weight in cyclohexane. The following results were obtained ... 

Under 0 conditions occurring near room temperature, [r ] = 0.83 dl g for a polystyrene sample of molecular weight 10. f Use this information to evaluate tg and for polystyrene under these conditions. For polystyrene in ethylcyclohexane, 0 = 70°C and the corresponding calculation shows that (tQ /M) = 0.071 nm. Based on these two calculated results, criticize or defend the following proposition The discrepancy in calculated (rQ /M) values must arise from the uncertainty in T>, since this ratio should be a constant for polystyrene, independent of the nature of the solvent. 

Fox and Floryf used experimental molecular weights, intrinsic viscosities, and rms end-to-end distances from light scattering to evaluate the constant in Eq. (9.55). For polystyrene in the solvents and at the temperatures noted, the following results were assembled ... 

Zimmt has reported the intensity of scattered light at various angles of observation for polystyrene in toluene at a concentration of 2 X 10" ... 

For polystyrene in butanone at 67 C the following values of KC2/R0 X 10 were measuredf at the indicated concentrations and angles. Construct a Zimm plot from the data below using k = 100 cm g" for the graphing constant. Evaluate M, B, and from the results. In this experiment... 

Table 17. Inorganic Synergists—Halogen System for Polystyrene and ABS...

The successflil appHcation of time—temperature superposition (159) for polystyrene foam is particularly significant in that it allows prediction of long-term behavior from short-term measurements. This is of interest in building and constmction appHcations. 

Coefficient of Linear Thermal Expansion. The coefficients of linear thermal expansion of polymers are higher than those for most rigid materials at ambient temperatures because of the supercooled-liquid nature of the polymeric state, and this applies to the cellular state as well. Variation of this property with density and temperature has been reported for polystyrene foams (202) and for foams in general (22). When cellular polymers are used as components of large stmctures, the coefficient of thermal expansion must be considered carefully because of its magnitude compared with those of most nonpolymeric stmctural materials (203). 

Plastics. Vehicles in offset inks for plastics (polyethylene, polystyrene, vinyl) are based on hard drying oleoresinous varnishes which sometimes are diluted with hydrocarbon solvents. Letterset inks for polystyrene employ vehicles of somewhat more polar nature. Polyester or other synthetic resins (acryhc) dissolved in glycol ethers and/or esters are used in some of the older inks. Uv inks are widely used for decoration of these preformed plastic containers. 

Nickel dialkyldithiocarbamates stabili2e vulcani2ates of epichlorhydrinethylene oxide against heat aging (178). Nickel dibutyldithiocarbamate [56377-13-0] is used as an oxidation inhibitor in synthetic elastomers. Nickel chelates of substituted acetylacetonates are flame retardants for epoxy resins (179). Nickel dicycloalkyldithiophosphinates have been proposed as flame-retardant additives for polystyrene (180—182) (see Flame retardants Heat stabilizers). 

Noryl. Noryl engineering thermoplastics are polymer blends formed by melt-blending DMPPO and HIPS or other polymers such as nylon with proprietary stabilizers, flame retardants, impact modifiers, and other additives (69). Because the mbber characteristics that are required for optimum performance in DMPPO—polystyrene blends are not the same as for polystyrene alone, most of the HIPS that is used in DMPPO blends is designed specifically for this use (70). Noryl is produced as sheet and for vacuum forming, but by far the greatest use is in pellets for injection mol ding. 

R. B. Bishop, Practical Pohymerisation for Polystyrene Cahners Books, Boston, Mass., 1971. 

The spreading rate of a polymer droplet on a surface has been measured (363,364). The diffusion constant was at least an order of magnitude smaller than that of the bulk. The monomer—surface friction coefficient for polystyrene has been measured on a number of surfaces and excellent... 

Processing is relatively easy. In general, products based on S—B—S are processed under conditions appropriate for polystyrene, whereas products based on S—EB—S are processed under conditions appropriate for polypropylene. Pre-drying is not needed and scrap is recycled. 

Most ion exchangers in large-scale use are based on synthetic resins—either preformed and then chemically reacted, as for polystyrene, or formed from active monomers (olefinic acids, amines, or phenols). Natural zeolites were the first ion exchangers, and both natural and synthetic zeolites are in use today. 

TABLE 16-7 Equilibrium Constants for Polystyrene DVB Cation and Anion Exchangers... 

FIG. 23-23 Batch and continuous polymerizations, (a) Polyethylene in a tiihiilar flow reactor, up to 2 km long hy 6,4 cm ID, (h) Batch process for polystyrene, (c) Batch-continuous process for polystyrene, (d) Suspension (head) process for polyvinylchloride, (e) Emulsion process for polyvinylchloride, (Ray and Laurence, in Lapidus and Amundson, eds, Chemical Reactor Theory Review, Frentice-Hall, 1977. )... 

Data for the yield strength, tensile strength and the tensile ductility are given in Table 8.1 and shown on the bar-chart (Fig. 8.12). Like moduli, they span a range of about 10 from about 0.1 MN m (for polystyrene foams) to nearly 10 MN m (for diamond). 

Tables 5.4 and 5.5 predict that unvulcanised natural rubber (8 = 16.5) will be dissolved in toluene (8 = 18.2) and in carbon tetrachloride (8 = 17.5) but not in ethanol (8 = 26.0), all values being in units ofMPa. This is found to be true. Similarly it is found that there is a wide range of solvents for polystyrene in the solubility parameter range 17.2-19.7 MPa. ...

The cooling requirements will be discussed further in Section 8.2.6. What is particularly noteworthy is the considerable difference in heating requirements between polymers. For example, the data in Table 8.1 assume similar melt temperatures for polystyrene and low-density polyethylene, yet the heat requirement per cm is only 295 J for polystyrene but 543 J for LDPE. It is also noteworthy that in spite of their high processing temperatures the heat requirements per unit volume for FEP (see Chapter 13) and polyethersulphone are, on the data supplied, the lowest for the polymers listed. 

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