Polystyrene samples

Fig. 4 X-ray refraction topography of a polystyrene sample with highly oriented micro cracks induced by strain in vertical direction.

The refractograp of figure 4 shows highly oriented micro cracks of a polystyrene sample. The orientation of the cracks is perpendicular to the mechanical strain direction. The X-ray refracted intensitiy can be interpreted as crack density, i.e. the inner surfaces within a unit volume. Changing the tilt angle (of polystyrene and polystyrene blend samples) with respect to the primary beam leads to significantly different distributions of crack orientation (Fig. 5). 

A polystyrene sample of molecular weight 10 shows an rms end-to-end distance under unperturbed conditions equal to 735 A. In polystyrene Mq = 104 and the length of the carbon-carbon bond along the backbone is 0.154 nm. Use these data to verify the numbers given for this polymer in Table 1.6. 

At 200°C the Newtonian viscosities of polystyrene samples of different molecular weights were studied by Spencer and Dillont and the following results were reported ... 

Suppose you wanted to estimate the viscosity of a polystyrene sample at 125°C using the Debye viscosity equation, but the only available value... 

The equations derived in Sec. 6.7 are based on the assumption that termination occurs exclusively by either disproportionation or combination. This is usually not the case Some proportion of each is the more common case. If A equals the fraction of termination occurring by disproportionation, we can write n = A[ 1/1 - p] + (1 - A)[2/(l - p)] and n /n = A(1 + p) + (1 - A)[(2 + p)/2]. From measurements of n and n /n it is possible in principle to evaluate A and p. May and Smith have done this for a number of polystyrene samples. A selection of their data for which this approach seems feasible is presented ... 

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. 

Both preparative and analytical GPC were employed to analyze a standard (NBS 706) polystyrene sample. Fractions were collected from the preparative column, the solvent was evaporated away, and the weight of each polymer fraction was obtained. The molecular weights of each fraction were obtained usmg an analytical gel permeation chromatograph calibrated in terms of both and M. The following data were obtained ... 

Three polystyrene samples of narrow molecular weight distribution were investigatedf for their retention in GPC columns in which the average particle size of the packing was varied. In all instances the peaks were well resolved. The following results were obtained ... 

Figure 12.3 Clrromatogr-ams of an ignition-resistant high-impact polystyrene sample (a) Microcolumn SEC fi ace (b) capillary GC trace of peak x . Peak identification is as follows 1, ionol 2, benzophenone 3, styrene dimer 4, palmitic acid 5, stearic acid 6, styrene trimers 7, styrene trimer 8, styrene oligomer 9, Irganox 1076 and Irganox 168 10, styrene oligomer 11, nonabromodiphenyl oxide and 12, decabromodiphenyl oxide. Reprinted with permission from Ref. (12).

Furusawa and Yamamoto [16] studied the adsorption process of polystyrene samples (M ranging from 16700 to 2xl06) with narrow molecular weight distribution (Mw/M = 1.01-1.07) at the -conditions (cyclohexane, 35 °C). Controlled pore glass with pore diameter of 1000 A was used as an adsorbent. 

The aim of the present paper is to report on the solution structure of polymers, to show how structure-property relationships can be derived in a simple manner, so that they can be used for technical applications. Some predictions will also be made concerning the viscous and elasticity yield as well as polymer shear stability. To demonstrate these theoretical predictions narrowly distributed polystyrene samples will mainly be used as examples. 

Fig-1- Bueche plot for various narrowly distributed polystyrene samples in toluene (A) Mw=... 

Fig. 10. Viscosity vs. shear rate for polystyrene samples of various molar masses in toluene at 25 °C...

Successful combination of a chromatographic procedure for separating and isolating additive components with an on-line method for obtaining the IR spectrum enables detailed compositional and structural information to be obtained in a relatively short time frame, as shown in the case of additives in PP [501], and of a plasticiser (DEHP) and an aromatic phenyl phosphate flame retardant in a PVC fabric [502], RPLC-TSP-FTIR with diffuse reflectance detection has been used for dye analysis [512], The HPLC-separated components were deposited as a series of concentrated spots on a moving tape. HPLC-TSP-FTIR has analysed polystyrene samples [513,514], The LC Transform has also been employed for the identification of a stain in carpet yarn [515] and a contaminant in a multiwire cable [516], HPLC-FTIR can be used to maintain consistency of raw materials or to characterise a performance difference. 

Beaucage [83] showed that it could be possible to get branching information for polymers using this approach. In Figure 14, where neutron scattering data for branched polystyrene is fit to the unified equation [83,107,110-112], it was shown that it is possible to calculate the parameters dmin and c, from such a fit [83]. These model branched polystyrene samples were synthesized by using divinyl benzene (10%) as a comonomer, to obtain controlled levels of branching but where the placement is random. 

Molecular Weight Characteristics and Quiescent Adsorption at the 0-Condition of the Polystyrene Samples... 

In figure 1 we present the experimental and calculated mK values of the copolymer poly(styrene-co-p-bromostyrene). From this study (3) we were able to show unequivocally that the tacticity of this polystyrene sample is pr — 0.55, where pr is the probability of racemic dyad replication. 

Guerra, G. Vitagliano, V. M. De Rosa, C. Corradini, P., Polymorphism in melt crystallized syndiotactic polystyrene samples, Macromolecules 1990, 23, 1539 1544... 

Fig HPLC of a polystyrene sample. This figure give Molecular weight of the fractions present in the sample. 

Figure 4. Arrhenius plot of rate constants determined for 600K MW polystyrene samples.

P.Br.25 also shows excellent lightfastness in polyolefins. Transparent polystyrene samples are heat stable up to 280°C, while specimens reduced considerably with Ti02 withstand up to 240°C. P.Br.25 is also used in polyester, in which it provides an interesting raw material for the manufacture of bottles. 

Table 7. Weight average molecular weight of a standard polystyrene sample (N.B.S. 705) by different methods...

Table 18. Values173) of (molecular weight x 10-4) for two polystyrene samples PS - PX prepared by Asahi Dow Chem. Co. Ltd. and PS - IU distributed by Macromolecular Division of I.U.P.A.C. see footnote for further details and explanation of abbreviations...

Number-average molar masses were determined using a vapor pressure osmometer (VPO) (Hitachi 117 Molecular Weight Apparatus) at 54.8 0.1°C in toluene (Fisher Scientific, certified A.C.S.) which was distilled from freshly crushed CaH2. The VPO apparatus was calibrated with pentaerythritol tetrastearate (Pressure Chemical). Gel permeation chromatographic (GPC) analyses were performed in tetrahydrofuran by HPLC (Perkin-Elmer 601 HPLC) using six y-Styragel columns (106, 105, 10l, 103, 500, and 100 A) after calibration with standard polystyrene samples. 

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