Polystyrene, 413 Table

Polystyrene. Table 3 shows the results obtained for three broad MWD polystyrene samples. The agreement for M and M values obtained from SEC/Viscometry analysis and the nominaY values supplied by the vendors is excellent. In addition the Mark-Houwink parameters, K and a values also are in excellent agreement with each other as well as with literature values.(28,39) This shows the consistency of the analysis method and the technique for determining the dead volume between detectors. The lower M value for the NBS 706 sample is due to the low molecular weight tail associated with the sample. 

Fig. 3.6. Effect of polydispersity on the relation between the number averages of reduced stored free energy and reduced shear rate for a series of polystyrenes (Table 3.3) in monobromo-benzene at 25° C (75). The following concentrations given in g/100cms are used PS III () ) 3.0, (4) 1.5, (a) 0.75 DII (o-) 0.80, (-o) 0.575, () 0.39 DIV ( -) 1.0, ( ) 0.75, (- ) 0.55 F (>j) 1.0, (A) 0.7, ( ) 0.4 Taps. No. 15 ( -) 1.0, (- ) 0.633, (f ) 0.4. The full line indicates the non-draining behaviour of a monodisperse polymer (80). The dotted line is the result of extrapolating the data for PS III to zero concentration. The (MJMn)-ratios of the samples are given near the experimental points...

Polystyrene and its Copolymers. Polystyrene (Table 15.7) is made by continuous bulk polymerization, initiated by peroxides and... 

Comprehensive tabulations of %, reported by numerous investigators for various polymer-liquid systems, have been compiled by Orwoll [43], who classified these data according to polymer (P), liquid (L), volume fraction of polymer (v), and temperature (T). Of the 85 x-values reported for the P-L systems in which P is polystyrene (Table XIX of Ref. 43), 23 had been measured at 25 °C, and therefore only these data were available for correlation with the swelling powers, C, determined for the corresponding liquids at 23 °C in 3M laboratories [180]. 

The C—C backbone of SPS takes a planar zig-zag conformation in the crystal whereas IPS takes a 3/1 helical conformation in crystal. This difference in chain conformation in the crystal affects the crystallization rate of these polystyrenes. Table 18.1 [32] compares the crystallization parameters between SPS and IPS. The work of chain folding, Q, of SPS is smaller than that of IPS, which suggests that the chain folding of SPS can take place more easily than that of IPS. Also, SPS has a smaller surface free energy. These differences are related to the crystallization rate difference between SPS and IPS, which have different stereoregularities. 

RUBBER MODIFICATION OF SYNDIOTACTIC POLYSTYRENE Table 19.1 Impact modification of sPS as described in EP 318 793 [15]... 

The burn results for polymers 15 and 19 show that the polymers are inherently flame retardant with low base flammability (Table 4). The polymer dripped but did not ignite the cotton when it was subjected to the UL-94 flame test, and with the addition of 1 wt% PTFE, it did not drip. The PCFC results show that these polymers have a high heat release capacity when compared with the BPC carbonates and aryl ethers, but it is still significantly less than that of the base commodity polymers, such as polyethylene or polystyrene (Table 5). 

Poly-a,P,P trifluorostyrene has slightly lower stability than polystyrene (Table 12). The relatively large amount of monomer formed suggests that chain scission is followed by depolymerization. Poly-2,3,4,5,6 penta-fluoropolystyrene is much more stable than polystyrene (Table 12). Wall et al. [269] attributed this increased stability to the loss of resonance interaction between the phenyl group and the chain because of the presence of the fluorine atoms. Perfluorostyrene polymerized by 7-irradiation has, however, been found recently to have a stability close to that of polystyrene a rate of weight loss of 0.4% per min was found at 335°C and complete decomposition of the polymer is observed at 432°C [270],... 

We performed calibration tests for three low-impedance wedge materials, polyetherimide, acrylic (Lucite), and polystyrene. Table 5-4 lists the liquids used for the calibration tests note that all of the liquids have similar densities but vary in viscosity. The calibration results are shown in Fig. 5-40, which reveals that Lucite is the best of the three as a wedge material for measuring viscosity. However, all of the measured viscosities are lower than their expected values. The discrepancies may be attributed to non-Newtonian fluid behavior, surface wetting, and poor sensitivity. 

An alternative method for this conversion was the treatment of the bromine end groups with sodium azide in DMF at 80X. Both methods led to complete conversion of the halogen groups which was clearly observed in the H-NMR spectrum for polystyrene (Table VQ) (. The azide end groups were also noticeable in IR-spectra at about 2100 cm For acrylates, the intensity of this peak was used to quantify the amount of azide present... 

Similar to the gel-type styrene copolymers, the hypercrosslinked networks based on both linear polystyrene and styrene-DVB copolymers are transparent materials, being in dry or swollen state. Nevertheless, alternatively to the conventional copolymers, the hypercrosslinked networks exhibit very low apparent density (Papp) when isolated from the reaction media and dried. The apparent density of the polymers (I) based on linear polystyrene (Table 7.7) decreases with increasing the degree of crosslinking ... 

The clarity, as measured by haze, is as good or better than any of the competitive commercial resins, and these resins are colorless. Some competitive materials such as cellulosic and SAN frequently have a bluish or yellowish cast, lapact polystyrenes, on the other hand, are opaque. Hie haze of the commercial production thus far realized has been consistently near one per cent, which puts it in a class with general purpose polystyrene. Table II summarizes data on appearance. 

A second-generation model comprised a mass balance of uptake and loss processes that more accurately reflected physiological processes through calibration to experimental data [154]. This model examined the mass transfer of PCBs from plastics to lugworms Arenicola marina) upon ingestion and by dermal contact in two environments closed laboratory bioassay systems and open marine systems. The results depended in part on the type of plastic, as polyethylene has a greater affinity for POPs than polystyrene. Table 4.9 summarizes those results. 

The mechanical properties of polylactic acid are similar to those of polystyrene (Table 4). Problems still unsolved are the too low glass transition temperature, the limited stability to hydrolysis and the slow crystallization rate. Main applications at development stage are in the sectors of bottles, thermoformed containers for food, films and fibers. 

Copolymers of polystyrene with acrylonitrile (SAN), a-methylstyrene (SMS), acryl-styrene-acrylester (ASA), or acrylonitrile-ethylene-propylene styrene (AES) exhibit better weathering stability than homo-polystyrenes, Table 5.3. All polymerized styrenes will yellow under long-term weathering conditions, however, and their... 

Stress-cracks are formed in parts molded from polystyrene when they are exposed to mechanical stresses and certain media. Here, influence of media that would normally not or only lightly attack stress-free molded parts can lead to crack formation. Fibrillated crazes are typical of polystyrene Table 5.71 provides typical dimensions [193]. 

TRANSITION METAL CATALYSTS FOR SYNDIOTACTIC POLYSTYRENE TABLE 2.5 Effects of the Bite Angle of Cp Ligands on Catalyst Performance... 

PROPERTIES OF SYNDIOTACTIC POLYSTYRENE TABLE 133 Mechanical Properties of Neat Polymers... 

The resnlts qnoted in Tables 13.9 and 13.10 show that lauric diethanolamide is almost completely extracted from 0.05 mm thick low-density polyethylene film into each of the five BPF extractants during 10 days exposure at 60 "C. Complete additive extraction wonld not necessarily occur in the case of thicker polyethylene films. Also, it has been shown that in the aqueous extractants most, or all, of the lauric diethanolamide extracted from polyethylene (Tables 13.9 and 13.10) or polystyrene (Table 13.11) is then hydrolysed to DBA and fatty acid, although, of course, this does not occur in the liqnid paraffin extractant. 

All older measurements on polystyrene were done on atactic, and as a result amorphous, polystyrene. Table III. 17 contains a list of the best data available to date. From zero to 5° K an average of the data by Reese (1966), Noer, Dempsey, and Gordon (1959) and Choy, Hunt, Salinger, and Chiang (1968) is reported. The data follow a T temperature dependence with a Debye temperature of 68° K for 4 vibrations per mole of repeating unit. At temperatures below about 1.5° K it can be seen. 

An assortment of values of the Hamaker constant A is collected in Table VI-4. These are a mixture of theoretical and experimental values there is reasonable agreement between theory and experiment in the cases of silica, mica, and polystyrene. 

The monolayer amount adsorbed on an aluminum oxide sample was determined using a small molecule adsorbate and then molecular-weight polystyrenes (much as shown in Ref. 169). The results are shown in the table. Calculate the fractal dimension of the oxide. 

ETHYLENE We discussed ethylene production in an earlier boxed essay (Section 5 1) where it was pointed out that the output of the U S petrochemi cal industry exceeds 5 x 10 ° Ib/year Approximately 90% of this material is used for the preparation of four compounds (polyethylene ethylene oxide vinyl chloride and styrene) with polymerization to poly ethylene accounting for half the total Both vinyl chloride and styrene are polymerized to give poly(vinyl chloride) and polystyrene respectively (see Table 6 5) Ethylene oxide is a starting material for the preparation of ethylene glycol for use as an an tifreeze in automobile radiators and in the produc tion of polyester fibers (see the boxed essay Condensation Polymers Polyamides and Polyesters in Chapter 20)... 

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. 

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