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Molecular weight melting temperature

For extrusion and blow moulding the polysulphones used are of higher molecular weight. Melt temperatures for blow moulding are of the order of 300-360°C with mould temperatures about 70-95°C. [Pg.601]

Molecular weight Melting temperature/°C Thermal ignition temperature/°C Crystal density at 20°C/gcm 3 Energy of formation/kJkg-1 Enthalpy of formation/kJ kg-1... [Pg.36]

Molecular weight Melting temperature/°C a-form /f-form... [Pg.40]

Molecular weight Melting temperature/cC Type A RDX Type B RDX... [Pg.42]

CO2 and NjO are isoelectronic, linear triatomics with similar molecular weights, melting temperatures and quadrupole moments. Although NjO has no inversion symmetry, it has been shown to resonate between two bonding configurations with opposing dipole moments N=N =0 and N= N =0 [88]. As a result, the net dipole moment of nitrous oxide is negligible... [Pg.178]

Gamma-irradiation technique is typically used to sterilize polyanhydrides (59). Aliphatic and aromatic homo- and copolymers were irradiated at 2.5 Mrad dose and the change in properties was monitored before and after irradiation. Properties such as molecular weight, melting temperature, and heat of fusion remained the same, and NMR and FT-IR spectra of the polymer were also similar... [Pg.5939]

Figure 1.1 The molecular weight-melting temperature relationship for the alkane series. An asymptotic value of about 145°C is reached for very high molecular weight linear polyethylenes. Figure 1.1 The molecular weight-melting temperature relationship for the alkane series. An asymptotic value of about 145°C is reached for very high molecular weight linear polyethylenes.
The table title reads Comparative table of the molecular weights, melting temperatures, viscosities, and solubilities of different poly(ethylene oxide) fractions . The results demonstrate the dependence of the melting point on chain length, a feature that is often used in pharmaceutical applications today. From [2]. Copyright Wiley-VCH. Reproduced with permission... [Pg.169]

Colour Molecular weight Melting temperature/°C Boiling temperature/°C Density at 20 °C/g cm Enthalpy of formation/kJ mol Energy formation/kJ mol Fine white crystalline solid 149.888 252 297 5.1 +308.78 +312.50... [Pg.37]

Colour Molecular weight Melting temperature/°C Thermal ignition temperature/°C Boiling point/°C Flash point/°C Density at 19 °C/g cm Molar volume at 20 °C and 760 Torr/cm moP Enthalpy of formation/kJ moP Energy formation/kJ moP Yellow crystalline solid 229.106 121.8-122.4 300 160-198 (decomp) 133.9 1.767 123.3 -214.35 -198.24... [Pg.43]

Molecular weight Melting temperature/°C Thermal ignition temperature/ C Boiling point/ C Flash point/ C Density at 20 °C/g cm ... [Pg.45]

Modification of BPA-PC for adaptation to the conditions of production of CD and CD-ROM disks, and of substrate disks for WORM and EOD was necessary. BPA-PC standard quaHties for extmsion and injection mol ding have, depending on molecular weight, melt flow indexes (MEI), (according to ISO 1130/ASTM 1238 in g/10 min at 300°C/1.2 kg, between less than 3 g/10 min (viscous types) up to 17 g/10 min. For CDs and optical data storage disks, however, MEI values exceeding 30 g/10 min, and for exceptionally short cycle times (5—7 s) even >60 g/lOmin are demanded at an injection mass temperature of 300°C (see Table 5). [Pg.157]

High diffusion coefficient (molecular weight, melt viscosity, temperature)... [Pg.190]

Fig. 1. Typical flow curve of commercial LPE. There are five characteristic flow regimes (i) Newtonian (ii) shear thinning (iii) sharkskin (iv) flow discontinuity or stick-slip transition in controlled stress, and oscillating flow in controlled rate (v) slip flow. There are three leading types of extrudate distortion (a) sharkskin like, (b) alternating bamboo like in the shaded region, and (c) spiral like on the slip branch. Industrial extrusion of polyethylenes is most concerned with flow instabilities occurring in regimes (iii) to (v) where the three kinds of extrudate distortion must be dealt with. The unit shows the approximate levels of stress where the sharkskin and flow discontinuity occur respectively. There is appreciable molecular weight and temperature dependence of the critical stress for the discontinuity. Other highly entangled melts such as 1,4 polybutadienes also exhibit most of the features illustrated herein... Fig. 1. Typical flow curve of commercial LPE. There are five characteristic flow regimes (i) Newtonian (ii) shear thinning (iii) sharkskin (iv) flow discontinuity or stick-slip transition in controlled stress, and oscillating flow in controlled rate (v) slip flow. There are three leading types of extrudate distortion (a) sharkskin like, (b) alternating bamboo like in the shaded region, and (c) spiral like on the slip branch. Industrial extrusion of polyethylenes is most concerned with flow instabilities occurring in regimes (iii) to (v) where the three kinds of extrudate distortion must be dealt with. The unit shows the approximate levels of stress where the sharkskin and flow discontinuity occur respectively. There is appreciable molecular weight and temperature dependence of the critical stress for the discontinuity. Other highly entangled melts such as 1,4 polybutadienes also exhibit most of the features illustrated herein...
The linear relation GC°=T observed in Fig. 12 is not sufficient evidence that would unambiguously support Eq. (6) and reveal the interfacial nature of the transition, because a bulk phenomenon may also produce such a temperature dependence. For instance, one might think of melt fracture and write down oc=Gyc that would be independent of Mw where yc would correspond to the critical effective strain for cohesive failure and modulus G would be proportional to kBT. Previous experimental studies [9,32] lack the required accuracy to detect any systematic dependence of oc on Mw and T. This has led to pioneers such as Tordella [9] to overlook the interfacial origin of spurt flow of LPE. It is in this sense that our discovery of an explicit molecular weight and temperature dependence of oc and of the extrapolation length bc is critical. The temperature dependence has been discussed in Sect. 7.1. We will focus on the Mw dependence of the transition characteristics. [Pg.256]

Many additional physical and chemical properties have been added. Whenever available, physical descriptions, formulas, molecular weights, melting points, boiling points, explosion limits, flash points, densities, autoignition temperatures, and the like have been supplied. [Pg.1964]

Figure 18. Solubility as a function of temperature for carbamazeprne (III) in 2-propanol. Experimental data obtained from Behme and Brooke (1991). Calculated curve via Margules Extrapolation Method as described by Frank et al. (1999) using the following input data solute-molecular weight, melting point, heat of fusion, and solubility in 2-propanol at 26 °C solvent-molecular weight and density. Figure 18. Solubility as a function of temperature for carbamazeprne (III) in 2-propanol. Experimental data obtained from Behme and Brooke (1991). Calculated curve via Margules Extrapolation Method as described by Frank et al. (1999) using the following input data solute-molecular weight, melting point, heat of fusion, and solubility in 2-propanol at 26 °C solvent-molecular weight and density.
The average molecular weight, polydispersity, temperature, hydrostatic pressure, and shear rate dependences of polymer melt viscosity will be discussed in Chapter 13, resulting in a set of correlations which can be used to obtain a rough estimate of melt viscosity as a function of all of these variables. A new correlation will be presented for the molar viscosity-temperature function. The dependences of the zero-shear viscosity of concentrated polymer solutions on the average molecular weight and on the temperature will also be discussed. Finally, a new model that was developed to predict the shear viscosities of dispersions of particles in both polymeric fluids and ordinary molecular fluids will be presented. [Pg.55]

Log melt viscosity of polysulphones of different molecular weights vs. temperature data shifted vertically for superimposition. The curve is log iq = 2000/(T + 40 — Tg). (Mills NJ and Nevin A, J. MacromoL Sci.-Phys., 4, 1970). [Pg.72]

In most materials, small amoimts of moisture will cause a change in the polymer s melt viscosity which, in turn, will affect the way it processes. When polymers, such as polycarbonate and polyester, are heated above the melt temperature, small amounts of moisture in the pellets or on the surface will cause a chemical reaction. This reaction can degrade the polymer, changing its molecular weight, melt viscosity, and mechanical strength. Larger amounts of moisture may result in a rough and scaly surface finish and even bubbles and voids in the product. [Pg.534]

The range of melt viscosities ordinarily encountered in materials is given in Table 10.5 (51). Polymer latexes and suspensions are aqueous dispersions with viscosities dependent on solid content and additives. Polymer solutions may be much more viscous, depending on the concentration, molecular weight, and temperature. [Pg.538]


See other pages where Molecular weight melting temperature is mentioned: [Pg.47]    [Pg.47]    [Pg.123]    [Pg.341]    [Pg.174]    [Pg.145]    [Pg.79]    [Pg.454]    [Pg.97]    [Pg.341]    [Pg.32]    [Pg.324]    [Pg.676]    [Pg.79]    [Pg.454]    [Pg.97]    [Pg.424]    [Pg.560]    [Pg.74]    [Pg.262]    [Pg.2805]    [Pg.6771]    [Pg.7729]    [Pg.560]   
See also in sourсe #XX -- [ Pg.45 , Pg.46 ]




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