Resin rheological behavior

Pyrogenic silica is normally used in amounts smaller than 1 wt% in order to control the resin rheological behavior. However, for scratch-resistant coating systems the... 

Linear novolac resins prepared by reacting para-alkylphenols with paraformaldehyde are of interest for adhesive tackifiers. As expected for step-growth polymerization, the molecular weights and viscosities of such oligomers prepared in one exemplary study increased as the ratio of formaldehyde to para-nonylphenol was increased from 0.32 to 1.00.21 As is usually the case, however, these reactions were not carried out to full conversion, and the measured Mn of an oligomer prepared with an equimolar phenol-to-formaldehyde ratio was 1400 g/mol. Plots of apparent shear viscosity versus shear rate of these p-nonylphenol novolac resins showed non-Newtonian rheological behavior. 

Fig. 54 Influence of the pigment concentration on the rheological behavior. P.Y.73 in air drying alkyd resin paint.

P.O.19 has stimulated only limited industrial interest and is rarely used in Europe. It provides a shade which in white reductions resembles that of P.O.34, but which is much duller. Its full shade is noticeably yellower than that of P.O.34. P.O.19, incorporated in medium-oil alkyd resin systems, is less lightfast, both in full shade and in white reductions, than opaque P.O.34 types. The commercially available type exhibits poor rheological behavior. 

In spite of the fact that the rheological behavior during c ire of the Ashlemd polyester resin looks very similar to that of the Dow vinyl ester resin, the Ashlcuid polyester resin is found to be more reactive them the Dow vinyl ester resin, with the same formulation emd initiator system used in this study. Some iii Kjrtemt differences in the rheological responses are reflected on (1) the values of (2) the time at which shrinkage begins to occur when the fluid is at rest emd (3) the slope of the -( ii- 22 versus cure time curve. 

However, additional factors must be considered in order to understand and fuially predict the rheological behavior of silica-resin mixtures. In particular, the type and strength of particle interactions and the influence of adsorption processes on these interactions are key factors which govern the rheology of liquid media containing pyrogenic silica for rheology control. 

A standard commercial film blowing LLDPE resin, LPX-30, was blended at different ratios with either other LLDPE s or a LDPE polymer. The characteristic properties of these materials are listed In Table II. The resins were generously donated to the project by Esso Chem., Canada. Prior to blending the polymers were thoroughly characterized by SEC, SEC/LALLS, solution viscosity, CNMR, Atomic Absorbance, and their rheological behavior was characterized In steady state and dynamic shear flow as well as In the uniaxial extenslonal deformation (44-46). 

ABS Resins The Relation between Composition and Rheological Behavior... 

This paper, the third in a rheotechnics series, reports on rheological studies performed at y higher than 10 1 sec-1. In two-phase polymer systems, Rosen and Rodriquez (3) hypothesized anomalous behavior (yield shear stress) at y = 10 1. Recently, Zosel (9) verified this hypothesis experimentally for ABS systems. A study of the rheological behavior of ABS resins at very low y is now in progress at our laboratories. The correlation between rheological behavior and moldability will be discussed in detail in a subsequent paper. 

We have calculated from the model the characteristics of these newly designed structures, which have been synthesized [23], and we have measured their rheological properties at room temperature. As Fig. 16.4 shows, it is possible to mimic the rheological behavior of the [SIS-SI] blend (we have applied a vertical shift on the curves for greater clarity). Also, the rheological behavior of the full formulations (Fig. 16.4) based on these newly designed copolymers yields the same properties as for [SIS-SI], which demonstrates that the tackifying resins act Hke a solvent of the elastomeric part of all the copolymers presented here. 

Investigations of turbidity spectra of PN-609-21M polyester resin in the presence of surfactant have permitted us to determine the concentration interval in which a surfactant significantly affects the system s condition and to define the character of this influence on copolymerizing systems. Investigation of the influence of these surfactants on the rheological behavior of the system was done with the aim of confirming the regularities and assumptions described above. 

Today, hb polymers are used and discussed widely for different applications, with a major use of these highly branched materials as reactive components in coating and resin formulations. In addition, potential applications as additive compounds in linear polymers, especially for improving not only rheological, flow and surface properties but also thermal stabihty and modulus, represent the main reasons for the development of hb macromolecules as specialty polymers. These application fields relate to the major features of hb polymers a highly branched, dense but irregular structure which leads to excellent solubility a low solution viscosity and a modified melt rheological behavior in combination with the option to introduce a wide variety of reactive end functionalities [6-11). 

Designation system was developed for vinyl chloride thermoplastic resins which may be used as the basis of specification. In respect to plasticizers, the system allows to include in specification, plasticizer absorption at room temperature, viscosity of paste, and rheological behavior of paste. The second part of ISO standard gives a list of ISO standards used for testing of properties included in designation system and describes preparation of sample. 

The 4-nonylphenol methanal resin fiom a methanal/phenol mole ratio = 0.67 reaction is a solid product with an average molecular weight of 1400 g mole, as determined in hexane by cryoscopy. Rheological investigation of all of the resins showed a non-Newtonian rheological behavior [122]. 

Obviously, the rheological performance of fumed silica in adhesives, resins, and paints is mainly determined by the stability of the colloidal network. This raises the question of which parameters influence the formation and stability of a colloidal silica network. In order to answer this question we have to understand a) the nature of interactions in silica/resin/solvent mixtures in terms of the silica-silica, silica-resin, and silica-solvent interactions, and b) how these interactions influence the rheological behavior of the mixtures. From this information we should be able to develop a comprehensive model that explains the rheological performance of different grades of fumed silica in different resin types. 

The step profile reveals that N20 and H18 dispersed in Palatal P4 exhibit an almost identical rheological behavior, whereas the apparent relative viscosities of N20 and H18 dispersed in Atlac 590 at low and moderate shear rates are distinctly different. To explain this behavior it is necessary to consider the polarity, functional groups, and chain length of the resins but also the surface properties of the fumed silica. All parameters together will influence the nature and strength of the colloidal forces, which govern the rheology of the mixtures. 

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