Dynamical mechanical spectra

Figure 2. Dynamic mechanical spectra of TEOS-PTMO materials made with 50 wt% TEOS (PTMO MW=650, 1000, 2000) (a) storage modulus, (b) tan8.

Figure 3. Dynamic mechanical spectra of TEOS-PDMS materials made with 48 wt% TEOS (PDMS MW = 1700), storage modulus and tank...

Fig.1 Dynamic mechanical spectra of PMDA/ODA polyimide and poly(phenylquinoxaline),...

Fig. 2a, b. Dynamic mechanical spectra of imide-aryl ether phenylquinoxaline block copolymers, copolymer 3a (---) and copolymer 3b (---)... 

Fig. 11. Dynamic mechanical spectra and thermogravimetric spectra for copolymer 6h...

Figure 1. Dynamic mechanical spectra of 73127 and 80/20 TGDDM/DDS epoxy.

Plasticization, whose main manifestation is the decrease of the glass transition temperature (a transition in dynamic mechanical spectra), is generally accompanied by an increase of the glassy modulus in the temperature interval between Tp and T. , an effect is known as antiplasticization. 

The mechanical and rheo-optical properties of Kraton 101 have been studied by Stein136) using films cast from methylethyl ketone and from toluene solutions. The stress-strain curves, birefringence-strain curve, stress relaxation, birefringence relaxation, and dynamic mechanical spectra are dependent upon the morphology of the copolymer which in turn is dependent upon the conditions of preparations of the samples. 

Figure 9 shows the dynamic mechanical spectra of a series of poly-(tetramethylene oxide) /poly (tetramethylene terephthalate) (PTMO/ PTMT) segmented copolymers (67). These materials reveal only one Tg and one Tm analogous to semicrystalline thermoplastics. The magnitude of both transition temperatures shifts progressively higher with increasing... 

Phase Composition and Simultaneous Polymerization. Theoretically the phase composition of the SIN s should not be determined by the true solubility of one polymer in the other. Even though the true solubility of one polymer in the other is low because the components of the SIN s are incompatible, simultaneous polymerization and gelation are expected to cause entrapment of one component in the other. The degree of entrapment presumably will be controlled by the relative rates of the two reactions and their degree of simultaneity. The phase composition is reflected in the glass transition behavior of the material. Thus a close look at the dynamic mechanical spectra of the SIN s is necessary to determine the effect of simultaneous polymerization on phase composition. 

Analyzer (DMA) module. Figure 9 gives the dynamic mechanical spectra of the Ashland polyester and Dow vinyl ester resins. It is seen in Figure 9 that the Ashland resin has a higher Young s modulus than the Dow resin, over a wide range of temperatures. 

The influence of the cyclohexane ring on the glass transition temperature and sub-Tg transitions has been studied by dynamic mechanical methods [10,16,42]. These comparative studies have focused on the influence of the cyclohexyl substituent on observed thermal transitions. A systematic study of cycloalkyl substituents on alternating carbons of a polyethylene backbone was performed to study the influence of these substituents on the dynamic mechanical spectra of the polymers [42], These workers also prepared materials in which the cycloalkyl substituents were spaced away from the polymer backbone by successively longer methylene chains, testing the influence of ring proximity... 

As one example. Figure 3 shows the ratio of loss to storage modulus (tan 8) in the dynamic mechanical spectra of a series of materials made with a silanol-terminated PDMS (weight-average molecular weight [M ] 1700) and TEOS as a function of acid catalyst content. [With regard to the sample nomenclature used in Figure 3, TEOS(48)-PDMS(1700)-50-0.045-80C indicates that the material was prepared with 48 wt % of TEOS, 52 wt % of... 

L-glutamic acid-L-leucine. The dynamic mechanical spectra of these materials display highly moisture-sensitive relaxations at —13° and between -60° and -90°C (73, 74). 

The dynamic mechanical spectra for human stratum comeum are shown in Figure 24. There is a drop in modulus (E ) starting at 0°C... 

The presence of carboxylic groups, introduced by maleic anhydride, allows modified HTI to cross-link with unconventional agents, e. g. polyvalent metal oxides, hydroxides, polyamines. For instance, a sample of HTI, completely reacted with maleic anhydride, has been cured with ZnO at 153 °C for 20 minutes and o %d interestii tensile properties. Furthermore, the dynamic-mechanical spectra (Fig. 29)... 

Dynamic Mechanical Spectroscopy (DMS). Rectangular bars (3 x 12 x 45 mm) were cut from the molded plaques and dynamic mechanical spectra (DMS) obtained using a Rheometrics System-4. Values of G. G" and tans at various temperatures were obtained by oscillatory torsion of the bars at 1 Hz and 0.2% shear strain temperatures were varied between -100°C and 120°C at 5°C Intervals in the transition regions and at 10°C intervals elsewhere. Thermal soak times were five minutes in all cases. 

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