Gordon-taylor relationship

Earlier work on chain extended HPLs has shown that these derivatives produce uniform (i.e., single phase) polymers with Tg varying in accordance with the Gordon-Taylor relationship (12). Polyurethanes from chain-extended HPLs were found to be rubber-like at room temperature with modulus declining as lignin content is reduced (8). Star-like structure determines functionality, Tg, viscosity, and several other properties that influence utility as polymer segment. 

Theoretically miscible polymer blends will show Tg values that are intermediate between those of the parent polymers. They follow such models as the Fox or Gordon-Taylor relationships (18,19). However, in the case of HPL/PVA blends, the Tg data did not follow any of these well known models, and Tg values above those of the parent polymers were observed (10). The quotient of the experimental blend-Ttf divided by the predicted (Fox) Tg consistently rose above 1.00 for blends exceeding 5% HPL content (10). This indicates molecular interactions between HPL and PVA. An... 

FIGURE 3.18 The variation of the glass transition temperature of binary systems with composition, presented in terms of the Gordon-Taylor relationship (a) phenobarbital-salicin and (b) antipirin-phenobarbital. (Reproduced from Fukuoka, E., Makita, M., and Yamamura, S., Chem. Pharm. Bull., 37, 1047, 1989. With permission.)... 

FIGURE 4.19 Gordon Taylor relationships for PLA, PLGA 75 25, and PLGA 50 50. 

Figure 5-6. (a) Dependence of T on p for mixtures of polymethyl methacrylate with diethyl phthalate. Comparison of experimental results with equation (5-8). Parameters found were ctjctp = 2.32, Tgd = -57 °C, Tgp = 104 °C.f [After F. N. Kelley and F. Bueche, J. Polym. Sci., 50 549 (1961)] (b) Variation of Tg for a miscible polymer blend of polycaprolactone (PCL) and poly(styrene-co-acrylonitrile) (SAN), with a description of the data using the Gordon-Taylor relationship, equation (5-27). The two points at low SAN content have a higher-than-expected Tg because of crystallization of the PCL. [After S-C. Chiu and T. G. Smith, J. Appl. Polym. Sci., 29,1797 (1984). Copyright 1984, Wiley Periodicals, Inc., a Wiley Company.]... 

This is a form of the Gordon-Taylor relationship, equation (5-27), although the original equation was expressed in terms in mass rather than volume fraction. 

The T of polymer blends can be related to the blend composition by different equations, as shown in Table 12.2. The T of miscible blends of poly(p-dioxa-none) with poly(vinyl phenol) (PPDO/PVPh) [74], as studied using the Fox [75], Gordon-Taylor [76], Couchman-Karasz [77] and Kwei [78] models, showed that the experimental data lay below the Fox equation, suggesting that the free volume of the blends was larger than predicted, assuming free volume additivity. On the other hand, the Gordon-Taylor and the simplified Kwei equations fitted the experimental T values appropriately. Other studies have shown that the Ta of SAN/PMMA blends was also effectively approached by the Gordon-Taylor relationship [79,80]. 

Fig. 7 Glass transition vs. water content relationship for amorphous indomethacin. Lines show fit to the Gordon-Taylor equation with K values of 0.33 (predicted) and 0.11...

Firstly the effect of on Tg of a food polymer is considered. To establish moisture content and relationship, the sorption isotherm for water/soy flour system is developed. Information of this kind is readily available in the literature for various systems (Labuza and Hyman, 1998). The Gordon-Taylor equation (Gordon and Taylor, 1952) is used to predict the effect of (using moisture content vs. relationship obtained from MSI) on Tg. The Gordon-Taylor equation has been used to predict the Tg of several binary mixtures (Roos, 1995 Morales-Diaz and Kokini, 1998). In general for most food polymers with a distribution of hydrophilic groups an increase in a results in a decrease in Tg (Slade and Levine, 1995). The Tg predicted with the Gordon-Taylor equation is used as a first part of our modification. 

Water acts as a plasticizer for soy flour (Yildiz and Kokini, 2001). Therefore, increase in water content will plasticize the matrix causing an increase in available free volume for molecular transport. Moisture diffusion as a result will be effected from the water activity of the system. The relationship between moisture content and a can be established using the moisture sorption isotherm (MSI) of soy flour. The glass transition temperature is a very important concept in the diffusion process. At the vicinity of the glass-transition temperature the diffusion process increases at a higher rate. Figure 46.1 shows the plasticization effect of moisture on soy flour and Gordon-Taylor prediction of Tg vs. moisture content (Yildiz and Kokini, 2001). 

The Gordon-Taylor-Wood (GTW) relationship is a common test for randomness in copolymers This treatment was applied to the present HPAM and copolymer systems as follows (1) a ser-... 

Fig. 6 Gordon-Taylor-Wood relationship for HPAM and AM-co-AA copolymers.

FIGURE 13.1 Experimental T values resulting from the antiplasticization effect of PVP90 (o), PVP12 (o), or MD simulated values for PVP (>t) in amorphous mixtures with indomethacin. r predicted is based on the Gordon-Taylor equation with the value of K estimated using the Couchman and Karasz relationship. 

The Tg composition relationship for both PDLLA/PMMA and PLLA/PMMA miscible systems obeyed the Gordon-Taylor equation. 

The most generallv accepted relationship was deduced by Gordon and Taylor... 

According to Gordon and Taylor constant k would be given by the relationship ... 

In 1993, the journal SAR and QSAR in Environmental Research was launched by Gordon and Breach to focus on all the important works published in the field and to provide an international forum for the rapid publication of SAR (Structure-Activity Relationship) and QSAR models in (eco) toxicology, agrochemistry, and pharmacology. Today, the journal, which is now owned by Taylor Francis and publishes three times more issues per year, continues to promote research in the QSAR field by favoring the publication of new molecular descriptors, statistical techniques, and original SAR and QSAR models. This field continues to grow very rapidly... 

The description of the historic Gordon-T ay lor and Wood equations for the glass transition of solutions and copolymers can be found in Gordon M, Taylor IS (1952) Ideal Copolymers and the Second-order Transitions of Synthetic Rubbers. I. Noncrystalline Copolymers. J Appl Chem 2 493-500 Wood LA (1958) Glass Transition Temperatures of Copolymers. 1 Polymer Sci 28 319-330 for the relationship to the volume changes, see Kovacs AJ (1964) Glass Transition in Amorphous Polymers. Phenomenological Study. Fortschr Hochpolym Forsch 3 394-508. 

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