Evaluation of P-v-T Properties of Crystalline Polymers Using Injection Molding Processes. Part I. Determination of P-v-T Properties in Solid Phase.

Abstract

The P-v-T properties of polymers play a very important role in the prediction of warpage and shrinkage using computer aided engineering (CAE) programs. The usual measurements of P-v-T properties generally need very low cooling rates in order to make the temperature distribution uniform in the specimen, but the cooling rate in injection moldings is very high and changes with molding conditions. Therefore, the P-v-T properties obtained by the usual methods have some problems in applying them to the analysis of crystallization behaviors in injection moldings. In order to solve these problems the practical P-v-T measurement method has been proposed by taking the cooling rate in injection molding process into account. The undercooling which is defined as the difference between the melting point and the crystallization onset temperature, can be represented as a function of the cooling rate and the pressure history in the injection molding process. We have found that the specific volume of the molded specimen at a pressure 1 atm at 293 K could be estimated as a function of the undercooling. By taking it into account, the specific volume variations with temperature and pressure were calculated from the thermal expansion coefficient ay and the compressibility i. Then the constants of Spencer-Gilmore's equation of state obtained from these P-v-T properties are determined as a function of undercooling. Hence it is shown that the obtained Spencer-Gilmore's equation of state accompanying with appropriate constants indicates good agreement with the P-v-T properties in the solid phase over the wide variations of injection molding conditions.

Modelling Amphetamine/Receptor Interactions: A Gas‐Phase Study of Complexes Formed between Amphetamine and Some Chiral Amido[4]resorcinarenes

“…Abstract in Italian: I complessi diastereomerici fra alcuni ammido [4]resorcinareni protonati chirali e la (R)-e (S)-anfetamina mostrano una notevole enantioselettività nella reazione con gli enantiomeri del 2-ammino butano in fase gassosa. L'origine della enantioselettività osservata viene discussa alla luce di calcoli di meccanica molecolare e di simulazioni di dinamica molecolare ed attribuita alla combinazione di fattori strutturali e dinamici, come la lunghezza e la struttura isomerica dei pendagli della molecola ospite e la frequenza e l'ampiezza delle loro oscillazioni, così come di quelle dell'anfetamina legata al resorcinarene mediante un protone.…”

“…The nature of such a time-dependent event is illustrated in Figure 7. After 13 ns, the host pendant H-bonded to the A (R) molecule moves up towards the upper rim of the resorcin [4]arene. Through this movement, the guest finds the way to shift rapidly from the ext to the down position of the host simply through a torsion of the pendant, and locks itself into the down cavity by dragging the pendant along with it.…”

“…Both (S)-(+)-amphetamine (d-amphetamine, A (S) ) and (R)-(À)-amphetamine (l-amphetamine, A (R) ) are thought to exert their effects by binding to the monoamine transporters and increasing extracellular levels of the biogenic amines, such as dopamine, norepinephedrine and serotonin. [1] It is hypothesized that A (S) acts primarily on the dopaminergic systems, [2][3][4] while A (R) is comparatively nore-pinephrinergic. [2,5] In all instances, the mechanisms of action of A (S) and A (R) proceed through preliminary interactions with the amino acids of the N terminus of human dopamine transporter (or their phosphorylated forms).…”

“…In addition, one needs to evaluate the effects of specific inorganic ions, including Cl À , on the substrate recognition step that impacts the entire uptake process. [8][9][10] We have recently been engaged in extensive mass spectrometric (MS) studies of the interactions between some representative chiral biomolecules (C) and specifically designed chiral macrocyclic receptors (M), such as the amido [4]resorcinarene 1 (S) (Figure 1), [11][12][13][14][15] in the gas phase, where interference from the solvent and the counterion is excluded. The molecular asymmetry of the selected hosts M is due to the four dissymmetric pendants, which may be spatially oriented…”

“…Diastereomeric protonbound complexes formed between (R)and (S)-amphetamine and some chiral amido [4]resorcinarene receptors display significant enantioselectivities when reacting with the enantiomers of 2-aminobutane in the gas phase. The origins of the measured enantioselectivities are discussed in the light of molecular mechanics calculations and molecular dynamics simulations and are ascribed to a combination of structural and dynamic factors, including the lengths and the isomeric structures of the host asymmetric pendants and the frequencies and amplitudes of their motion, as well as those of the proton-bonded amphetamine guests.…”