Polyamides experimental

These polymers, typical of polyamides with fewer than four main chain carbon atoms in the repeating unit, decompose before melting and have to be processed from solution. Several of the polymers may, however, be spun into fibres. Over thirty years ago Courtaulds produced silk-like fibres on an experimental commercial scale from poly-(L-alanine) and from poly-(a-methyl-L-glutamate). The latter material is also said to be in use as a synthetic leather in Japan. The... 

Other polyamides produced experimentally include polymers with active lateral groups (hydroxy, keto groups etc.), polymers with heteroatoms (sulphur and oxygen) in the polyamide-forming intermediates, polymers with tertiary amino groups in the main chain and polymers with unsaturation in the main chain. There does not, however, appear to have been any serious attempt to develop unsaturated polyamide analogues to the polyester laminating resins. 

These experimental results show conclusively that the deformation factor occurring in the theoretical equation of state offers only a crude approximation to the form of the actual equilibrium stress-strain curve. The reasons behind the observed deviation are not known. It does appear, however, from observations on other rubberlike systems that the type of deviation observed is general. Similar deviations are indicated in TutyP rubber (essentially a cross-linked polyisobutylene) and even in polyamides having network structures and exhibiting rubberlike behavior at high temperatures (see Sec. 4b). 

Fig. 101.—Experimental and theoretical (dashed line) stress-strain curves for tetra-linked polyamide with y/V) X10 = 1.34 at low elongations. Temperatures (in °C) were 229° 241° O 253° 281° 3. The range is too small to show a definite temperature coefficient beyond the experimental error. (Schaefgen and Flory. )...

FIGURE 17.21 2DLC contour plot of a modified polyamide 6.6, first dimension LCCC, second dimension SEC, experimental conditions see discussion of Fig. 17.19. (See color plate.)... 

Polyamides are converted to polypeptides (as just shown), and nucleotides, because of the dehydrating properties of polyamides, to polynucleotides. This hypothetical model can accept the delivery of HCN polymers from space (e.g., via meteorites) as well as photochemical reactions in a reducing atmosphere. In spite of some convincing experimental evidence, the HCN world favoured by Matthews still awaits further convincing experimental evidence (this is also true for other hypothetical worlds ). 

Lyotropic polymeric LC, formed by dissolving two aromatic polyamides in concentrated sulphuric acid, have been studied using variable-director 13C NMR experiments.324 The experimental line shapes at different angles w.r.t the external field were used to extract macromolecular order and dynamic in these ordered fluids. An interesting application of lyotropic LC is for the chiral discrimination of R- and S-enantiomers, and has recently been demonstrated by Courtieu and co-workers.325 The idea was to include a chiral compound 1-deutero-l-phenylethanol in a chiral cage (e.g., /1-cyclodextrin) which was dissolved and oriented by the nematic mean field in a cromolyn-water system. Proton-decoupled 2H NMR spectrum clearly showed the quad-rupolar splittings of the R- and S-enantiomers. The technique is applicable to water-soluble solutes. 

The NMR spectra (300 MHz) of the model diamides 1 and 2, and the polyamide 3, were recorded in trifluroacetic acid-d (TFA-d). Since the xylaramide component of 1-3 is symmetrical, one observes a single average coupling for H2-H2 and Experimental... 

The most relevant property of stereoregular polymers is their ability to crystallize. This fact became evident through the work of Natta and his school, as the result of the simultaneous development of new synthetic methods and of extensive stractural investigations. Previously, the presence of crystalline order had been ascertained only in a few natural polymers (cellulose, natural rubber, bal-ata, etc.) and in synthetic polymers devoid of stereogenic centers (polyethylene, polytetrafluoroethylene, polyamids, polyesters, etc.). After the pioneering work of Meyer and Mark (70), important theoretical and experimental contributions to the study of crystalline polymers were made by Bunn (159-161), who predicted the most probable chain conformation of linear polymers and determined the crystalline structure of several macromolecular compounds. 

The Flory-Williams RIS models describing the conformational characteristics of polyesters and polyamides are combined to calculate the dimensions of the alternating polyesteramide PEA. Excellent agreement is found with experimental values of the unperturbed dimensions. New determinations of molecular dipole moments are reported for dimethyl-frans-1,4-cyclohexanedicarboxylate and for trans-1,4-cyclohexanedlol diacetate. 

This paper intends, without exhausting the subject, to present a comprehensive review on the experimental techniques in grafting on polyamides. No attempt was made to discuss mechanistic aspects of these reactions. A list of references based on monomers is presented at the end of this review. 

Analysis of the non-isothermal polymerization of E-caprolactam is based on the equations for isothermal polymerization discussed above. At the same time, it is also important to estimate the effect of non-isothermal phenomena on polymerization, because in any real situation, it is impossible to avoid exothermal effects. First of all, let us estimate what temperature increase can be expected and how it influences the kinetics of reaction. It is reasonable to assume that the reaction proceeds under adiabatic conditions as is true for many large articles produced by chemical processing. The total energy produced in transforming e-caprolactam into polyamide-6 is well known. According to the experimental data of many authors, it is close to 125 -130 J/cm3. If the reaction takes place under adiabatic conditions, the result is an increase in temperature of up to 50 - 52°C this is the maximum possible temperature increase Tmax- In order to estimate the kinetic effect of this increase... 

Various 66 polyamide continuous yarns were also examined (referred to as, "type 2", "type 4" and "type 5") these are experimental yarns prepared in different conditions and supplied by RPT. 

To see if oxidative spreading could take place between different polymers, initiation of stabilised PP using a piece of unstabilised polyamide 6 (PA 6) was performed [79]. However, PA 6 can not initiate oxidation in PP even if oxidising PA 6 is placed in direct contact with PP. To clarify the processes of cross spreading between different polymers more experimental work is necessary. 

Detailed kinetic schemes have also been proposed for many other polymers and the work of Bockhom et al.6-8 is representative of this large area of the literature for schemes relating to polyamide 6, PP, PE, and other polymers. Other experimental approaches, mainly aimed at identifying Arrhenius parameters in similar schemes, are discussed by Howell,9 Lehrle et al.,10 Shyichuk,11 Wilkie,12 and Holland and Hay.1314... 

A test set of 6 to 13 aroma compound partition coefficients between different food contact polymers (low density polyethylene (LDPE), high density polyethylene (HDPE) polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA)) and different food simulant phases (water, ethanol, aqueous ethanol/water mixtures, methanol, 1-propanol) were taken from the literature (Koszinowski and Piringer, 1989, Baner, 1992, Franz, 1990, Koszinowski, 1986, Franz, 1991, Baner, 1993, Piringer, 1992). Table 4-2 shows the test set of 13 different aroma compounds, with their properties and their structures. The experimental data were compared to estimations using different estimation methods of UNIFAC-FV, GCFLORY (1990), GCFLORY (1994) and ELBRO-FV. 

Introduction of ring-opening metathesis as a versatile polymerisation technique (ROMP) by Chauvin and Herisson Nobel Prize Chemistry to Paul J. Flory for his fundamental achievements, both theoretical and experimental, in the physical chemistry of the macromolecules Fully aromatic polyamides developed Aramids, being lyotropic liquid crystalline polymers of high strength, due to extended molecular chains (Morgan and Kwolek)... 

Although nylon 66 and 6 account for most of the polyamide fibers produced, a great many others have been experimentally synthesized and have been developed and manufactured in commercial amounts. Of these, some have been made into fibers, some with limited economic success. These nylons are identified by either the same numbering system used for nylon 66 or 6 or by a combination of numbers and letters, as follows ... 

---