Effect Of Solvent Treatment Research Articles

The dyeability and properties of some structurally modified poly(ethylene terephthalate) filaments

AbstractThe effect of solvent treatment on the dyeability and mechanical properties of drawn poly(ethylene terephthalate) (PET) filaments has been studied. It is observed that strongly interacting solvents such as N,N‐dimethyl formamide (DMF) improved the dyeability of PET which has been treated with these solvents at 74°C for 15 min before dyeing with disperse dyes at 100°C. Pretreatment in N,N‐dimethyl formamide and acetonitrile also resulted in a lowering of tensile strength and initial modulus, whereas subsequent dyeing caused further reduction in extensibility but initial modulus results are less consistent.

Molecular fractionation in melt-crystallized polyethylene: 2. Effect of solvent extraction on the structure as studied by differential scanning calorimetry and gel permeation chromatography

The effect of solvent treatment (extraction) on melt-crystallized polyethylene is considered in this second paper in a series on molecular fractionation (segregation) in polyethylene. Polyethylenes with a variety of thermal histories were treated with p-xylene at different temperatures and the changes in the samples were followed by differential scanning calorimetry and gel permeation chromatography. Information is obtained concerning the general dissolution behaviour of the polycrystalline samples including the selectivity of the extraction of the segregated species, how crystallinity varies within the structures and the molecular structure of the segregated component.

Effect of solvent treatments on the mechanical properties of nylon 6

AbstractThe effects of absorbed solvents and chemical agents on the stress‐strain and dynamic mechanical properties of nylon 6 film have been examined. The agents investigated were: water, benzyl alcohol, phenol and iodine. These materials produce changes in the crystalline structure as well as plasticization when they are absorbed. Repeated introduction and removal of phenol indicated that the change of structure takes place completely during the first absorption; after that, the effects of absorption are reversible. The pure plasticizer effect can therefore be observed by comparison of a sample containing plasticizer and a sample from which the plasticizer has been subsequently removed. The general effect of absorbed plasticizer (except for iodine) seems to depend primarily on the amount of plasticizer absorbed, and very little on its exact chemical nature. However, different agents can produce different crystalline forms. A method of analyzing the stress‐strain curve is hypothesized based on the concept of a two‐phase solid state structure consisting of a crystalline lattice imbedded in an amorphous matrix.

The relation between structure and function in electron-transport systems. II. Effect of solvent treatment on membrane structure

Changes in the structure of membrane fragments from beef heart mitochondrial cristae have been observed by negative staining technique following solvent treatment of the membranes. The changes in structure have been related to previously observed changes in enzyme activity. Isooctane treatment results in very little change in outer knob or inner bead structure except to cause an apparent spreading of the inner beads. Both succinoxidase and NADH-oxidase activity can be recovered. Ether treatment causes loss of outer knobs and a breakdown of inner beads to 30-Å particles. Succinoxidase activity is unaffected by this treatment but NADH-oxidase activity is lost. Finally acetone extraction causes both loss of knobs and further disintegration of inner beads to less than 30-Å units. Succinoxidase activity can still be restored to these membranes by addition of coenzyme Q, phospholipid and cytochrome c, whereas NADH-oxidase activity cannot be restored. In contrast to the changes observed by negative staining, membranes fixed with osmium, tetroxide and sectioned still show normal membranous structure.

Enzymes of cancer nuclei

I N preparing nuclei by means of non-aqueous solvents, there are several technical factors that must be considered with respect to the study of enzymes. These include the effect of freezing, the effect of lyophilization, and the effect of solvent treatment. Siebert [lo] has presented evidence that the solvents used had little effect on the activity of many of the enzymes studied. The effects of freezing and lyophilization do not appear to have been defined however and could very well have a profound effect upon the results and their interpretation. Berenbom et al. [3] studied the effect of freeze-drying on the activities of several hydrolytic and oxidative enzymes in mouse liver about ten years ago. They found that the hydrolytic enzymes suffered only slight losses in activity as a result of this treatment. Cytochrome oxidase and succinoxidase, however, were inactivated 50 per cent or more by freezing alone. The possibility must thus be considered that selective effects are being observed in the study of lyophilized tissues. If one assumes for the purposes of discussion that freezing and lyophilization also did not affect the enzyples studied by Siebert [lo], the results indicate that with one notable exception (DPN-pyrophosphorylase), most of the enzymes studied were present in the isolated nuclei in about the same concentration as in the original tissue. It is the interpretation of the latter findings that is the main point at issue. This is an important point because if the results are accepted at face value, one would have to conclude that the nucleus is able to carry out glycolysis, certain oxidations and hydrolytic functions. In short, it would almost appear as if the nucleus is able to conduct all of the functions that the cell is able to perform. The late Dr George H. Hogeboom and the author have always felt however that it is very difficult to interpret such data [9]. The nucleus, for example, accounts for 10 per cent or less of the mass of the liver cell. Consequently, if the concentration of enzyme in the nucleus is the same as in the original tissue, less than 10 per cent of the total tissue enzyme would actually be localized in the nucleus. The remaining 90 per cent would have to be localized in the cytoplasm. In order to accept the association of such small amounts of