Structure Of PA6 Research Articles

Enhancement of the Processability and Properties of Nylon 6 by Blending with Polyketone

Polyketones (PKs) having strong hydrogen bonding properties and a chain extender are used as additives in the melt processing of nylon 6 (PA6). Their effect on the chain structure and properties of PA6 is studied to enhance the processability of PA6 in melt processing. The addition of the chain extender to PA6 increases the melt viscosity by forming branches on the backbone. The addition of PKs results in an additional increase in viscosity through the hydrogen bonding between N–H of PA6 and C=O of PK. The change in the N–H bond FT-IR peak of PA6 and the swelling data of the PA6/PK blend containing a chain extender, styrene maleic anhydride copolymer (ADR), suggest that incorporation of chain extender and PK in the melt processing of PA6 results in physical crosslinks through hydrogen bonding between the branched PA6 formed by the addition of chain extender and PK chains. This change in the chain structure of PA6 not only increases the melt strength of PA6 but also increases randomness resulting in decreased crystallinity.

Dependence of Structural Characteristics of Polyamide Textured Yarns on the Parameters of the False Twist Yarn Texturing Process

In the false twist texturing process, due to the action of mechanical forces and heat, a disorientation of structural elements happens at all levels of the supramolecular structure. These changes are related to changes in the texturing parameters and mechanical properties of yarn. In this paper, investigated is the effect of technical-technological texturing parameters in the false twist texturing process on the structure of PA6.6 yarns. POY multifilament PA6.6 with a fineness of 22f07x1 dtex was used as experimental material. The yarn was textured on a friction texturing machine - ICBT model FT 15 E3. The exiting yarn speed (Vi) changed as 600, 700, 800 and 900 m/min; the heater temperature (T) was 200, 210 and 220 °C, and the ratio of the disk surface speed to the linear yarn speed (D/Y) was 1.9 and 2.1. The values of strain were kept constant at 1.305 (tension in texturing zone) and 0,954 in the winding zone. Analysed were the density, degree of crystallinity, degree of orientation, single filament diameter, the content of -NH2 and -COOH end groups, and the total content of end groups. From the results obtained it can be seen that the effect of the heater temperature is more significant than that of Vi and D/Y on the structural characteristics analysed. Analysing the experimental results it was found that linear positive correlations were established between the texturing speed and end (-NH2) groups, the texturing speed and end (-COOH) groups and the texturing speed and the total content of end groups. The correlation factor between the process parameters and yarn structural characteristics analysed is determined.

Investigation and Estimation of Structure of Web from Electrospun Nanofibres

During the electrospinning process the web of nanofibres is manufactured by means of electrostatic forces between two electrodes. The diameters of nanofibres usually differ and they depend on various parameters. The different fineness of fibres influences the structure of the web and herewith the end‐use properties of such kind of nanomaterial. Analysis of nanofibres diameters distribution also shows big differences; even more, the distributions are not spread along the normal distribution. Understanding the influence of electrospinning parameters and the reason why the shapes of distributions are so sophisticated is very important. The goal of this paper is to analyse the distribution of diameter and to propose the new criterion for nanofibres diameter comparison and web of nanofibres estimation. In this paper the influence of covering time of support material on structure of PA6.6 nanofibre web has been investigated. It was estimated that this parameter does not have a significant influence on the average diameter of nanofibres, and only the structure of web has been influenced by the changes in covering time. According to the results provided the phenomena of nanofibres sticking on the support material at the time of electrospinning can be proved and explained.

Influence of a cooling rate on a structure of PA6

The structure of the plate specimens obtained from the molten PA6 that was cooled at rates between 2 and 2000 °C/min have been studied. The cooling rate of 2000 °C/min did not ensure a complete amorphization of the specimens. The amorphous phase created by supercooling is unstable and at room temperature undergoes a noticeable cold crystallization. The access of water to the specimen from the surrounding air accelerates this process. Variations in the cooling rate of the melt reflect in rearrangement of the amorphous phase of PA6. Owing to the effect of interaction with the crystalline phase, the amorphous regions undergo changes in molecular weight and MWD of the chain segments between junctions in topological regions, temperatures of the glass transition and β-relaxation, compaction, etc.

Effect of a plasticizer on the structure of PA-6 deformed in an adsorption-active medium

The permeation of a liquid under the action of a pressure gradient has been used to investigate how the evolution of the parameters of the porpous structure of PA-6 with various moisture-contents depends on the degree of extension in an adsorption-active medium. As the plasticizer concentration in the polymer is increased, a transition is shown to occur from classical localized crazing to delocalized crazing.

Effect of liquid media on mechanical properties of polyamide-6 according to initial moisture content

The effect of adsorption-active and plasticizing liquid media on mechanical properties and the structure of PA-6 was studied in a wide range of moisture contents of the polymer. During deformation of PA-6 in a plasticizing medium the initial elastic modulus varies with any moisture content. On transferring amorphous ranges of PA-6 from the glassy to the high-elastic state the efficiency of action of adsorption-active media sharply drops and the plasticizing liquid assumes maximum influence.