Selected physical properties and structure of materials based on modified polyamide 6
Authors: Gnatowski Adam , Kijo-Kleczkowska Agnieszka 
Published: July 2019

Purpose
The main purpose of polymeric mixtures manufacturing is wish to eliminate or reduce drawbacks which polymers are characterised by and also to strive for reduction of the price of expensive polymers with particular very precious properties by mixing them with cheaper polymers but without significant deterioration of their properties. In the work some investigation results have been presented for PA6 which is miscible in viscoelastic state with polymer, with ability to create physical bounds with substances of inorganic as well as organic origins. For this purpose, polyvinylpyrrolidone (PVP) has been used with law molecular weight (10 ± 2,5 thousand). The functionalactive material was prepared with sharp tuning sorption ability across physical modification polycapramide mixed from bipolar polyvinylpyrrolidone in batch – free state, which characterises high ability complex. In the paper, some results of chosen properties of PA with the addition of polyvinylpyrrolidone (PVP) have been presented. In chance of mixing PA6 with PVP forms solution PVP in PA6, to which proper are large intermolecular influence, in this case hydrogen bond. It is possible to foresee that under the influences of large tangent stresses and intermolecular interaction colloidal solution PVP in PA forms with sure homogeneity, after cooling of it the inversion of winding phases is not noticeable In the mixtures on the basis of such polymers the intermolecular interactions occur, and they differently influence parameters of the modified materials. Conducted investigations have proved opportunity of physical modification of PA6 during mixing, in viscoelastic state, with polyvinylpyrrolidone. The modified polymer has dielectric properties and a reduced susceptibility to water absorption. It can be used as an insulation material, in all industrial sectors, including the energy sector.

Design/methodology/approach
For examinations, the following mixtures were made out: PA 99%/PVP 1%, PA 98%/PVP 2%, PA 90%/PVP 10%. Making mixtures out was begun with weighing elements out on numerical Sortorius AG GO TTINGEN scales and CAS MODEL: SW-1 (PA, PVP). Next elements of mixture were mixed with themselves mechanically. The process of drying was carried out in the ZELMET drier with the thermal kc-100/200 chamber in the temperature 80 °C for 12 h. The process of mixing up was carried out in the arrangement plasticising injections moulding machine of the voluted KRAUSS MAFFEI company KM 65-1600C1 (D screw = 30 mm and the L = 27D, the nozzle about d = 4 mm and the l = 2d) at the following parameters: is the nozzle temperature 230 °C, the speed of turnovers of the screw 210 obr/min. Granulated product of mixtures were get on the rotor grinder. Samples for examinations were made on the computer-operated injection moulding machine of type of KM 65-1600C1 of the KRAUSS MAFFEI company. The conditions which complement the homogeneity of a mixture – these include mixing processes with high shear stresses with the range of temperatures for viscoelastic state for the individual polymers. Such conditions are met by multiple mixing in the injection machine cylinder with extended perpetual screw length (L/D = 25 ÷ 42). Permanent conditions of injecting samples for the research on physical properties were the following: nozzle temperature – 230°C; worm area I temperature – 190°C; worm area II temperature – 210°C; worm area III temperature – 230-245°C, mould temperature 40°C, injection pressure – 60 MPa, clamping time – 5 s, cooling time – 30 s The research on chosen physical properties of getting polymer materials was carried out: hardnesses on hardness testing machine, impact resistance by Charpy’s method, mechanical properties while tension over the endurance machine the INSTON with tension speed of 90 mm/min, softening point by Vicat’s method was determined using testing machine type HAAKE N8, the investigation of DSC method and DMTA method using testing machine type Netzsch, water absorbing power test. The research on the structure was also carried out on the optical microscope type NIKON ECLIPSE E200.

Findings
In the paper, for the physical modification of PA 6, the polyvinylpyrrolidone (PVP) – amorphous polymer which is capable of ionisation and creation of complexes with the transition of the charge with many electrophilic compounds and also proton donors have been used. PVP does not change into the viscoelastic state but it is easily soluble in organic and inorganic solvents and the best in water. Its characteristic is high sorption capacity. As a result of ionisation changes PVP preserve the conformation changes. In case of mixing of polar PA6 polymers with PVP, a PVP solution is being created in PA, to whom big intermolecular interactions are proper for, in it hydrogen bonds. Reducing of polarity occurs of both polymers as a result of hydrogen bonds in created macromolecules. Macromolecule so they are interfering easily in fused condition creating the mixture about reliable homogeneity. An effect is applying to mixing with PA6 in case of dissolving PVP in the PA6 stop under the influence of big adjacent tensions in screw extruder what is calling changes of the supermolecular structure and properties of the material after chilling of stop in the form during injecting. The resultant homogeneous mixture is marked by one reflex narrowed in comparison with output PA6 of melting visible on DSC thermogram with moving to the page of higher tmmax temperatures. PA6/PVP mixtures are also providing effects of examinations about the homogeneity with DMTA method which shows results that the mixture is marked by one reflex of mechanical losses on the plot from (Tg) from the maximum at bigger than PA6 Tg (about 10 ÷ 15°C), and it is possible at the same time to reason that the mixture has not very thick frictional network as a result of the exchange of intermolecular bonds what is displayed itself in the increase in Tg intensity. The results of investigations show that PA with PVP additions create more stable material with visible homogeneity (due to strong intermolecular interactions) which is characterised by satisfactory mechanical properties which insignificantly differ from PA6 properties, but which shows higher deformability and sorptive power.

Originality/value
The results of investigations show that PA with PVP additions create more stable material with visible homogeneity (due to strong intermolecular interactions) which is characterised by satisfactory mechanical properties which insignificantly differ from PA6 properties, but which shows higher deformability and sorptive power. The modified polymer has dielectric properties and a reduced susceptibility to water absorption. It can be used as an insulation material, in all industrial sectors, including the energy sector.