Mátyás Andó

Electrical Properties of Magnesium Catalyzed Cast PA6 Semi-Finished Products

Graphite and conducting carbon black have been added to magnesium catalyzed cast polyamide-6. Surface resistivity has been measured on samples containing various amounts of additives in wet, standard, and dry states. The samples exhibited antistatic properties at already 2.5 wt% graphite loading. To reach similar properties 1 wt% high conducting graphite and 0.5 wt% high conducting carbon black was needed. It is important to note, that in the case of the high conducting additives above a certain concentration (above 2 wt% for high conducting graphite and above 0.5 wt% for high conducting carbon black) the surface resistivity decreases rapidly to the order of 107 Ω, belonging to the electrostatic dissipative class.

Effect on Friction for Different Parameters in Roll–Slip of Polyamide–Steel Nonconformal Contacts

Standards for tribological testing focus mainly on sliding, but in applications like gears, rollers, etc., rolling appears together with sliding, resulting in roll–slip situations. In this study, the roll–slip behavior of polymer materials was tested using a twin-disc experimental test setup. Three different loads of 61 N (13 MPa), 110 N (18 MPa), and 161 N (22 MPa) together with five different speeds ranging from 10 to 700 rpm were used for a slip ratio of 15%. Two different counter materials were used: tool steel (M238) and nonalloyed structural steel (S335). Both of the counter materials showed a friction behavior that was almost linear to the increase in load for high speeds at 700 rpm. But at speeds below 200 rpm the tool steel showed an exponential behavior. At low loads (61 and 110 N) there was an exponential increase in friction force that became more linear after 110 N. From a velocity point of view both of the counter materials showed similar friction behavior with a different value in friction force. By comparing the behavior for both of the counter materials against polyamide 6, the tool steel showed an increased friction force that makes the nonalloyed structural steel a more suitable counter material for polyamide.

Dynamic Mechanical Tests on Magnesium Catalyzed Cast Polyamide 6 Composites Having Different Additives

Due to the effect of graphite and montmorrilonit additives, the impact strenght slightly decreases, but by the influence of softening material, the value of impact strength can be three times more than the pure PA6. It is determined that graphite can be added until 3%, montmorrilonit can be added until 6% and softening material can be added until 15% to the base matrix. These samples give basis for special characteristics examinations.

Investigation on the Flammability of Diverse Cast PA6 Semi-Finished Products

Cast PA6 (magnesium–polyamide 6 (MgPA6)) compounds produced using a magnesium catalysis are presently replacing other polyamides in semi-finished engineering products. Because of this increased use, the flammability of MgPA6 containing montmorillonite, graphite, carbon black, and a plasticizer is investigated. In these studies, we observed that the presence of montmorillonite deteriorates rather than improves the flame-retardant properties of MgPA6. We also noted that the presence of a plasticizer enhances the dripping tendency and consequently the burning rate of PA6 in the UL 94 Test for Flammability of Plastic Materials. In addition, the presence of carbon black reduces the fire performance of the resin while graphite improves the UL 94 classification of PA6 to a V-2.