Three types of composites of polyamide 6 (PCL) with hybrid tribological additives were synthesized via anionic adiabatic ‘‘in situ’’ polymerization of 6-hexanelactam (epsilon-caprolactam) initiated with metallic sodium and activated with either cyclic trimer of phenyl isocyanate or diphenylmethane 4,4’-diisocyanate. Combinations of the additives and their maximum applied concentrations (in wt.-%) were the following: MoS2/graphite(G)/oil(O) (5/16/9), short carbon fibers (CF)/G/O (5/20/10), and copper phthalocyanine (CPC) (7). Dynamic mechanical thermal analysis (DMTA) indicates a secondary (beta) transition at about -65 °C and the main (alpha) transition at temperatures close to 20 °C; the storage modulus passes through a shallow maximum as a function of the total content of additives. Tensile creep and indentation creep concurrently evidenced some increase in compliance with rising fraction of incorporated compounds. Stress-strain tests in flexure show that flexural strength and toughness monotonically decreased with the content of MoS2/G/O or CF/G/O, whereas the flexural modulus passed through a flat maximum. On the other hand, the strength and modulus were decreasing with CPC content, while toughness and Charpy impact tests showed some improvement.
Structure and mechanical properties of composites of poly(6-hexanelactam) combining solid tribological additives and reinforcing components
Fambri, Luca
2004-01-01
Abstract
Three types of composites of polyamide 6 (PCL) with hybrid tribological additives were synthesized via anionic adiabatic ‘‘in situ’’ polymerization of 6-hexanelactam (epsilon-caprolactam) initiated with metallic sodium and activated with either cyclic trimer of phenyl isocyanate or diphenylmethane 4,4’-diisocyanate. Combinations of the additives and their maximum applied concentrations (in wt.-%) were the following: MoS2/graphite(G)/oil(O) (5/16/9), short carbon fibers (CF)/G/O (5/20/10), and copper phthalocyanine (CPC) (7). Dynamic mechanical thermal analysis (DMTA) indicates a secondary (beta) transition at about -65 °C and the main (alpha) transition at temperatures close to 20 °C; the storage modulus passes through a shallow maximum as a function of the total content of additives. Tensile creep and indentation creep concurrently evidenced some increase in compliance with rising fraction of incorporated compounds. Stress-strain tests in flexure show that flexural strength and toughness monotonically decreased with the content of MoS2/G/O or CF/G/O, whereas the flexural modulus passed through a flat maximum. On the other hand, the strength and modulus were decreasing with CPC content, while toughness and Charpy impact tests showed some improvement.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione