Polyamide 6 and high molecular weight phenol novolac blend having excellent mechanical properties in humid conditions

Abstract

Polymer blends of polyamide 6 (PA6) and phenol novolac (PN) were prepared by melt mixing. Up to 30 wt% of high molecular weight PN (HPN) or low molecular weight PN (LPN) was blended with PA6, and the physical and mechanical properties were examined. The water absorption of PA6 is inhibited by PN, and this effect is independent of the molecular weight of PN. PA6 and PN are miscible, and their blends show a single glass transition temperature ( T g) that is higher than that of PA6. HPN can enhance the T g of PA6 more efficiently than LPN because of its high T g. PA6 and the PA6/LPN blend after immersion in water had lower-than-room-temperature T gs transitioning to rubbery states. In contrast, the PA6/HPN blend after immersion in water had a higher-than-room-temperature T g. The PA6/HPN blend in water has excellent mechanical properties in its glassy state compared to those of PA6 in the dry state. Thus, the PA6/HPN blend can be used to broaden the applications of PA6, especially in humid conditions.

Effect of Fibre Orientation and Hostile Solutions on Stress Relaxation of Glass/Polyamide Composites

“…In fact, exposure to corrosive fluids significantly compromises the load carrying capacity, due to the lower mechanical properties of the matrix and the lower fibre/matrix bond strength [11,13,53]. Studies developed by Hirai et al [56] showed, for example, that PA6 is easily plasticized when subjected to wet conditions, which significantly affects its mechanical performance. Other evidence from Table 3 and Figure 3 is the higher effect of the hostile environments on the laminates with fibres at 0 • (74.8% for HCl and 227.2% for NaCl solutions) than in the other orientations.…”

Multifaceted property tailoring of polyamide 6 by blending miscible and immiscible components: ternary blends of polyamide 6/polyethylene terephthalate/phenol novolac

“…PA6/PET/PN20 also displayed high moduli in the glassy state, owing to the high T g of PA6 in PA6/PET/PN20, which is above room temperature. However, embrittlement, a disadvantage of excess PN loading to PA6, 20 was observed.…”

“…Various polymer blends have been proposed to improve the mechanical properties of PA6 under humid and high-temperature conditions. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Owing to the small mixing enthalpy of macromolecules, almost all polymer combinations are immiscible 5 and thus, previous studies have mainly conducted PA6 polymer blending with immiscible components. [7][8][9][10][11][12][13][14] Blending high-T g polymers, such as poly(phenylene sulde), 7,8 poly(phenylene oxide), [9][10][11] and polycarbonate (PC) [12][13][14] with PA6 are representative approaches to increase the PA6 stiffness at high temperatures.…”

“…On the other hand, phenol-containing polymers, such as phenol novolac (PN) and PA6 blends, have been reported as miscible systems. [15][16][17][18][19][20][21] PN forms strong hydrogen bonds with PA6, which contribute to the miscibility of such blends. 16,18 Miscible components can increase the T g of PA6, and we previously reported that high-molecular-weight PN efficiently increases the T g of PA6.…”

“…16,18 Miscible components can increase the T g of PA6, and we previously reported that high-molecular-weight PN efficiently increases the T g of PA6. 20 Furthermore, it has been reported that PN prevents water absorption of PA6 by the contribution of strong hydrogen bonding. 15,[18][19][20] Although miscible and immiscible components are known to enhance different PA6 properties, to the best of our knowledge, no studies on PA6 ternary blends comprising both immiscible and miscible components have been conducted to date.…”