Effects of grafting and long-chain branching structures on rheological behavior, crystallization properties, foaming performance, and mechanical properties of polyamide 6

Abstract

Polyamide 6 (PA6) was modified with ethylene maleic anhydride syndiotactic copolymer resin (ZeMac), and triglycidyl isocyanurate (TGIC) as modifiers to prepare a grafting structure and a long-chain branching structure, respectively. The effects of two modifiers on the rheological behavior, crystallization properties, foaming performance, and mechanical properties of PA6 were systematically studied by rotating rheometry, differential scanning calorimetry and scanning electron microscopy. The results showed that there were differences in crystallization properties between the two modification methods, but they significantly improved the rheological, foaming performance, and mechanical properties of PA6. In particular, PA6 with long-chain branching structure through TGIC modification showed better performance in various physicochemical characterizations. The introduction of ZeMac reduced the average diameter of bubbles in pure PA6 from 146.32 to 88.12 µm, and the density of bubbles increased from 1.69 × 105 to 5.35 × 105 cells·cm−3. The introduction of TGIC reduced the average diameter of bubbles in pure PA6 from 146.32 to 64.36 µm, and the density of bubbles increased to 1.31 × 106 cells·cm−3. Moreover, the mechanical properties of both nonfoamed and foamed samples were improved after modification.

Recycling of polyamides: Processes and conditions

“…In conclusion, several methods have been developed to recycle PA under different compositions and structures: blends, multilayers and (nano)composites. Unfortunately, not much information has been found on PA foams 128 and biobased-PA, 129 as well as the effect of different additives such as flame retardants, antioxidants, stabilizers and plasticizers. 130 Another subject of high interest would be to investigate into more details crosslinked PA. 131 In addition, most of the literature focused on aliphatic polyamides (PA6 and PA6.6).…”

Effect of viscosity on foaming behavior and surface quality of foamed Polyamide 6

“…Cao et al selected ethylene-maleic anhydride (ZeMac) grafted PA6 and triglycidyl isocyanurate (TGIC) for chain extension modification. 21 The results showed that the grafting and longchain branching structure improved the entanglement between molecular chains, restricted the movement of molecular chains, and the polymer viscosity increased accordingly, and the viscosity increased with the increase of modifiers. Xu used trifunctional epoxy resin as a crosslinking agent to crosslink PA6 during chemical extrusion foaming molding.…”

“…11,12 To enhance the quality and performance of PA6 micro-foam products, it is imperative to address the issue of low melt strength. Several potential solutions include incorporating nano-clay, 11,13 fiber blends, [14][15][16] chain expansion, [17][18][19][20][21] and crosslinking. 22 According to research, adding nano-clay to PA6 can increase its activation energy, improving both the crystallization rate and nucleation efficiency.…”

“…To enhance the quality and performance of PA6 micro‐foam products, it is imperative to address the issue of low melt strength. Several potential solutions include incorporating nano‐clay, 11,13 fiber blends, 14–16 chain expansion, 17–21 and crosslinking 22…”

“…It was found that the viscosity of PA6 increases with the amount of chain spreading agent used, but viscosity shows the opposite trend, with increasing high‐temperature residence time. Cao et al selected ethylene‐maleic anhydride (ZeMac) grafted PA6 and triglycidyl isocyanurate (TGIC) for chain extension modification 21 . The results showed that the grafting and long‐chain branching structure improved the entanglement between molecular chains, restricted the movement of molecular chains, and the polymer viscosity increased accordingly, and the viscosity increased with the increase of modifiers.…”