The main benefits of blending LDPE with PA6 are: firstly, it significantly improves the water absorption of PA6; secondly, it increases the impact strength of PA6. A commonly used halogen-free flame retardant for PA6 is aluminum diethylphosphinate(ADP). Blending LDPE with PA6 can also alter the crystallinity or morphology of PA6, improving its transparency. Compared to toughening PA6 with elastomers, toughened PA6 with LDPE exhibits less decrease in flexural and tensile strength, maintaining the basic rigidity of PA6 while improving its toughness, thus possessing high practical value.

Since PE is a non-polar polymer while PA6 is a polar polymer, LDPE and PA6 are not thermodynamically compatible. When blending, PE must be modified or a compatibilizer added; otherwise, phase separation easily occurs in the blend melt during molding, resulting in poor impact strength, poor surface gloss, and a tendency to peel and crack under stress. Modification of LDPE mainly involves introducing polar groups into the LDPE molecular chain, i.e., grafting highly reactive monomers onto LDPE. Currently used compatibilizers include PE-g-MAH, LDPE and LDPE-g-BuA-co-MA, maleic anhydride, and EPDM-g-MAH. However, the performance of PA6/LDPE blends varies depending on the compatibilizer used. Adding LDPE-g-MAH to the PA6/LDPE system effectively improves the compatibility between the blend components, and the blend exhibits significant toughening effects both in the dry state and at low temperatures, while ungrafted LDPE has no toughening effect on PA6.

When the LDPE-g-MAH content reaches 40%, the impact strength of the PA6/LDPE alloy is 5-6 times higher than that of pure PA6. For example, when a company uses a PA6/LDPE (100/10) blend to produce automotive wiring harnesses, adding 2% LDPE-g-MAH as a compatibilizer to the blend results in a product with a notched cantilever beam impact strength of 82 kJ/m² and a tensile strength of 45.3 MPa. The product maintains the rigidity of PA6 while significantly improving impact toughness and exhibiting good gloss. When using LDPE-g-(BuA-co-MA) as a compatibilizer in a PA6/LDPE blend at a concentration of 2.4%, after blending at 250°C, the tensile modulus, flexural strength, tensile strength, elongation at break, and water absorption decrease with increasing LDPE content, while the impact strength increases.

PA6/LDPE blends use EVASH as a compatibilizer at a dosage of 1% to 10%. After mixing at approximately 250°C, the tensile properties and elastic modulus of the PA6/LDPE blend increase with the increase of EVASH dosage. When the EVASH dosage in the PA6/LDPE (50/50) blend is around 10%, the yield strength of the blend is around 22 MPa, and the elongation at break is around 80%. Without the compatibilizer, the yield strength is approximately 10 MPa, and the elongation at break is approximately 10%. Furthermore, the compatibilizing effect varies depending on the SH concentration in the EVASH compatibilizer; generally, the higher the SH concentration in the EVASH, the higher the elastic modulus of the blend.