Dyeing performances of ramie fabrics modified with an amino-terminated aliphatic hyperbranched polymer

An amino-terminated aliphatic hyperbranched polymer (HBP-NH₂) was used to modify ramie fabric. The molecular weight of HBP-NH₂ was established by GPC. HBP-NH₂ structure might represent as BA₄BA₃BA₃ (third generation). The total amine value, secondary amine value and primary amine value of HBP-NH₂ were 291.59, 210.14 and 81.45 mg/g respectively with hydrochloric acid—ethanol titration method. The unmodified and modified ramie fabrics were characterized by XRD and FE-SEM. XRD results showed a transformation of crystalline structure from ramie cellulose I to cellulose II allomorph during mercerization and epichlorohydrin modification, and the crystalline structure of cellulose II maintained with obvious crystallinity index increase after HBP-NH₂ modification. Nitrogen content of HBP-NH₂ modified fabrics were 1.25–2.61 %. Cationization degree (D_C) of HBP-NH₂ modified ramie fabrics were 4.41–9.40 %. C.I. Reactive Red 2 was applied to study the dyeing performance of modified fabrics. The modification parameters were optimized as 50 °C for 5 h when the concentration of HBP-NH₂ was 8 g/L. K/S value and dye uptake of modified fabric was 23.64 and 85.6 % respectively under optimal modification conditions. The washing, rubbing and light fastness of modified ramie fabrics were acceptable. The tensile strength and tear strength of HBP-NH₂ modified ramie fabrics were lower than those of unmodified fabrics. The warp, weft of tensile and tear strength retention of modified fabrics were between 85.23 and 87.50 %. The HBP-NH₂ modification mechanism and dyeing mechanism on ramie fabric were suggested.