Towards scalable production of polyamide 12/halloysite nanocomposites via water-assisted extrusion: mechanical modeling, thermal and fire properties

Abstract

In this study, polyamide 12 (PA12)/untreated halloysite nanotubes (HNTs) nanocomposites are prepared in a semiindustrial scale extruder using a non-traditional "one step" water-assisted extrusion process. A morphological study is carried out using a combination of scanning electron microscopy and transmission electron microscopy analyses to evaluate the influence of water injection and filler content on the quality of clay dispersion. The use of water injection slightly improves the nanoscale dispersion at low HNTs content (<8 wt.%), while this effect is more pronounced at higher filler loading (16 wt.%). A mechanism explaining the physico-chemical action of water during extrusion is proposed. The materials are characterized with respect to their mechanical, thermo-mechanical, thermal and fire properties. A strong correlation is found between nanostructure and physical properties; the more uniform dispersion of the clay nanotubes, the higher mechanical reinforcement, thermal stability and fire retardancy of PA12 nanocomposites. Tensile tests results are interpreted in terms of three mechanical models: the Halpin-Tsai's model for stiffness and the interfacial strength model and the Pukanszky's equation for yield strength. Linear fits of the experimental data confirm that the superior reinforcement of nanocomposites prepared using water injection results from improved clay dispersion and better interfacial adhesion between PA12 and HNTs. In view of these promising results, the proposed direct melt compounding method could be easily scaled-up towards the production of PA12-HNTs nanocomposites at an industrial scale.

Structural interpretations on tensile fracture mechanism and elongational rheology of poly(vinylidene fluoride)/halloysite nanotubes nanocomposites

“…Undoubtedly, larger A value means better filler dispersion state in matrix. The Young's modulus of the HNTs, E f , is reported to be about 140 GPa . The Young's modulus of the PVDF matrix measured by tensile tests, E m , is 1.05 and 1.08 GPa for the P and P‐W samples, respectively, in this work.…”

“…Herein the Halpin‐Tsai equation is used to fit the experimental data to calculate the average aspect ratios of HNTs in the PVDF matrix. The average aspect ratio of filler (e.g., HNTs and carbon nanotube ) can be used to indirectly estimate its dispersion state in a polymer matrix. Undoubtedly, larger A value means better filler dispersion state in matrix.…”

“…Water‐assisted mixing extrusion (WAME), as an environmentally friendly approach, can be utilized to prepare nanocomposites with enhanced nanofiller dispersion in polymers and so is of growing interest . The researches performed by Bailly and co‐workers demonstrated that polypropylene/HNTs, polyethersulfone/HNTs, and polyamide 12 (PA12)/HNTs nanocomposites prepared by WAME exhibit lower flammability than those prepared by conventional extrusion as a result of better dispersion of HNTs. Recently, the present authors adopted WAME to prepare poly(vinylidene fluoride) (PVDF)/HNTs, PVDF/graphene oxide (GO), and poly(methyl methacrylate)/expanded graphite (PMMA/EG) (nano)composites.…”

埃洛石纳米管增强聚合物复合材料研究进展

“…其他带有氢键官能团的物质,如氰尿酸三 聚氰胺、三聚硫氰酸、二苯胍、异氰尿酸酯、环糊 精等, 加入 PP/HNTs 体系中, 同三聚氰胺对体系力学 性能影响相似. 在聚合物基体中通过氢键构筑杂化 68.1%(FM) [46] PA6 熔融挤出 新西兰 5 无 88.3%(EB), 增大(TS, TM) [47] PA6 熔融挤出 新西兰 30 无 降低(EB), 增大(TS, TM) [48] PA6 熔融挤出 美国 6 PA 母粒稀释(含 30 wt%HNTs) 33.3%(IS), 30.3%(TS), 增大(TM), 变化不大(EB) [49] PA6 熔融挤出 中国湖北 9 MAPTS 改性 21%(TS), 29%(FS), 56%(FM) [50] PA6 熔融挤出 美国 5 APTES 改性 21%(TS), 45%(TM), 41%(FS), 51%(FM) [51] PA11 熔融挤出 美国 6 PA 母粒稀释 20%(TS), 46.7%(TM) [52] PA12 水辅助挤出 美国 16 无 增大(TS, TM), 减小(EB) [53] [55] 熔融挤出 中国湖北 23 三聚氰胺等改性(氢键) 减小(IS) ,变化不大(TS), 32.9%(FS), 106%(FM) [56] 熔融挤出 中国湖北 23 BBT 改性 随 BBT 加入而减小(IS), 增大(TS), 46.9%(FS), 127.5%(FM) [31] 熔融挤出 中国湖北 23 EPB 改性 随 EPB 加入而减小(IS), 变化不大(TS), 62.2%(FS), 116.5%(FM) [30] 熔融挤出 中国湖北 23 CBS 改性 随 CBS 加入而减小(IS), 变化不大(TS), 44.4%(FS), 128.1%(FM) [32] 熔融挤出 中国贵州 10 MT2EtOH 溶液表面处理 26.9%(IS) ,变化不大(TS) [57] 熔融挤出 美国 8 季铵盐改性、母粒稀释 77%(IS), 35%(TS), 40%(TM), 23%(FS), 48%(FM), 减小(EB) [33] 图 5 (网络版彩图)PP 中加入 HNTs 量-韧性和强度变化的 关系图 [55], g-HNTs; [56], 三聚氰胺(2.8 wt%)改性; [31], BBT(7.1 wt%)改性; [ [62] EPDM 开炼 新西兰 47.6 MAH-g-EPDM 改性 764%(TS), 334%(M100), 134% (EB) [63] EPDM 密炼 美国 9.1 无 30.4%(TS), 52.6%(M100), 变化不大(EB) [64] EPDM 开炼 新西兰 21.4 MPS 改性 264.4%(TS), 58.9%(M100), 134% (EB) [23] xSBR 共凝聚法、开炼 中国湖北 21.3 无 53%(TS), 266%(M100), 减小(EB) [66] SBR 开炼 中国湖北 26.9 MAA(7.6 wt%)改性 341%(TS), 150%(M300), 增大(EB) [67] SBR 开炼 中国湖北 26.9 SA(7.6 wt%)改性 408%(TS), 200%(M300) [29] SBR 开炼 中国湖北 35.2…”

Nicotinamide‐based poly(ether amide)s: a novel type of soluble thermally stable polyamides

“…Reducing crystallinity by importing side groups, introducing bulky groups, and entering of polar units along the main chain improve the solubility performance. Also, copolymerization is another major modification for making the polyamides processable …”