Fabrication of high-stability Ni-PSF@PAO40 microcapsules and their lubricating properties in polyamide 6

Abstract

Novel Ni-PSF@PAO40 microcapsules (NPPMS) with high stability were prepared by using a combined processing method of electroless nickel plating and solvent volatilization. The results indicate that Ni is completely assembled on the surfaces of PSF/PAO40 microcapsules with the encapsulation capacity of NPPMS achieved at 50%. Organic solvents immersion shows that NPPMS have an excellent chemical stability. Macro thermal stability tests reveal that the softening temperature of NPPMS is increased up to over 400 °C while it becomes lower than 200 °C for PSF/PAO40 microcapsules. Furthermore, NPPMS were embedded into polyamide 6 (PA6) to prepare PA6/NPPMS composites. The cross-sectional morphology shows that NPPMS are intact in PA6 matrices. The microhardness of PA6 is effectively improved with the incorporation of NPPMS. As compared with neat PA6, the coefficient of friction (COF) for PA6/NPPMS composites with 10% NPPMS could be reduced by 87.7% (from 0.49 to 0.06) and the wear rate could be decreased by 96.8% (from 1.29×10−5 to 4.15×10−7 mm3/(N·m)). Further studies confirmed that increasing test loads and test temperatures was beneficial to improve the lubrication performance of NPPMS despite the opposite trend occurred when increasing the sliding speeds. It has been demonstrated that synergistic effects between PAO40 and Ni layer play an important role in improving the tribological properties of PA6. Therefore, NPPMS significantly improve the ability of microcapsules to resist a harsh environment, which has important scientific significance for expanding the use of microcapsules more practically in self-lubricating composites.

Influence of PAO@PSF microcapsules on the tribological properties of polyvinylidene fluoride matrix recovered from waste membranes

“…9. Firstly, the microcapsules in the PVDF composite rupture under the action of load and frictional contact during the sliding process, and the encapsulated lubricating oil is then released to the friction surface and forms an oil lubricating lm [32,37,[39][40][41]. This oil lubricating lm helps to separate the contact surfaces, thereby reducing the friction coe cient and wear rate.…”

“…Among them, microcapsules containing lubricating oil are well known as a novel core-shell additive that enables the incorporation of lubricating oil into polymer matrices. Many related studies have reported that microcapsules have amazing effects in enhancing the tribological properties of polymers, such as epoxy [37,38], polyamide 6 [39,40] and polypropylene [41]. In self-lubricating composites, as the solid matrix wears, the liquid lubricant is released to the friction surface without external intervention or maintenance, resulting in a signi cant reduction in matrix wear [37][38][39].…”

The sustainable recycling of polyvinylidene fluoride membrane for tribological application

“…Therefore, the antifriction and wear mechanisms of PVDF composites are shown in Figure 9. On one hand, during the sliding process, under the action of load and frictional contact, the rupture of microcapsules in the PVDF composite results in release of the encapsulated lubricating oil to the friction surface and thus forming an oil lubricating film 32,37,[39][40][41] ; this oil lubricating film separates the contact surfaces, and thereby reducing the friction coefficient and wear rate. On the other hand, the presence of a large amount of wear debris trapped in the cavity of broken microcapsules will be helpful for the decrease of wear rate.…”

“…[33][34][35][36] At this case, microcapsules containing lubricating oil are well known as a novel core-shell additive that enables the incorporation of lubricating oil into polymer matrices. Various related studies have reported amazing effects of the microcapsules in enhancing the tribological properties of different polymers, such as epoxy, 37,38 polyamide 6, 39,40 and polypropylene. 41 During the wearing of solid matrix, the liquid lubricant is released from the selflubricating composites to the friction surface without external intervention or maintenance, resulting in significant reduction in the matrix wear.…”

Self‐lubricating epoxy composite coating with linseed oil microcapsule self‐healing functionality

“…Filling the polymer with microcapsules loaded with liquid lubricant can effectively improve its tribological properties. 18 When the microcapsules rupture during repeated friction, the liquid lubricant is released onto the wear surface, significantly reducing both friction coefficient and wear rate. Khun et al 19 prepared microcapsules containing paraffin and developed paraffin microcapsules/epoxy composites.…”