A huge quantity of dark-colored waste cotton fabrics with a high content of dye powder is dumped in landfills and incinerated, which is a waste of resources and pollutes the land and atmosphere. Also, it is meaningful to effectively strip the color from these dark-colored waste cotton fabrics with minimal damage to the strength of the textiles. In this study, a dark-colored waste cotton fabric dyed with reactive dyes was subjected to chemical treatment with redox decoloring agents. The effects of various treatments on the coloration and mechanical properties of the fabric were compared. This work developed an effective Na₂S₂O₄–H₂O₂ system for decolorizing waste cotton fabric, with numerous advantages over conventional physicochemical approaches including achieving a CIE whiteness index of 74.1, tensile strength loss of 24.0%, weight loss of 1.2%, decoloration rate of 97.8%, and a degree of polymerization of 735.3. Furthermore, a mechanism was proposed to explain the two-step synergistic decolorization process.

In order to reduce the damage to tissue and fill the interstices between fibers, multifilament sutures are frequently treated with certain coating materials. The objective of this study was to create and characterize dopamine hydrochloride (DA) and carboxymethyl chitosan (CMCS) coatings on surgical sutures and investigate their effects on the frictional performance of the surgical sutures during sliding through a skin substitute. The effects of the treatment on the physical and chemical characteristics of the surgical sutures were evaluated. The friction force of the surgical sutures during sliding through the skin substitute was experimentally determined using a penetration friction apparatus. The coefficient of friction (COF) was calculated using a linear elastic model and was used to estimate the frictional behavior of the surgical suture-skin interactions. The results showed that the DA coating could evenly deposit on the surface of the etched multifilament surgical suture surfaces in a weakly alkaline buffer solution. The CMCS coating material could form a uniform film on the surface of the sutures. Minor changes in the surface roughness of the multifilament surgical sutures with different treatments occurred in this study. The friction force and the COF of the multifilament surgical sutures with DA and CMCS coating showed little change when compared with untreated multifilament surgical sutures.

Purpose: The purpose of this paper is to investigate the tribological performance of graphene oxide (GO) sheets as water-based lubricant additive when ultra-high molecular weight polyethylene (UHMWPE) plates slid against 316L stainless steel ball using a reciprocating tribometre. Design/methodology/approach: The factors influencing the tribological performance were considered, including the viscosity of the GO dispersion, normal load, sliding velocity and the roughness of UHMWPE. The surface microstructure and properties of UHMWPE were studied by means of scanning electron microscopy, laser confocal microscopy, Raman spectroscopy and contact angle measurements. Findings: The results revealed that the GO dispersion reduced friction and sliding-wear. The surface images of the wear UHMWPE plates indicated that GO sheets were prone to adsorption on the surface and form a thin physical tribofilms at the substrate. Originality/value: Based on the experimental findings for the evolution of the microstructure morphology and the development of subsurface cracks, less debris and cracking can be observed in the UHMWPE plates lubricated by GO dispersion.

With the development of fine surgery and desire for low-injury methods, the frictional properties of surgical sutures are one of the crucial factors that can cause damage to tissue, especially for some fragile and sensitive human tissues such as the eyeball. In this study, dopamine hydrochloride and graphene oxide were used as external application agents to prepare a biological coating for the surface of multifilament surgical sutures. The effects of this biocoating on the surface morphology, chemical properties, mechanical properties, and tribological properties of surgical sutures were studied. The friction force and the coefficient of friction of surgical sutures penetrating through a skin substitute were evaluated using a penetration friction apparatus and a linear elastic model. The tribological mechanism of the coating on the multifilament surgical sutures was investigated according to the results of the tribological test. The results showed that there were uniform dopamine and graphene oxide films on the surface of the surgical sutures, and that the fracture strength and yield stress of the coated sutures both increased. The surface wettability of the surgical sutures was improved after the coating treatment. The friction force and the coefficient of friction of the multifilament surgical sutures with the dopamine hydrochloride and graphene oxide coating changed little compared to those of the untreated multifilament surgical sutures.