Abstract:Polyamide 6.6 is one of the most widely used polymers in the textile industry due to its durability; however, it has rather limited modification potential. In this work, the controlled surface modification of polyamide 6.6 fibres using the solvent system CaCl2/H2O/EtOH was studied. The effects of solvent composition (relative proportions of the three components) and treatment time on fibre properties were studied both in situ (with fibres in solvent) and ex situ (after the solvent was washed off). The fibres s… Show more
“…By the addition of ethanol, the solvation shell is disturbed and a complex formation between the calcium ion and polyamide is thermodynamically preferred. The amount of water is playing an important role on the kinetics of the dissolution [133].…”
Section: Polyamide In Cacl2/ethanol/water Systems As the Model Compoumentioning
Many biopolymers exhibit a strong complexing ability for multivalent ions. Often such ions form ionic bridges between the polymer chains. This leads to the formation of ionic cross linked networks and supermolecular structures, thus promoting the modification of the behavior of solid and gel polymer networks. Sorption of biopolymers on fiber surfaces and interfaces increases substantially in the case of multivalent ions, e.g., calcium being available for ionic crosslinking. Through controlled adsorption and ionic crosslinking surface modification of textile fibers with biopolymers can be achieved, thus altering the characteristics at the interface between fiber and surrounding matrices. A brief introduction on the differences deriving from the biopolymers, as their interaction with other compounds, is given. Functional models are presented and specified by several examples from previous and recent studies. The relevance of ionic crosslinks in biopolymers is discussed by means of selected examples of wider use.
“…By the addition of ethanol, the solvation shell is disturbed and a complex formation between the calcium ion and polyamide is thermodynamically preferred. The amount of water is playing an important role on the kinetics of the dissolution [133].…”
Section: Polyamide In Cacl2/ethanol/water Systems As the Model Compoumentioning
Many biopolymers exhibit a strong complexing ability for multivalent ions. Often such ions form ionic bridges between the polymer chains. This leads to the formation of ionic cross linked networks and supermolecular structures, thus promoting the modification of the behavior of solid and gel polymer networks. Sorption of biopolymers on fiber surfaces and interfaces increases substantially in the case of multivalent ions, e.g., calcium being available for ionic crosslinking. Through controlled adsorption and ionic crosslinking surface modification of textile fibers with biopolymers can be achieved, thus altering the characteristics at the interface between fiber and surrounding matrices. A brief introduction on the differences deriving from the biopolymers, as their interaction with other compounds, is given. Functional models are presented and specified by several examples from previous and recent studies. The relevance of ionic crosslinks in biopolymers is discussed by means of selected examples of wider use.
“…In an earlier work, the surface roughness of a PA66 fiber treated with the CaCl 2 /H 2 O/EtOH solvent used in this study was analyzed and it was found that the surface roughness increases significantly after the treatment, which is also the case for PA66 fabrics. 13 Especially in sport textiles, it is desired to obtain materials with a high UPF, without compromising performance-related properties, such as air permeability. Therefore, we investigated the influence of the fabric treatment on the air permeability.…”
Section: Resultsmentioning
confidence: 99%
“…In an earlier work, the surface roughness of a PA66 fiber treated with the CaCl 2 /H 2 O/EtOH solvent used in this study was analyzed and it was found that the surface roughness increases significantly after the treatment, which is also the case for PA66 fabrics. 13 Figure 2.Cover factor versus treatment time of polyamide 66 fabrics. The red reference line at 99.1% shows the cover factor of untreated polyamide 66 fabric.…”
Section: Resultsmentioning
confidence: 99%
“…In our previous work, we reported about the high surface roughness of a PA66 single fiber, measured with the 3D laser-scanning confocal microscope. 13 When we were trying to determine the surface roughness of the fabric with the 3D laser-scanning confocal microscopy, we found it was not possible since the original fabric itself shows some unevenness. Nevertheless, we measured the surface roughness of the single fibers and the fibers and the fabric observed with the 3D laser-scanning confocal microscopy look similar; therefore it can be concluded that there is also an increase in surface roughness on the treated fabric.…”
We reported previously that treatment of polyamide 66 with a mixture of CaCl2/EtOH/water results in a significant increase of surface roughness. A higher surface roughness is correlated with greater light scattering propensity, and therefore we investigated if polyamide 66 fabrics treated with the mixture exhibit lower ultraviolet (UV) transmission. The work was performed on a commercially available plain-woven polyamide 66 fabric, and the UV protection factor (UPF) increased from a value of 25 (of the fabric as received) to >100 (after a 1-min treatment with the mixture). There was no significant change in cover factor of the fabric. As the solvent mixture is environmentally benign and the desired effects are obtained with short treatment times, we believe this process may be a more sustainable alternative to the use of UV absorbers that is the state-of-the-art technology at the present time. In this paper, we have described the treatment and its effects on substrate topography and mechanical properties.
“…We have previously investigated the dissolution and swelling action by complexation. 21,22 However, another very important requirement for a possible application of this solvent system for the recovery of PA from textile waste is the intake polymer structure of the dissolved and reprecipitated polymer. This can only be achieved through a proper decomplexation process leading to PA free of Ca 2+ in the ideal case.…”
The 'circular economy' concept envisages deriving the maximum value out of resources and reducing waste to a minimum. In textiles, that includes the recovery of fiber materials out of used clothing and reusing them in the construction of new clothes. Processes such as mechanical separation, depolymerization treatment, and selective dissolutions of individual polymers are applied. We investigate the approach of selective nondestructive dissolution and recovery of polyamide fiber from mixed textile waste by using the solvent system CaCl 2 /ethanol/water (CEW) based on complexation and decomplexation of polyamide (PA). The results show that PA is precipitated and decomplexed by simple addition of water and a substantial amount of previously incorporated calcium by complexation, is removed. The recovered polyamide shows properties similar to pristine polyamide. Investigation on a mixed textile waste model of polyamide/wool demonstrates that CEW treatment can successfully separate different fiber materials. The nondestructive approach in dissolving PA using CEW, clearly shows the benefit, that PA fiber can be separated by controlled complexation/decomplexation without degradation, thus avoiding the repolymerization step. Furthermore, the solvent system is made of abundantly available materials that are inexpensive and used widely in industrial-scale operations. Thus, the concept will make significant contribution to a green textile recycling approach.
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