Kwan Moon Sin

Low temperature plasma-treated nylon fabrics

Abstract Nylon 6 fabrics were treated with low temperature plasma (LTP) with three non-polymerizing gases: (i) oxygen, (ii) argon and (iii) tetrafluoromethane. After plasma treatment, the properties of the fabric, including surface morphology, low-stress mechanical properties, air permeability and thermal properties, were investigated. The nylon fabrics treated with different plasma gases exhibited different morphological changes. Low-stress mechanical properties obtained by means of the Kawabata evaluation system fabric (KES-F) revealed that the surface friction, tensile, shearing, bending and compression properties altered after the treatments. The changes in these properties are believed to be related closely to the inter-fiber/inter-yarn frictional force induced by the LTP treatment. A slightly decrease in the air permeability of the treated fabrics was found which is probably due to plasma action effecting on increase in the fabric thickness and a change in the fabric surface morphology. The change in the thermal properties of the treated fabrics was in good agreement with the above findings and can be attributed to the amount of air trapped between the yarns. This experimental work suggests that the changed properties induced by LTP can effect an improvement in certain textile products.

Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

Abstract Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment.

Study of plasma-etched and laser-irradiated polyamide materials

Abstract.Surface morphological structures of the Low Temperature Plasma (LTP) and UV Excimer Laser treated polyamide materials were investigated. The effects of different parameters were studied by using Scanning Electron Microscope (SEM). For LTP treatment, different non-polymerizing gases (oxygen, argon), discharge power and exposure time were selected as treatment parameters. For Laser treatment, high-fluence (above ablation threshold), low-fluence (below ablation threshold) and number of pulses were studied. High-fluence laser treatment gives the most distinct ripple-like structures on the surface of polyamide and these structures are more obvious when the number of pulses increases. Low-fluence treated polyamide develops some stripes of sub-micron size within a narrow fluence window. On the other hand, oxygen and argon plasma also gives ripple-like structures but with smaller dimensions than those due to high-fluence laser treatment. Although the morphological modification features on the polyamide fiber surface developed under laser and LTP treatments are not identical, they have certain similarity.

Surface Modification of Polyamides Materials with Low Temperature Plasma

The surface properties of materials are often the important determinants of their usefulness, and many of the chemical treatments now in use are aimed at modifying these properties. The important properties of polymer materials such as adhesion, friction, wetting, penetrability and biological compatibility are strongly influenced by their surface characteristics. Low Temperature Plasma (LTP) is a technology which can produce not only interesting morphological modification on the surface of the polymers, but also can replace less environmental-friendly finishing processes. In this paper, four non-polymerizing plasma gases: oxygen, argon, tetrafluoromethane and 75%/25% nitrogen/hydrogen mixture were used to modify Nylon 6 filaments and fabrics. The results of SEM study reveals that interesting morphological changes on the surface of treated samples. Besides, with the appropriate LTP treatment, the fabric properties, such as the hydrophobicity of polyamides, surface luster, etc. can be greatly modified.

Comprehensive study of pulsed UV-laser modified polyamide fibers

Abstract. Polyamide fibers (nylon 6) are modified by UV-radiation using a pulsed excimer laser with different treatment parameters. The treated samples are characterized by using a scanning electron microscopy (SEM), tapping mode atomic force microscopy (TM-AFM), x-ray photoelectron spectroscopy (XPS), and chemical force microscopy (CFM). Depending on the conditions during the irradiation, different surface modifications are obtained which can generally be distinguished as high-fluence (above the ablation threshold) and low-fluence (below the ablation threshold). Topographical results indicate that ripple-like structures of micrometer size are developed under high-fluence laser irradiation. On the contrary, smaller sub-micron structures are formed by low-fluence treatment. XPS results show that bond scission occurs on the polymer surface under the action of high-fluence while low-fluence modifies the sample by an oxidative process. Changes in surface chemical properties of the laser-irradiated polyamide are supported by chemical force microscopy experiments with gold-coated AFM tips modified with -COOH terminated self-assembled alkanethiol monolayers (SAMs).

Quantifying the quality of D65 simulator

This study investigated the influence of various D65 simulators on visual color matching seen under five D65 simulators. These five D65 simulators were categorized by CIE No. 51 method from A to D. The gray scale rating method was used to assess the visual difference of 77 textile metamers. The instrumental color difference of each metamer was calculated using SPD of CIE illuminant D65 and real SPDs of D65 simulators. The performance factor (PF/3) was used to indicate the agreement between visual differences under five D65 simulators as well as instrumental color difference and visual difference. The observer accuracy and observer repeatability were also analyzed by PF/3 measure. The experiment results showed that the visual data obtained from category A and B D65 simulators had a good agreement in PF/3 measure. The results also indicated that better agreement between instrumental and visual color difference was obtained if the real SPDs of D65 simulator were used instead of the CIE illuminant D65 data. The general color rendering index, Ra, for each D65 simulator was calculated by CIE No. 13.3 method. However, this index was inconsistent with MI(vis) in CIE No.51 method.