Ultraviolet Blocking Properties Research Articles

Intumescent flame‐retardant and ultraviolet‐blocking coating screen‐printed on cotton fabric

Herein, we report an interlayer-confined strategy to intercalating two-dimensional zirconium phosphate (ZrP) within reduced graphene oxide (RGO) interlayers, generating the hierarchical ZrP–RGO hybrids. The hybrids were then blended with ammonium polyphosphate to fabricate an intumescent flame-retardant coating on cotton fabric through an automatic screen printing. The resulting cotton fabric shows an excellent self-extinguishing performance when subjected to a butane flame. During combustion, its peak heat release rate and total heat release are significantly decreased by 92.1% and 61.8% in contrast with control cotton fabric, and a flame-retardant mechanism is reasonably proposed by the condensed and gaseous analysis. Furthermore, the flame-retardant cotton fabric exhibits an excellent ultraviolet-blocking performance with the high ultraviolet protection factor of 201.51. Even after 300 cycles of abrasion, the coated cotton fabric retains the superior flame-retardant and ultraviolet-blocking properties. This work provides a simple and feasible strategy to prepare the multifunctional fabrics.

Fabrication of cellulose nanofiber-based functional color indicator film incorporated with shikonin extracted from Lithospermum erythrorhizon root

Cellulose nanofiber (CNF)-based functional films were prepared by adding shikonin extracted from dried roots of gromwell (Lithospermum erythrorhizon) using a solution casting method. The shikonin added CNF film showed distinctive color changes depending on the pH in the range of 2–12. The shikonin was evenly dispersed in the CNF matrix to form a compatible red colored film. The addition of shikonin (10%) improved the mechanical properties of the CNF film without significantly affecting the crystal structure, water vapor barrier, and thermal stability properties of the film. The CNF/shikonin composite film showed remarkable ultraviolet blocking properties without much-sacrificing transparency. Besides, the composite film showed potent antimicrobial and antioxidant activities. The CNF-based color indicator films with improved physical and functional properties have a high potential for active and intelligent food packaging applications.

Ultrafast gelling using sulfonated lignin-Fe3+ chelates to produce dynamic crosslinked hydrogel/coating with charming stretchable, conductive, self-healing, and ultraviolet-blocking properties

Developing an ecological and economical method for fabrication and application of polymer hydrogels is important for the hydrogel/coating electronics. Here, a dynamic oxidation and coordination system composed of sulfonated lignin (SL) and Fe3+ was introduced to assemble multifunctional Fe-SL-g-polyacrylic acid (PAA) hydrogel at 20 ℃ in a time scale of minutes instead of hours. The SL-Fe3+ system can rapidly activate the ammonium persulfate (APS, initiator), and then it instantaneously provides abundant semiquinone and hydroxyl radicals to accelerate the formation of polymer chains. Moreover, the functional SL-Fe3+ chelates can also reversibly crosslink the polymer chains to form multifunctional hydrogels. Surprisingly, the resultant hydrogel obtained charming extension ratio (up to 1680%), conductivity (up to 7.0 × 10-2 S·m−1), and adhesive strength (up to 36.4 kPa). This technology was also applied to rapidly fabricate a transparent (up to 81%, thickness: 2 mm), UV-blocking (up to 99.7%, thickness: 2 mm), adhesive, and conductive hydrogel coating on substrates. Besides, the dynamic coordination inside the hydrogel imparts desirable self-healing capabilities to damaged network, with up to 98.5% recovery in conductivity and 85.7% in extension ratio. In short, this technology based on the sustainable SL-Fe3+ system greatly facilitates the rapid and low-cost preparation of multifunctional hydrogel/coatings, which have promising industrial applications in human–machine electronics.

Synthesis of carbon nanotubes composite nanofibers for ultrahigh performance UV protection and microwave absorption applications

We report in this research the ultraviolet (UV) protection and microwave absorption properties of polyacrylonitrile (PAN)/multi-walled carbon nanotubes (MWCNTs) composite nanofibers based lightweight and flexible composite structure. The morphological analysis of the synthesis composite nanofibers exposed that the nanofibers average diameter decreases from 271 ± 32 to 161 ± 22 nm with increasing from 0 to 10 wt% MWCNTs content in solution. The increased content of MWCNTs in composites leads to higher impact among them; then, better UV blocking properties were attained. The maximum UV protection (UPF) value of composite nanofibers reaches UPF = 677 with a thickness of 100 μm. The microwave absorption property of the composite nanofibers was examined in the X-band frequency range. The optimal microwave reflection loss value is −14.43 dB at 11.49 GHz in composite nanofibers containing 10 wt% MWCNTs. This research has expertly made known the potential of developing electrospun composite nanofibers containing carbon nanotubes as lightweight and ultra-thin UV protection and microwave absorption materials.

Thermally-induced cellulose nanofibril films with near-complete ultraviolet-blocking and improved water resistance

In recent years, ultraviolet (UV) protection films made from cellulose nanofibril (CNF) have drawn significant attention, owing to its high transparency, high mechanical strength and relatively high thermostability. Generally, CNF films had poor UV-shielding performance, and required UV absorbent to enhance their UV-shielding ability. Herein, a simple thermal treatment is proposed to directly improve the UV blocking properties of CNF films without incorporating UV absorbent. After thermal treatment at 160 °C, the CNF films exhibited a near-complete UV blocking ability. In particular, they exhibited full absorption of ultraviolet A (UVA) and ultraviolet B (UVB), and also showed a high visible light transmittance of 72%. In addition, the UV-shielding films performed stable UV-blocking when exposed to UV irradiation. Simultaneously, the hornification induced by thermal treatment endowed an improved hydrophobicity for CNF films. However, the tensile strength of the CNF films decreased from 133 MPa to 81 MPa after thermal treatment at 160 °C.

Polymer Brushes Tethered ZnO Crystal on Cotton Fiber and the Application on Durable and Washable UV Protective Clothing

AbstractTo improve the durability and washability of ultraviolet (UV) protective fabrics, grafted polymer brushes are introduced as platforms for in situ growth of zinc oxide (ZnO) nanostructure on modified cotton fibers, using the electroless deposition approach. Hollow cotton fiber acts as a microreactor for ZnO deposited on both inner and outer surfaces. More importantly, adjusting the reaction in a microenvironment enables effective control of the morphology of ZnO crystals and the functionalized fabric shows durable UV blocking properties. Unlike other finishing processes, the functional ZnO nanocrystals are grown not only on the surface of the fibers but also inside of the hollow cotton fibers, but with a different morphology. This unique property, postmodification allows the functional fabrics to show good antifriction capability, washability, and durability. The combination of zinc oxide and textiles brings out new features for plain cloth, and the final product can be applied to outdoor clothing, protective suits, tents, and curtains, etc.

Modification of poly(ethylene terephthalate) by copolymerization of plant-derived α-truxillic acid with excellent ultraviolet shielding and mechanical properties

Ultraviolet-shielding poly(ethylene α-truxillate-co-ethylene terephthalate) (PETT) was synthesized via the addition of α-truxillic acid (TA) as a third monomer in the copolymerization modification of poly (ethylene terephthalate) (PET). The effects of TA, with its semi-flexible/semi-rigid special structure, on the chemical structure, thermal properties, crystallization behavior, ultraviolet blocking properties, and mechanical properties of PETT were then investigated. Thermal analysis revealed that a small amount of TA significantly reduced the crystallinity and melting temperature of PETT but did not affect its thermal stability. Notably, the material exhibited excellent thermal properties in processing applications. With the addition of only 10 wt%, PETT could block ~100% of the ultraviolet spectrum (<400 nm), making up for the defect that pristine PET cannot shield the UV-A spectrum (320–400 nm). The yield stress also increased significantly from 29.8 MPa for the neat PET to 40.2 MPa for PETT (10 wt% TA). In addition, the TA is plant-derived and synthesized by environmentally friendly photodimerization reaction. A small amount of TA provides PET with excellent ultraviolet shielding performance and mechanical properties, broadening its application prospects in the field of anti-ultraviolet packaging materials.

UV-blocking, superhydrophobic and robust cotton fabrics fabricated using polyvinylsilsesquioxane and nano-TiO2

UV-blocking, superhydrophobic and robust cotton fabrics were successfully developed by combination of polyvinylsilsesquioxane (PVS) and nano-TiO2 for the first time. The influence of the add-on amount on morphologies, ultraviolet (UV) protection, hydrophobicity, mechanical properties, rigidity and thermal degradation of the treated cotton fabrics was studied. The nano-TiO2 particles were found to be embedded in the PVS film layer on the surface of cotton fibers by covalent Ti–O–Si bonds after curing. The UV blocking and hydrophobic properties of the functionalized cotton fabrics were also improved with increases in the amount of add-on, compared to the reference materials. The improvements on the UV blocking, water repellency and rigidity of the treated cotton fabrics are likely attributed to synergism between the PVS polymer and nano-TiO2. The mechanical properties of the finished cotton fabrics are significantly enhanced by treatment of composite coatings. However, the resistance to thermal degradation evidently did not change despite changes in the add-on amount. Hence this strategy for developing the composite coatings can guide in constructing the advanced functional surface, and the discovery of this new class of UV-blocking, superhydrophobic and robust cotton fabrics has many potential applications such as advanced UV-blocking textiles, stretchable electronic devices and self-cleaning fields.

AgNps-PVA–coated woven cotton fabric: Preparation, water repellency, shielding properties and antibacterial activity

Nowadays, there is a large demand for smart textiles by consumers. Smart textiles have different functions, and can provide comfort, safety and protection. In this study, electro-conductive woven cotton fabric is prepared in two steps. The cotton fabric samples are first impregnated and padded with a polyvinyl alcohol solution of 5% for multiple cycles (1, 3, 5 and 7 cycles) and dried. Then, silver nanoparticles are deposited onto the fabric through magnetron sputtering technology. The coated samples are examined using a Fourier transform infrared spectrometer, scanning electron microscope and X-ray diffractometer. The ultraviolet blocking, infrared reflection, electromagnetic shielding, and antibacterial properties are evaluated, as well as the contact angle, light transmittance and electrical conductivity. The results show that a polyvinyl alcohol film is successfully formed and the cotton fabric fibers are stuck together through hydrogen bonds. The light transmittance is increased after the polyvinyl alcohol pretreatment. After undergoing seven cycles of coating with polyvinyl alcohol, the silver nanoparticles-coated samples show large contact angle of 127.6°, excellent ultraviolet blocking property, a high infrared reflectivity of 30%, electrical resistivity of 1.46 × 10–6 Ω·m, electromagnetic interference shielding effectiveness of −20 dB and antibacterial efficacy of &gt;99.5%. Compared to the untreated and silver-coated cotton without impregnation of polyvinyl alcohol, the silver nanoparticles–polyvinyl alcohol-coated cotton fabric sample has excellent performance, which makes it a promising textile with a multitude of protective properties.

Preparation of silver-coated silk fabrics with antibacterial activity using silver carbamate and hydrogen reduction

A new method was studied to efficiently metallize silk fabrics, and silver-coated silk fabrics were prepared and characterized. In this study, silver 2-ethylhexylcarbamate was used as the silver precursor, and a hydrogen atmosphere was used to reduce the precursors, thus forming silver nanoparticles on the surface of silk fabric. The silver-coated silk fabric was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) spectroscopy, and the results confirmed that 20-70 nm silver nanoparticles were uniformly generated without damaging the silk fabric. The silver-coated silk fabric showed excellent ultraviolet blocking properties and antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). This method provides a way to improve the antibacterial ability of silk fabrics while avoiding damage to the silk.

Design and characterization of self-cleaning cotton fabrics exploiting zinc oxide nanoparticle-triggered photocatalytic degradation

Self-cleaning surfaces are functional structures with application in smart textiles. In this study, self-cleaning cotton fabrics were fabricated by coating photocatalytic zinc oxide nanoparticles (ZnO NPs) on cotton surfaces, using a traditional dip-pad-dry-cure coating process. The coatings and ZnO content-dependent self-cleaning properties of the coated fabrics were investigated to evaluate their potential in practical application. The ZnO NP-coated cotton fabrics were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, and thermogravimetric analysis. Methylene blue was used as a test contaminant to qualitatively assess the self-cleaning properties of the fabrics. The removal efficiency was determined for fabrics with different ZnO contents, under different solar irradiation times. Consecutive photocatalytic degradations were carried out to investigate the self-cleaning durability of the fabrics. This involved repeatedly contaminating the same fabric position and subsequent cleaning by photocatalytic degradation. The self-cleaning properties of the fabrics depended on their ZnO NP content. A higher wt% of ZnO NPs in the coated fabric resulted in more pronounced photocatalytic degradation than fabrics with a lower wt%. The self-cleaning performance of the higher wt% ZnO NP fabric decreased slightly after the third consecutive photocatalytic degradation. Results of wash fastness showed color removal after 10 times washing under light irradiation. Moreover, the ZnO NP-coated fabrics exhibited excellent ultraviolet blocking properties. These findings provide a potential model for the practical application of self-cleaning textiles.

Negligible cytotoxicity induced by different titanium dioxide nanoparticles in fish cell lines

Titanium dioxide nanoparticles (TiO2-NPs) have a wide number of applications in cosmetic, solar and paint industries due to their photocatalyst and ultraviolet blocking properties. The continuous increase in the production of TiO2-NPs enhances the risk for this manufactured nanomaterial to enter water bodies through treated effluents or agricultural amendments. TiO2-NPs have shown very low toxicity in a number of aquatic organisms. However, there are no conclusive data about their deleterious effects and on their possible mechanisms of toxic action. At this level, in vitro cell culture systems are a useful tool to gain insight about processes underlying the toxicity of a wide variety of substances, including nanomaterials. Differences in the physiology of different taxa make advisable the use of cells coming from the taxon of interest, but collecting data from a variety of cellular types allows a better understanding of the studied processes. Taking all this into account, the aim of the present study was to assess the toxicity of three types of TiO2-NP, rutile hydrophobic (NM-103), rutile hydrophilic (NM-104) and rutile-anatase (NM-105), obtained from the EU Joint Research Centre (JRC) repository, using various fish cell lines (RTG-2, PLHC-1, RTH-149, RTL-W1) and rainbow trout primary hepatocytes. For comparative purposes, the effect of different dispersion protocols, end-point assays and extended exposure time was studied in a fish cell line (RTG-2) and in the rat hepatoma cell line (H4IIE). TiO2-NPs dispersions showed a variable degree of aggregation in cell culture media. Disruption of mitochondrial metabolic activity, plasma membrane integrity and lysosome function was not detected in any cell line after exposure to TiO2-NPs at any time and concentration ranges tested. These results are indicative of a low toxicity of the TiO2-NPs tested and show the usefulness of fish cells maintained in vitro as high throughput screening methods that can facilitate further testing in the framework of integrated testing strategies.

Robust ultraviolet shielding and enhanced mechanical properties of graphene oxide/sodium alginate composite films

To enhance the mechanical performance and ultraviolet shielding property, graphene oxide was incorporated as the functional nanofiller into a sodium alginate matrix to form a composite film via a solvent-casting method. The as-obtained films were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermal gravimetric; their mechanical and ultraviolet blocking properties were also systemically evaluated and compared. The results showed that the maximum tensile strength increased to 84 MPa at 6 wt.% graphene oxide loading, nearly 265% greater than that of pure sodium alginate film. The increased tensile strength may have resulted from the existence of hydrogen bonding and high interfacial adhesion between graphene oxide filler and sodium alginate matrix. Furthermore, the sodium alginate/graphene oxide films also demonstrated robust ultraviolet shielding capacity; the corresponding ultraviolet protection factor reached up to 133.61 at 8 wt.% graphene oxide loading.

Multifunctional cotton fabrics with graphene/polyurethane coatings with far-infrared emission, electrical conductivity, and ultraviolet-blocking properties

In order to introduce multifunctional properties into flexible cotton fabric, graphene and waterborne anionic aliphatic polyurethane composites were prepared and then deposited on the surface of the fabric substrate through facile pad-dry-cure process. The fabrics thus obtained were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy, and their functional properties such as far-infrared emission, electrical conductivity, and ultraviolet (UV) blocking were studied. The coating process enhanced the far-infrared emissivity up to 0.911 in the wavelength range of 4–18 μm. In addition, the ultraviolet protection factor (UPF) of the fabric with 0.8-wt% graphene could reach 500, up to 60-fold higher than that of pristine cotton fabric (UPF 8.19), and its electrical resistivity was decreased from 1.15 × 107 to 2.94 × 10−1 Ω m, which is almost 8 orders of magnitude. The fabrics have also been found to be stable even after 10 cycles of laundering.

Broad spectrum UV protection by crystalline organic microrod sunscreens

Ultraviolet (UV) light has the potential to cause many adverse effects on the body including causing the cancers melanoma and squamous cell carcinoma. The use of sunscreens to protect against these harmful effects has become common practice. However, many of the sunscreens currently being used have the ability to cross the skin barrier and enter the body. These components can produce reactive oxygen species inside the body which can cause damage to cells. We have developed a sunscreen product that contains organic particles that are too large to diffuse into the skin. These particles are formed from four FDA approved UV blocking molecules that are solids at room temperature. The components are first mixed together, melted, and then emulsified in water and allowed to cool. Once cooled, the particles slowly crystallize in the solution forming sphere to rod-like particles about one micron wide and one to tens of microns in length. SPF measurements of the samples showed comparable results to two commercially available sunscreens with SPFs of 50. The particles were shown to maintain their excellent UV blocking properties after exposure to UV light and show great promise as possible sunscreens.

UV Blocking Properties of Reactive Dyed Mercerized Fabric

This paper is concerned with the effect of mercerization on the ultraviolet (UV) blocking property of 100% cotton knitted fabrics with different structures. In this study, we proposed that the mercerization process may enhance UV blocking property of 100% cotton knitted fabrics. UV measurement is carried out using a spectrophotometer and the results revealed that mercerization process did not have significant improvement on the UV blocking properties but the fabric structure did.

Functionalization of cotton fabric at low graphene nanoplate content for ultrastrong ultraviolet blocking

Flexible fabric with remarkable ultraviolet (UV) blocking was deemed as the feasible personal protection to shield human body against external ultraviolet radiation. In this paper, graphene nanoplate (GNP) as a novel UV absorber was utilized to functionalize the surface of cotton fabric at low content (0.05–0.4wt.%) via pad-dry-cure method. The morphology and structure of the as-obtained modified cotton fabrics were characterized with scanning electron microscope, atomic force microscope, Fourier transform infrared spectroscopy, UV–vis spectroscopy and X-ray photoelectron spectroscopy, respectively. Furthermore, the ultraviolet protection factor (UPF) was applied to evaluate UV blocking properties of the samples. The results indicated that the modified cotton fabric performed ultrastrong protection against UV radiation, up to 10-fold increment of UPF (from 32.71 to 356.74) was endowed only by incorporating graphene nanoplate 0.4wt.%.

Civilian Pilot Exposure to Ultraviolet and Blue Light and Pilot Use of Sunglasses

Population and animal studies indicate that long-term exposure to short-wavelength visible light and ultraviolet (UV) radiation causes increased risk of certain ocular pathologies such as cataracts and maculopathy. The potential risk to flight crew is unknown. The UK Civil Aviation Authority (CAA) has issued guidance to pilots regarding sunglass selection; however, it is not known if this guidance is appropriate given pilots' unique occupational environment. A search and appraisal of the relevant literature was conducted which showed that within the airline pilot population, there is limited evidence of a higher prevalence of cataracts. There are no data of other known UV-related ocular pathology. There is some evidence of higher prevalence of skin melanomas. Studies measuring cockpit UV radiation levels are limited and leave unanswered questions regarding airline pilot exposure. Data from optical transmission of cockpit windshields demonstrates the UV blocking properties at sea level. No studies have addressed the occupational use of sunglasses in airline pilots. Although it is likely that an aircraft windshield effectively blocks UV-B, the intensity of UV-A and short wavelength blue light present within the cockpit at altitude is unknown. Pilots may be exposed to solar radiation for periods of many hours during flight where UV radiation is known to be significantly greater. Aircraft windshields should have a standard for optical transmission, particularly of short-wavelength radiation. Clear, untinted prescription glasses will offer some degree of UV protection; however, sunglasses will offer superior protection. Any sunglasses used should conform to a national standard.