Excellent UV Resistance Research Articles

Poly(lactic acid)/lignin films with enhanced toughness and anti-oxidation performance for active food packaging

In this study, grafting of star-like lignin microparticles (LMP) onto PLA (LMP-g-PLA) was successfully realized by ring open polymerization of l-lactide, initiating from the hydroxyl groups on LMP surface. After that, various amount of LMP-g-PLA were melt blended with neat PLA and ethylene–vinyl acetate–glycidyl methacrylate (NPG) to prepare different PLA composites films, by exploiting the interfacial reactions between epoxy groups of NPG and carboxyl and hydroxyl groups of both LMP-g-PLA and PLA. Mechanical test results show that the addition of LMP-g-PLA made a significant contribution to the toughness of PLA/NPG blend, as the elongation at break increased up to 236% in PLA/NPG/1LMP sample. Although the addition of NPG and LMP-g-PLA hindered the crystallization capacity of PLA, good dispersion of LMP-g-PLA and compatibility between LMP and PLA acted as longer tortuous paths, consequently reducing the water vapor transmission rate. Meanwhile, the UV–Vis spectroscopy results showed that PLA/NPG/LMP films have excellent UV resistance behaviour without sacrificing too much the transparency. Results from overall migration tests and testing of anti-oxidant behaviour demonstrated that PLA films blended with NPG and lignin can be used as competitive materials in active food packaging industry.

Polydopamine-induced growth of mineralized γ-FeOOH nanorods for construction of silk fabric with excellent superhydrophobicity, flame retardancy and UV resistance

Due to the increasing pollution produced by the textile industry, environmentally friendly methods are becoming extremely important. In this work, silk fabrics (SFs) were modified with a series of natural polyphenols under the catalysis of laccase and then reacted with a ferrous solution to construct fabric surfaces with a micro-nano structure. Among the modified SFs, dopamine-Fe-modified silk fabric (PDA-Fe-SF) had an outstanding hydrophobicity and was screened as a research model. The preparation process was simple and eco-friendly, as it did not use toxic organic solvents, fluorine-containing substances, or halogen-containing and phosphorus-containing flame retardants. The structure and properties of the modified silk fabrics were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), a vertical combustion test and so on. The results showed the surface of the PDA-Fe-SF was coated with dense and uniform needle-like γ-FeOOH nanorods and had a high contact angle (CA) of up to 165° and good self-cleaning performance. The damaged carbon length of the burned fabric was only 10.5 cm in the vertical combustion test, and the UPF value of the PDA-Fe-SF can reach 72, which classifies this material in the Excellent UV protection level. The modified silk fabrics had good mechanical properties and durability. Through the electrostatic potential analyses of polyphenols and their oligomers, the FeOOH formation mechanism of the surface morphology could reveal that the differences in the polymerization types, structures and water solubilities of the polyphenol polymers would affect the way in which the polymers deposit and the amount of deposition that occurs, and the number of coordination sites for Fe2+ and the resulting various surface morphologies on the silk fabric could be determined.

Improvement of Electrical Insulation in Silicone Rubber by Adding Al2O3

Polymer Nano composite in recent time has shown high improvement in mechanical, chemical and electrical properties. Granting all these, the use of polymer nano-composites has only recently begun starting explorer. In recent times, polymer materials has shown remarkable improvement in electrical insulation because of their numerous advantages in out-door insulation systems because of their negligible weight, better pollution performance, low cost, good dielectric properties with easy processing. In polymer materials, silicone rubber is one of the lead polymer currently used and has high ending properties like high voltage insulator, thermal stability, excellent UV resistance and hydrophobicity. Therefore, Silicone rubber with fillers can overcome few drawbacks such as low strength and insulating properties.Oxides with different properties can help silicone rubber to enhance its properties. Oxides such as alumina, zirconia are being widely used in silicone rubber. Alumina which has strong thermal conductive and compressive strength with good electrical is used in silicone rubber. Here Silicone rubber nano composites are prepared by incorporating Al2O3 nano partic les. Electrical, Chemical properties like NaCl, HCl, and corrosion tests were conducted to know the performance of silicone rubber insulation at pollutant conditions. Dielectric tests were also done to know whether Al2O3 has made any effect with silicone rubber. Tensile strength and Hardness test were carried out to determine mechanical strength of the rubber.

Facile fabrication of cellulose composite films with excellent UV resistance and antibacterial activity

Research on biodegradable cellulose composite film with unique properties is of significance to alleviate current dependency on petroleum-based polymers, and to promote highly efficient utilization of lignocellulosic biomass. Lignin nanoparticles (LNPs) have been considered as a promising material for high value-added products. In this study, LNPs were prepared from corncob lignin via anti-solvent precipitation method, and then characterized by FTIR, TGA, AFM, and NMR. The CNF@CLNPs composite film was fabricated by blending CLNPs with CNF. The results showed that the CLNPs had an average diameter of about 118 nm, meanwhile the main structures and properties of corncob lignin were maintained. The CNF@CLNPs composite film exhibited a high ultraviolet resistance, and a good antibacterial activity against both Escherichia coli and Staphylococcus aureus. It is expected that the CNF@CLNPs composite film would have potential applications in outdoor materials and food packaging.

Facile and Effective Fabrication of Highly UV-Resistant Silk Fabrics with Excellent Laundering Durability and Thermal and Chemical Stabilities.

As the most favored high-quality biopolymer, silk fiber is widely used in the textile and medical industries owing to its impressive mechanical properties, wear comfort properties, and biocompatibility. However, its photoinstability, chemical instability, and thermal instability seriously hinder its utilization in luxurious fashionable apparels. Therefore, we herein report the preparation of an ultrathin and uniform TiO2-Al2O3 cloth with a thickness of just six in a thousand of fiber on silkworm silk fiber via atomic layer deposition. In this ultrathin composite cloth, the outer TiO2 layer acts as a sacrificial ultraviolet (UV) absorbent to dissipate large amounts of UV energy. Free radicals and electrons generated by the TiO2 layer are effectively blocked outside the surface of the bulk silk fiber by the inner insulating Al2O3 layer. The excellent UV-resistance of the modified silk fiber was confirmed by a lack of fade in the silk fabric after exposure to UV light for 60 min (equal to continuous exposure to strong sunlight for 3285 days). Compared with silk fiber, the tenacity of the prepared SF-200Al2O3-800TiO2 increased by 18.9% even after sunlight exposure. In addition, both the chemical and thermal stabilities of the modified silk fiber were improved. This technology is expected to have potential applications in various fields, such as high-end fabric development and smart materials, and will further guide material design for future innovations in functional fibers and devices.

Superhydrophobic Cu-based materials with excellent durability, stability, and regenerability grounded of self-similarity

The superhydrophobic materials have generated wide interest due to the broad application prospect. However, the superhydrophobicity of artificial superhydrophobic surfaces is easy to lose and which has caused widespread concern. In this work, Cu-based superhydrophobic materials with self-similarity in texture and composition both externally and internally were fabricated using a facile and environment-friendly approach. The as-prepared Cu-based materials not only behave excellent superhydrophobicity, but also show outstanding repellence universality to various liquids, excellent UV resistance and storage stability, and wide pH toleration. More importantly, the as-prepared samples present outstanding superhydrophobicity regenerability once the superhydrophobicity has been destroyed by abrasion, scratch, or fouling. In addition, the Cu-based superhydrophobic materials take on excellent self-cleaning performance and pollutants are difficult to adhere onto the material surfaces. Even if some pollutants have adhered onto the surfaces, they can be cleaned up easily by rolling water droplets. The superhydrophobic Cu-based materials with self-similarity in texture and composition both externally and internally were prepared. The as-prepared superhydrophobic materials show outstanding repellent universality to various liquids, excellent UV resistance and storage stability, wide pH toleration, and self-cleaning performance. More importantly, the block materials present outstanding superhydrophobicity regenerability once the surfaces have been destroyed by abrasion, scratch, or fouling.

Synthesis and Characterization of Nano-TiO2/SiO2-Acrylic Composite Resin

Waterborne acrylic resin is widely used as a binder of waterborne printing ink because of its excellent comprehensive properties. However, its further developments and applications are hindered by its poor UV resistance and water resistance. Therefore, an approach to prepare acrylic resin with excellent UV resistance and water resistance is described in this present study. The nano-TiO2/SiO2 composite particles were first modified with a silane coupling agent (KH-570) and a titanate coupling agent (NDZ-101) and then embedded into acrylic resin via a blending method. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetry analysis (TGA) were applied to investigate the structure and morphology of the modified nano-TiO2/SiO2 composite particles. The effects of the modified nano-TiO2/SiO2 composite particles on the UV and water resistance of the acrylic resin were investigated by UV spectroscopy and water resistance analysis. The weight loss of modified nano-TiO2/SiO2 was about 20% when heated to 600°C, which indicated that the nano-TiO2/SiO2 composite particles were modified by the coupling agents successfully. The UV-Vis spectra of acrylic resin showed that the UV resistance was improved upon the addition of nano-TiO2/SiO2. The water absorption of the nano-TiO2/SiO2-acrylic resin was less than 5%, indicating that the water resistance of the material was improved.

Preparation and characterization of poly(urethane-siloxane)/titanium-dioxide nanocomposites

This work is focused on preparation of poly(urethane-siloxane)/titanium-dioxide nanocompo-sites (PUSNs) with enhanced features. PUSNs were prepared by the in situ polymerization re-action using titanium-dioxide as a nano-filler in different amounts (1, 2, 3 and 5 wt.%) with respect to the poly(urethane-siloxane) (PUS) matrix. PUS copolymer was based on ?,?-dihy-droxy-ethoxypropyl-poly(dimethylsiloxane), 4,4?-methylenediphenyldiisocyanate and 1,4-bu-tanediole. In order to investigate the influence of TiO2 content on the structure, UV resistance, thermal properties, hydrophobicity and morphology of the prepared PUSNs, FTIR spectro-scopy, UV-Vis diffuse-reflectance spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), contact angle measurements, surface free energy (SFE) analysis, water absorption, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were performed. The PUSNs showed excellent UV resistance, high hydrophobicity, low surface free energy and also higher thermal stability and rougher surface and cross-section relief structure as compared to the pure PUS copolymer. Based on the obtained results it can be concluded that prepared PUSNs could be potentially used as protective coatings.

Multifunctional Cellulose Ester Containing Hindered Phenol Groups with Free-Radical-Scavenging and UV-Resistant Activities.

Excessive radicals and UV irradiation can trigger oxidative and physiological stresses, which cause tissue aging, human disease, food spoilage, and material degradation. In this study, a multifunctional cellulose ester containing hindered phenol groups, cellulose 3,5-di- tert-butyl-4-hydroxybenzoate (CBH), with free-radical-scavenging and UV-resistant activities was synthesized and used as a functional material. The obtained CBHs can effectively scavenge reactive nitrogen free radicals and hydroxyl free radicals in both solid and solution states. Moreover, CBHs have no cytotoxicity, and, on the contrary, they promote the proliferation of human epidermal keratinocytes. Benefiting from excellent solubility, processability, and formability, CBHs have been readily processed into flexible films, transparent coatings, and nanoribbons membranes. The highly transparent and flexible CBH film completely absorbs the light of 200-300 nm range and partially absorbs the light of 300-400 nm range, indicating a UV-shielding capability. After the CBHs were loaded on an ordinary facial mask by electrospinning or added into a hand cream, the resultant facial mask and hand cream exhibited outstanding free-radical-scavenging properties. In addition, CBHs can also be used to fabricate functional sprays with antioxidative and UV-shielding activities. Accordingly, the obtained CBHs have a huge potential in cosmetics, personal care products, biopharmaceuticals, papermaking, and art protection because of their excellent antioxidation, nontoxicity, UV resistance, formability, and odorless properties.

Fabrication of highly durable polysiloxane-zinc oxide (ZnO) coated polyethylene terephthalate (PET) fabric with improved ultraviolet resistance, hydrophobicity, and thermal resistance

Developing a universal strategy to improve the properties of polyethylene terephthalate (PET) fibers, such as UV resistance, hydrophobicity, and thermal resistance, is highly desirable in expanding the application of PET fibers. Herein, a highly durable and robust ZnO layer was deposited onto PET fabric via radiation-induced graft polymerization (RIGP) of γ-methacryloxypropyl trimethoxysilane (MAPS) and the subsequent sol-gel in situ mineralization with zinc acetate to produce wurtzite nanocrystalline ZnO. The as-obtained material, denoted as PET-g-PMAPS/ZnO. The interfacial layer consisted of Zn-O-Si and Si-O-Si covalent bonds not only leads to an improvement in adhesion between ZnO nanoparticles and its support, but it also overcomes the poor film-forming ability of inorganic particles. Most importantly, photocatalytic self-degradation of its organic support caused by the high photocatalytic activity of ZnO can be eliminated because of high bond energy of the organic-inorganic hybrid structure. PET-g-PMAPS/ZnO exhibited excellent thermal resistance, UV resistance and durability. Superhydrophobicity was achieved by simply annealing the PET-g-PMAPS/ZnO fabric at 200 °C in ambient air, and the coated fabric still retains its superhydrophobicity after 40 laundering cycles test and even stored for a few weeks. This study presents an effective method to overcome the bottle-necks in growing inorganic nanocrystals on polymeric supports surface.

Poly(dopamine) coated graphene oxide as multi-functional filler in waterborne polyurethane

Graphene oxide, known as an excellent reinforcing agent in polymer composites, was modified with dopamine and then incorporated into waterborne polyurethane (W-PU) via water solution blending. The addition of dopamine modified graphene oxide (D-GO) in W-PU is able to strengthen the stress transfer from the polymer matrix to the filler, and hence dramatically enhance the mechanical properties of the W-PU with increased ultimate Young’s modulus and moderately improved elongation at break. Also, since poly(dopamine) contains abundant phenolic groups in the structure, this project also aims to improve the antioxidant property of polyurethane. Impressively, it is found that the D-GO filler significantly slows down the rate of photo-degradation and thermo-oxidative degradation, lowering the drops of tensile stress, yield strain and elongation at break after UV irradiation. Besides, compared with neat PU and 1 wt% D-GO containing W-PU nano-composite, in which even no electrical conductivity can be observed, nano-composites containing 4 wt% D-GO exhibits a considerable electrical conductivity up to 0.82 S m−1. This work demonstrates that D-GO is not only a promising candidate in aiding PU as an impressive coating materials with excellent UV and thermal oxidation resistance, but also can act as an anti-static material.

Facile fabrication of robust fluorine-free self-cleaning cotton textiles with superhydrophobicity, photocatalytic activity, and UV durability

We present a facile and an inexpensive approach to prepare robust fluorine-free self-cleaning cotton textiles by surface modification with anatase TiO2 sol and polydimethylsiloxane (PDMS) using a simple dip-coating method. The synergetic effect of the anatase TiO2 particles and PDMS was critical and essential for obtaining a superhydrophobic coating with photocatalytic activity and UV durability. The coated cotton textiles not merely exhibited desirable superhydrophobic property with a water contact angle (WCA) of 153.8°, but also performed the considerable photocatalytic activity by the decomposition of oil red O under UV exposure. Importantly, the as-obtained self-cleaning cotton textiles were stable under various harsh conditions such as acidic, alkaline, corrosive organic solutions, and laundering. Moreover, the coated cotton textiles could also maintain its superhydrophobicity when exposed to long-term UV irradiation, displaying its excellent UV resistance. Therefore, this simple preparation approach can be regarded as a promising way to construct self-cleaning surfaces for scale up production.

Silicone-Containing Biodegradable Smart Elastomeric Thermoplastic Hyperbranched Polyurethane.

Silicone-containing biobased hyperbranched polyurethane thermoplastic elastomers at different compositions were reported for the first time. The structures of the polymers were evaluated from Fourier transform infrared spectroscopy, NMR, X-ray diffraction, and energy-dispersive X-ray spectroscopy analyses. The synthesized elastomers possess high molecular weight (1.11–1.38 × 105 g·mol–1) and low glass transition temperature (from −40.0 to −27.3 °C). These polymers exhibited multistimuli responsive excellent repeatable intrinsic self-healing (100% efficiency), shape recovery (100%), and efficient self-cleaning (contact angle 102°–107°) abilities along with exceptional elongation at break (2834–3145%), high toughness (123.3–167.8 MJ·m–3), good impact resistance (18.3–20.3 kJ·m–1), and adequate tensile strength (5.9–6.9 MPa). Furthermore, high thermal stability (253–263 °C) as well as excellent UV and chemical resistance was also found for the polymers. Most interestingly, controlled bacterial biodegradation under exposure of Pseudomonas aeruginosa bacterial strains demonstrated them as sustainable materials. Therefore, such biobased novel thermoplastic polyurethane elastomers with self-healing, self-cleaning, and shape memory effects possess great potential for their advanced multifaceted applications.

PEG-ran-PPG Modified Epoxy Thermosets: A Simple Approach To Develop Tough Shape Memory Polymers

In this work, we prepared thermoresponsive shape memory epoxy thermosets by blending epoxy resin with poly(ethylene glycol-ran-propylene glycol) random copolymer (PEG-ran-PPG or RCP). Incorporation of RCP precisely tuned the temperature showing the shape memory effect of epoxy thermoset, which was established by dynamic mechanical analysis (DMA) and fold-deploy test. FTIR spectroscopy confirmed that the compatibility of the system is caused by intermolecular hydrogen bonding and only at high RCP concentration some phase separation starts. DMA and thermomechanical analysis provided evidence for the interactions of RCP chains with epoxy thermoset. The impact strength considerably increased especially for 30 and 40 wt % RCP modified blends. Furthermore, the blends exhibited good thermal stability in conjunction with excellent UV resistance.

A novel strategy for durable superhydrophobic coating on glass substrate via using silica chains to fix silica particles

The practical application of superhydrophobic coatings on glass is usually restricted by their poor wear resistance due to the insufficient adhesion. A double-silica-layered structure was proposed to reinforce the coating adhesion on glass substrate. The wettability, surface morphologies, and chemical composition were investigated by water contact angle measurement, scanning electron microscopy (SEM), and fourier transformed infrared (FTIR) spectroscopy. The prepared superhydrophobic coating displays a good wear-resistance by emery paper and sand abrasion, which also has excellent thermal stability and UV resistance. This strategy shows a bright future for durable superhydrophobic coating on glass.

Preparation and Characterization of Poly-1,2,3-triazole with Chiral 2(5H)-Furanone Moiety as Potential Optical Brightening Agents.

A series of novel heterocyclic polymers with fluorescent brightening properties are synthesized via Click polymerization. Fast synthesis of poly-1,2,3-triazoles (Mn ≥ 9.31 kDa) is described herein, with a high yield of up to 95%. The Click polymerization approach has a number of advantages, including facile operation and outstanding isolation yield. The resultant polymers have a high thermal stability, excellent UV resistance, as well as acid and light fastness. On embedding with optical brightening agents, the polymers display strong fluorescent brightening properties in the tetrahydrofuran solution. Moreover, these products have a strong solution emission intensity and extraordinary photostability under UV light.

Properties of anti-UV-finished cotton fabrics cured by blue light irradiation

To decrease the pollution discharge and energy consumption resulting from textile finishing using the conventional pad-dry-cure process, a blue light-curable digital finishing for textile was innovatively proposed. Based on the mechanism of blue light curing technique, a combination of the blue light curing process and anti-UV finishing was established in this study. A blue light-curable anti-UV finishing solution containing oligomers, monomers, photoinitiators, and anti-UV agents was padded onto the surface of the cotton fabrics, and then cured to form a tough film under blue light irradiation. The ultraviolet protection factor (UPF) value of the finished cotton fabrics was 50, the top level of international standards, demonstrating excellent UV resistance. The finished cotton fabrics also showed good rubbing and washing durability, and acceptable handle. The integration of an anti-UV finishing with the blue light curing technique presents some unique advantages in terms of environmental protection and application potential.

Preparation and characterization of self-photostabilizing UV-durable bionanocomposite membranes for outdoor applications

Here, we report a durable and ultraviolet (UV) resistant nanocomposite membrane of chitosan (CS) with effective photostabilization ascribed to Zinc oxide (ZnO) nanoparticles. Zinc oxide nanoparticles were successfully dispersed in the solution of chitosan polymer. The nanocomposite films with the homogenous dispersion of ZnO nanoparticles in the chitosan matrix were obtained by solution casting method and the influence of ZnO nanoparticles as a photostabilizer was studied. The nanocomposite membranes were photoirradiated by polychromatic radiations with λ>300nm using mercury vapour lamps in SEPAP instrument. The resulting nanocomposite material exhibited excellent UV-resistance in very low percentages of ZnO nanoparticles. The chitosan membranes showed fast degradation attributes than the nanocomposite membranes. ZnO nanoparticles effectively absorbed UV radiations, thus protecting polymer from radiation degradation. The neat and irradiated nanocomposites of chitosan and ZnO nanoparticles (CS/ZnO) were characterized by Fourier Transform Infrared Spectroscopy (FT-IR) spectroscopy for the chemical changes/degradation taking place. Chitosan nanocomposites were further characterized for tensile properties, contact angle measurements and surface morphology.

Effect and origin of the structure of hyperbranched polysiloxane on the surface and integrated performances of grafted Kevlar fibers

Four hyperbranched polysiloxanes (HPSis) with different molecular weights and concentration ratios of double bonds to epoxy groups (1:6.5–1:0.7) were synthesized and characterized. Each HPSi was facilely grafted onto surfaces of Kevlar fibers (KFs) to develop novel modified fibers (HPSi-g-KFs). The structures and integrated properties of HPSi-g-KFs as well as the origin behind were systematically investigated. Results show that HPSi-g-KFs have much rougher surface morphologies, and their surface free energies are as high as about 1.7 times that of KFs, showing greatly improved wettability. Besides, HPSi-g-KFs have excellent UV resistance after 168h UV irradiation, the retentions of tenacity, energy to break, modulus and break extension are as high as 92, 86, 95 and 96%, respectively, while those of KFs are 66–85%. In addition, compared with KFs, HPSi-g-KFs have higher tensile tenacity and energy to break with similar modulus and break extension, much better thermal stability and flame retardancy. The nature of HPSi has different influence on different property of fibers, the HPSi with smaller molecular weight and more epoxy groups is beneficial to prepare HPSi-g-KFs with better wettability, while that with larger molecular weight and more double bonds tends to prepare HPSi-g-KF with better flame retardancy and UV resistance.

Polyurethane coatings for metal and plastic substrates

Polyurethane coatings offer many advantages for metal substrate applications. Polyurethanes have excellent appearance (“wet look”), mechanical performance, UV resistance, and chemical resistance compared with other coatings. Polyurethanes can be applied as higher solids or powder coatings without loss of performance. As a result, polyurethanes are the market leader for coating metallic and plastic substrates in numerous high-end and highly visible applications today. In the future,the performance of urethane coatings will allow them to be used in a broader spectrum of applications.