Effect of the combination of a benzotriazole‐type ultraviolet absorber with thermal stabilizers on the photodegradation of poly(vinyl chloride)

The effect of the combination of a benzotriazole type of UV absorber (UV326) with different types of thermal stabilizers, including an organic calcium complex and an organotin mercaptide, on the photodegradation of poly(vinyl chloride) (PVC) was investigated by color difference measurements, UV‐vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and viscosity‐average molecular weight (M_η) determinations. Films of PVC containing 0.5 phr of UV326, with or without 2 phr of thermal stabilizer, were prepared by solution casting and subjected to accelerated UV weathering under xenon light with an irradiance of 0.51 W/(m² nm) at 65°C. The results revealed that both UV326 and the mixture of UV326 with the organic calcium complex displayed good performance in inhibiting the photodehydrochlorination and photooxidation of PVC. In contrast, the combination of UV326 and the methyltin mercaptide remarkably accelerated the discoloration of PVC when the irradiation time increased from 300 to 400 h because of the UV sensitivity of the organotin. However, carbonyl index data indicated that a hydrogen abstraction reaction did not take place between UV326 and the methyltin mercaptide, so that the photooxidation of the PVC film was prevented effectively during the whole period of exposure, a result which may be attributed to the strong steric hindrance effect of the tert‐butyl group at the 3‐position of the phenyl ring in UV326. The changes of M_η were in good accordance with the results obtained from other characterizations. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers     

Combined effect of hindered amine light stabilizer and ultraviolet absorbers on photodegradation of poly(vinyl chloride)

The combined effect of a basic hindered amine light stabilizer (HALS) and ultraviolet absorbers (UVAs) on casted poly(vinyl chloride) (PVC) films, during photodegradation, was studied by color change, ultraviolet‐visible (UV–vis) spectroscopy, Fourier‐transform infrared (FTIR) spectroscopy, and viscosity‐average molecular weight. It was found that the basic amine groups in the HALS (T770) could promote the dehydrochlorination, thereby accelerating the photooxidation of PVC films. Meanwhile, T770 could scavenge the radicals formed and restrain the aging of PVC to some extent. The above‐mentioned aspects were competing factors: the former played a dominant role during the first 100 h, while the latter counteracted the former effect to some extent between 100 and 300 h. A benzotriazole derivative (UV326) absorbs more UV radiation in the UV‐A region (320–400 nm), which mainly causes the photodegradation of PVC samples, than a benzophenone derivative (UV531). Thus, UV326 is a more efficient UV absorber than UV531 in prohibiting the photooxidation and chain scission of PVC films. The combination of T770 and UV326 effectively protected PVC films from dehydrochlorination and photooxidation. The combination of T770 and UV531 accelerated the dehydrochlorination and discoloration of PVC films. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

Preparation and characterization of UV‐curable organic/inorganic hybrid composites for NIR cutoff and antistatic coatings

In this study, UV‐curable organic/inorganic hybrid composite coatings with near infrared (NIR) cutoff and antistatic properties were prepared by high‐shear mixing of two kinds of polymer matrices and coated on plastic and glass substrates by the doctor‐blade method. This study also investigated the morphology, stability, optical properties, electrical resistivity, and durability of the UV‐cured composite coats. It was found that the composite coatings were very stable under centrifugation. Moreover, the films with transmittance of above 80% in a visible light region (400–800 nm) and of ～ 40% to 50% in the NIR region (1000–1600 nm) showed low haze of 6.9%, electrical resistivity of around 2.3 × 10⁷ Ω/square. Thus, excellent adhesion, scratch, and weathering durability can be produced on polycarbonate substrate at room temperature. The experimental results reveal that UV‐curable organic/inorganic hybrid composites can be used effectively to fabricate films with NIR cutoff as well as antistatic properties, indicating a high potential for practical application in architectural, automotives, and optoelectronics. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of PVC/CsxWO3 composite film with excellent near-infrared light shielding and high visible light transmission

Near-infrared (NIR) shielding is essential not only in the building and automobile glass films but also in achieving energy conservation. However, effectively shielding NIR and maintaining high transmittance in the visible light region have been great challenges in the past decade. Recently, hexagonal cesium tungsten bronze (Cs_xWO₃) nanoparticles have been widely studied due to the excellent transparency in the visible light region and strong heat-shielding ability in the NIR region. Herein, a design concept of transparent polyvinyl chloride (PVC)/Cs_xWO₃ composite film, as a heat insulation material for glasses, was proposed. To achieve this purpose, the PVC/Cs_xWO₃ composite film was prepared by incorporating Cs_xWO₃ slurry with better dispersion than traditional Cs_xWO₃ nanoparticles powder into a transparent PVC matrix. By the UV-Vis-NIR spectrophotometer characterization, the PVC/Cs_xWO₃ composite film containing 2.1 phr Cs_xWO₃ slurry displays high blocking of NIR (78%) and high transmittance of visible light (76%). In order to further understand the actual heat insulation effect from the PVC/Cs_xWO₃ composite films, the indoor sunlight simulation test and outdoor cooling experiment with solar illumination variations were carried out, which both showed heat insulation that is superior to the antimony tin oxide and indium tin oxide thin films prepared in our previous work. In addition, the mechanical property of PVC/Cs_xWO₃ composite films shows almost no change with the increase of Cs_xWO₃ slurry. The PVC/Cs_xWO₃ composite films simultaneously achieve excellent shielding of NIR and high transmittance of visible light, which makes it an ideal material to alleviate the current building energy consumption issues.     

具有屏蔽蓝光性能的PVA基功能薄膜的制备及性能研究

依据颜色互补原理,以聚乙烯醇(PVA)为基材,黄颜料为蓝光吸收剂,制备具有屏蔽蓝光特性的PVA基功能薄膜。通过调控黄颜料的种类和含量,研究了不同种类的黄颜料对蓝光屏蔽性能和薄膜透光率的影响。研究发现,耐晒黄的蓝光屏蔽性能最佳,且当其含量为0.5%时,蓝光屏蔽性能达到饱和状态。     

Fabrication of oxide-based near infrared-shielding coatings for a smart window to prevent infrared-induced photoaging in human skin

Oxide-based near infrared (IR)-shielding coatings consisting of quarter‐wave stacks of oxygen-deficient tantalum oxide (Ta₂O_5?x) and silicon oxide (SiO₂) multilayers and tin-doped indium oxide (In₂O₃) (ITO) films with the thicknesses of 200–600 nm can block the passage of IR-A (wavelength: 760–1400 nm) and IR-B (wavelength: 1400–3000 nm) radiation, respectively. In this study, the optical properties and microstructure of these oxide-based IR-shielding coatings were investigated. Transmission electron microscopy images indicated that amorphous Ta₂O_5?x/amorphous SiO₂ multilayers were uniform and dense. ITO films were found to be highly crystalline and show carrier concentrations of up to 7.1 × 10²⁰ cm^?3, resulting in the strong IR-B optical absorption due to the plasma excitation of the free carriers. Oxide-based IR-shielding coatings with an ITO thickness of 420 nm were found to have near-IR shielding rates of >90% and an average visible light transmittance of >70%. The effects of IR on human keratinocytes were studied to evaluate the IR-induced photoaging in human skin. It was found that the downregulation of cellular proliferation and the enhancement of senescence-associated β-galactosidase activity induced by IR irradiation were significantly inhibited by oxide-based IR-shielding coatings. Thus, this study provides a facile method for the development of coatings for smart windows with high IR-shielding ability and high visible light transmittance.     

Wavelength sensitivity of the photodegradation of poly(methyl methacrylate)

Poly(methyl methacrylate) (PMMA) was photolyzed with monochromatic light of wavelengths 260, 280, 300, 320, 400, and 500 nm in vacuo by the use of the Okazaki Large Spectrograph. UV spectral changes, the quantum yields of main-chain scission (?cs), and effects of wavelength were investigated. UV spectral changes around 280 nm were observed with irradiation at 260 nm. The ?cs has a maximum value in case of irradiation with 300 nm light. It turned out that photodegradation of PMMA took place by irradiation of 260–320 nm light but did not by irradiation with the light longer wavelength than 340 nm. The average values of ?cs obtained in this work were 0.84 × 10^?4, 1.06 × 10^?4, 4.21 × 10^?4, 1.23 × 10^?4, 0, and 0 for irradiations at 260, 280, 300, 320, 400, and 500 nm, respectively. It was found that the photo-induced side-chain scission initiates the main-chain scission of PMMA by irradiation of 260 and 280 nm light. © 1993 John Wiley & Sons, Inc.     

Influence of UV absorber on photodegradation processes of poly(vinyl chloride) with different average degrees of polymerization

The influence of UV absorber (Chimassorb81) on the photodegradation mechanism of different average degrees of polymerization (DP ) of poly (vinyl chloride) (PVC) with UV‐irradiation time was investigated by viscosity‐average molecular weight determination, UV‐vis spectroscopy, FTIR, contact angle measurement, and scanning electron microscopy (SEM). The PVC films with different DP (1000 and 3000), which contained 0.3 or 0.5 phr Chimassorb81, were prepared by solution casting. It was carried out by exposing specimens to xenon‐arc light source with a spectral irradiance of 0.68 W/(m² nm) at 63°C. It is found that the Chimassorb81 is efficient photostabilizer for PVC with different DP . Although the Chimassorb81 delays the photodegradation of PVC, it does not influence the photodegradation mechanisms of PVC with different DP . The main photodegradation reaction for the lower DP of PVC is dehydrochlorination in the initial stage of UV‐irradiation, and then the crosslinking and chain scission reactions occurred after long irradiation. However, the main reaction of the higher DP of PVC is not dehydrochlorination but crosslinking and chain scission in the initial stage of UV‐irradiation. The results of carbonyl index, C? Cl index, contact angle measurement, and SEM also show that the photostability of Chimassorb81 is more effective for the higher DP of PVC, especially in the presence of higher concentration of Chimassorb81. POLYM. ENG. SCI., 47:1480–1490, 2007. © 2007 Society of Plastics Engineers     

Preparation of epoxy-silica-acrylate hybrid coatings

Summary An organic-inorganic epoxy-silica-acrylate hybrid coating had been prepared by radical solution copolymerization and sol-gel process. The room curing reaction of the hybrid coating was discussed, and its structure, optical properties and thermal stability were studied. The hybrid coatings have multiple functional groups, and the inorganic phase and organic phase are linked by the chemical bonding. When tetraethylorthosilicate (TEOS) mass fraction were 10% and 20%, hybrid coatings had inorganic particle mean sizes of 36 nm and 45 nm, respectively, together with their homogeneously distribution within the polymeric matrix. With increasing of TEOS content, the transmittance in the visible region and the yellow index (YI) of the hybrid coatings after UV irradiation decrease, while the absorbency at 300–400 nm, the onset decomposition temperature and maximum weight loss temperature increase.     

纳米TiO_2和纳米CaCO_3对EVAC流滴棚膜性能的影响

采用内添法,将纳米二氧化钛(nano-TiO_2)或纳米碳酸钙(nano-CaCO_3)与流滴剂司班60等助剂混合后,利用挤出机制备以乙烯–乙酸乙烯酯塑料(EVAC)为载体的流滴母粒,进而通过吹塑工艺制备EVAC流滴棚膜,探讨了nano-TiO_2或nano-CaCO_3用量对EVAC流滴棚膜拉伸性能、流滴性和透光性的影响。结果表明,适当的加入nanoTiO_2或nano-CaCO_3,均能提高棚膜的拉伸强度,当母粒中nano-CaCO_3用量为4份时,棚膜的纵横向拉伸强度达到最大,而母粒中nano-TiO_2用量为2份时,即可使棚膜的纵横向拉伸强度达到最大;nano-TiO_2的加入略微改善了棚膜的流滴性,而nano-CaCO_3使棚膜的流滴性降低;添加nano-TiO_2或nano-CaCO_3后,棚膜对紫外光均有明显的屏蔽效果,对可见光的透光率也均有所提升,其中添加nano-TiO_2的棚膜的紫外光屏蔽效果以及对可见光的透光率均明显高于添加nano-CaCO_3的棚膜。     

改性聚碳酸酯板材的制备及性能研究

采用由丙烯酸类树脂、有机溶剂和紫外线吸收剂(UVA)组成的抗紫外线透明涂层制备改性聚碳酸酯(PC)板材,通过透光率/雾度测定仪、加速老化测试仪、分光光度计研究了涂层对PC板材光学和力学性能的影响。结果表明,抗紫外线涂层与PC板表面具有极佳的附着力,这种涂层具有优异的抗紫外线性能,未涂覆涂层的PC板经紫外光老化120h后黄色指数达到11左右,而涂覆该涂层的PC板的黄色指数仅为1左右,同时该板材能有85%以上的可见光透过率,120h紫外光加速老化后,板材的可见光透过率和力学性能基本保持不变。     

Facile growth of novel morphology correlated Ag/Co-doped ZnO nanowire/flake-like composites for superior photoelectrochemical water splitting activity

In this paper, novel morphology correlation between silver nanowires (AgNWs) and cobalt (Co)-doped ZnO (Co-ZnO) flake-like thin films (nanowire/flake-like) has been proposed for enhanced photoelectrochemical (PEC) water splitting activity. Here in, high-quality AgNWs/Co-ZnO heterostructures enabled superior visible light water splitting activity compared to the pure ZnO and AgNWs/ZnO. To address the strategic effect of AgNWs coupling and transition metal (Co-2?at%) doping into the ZnO host lattice, we have carried out the X-ray diffraction, field emission scanning microscopy, X-ray photoelectron spectroscopy, UV–Vis transmittance, water contact angle and PEC analyses. In this way, PEC water splitting activity was mainly examined by linear sweep voltammetry (I-V), amperometric I-t and photoconversion efficiency (η) studies. The experimental results provide clear evidence of morphology correlation between AgNWs and Co-ZnO flake-like structures for strong visible light absorption. Specifically, AgNWs/Co-ZnO composites exhibited significant enhancement in the photocurrent density (7.0?×?10^?4 A/cm²) than AgNWs/ZnO (3.2?×?10^?4 A/cm²) and pure ZnO (1.5?×?10^?6 A/cm²). As a result, detailed AgNWs/Co-ZnO geometry has great potential for photoconversion efficiency (0.73%). In a word, the merits of controllable AgNWs/Co-ZnO heterostructure are proposed to improve the visible light harvesting and charge carrier generation for energy conversion devices.     

Exceptionally good,transparent and flexible FeS2/poly(vinyl pyrrolidone) and FeS2/poly(vinyl alcohol) nanocomposite thin films with excellent UV‐shielding properties

Composites of nanocrystalline iron disulfide (FeS₂) coated with poly(vinyl pyrrolidone) (PVP) or poly(vinyl alcohol) (PVA) have been successfully synthesized using a solvothermal process, in which PVP and PVA serve as soft templates. Transparent, flexible thin films of these nanocomposites were prepared from homogeneous solution using a solution‐casting approach. X‐ray diffraction and thermogravimetric analysis and energy‐dispersive X‐ray, Fourier transform infrared and UV‐visible absorption spectroscopic techniques were employed to study the structural and optical properties of these nanocomposite films. UV‐visible spectra in transmission mode reveal the UV‐shielding efficiency of these nanocomposite films and the films are found to be exceptionally good for UV‐shielding applications in the wavelength range 200 to 400 nm. The present work aims at developing transparent and flexible UV‐shielding materials and colour filters using cost‐effective and non‐toxic inorganic–polymer nanocomposites. © 2012 Society of Chemical Industry     

Preparation and characterization of transparent ZnO/epoxy nanocomposites with high-UV shielding efficiency

Transparent ZnO/epoxy nanocomposites with high-UV shielding efficiency were reported in this paper. First, zinc oxide (ZnO) precursor was synthesized via the homogeneous precipitation method and ZnO nanoparticles were then made by calcination of the precursor at different temperature. The structural properties of the as-prepared ZnO nanoparticles were studied in detail using thermogravimetry (TGA), differential thermal analysis (DTA), X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR) and transmission electron microscopy (TEM), respectively. Transparent ZnO/epoxy nanocomposites were subsequently prepared from transparent epoxy (EP-400) and as-prepared ZnO nanoparticles via in situ polymerization. Optical properties of ZnO/epoxy nanocomposites, namely visible light transparency and UV light shielding efficiency, were studied using an ultraviolet-visible (UV-vis) spectrophotometer. The optical properties of the as-obtained nanocomposites were shown to depend on ZnO particle size and content. The nanocomposite containing a very low content (0.07% in weight) of ZnO nanoparticles with an average particle size of 26.7 nm after calcination at 350 °C possessed the most optimal optical properties, namely high-visible light transparency and high-UV light shielding efficiency, that are desirable for many important applications.     

Photo‐Induced Hydrogel Formation Based on g‐C3N4 Nanosheets with Self‐Cross‐Linked 3D Framework for UV Protection Application

Composite hydrogels of graphitic carbon nitride nanosheets (CNNS) and polyacrylamide (PAM) with superior UV absorption and visible transparence capabilities are reported. CNNS is employed not only as a photocatalytic initiator to trigger the polymerization of acrylamide, but also as a cross‐linker to 3D connected PAM chains via hydrogen bonds. The obtained CNNS/PAM hydrogels are highly moldable for preparing various forms, and have good mechanical properties, self‐healing ability, and photo‐stability. Furthermore, the composite hydrogels have a wide spectral range for UV absorption compared to conventional UV protective materials. Besides the complete screening of UVB (280–315 nm) in sun radiation, the CNNS/PAM hydrogel film can also filter >95% UVA radiation (315–400 nm) by regulating the coating thickness, meanwhile retaining a high visible transmittance. Therefore, the CNNS/PAM hydrogels have potential applications for shielding UV radiation. Additionally, this strategy provides a common and facile route to fabricate functional composite hydrogels via photo‐induced polymerization.     

Packaging materials with tailor made light transmission properties for food protection

Packaging material with optimal light barrier properties can prevent food quality deterioration. For dairy products, wavelength in the visible region between 400–450 nm and 600–650 nm should be blocked out due to the content of chlorophyll in dairy products. Six low density polyethylene blown films were formulated with the combination of four different pigments and additives: green, yellow, silver additive, and optical brightener, in addition to four reference samples. All films were transparent. Optical properties and light transmission were measured for each film, and microscopy analyses were used to investigate the surface topography. The sample containing high concentration of both green and yellow pigments had the lowest value in gloss and transmittance. This film blocked the light below 450 nm and transmitted 10% at 600–650 nm. Optical brightener had an effect only on visual appearance but not on light transmission properties. Samples containing silver additive were more intense green and gave a higher light transmission in blue region (380–500 nm) and lower in red region (600–700 nm) compared with samples without silver additive. These developed films can be applied in dairy products and other food products in the future. POLYM. ENG. SCI., 52:2015–2024, 2012. © 2012 Society of Plastics Engineers     

Anti-infrared/ultraviolet property of fullerene-containing polyacrylate film

Abstract

High-optical quality polyacrylate films containing a small load of C₆₀ were prepared by blending the soluble polyacrylate with the fullerene C₆₀ derivative poly-[2-(acrylamido)-2-methylpropane sulfonic acid] (PAMPS)-C₆₀. TEM was used to observe the morphological structure of the fullerene-containing polyacrylate solution. The anti-infrared/ultraviolet property was characterised by UV–VIS and FTIR in the wavelength range of 190–5000 nm. Experimental results demonstrated an improved anti-IR/UV property of polyacrylate as well as good diaphaneity. In the visible spectrum, its transmittance was greater than 80%. In the UV region, the transmittance decreased to 10% (<300 nm). Meanwhile, the transmittance was 55·7% in the near IR wave range (4000–14000 cm^?1) and 31% in the middle IR wave range (2000–4000 cm^?1), respectively. This new nanocomposite material has great potential to serve as an anti-IR/UV thin coating to implement heat insulation in many applications.     

Effect of the combination of a benzophenone‐type ultraviolet absorber with thermal stabilizers on the photodegradation of poly(vinyl chloride)

The effect of the combination of a UV absorber (Chimassorb 81) with different types of thermal stabilizers, including an organic calcium complex and an organotin mercaptide, on the photodegradation of poly(vinyl chloride) (PVC) was investigated by color difference measurements, UV–Vis spectroscopy, Fourier‐transform infrared spectroscopy, thermogravimetric (TG) analysis, and viscosity‐average molecular weight determination. Films of PVC containing 0.5 phr of Chimassorb 81, with and without 2 phr of a thermal stabilizer, were prepared by solution casting. Then the accelerated UV weathering of the films was carried out under xenon light with an irradiance of 0.51 W/(m² · nm) at 65°C. The results showed that both Chimassorb 81 and the mixture of Chimassorb 81 with the organic calcium complex showed good behavior in inhibiting the photodehydrochlorination and photooxidation of PVC. In contrast, the combination of Chimassorb 81 and methyltin mercaptide significantly accelerated initial color development during the final 200 h of exposure because of the UV sensitivity of the organotin. Moreover, when Chimassorb 81 and the methyltin mercaptide were used together to stabilize PVC films, the expected antioxidant effect of the mixture was not observed, in contrast to the behavior found with other stabilized systems, perhaps because the Chimassorb 81 had been depleted by the methyltin mercaptide during the UV irradiation. The TG analysis revealed that ultraviolet irradiation had caused severe destruction of the PVC chains. However, addition of Chimassorb 81 or the combination of Chimassorb 81 with the organic calcium complex effectively prevented the destruction, as was demonstrated by changes in the activation energies for thermal degradation. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers     

Sb-doped SnO2 (ATO) hollow submicron spheres for solar heat insulation coating

Antimony doped Tin Oxide (ATO) hollow submicron spheres were synthesized with a carbon ball template using the hydrothermal method, and compared to commercial nano-ATOs that differed in particle size. To study the thermal insulation performance and the mechanism of different ATOs, their morphology, crystalline structure and microstructure were examined using XRD, SEM and HRTEM. Meanwhile, the optical and thermal characteristics of the different ATOs, including absorption, reflectance, thermal conductivity, infrared emissivity (8–14 μm), and specific heat capacity, were also measured. Silicone acrylic emulsion coatings containing different dosages of ATO were then prepared, and their UV–Vis–NIR transmittance and solar heat shielding performances were tested. ATO hollow submicron spheres showed a thermal insulation performance comparable to that of nano-ATO, but their main respective thermal insulation mechanism was different. ATO hollow submicron spheres primarily relied on better particle dispersion, lower thermal conductivity, higher specific heat capacity and higher infrared emissivity. The 50 nm ATO absorbed the least solar heat but reflected the most light, while 100 nm ATO showed the opposite behavior. Both nano-ATOs had better transmittance in the visible light range but relatively low transmittance in the ultraviolet and infrared range. The results of this study indicate that ATO hollow submicron spheres are promising materials equivalent to nano-spheres that can be applied as a coating for energy conservation.     

Facile fabrication of high-efficiency near-infrared absorption film with tungsten bronze nanoparticle dense layer

An excellent transparent film with effective absorption property in near-infrared (NIR) region based on cesium-doped tungsten oxide nanoparticles was fabricated using a facile double layer coating method via the theoretical considerations. The optical performance was evaluated; the double layer-coated film exhibited 10% transmittance at 1,000 nm in the NIR region and over 80% transmittance at 550 nm in the visible region. To optimize the selectivity, the optical spectrum of this film was correlated with a theoretical model by combining the contributions of the Mie-Gans absorption-based localized surface plasmon resonance and reflections by the interfaces of the heterogeneous layers and the nanoparticles in the film. Through comparison of the composite and double layer coating method, the difference of the nanoscale distances between nanoparticles in each layer was significantly revealed. It is worth noting that the nanodistance between the nanoparticles decreased in the double layer film, which enhanced the optical properties of the film, yielding a haze value of 1% or less without any additional process. These results are very attractive for the nanocomposite coating process, which would lead to industrial fields of NIR shielding and thermo-medical applications.

PACS

78.67.Sc; 78.67.Bf; 81.15.-z