Surface characterization of weathered and heat‐treated wood‐based composites reinforced by styrene maleic anhydride

The aim of this study was to investigate the effect of heat‐treated lignocellulosic filler on the surface characteristics and decay resistance of the wood flour/styrene maleic anhydride (SMA) composites. In this study, heat treatment was conducted at 212°C for 8 hours. Test specimens were prepared by injection molding at 220°C. Weathering tests were performed by cycles of UV‐light irradiation for 8 hours, water spray for 15 minutes, and then conditioning for 3.45 hours in an accelerated weathering test cycle chamber. Heat‐treated wood flour/SMA composites were evaluated for color changes, and attenuated total reflectance Fourier transform infrared (FTIR) spectroscopy was used to analyze chemical changes on the sample surfaces. The wood decay tests were performed of white rot fungus, Trametes versicolor (L.: Fr.) Pilat was based on mini‐block specimens on 48% malt extract agar in petri dishes. The study showed that color changes occurred when heat‐treated filler rate is increased in this material. Therefore, materials in 10% filler rate show lower color changes than other variation. As a result of the FTIR analysis, the addition of wood filler into the SMA causes changes in the chemical structure. In addition, the increase in wood filler reduced the resistance to weathering. Decay results showed that thermally modified wood has lower mass loss caused by fungal attack than untreated wood material. The weight loss decreases with the increase in wood flour rate expect 10%T and 10%UT in all composites.     

硬木家具上蜡装饰表面耐光性研究

为研究不同上蜡工艺装饰后硬木家具表面的耐光性,本文以大果紫檀为基材,分别对其传统烫蜡材、溶剂型漆托蜡材与水性漆托蜡材等3种上蜡工艺装饰的木材进行紫外光加速照射,测定在光照过程中其表面颜色、光泽、纹理等变化,并利用傅里叶红外光谱观察不同上蜡材表面的化学组成及光照中化学成分的变化。结果表明:溶剂型漆托蜡材与水性漆托蜡材的耐光性优于传统烫蜡材;而且,传统烫蜡涂层可在短时间内延缓木材的老化,长时间的光照下蜡层基本失去了保护作用。     

Dansyl,a fluorescent photoprotecting group for microarray applications

BACKGROUND: The fluorescence dye 5‐dimethylamino‐1‐naphthalenesulfonyl chloride (Dansyl chloride) is commonly used for labeling the N‐terminus of proteins and peptides. Apart from the fluorescence, the ? SO₂? NH? bonds formed are susceptible to photolytic cleavage and will subsequently restore free amines. Consequently, Dansyl amides could act as a fluorescent photoprotecting group with novel application in solid phase synthesis or in microarray technologies. RESULTS: Commercial microscope glass slides were silanized with (3‐aminopropyl) triethoxysilane, exposed amines were activated with 1,4‐phenylene diisothiocyanate and subsequently reacted with dansylated polyethylene imine (PEI). The resulting fluorescence of the surface was determined and used as a measure of the homogeneity of the introduced functional groups. Using a mask, Dansyl‐PEI modified slides were locally exposed to photolytic cleavage within irradiation energy of 100 J cm^?2. Inscribed structures would be easily recognized due to their loss of fluorescence. The restored amines in deprotected areas were reacted with phosphorylated capture oligonucleotides followed by hybridization with complementary Cy5‐labeled targets. CONCLUSIONS: Capture probes immobilized precisely in structures exposed to UV‐light while non‐irradiated areas remained blocked. Such pre‐structured surfaces allow the production of highly reproducible microarrays without any specific problems of spotting imperfections. Gridding and segmentation of the determined sample allocation facilitate spot finding and spot analysis. Copyright © 2012 Society of Chemical Industry     

The effect of wool surface and interior modification on subsequent photostability

Wool surface and interior modification can impart favorable properties, such as felting/shrink resistance, settability, or improved affinity for dyes. However, in principle such modification may have an either beneficial or adverse effect on the subsequent photostability of the modified wool. In this study, a range of representative physical and chemical modification approaches including the use of helium gas plasma, papain, acylation with acid anhydride, and permanganate oxidation were applied to wool fabrics, and the subsequent effects characterized using scanning electron microscopy, FTIR‐ATR, contact angle goniometry, fluorescence spectrophotometry, and tensile strength test. The relative photostability of control and treated wool were evaluated in terms of coloration changes under UVA, UVB, and blue light irradiation. We have shown that the subsequent photostability of modified wool fabrics is highly dependent on the modification type, and this factor should be carefully considered in the design and application of wool treatments. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Weathering,water absorption,and durability of silicon,acetylated, and heat‐treated wood

In this study, two colloidal dispersions of pure amorphous silicon dioxide particles, acetylated, and heat‐treated samples were tested for a possible application as a wood protection agents. The silicon, acetylated, and heat‐treated samples were exposed to an accelerated weathering experiment, and their dimensional stability was assessed. The weathering experiment comprised cycles of 2 h UV‐light irradiation followed by water spray for 18 min. The surface changes of the weathered samples were characterized by FT‐IR spectroscopy and color measurements. According to results, the silicon treatments showed lower color changes than untreated ones. However, acetylated and heat‐treated samples provided the lowest color changes. The resistance of the silicon, acetylated, and heat‐treated wood to decay was studied by means of brown and white rot fungi in laboratory decay tests. Decay test results revealed that acetylated and heat‐treated wood samples showed better decay resistance against P. placenta and C. versicolor than silicon treatments. Samples modified with silicon were exposed in above ground standard lap‐joint test in Ultuna, Sweden. The dispersions of pure amorphous silicon dioxide impregnated in wood did not significantly influence its hygroscopic and dimensional behavior. However, the silicon treatment reduced the color changes caused by weathering. The silicon impregnated samples showed a weak fungal discoloration similar to that of chromated copper arsenate impregnated controls in above ground standard lap‐joint test. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4506–4513, 2006     

Improvement of the photostabilization of PVC films in the presence of 2N‐salicylidene‐5‐(substituted)‐1,3, 4‐thiadiazole

The photostabilization of poly(vinyl chloride) (PVC) films by 2N‐salicylidene‐5‐(substituted)‐1,3,4‐thiadiazole compounds was investigated. The PVC films containing concentration of complexes 0.5% by weight were produced by the casting method from tetrahydrofuran (THF) solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl, polyene, and hydroxyl indices with irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were also tracked (using THF as a solvent). The quantum yield of the chain scission (ϕ_cs) of these complexes in PVC films was evaluated and found to range between 4.72 × 10⁻⁸ and 8.99 × 10⁻⁸. Results obtained showed that the rate of photostabilization of PVC in the presence of the additive followed the trend: According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among them, UV absorption, peroxide decomposer, and radical scavenger for photostabilizer mechanisms were suggested. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Surface characterization of wood treated with boron compounds combined with water repellents

Longer weathering exposure periods are more reliable for end‐use performance evaluations of wood surfaces. This study aimed to investigate the effect of boron impregnation on the surface composition and color of Scots pine (Pinus sylvestris L.) wood exposed to 18 months of natural weathering in the West Black Sea Region of Turkey. All measurements were performed at 6 month intervals. Samples were first impregnated with boron compounds and then for a second time using five different water‐repellent materials. Polyethylene glycol and aluminum sulfate were introduced with the boric acid as single impregnations. With increased weathering time, the samples darkened, while sodium silicate kept the color change to a minimum. Nano boron‐impregnated samples exhibited more effective results than those impregnated with boric acid. The FTIR analysis results demonstrated that the impregnation process had caused significant changes in the chemical structure of the samples. The changes in the chemical structure of the wood resulting from the impregnation process were partially maintained during the weathering.     

Effect of additive concentration and gamma radiation on the molecular and color properties of poly(vinyl chloride)

The effects of addition of different monomers on the molecular properties of poly(vinyl chloride) (PVC) have been studied. Three different additive monomers from N‐phenyl maleimide derivatives were added with the same concentration 0.02 gm/1 gm PVC as stabilizers to PVC. These stabilizers are N‐phenyl maleimide, Para‐carboxy N‐phenyl maleimide, and Para‐amide carboxy N‐phenyl maleimide (PA‐NPMI). Their stabilizing efficiencies were evaluated by measuring the intrinsic viscosity of the solution samples. The results reveal that the type of the additive monomer plays a major role in determining the stabilizing potency of these materials. It was found that the PA‐NPMI is the most effective stabilizer that improves the intrinsic viscosity of pure PVC from 1.02 to 1.19. So, the effect of its addition with different concentrations was studied. The results indicate that the sample with 0.015 gm PA‐NPMI/1 gm PVC has higher intrinsic viscosity. Thus, this sample was chosen to be a subject for further study to investigate the effect of gamma irradiation on its molecular and color properties. Samples from the 0.015 gm PA‐NPMI/1 gm PVC were irradiated with gamma doses in the range 5–100 kGy. It is found that the irradiation in the dose range 20–60 kGy enhances the intrinsic viscosity of the samples. In addition, the transmission of these irradiated samples in the wavelength range 200–2500 nm, as well as any color changes, was studied. The color intensity ΔE was greatly increased with increasing the gamma dose, and was accompanied by darkness with a significant increase in the yellow color component. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of laser CO2 irradiation on various properties of polyester fabric: Focus on dyeing

In this research, the effect of CO₂ laser on various properties of polyester fabric specially dyeing was studied. Three disperse dyes of red, yellow, and blue were used and irradiation was performed before and after dyeing. To evaluate the color changes due to laser treatment, CIELAB ΔE color difference values were calculated. The morphology of the irradiated surfaces was examined by scanning electron microscopy. Other properties including color fastness, bending rigidity, wettability, and crystal size were also examined. The results revealed that laser treatment had an increasing effect on the color difference value. Among the three laser parameters examined in this work, laser power had the strongest effect. While no significant color fastness improvement with low laser intensity was observed, high‐intensity laser irradiation increased the light and rubbing fastness. Properties such as wettability and bending rigidity were negatively affected by an increase in laser intensity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Enhancement of Photostabilization of Poly(vinyl chloride) Doped with Sulfadiazine Tin Complexes

New sulfadiazine tin complexes were synthesized in 67–80% yields from the reaction of sulfadiazine, and different organotin(IV) chlorides and their structures were established. The synthesized complexes were used as additives at a low concentration (0.5% by weight) to enhance poly(vinyl chloride) (PVC) photostability. The PVC samples containing sulfadiazine tin complexes (thickness = 40 μm) were fabricated and irradiated with ultraviolet light at room temperature for 300 h. The changes that occurred within the PVC samples upon irradiation were investigated by inspecting the loss in weight, reduction in the average molecular weight, formation of small degradation fragments containing polyene, carbonyl, and hydroxyl moieties, and changes in the ultraviolet absorption intensity of polymeric materials. The surface morphology of irradiated PVC samples was investigated using optical, atomic force, and scanning electron microscopies. There were lesser changes within the PVC samples with sulfadiazine tin complexes compared to the blank PVC sample. The dimethyltin(IV) complex was found to be the most efficient additive in stabilizing PVC against irradiation. The role played by the complexes in reducing the photodegradation of PVC was investigated, and a mechanism was proposed. J. VINYL ADDIT. TECHNOL., 26:370–379, 2020. © 2019 Society of Plastics Engineers     

New photochemical approach to cellulose fabric and photoinitiator system

The surface modifications of cellulose substrate based on the photo‐induced reaction are closely related with the radicals introduced on the surface of cellulose substrates by light irradiation. We have evaluated the ability of radical formation in lyocell fabric and two water‐soluble photoinitiator systems by using photoluminescence analyses. Namely, the relative quantum yields of fluorescence and phosphorescence were estimated by the integrated emission intensity under the same values of light absorbance and the identical measuring conditions. First of all the [2‐(acryloyloxy)ethyl](4‐benzoylbenzyl)dimethylammonium bromide (PIA) system had larger UV absorbance values below 287 nm than [3‐(3,4‐dimethyl‐9‐oxo‐9h‐thioxanthene‐2‐yloxy)‐2‐hydroxypropyl]trimethylammonium chloride (PIB) system at the same concentration. The relative quantum yields of fluorescence and phosphorescence emission in PIA system were smaller than those in PIB system even if the two systems had the same values of light absorbance. Therefore it was found that the PIA system was more easily transited to the triplet‐state and the transited molecules reacted with the cellulose substrates more effectively. The modified cellulose fabric with 2‐(dimethylamino)ethyl chloride hydrochloride (AM1) and PI system had only a little different UV absorbance and photoluminescence properties from the untreated fabric system. However, the fabric modified with 2‐(4‐chlorophenyl)‐ethylamine (AM2) and PI system showed relatively big differences. The UV absorbance values were increased and the relative quantum yields of photoluminescence were decreased remarkably. We have acquired that the tertiary amine treated cellulose fabric were very effective in photo‐induced modification of cellulose. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Photoaging and stabilization of rigid PVC/wood‐fiber composites

Ultraviolet (UV) weathering performance of unpigmented and rutile titanium dioxide pigmented rigid polyvinyl chloride (PVC)/wood‐fiber composites has been studied. The composite samples were manufactured by dry‐blending PVC, wood fibers, and other processing additives in a high‐intensity mixer. The dry‐blended compounds were extruded and compression molded into panel samples. The manufactured samples were artificially weathered using laboratory accelerated UV tests. Composite samples were exposed to 340‐nm fluorescent UV lamps and assessed every 200 h, for a total of 1200 h of accelerated weathering. Each assessment consisted of a visual examination of surface roughness or erosion, a contact angle measurement, a FTIR collection, and a color measurement. The experimental results indicated that wood fibers are effective sensitizers and that their incorporation into a rigid PVC matrix has a deleterious effect on the ability of the matrix to resist degradation caused ultraviolet irradiation. The light stability of these composites could be improved quite efficiently with the addition of rutile titanium dioxide photoactive pigment during formulation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1943–1950, 2001     

Wood photography using light irradiation and heat treatment

To apply the coloring method using light irradiation and thermal treatment to print photographs on wood, the effect of the transmittance of negative films was investigated. ΔE* decreased with light irradiation when specimens covered with films with transmittances exceeding 20% were irradiated for 100 h. It was thought that this phenomenon was due to the decrease in Δb*. The color of light‐irradiated wood changed remarkably with thermal treatment; however, the change in the color of exposed specimens covered with films with transmittances exceeding roughly 20% became constant. Clear photographs could be printed on wood using negative films with transmittances less than approximately 20%. Furthermore, the difference between the maximum and minimum values of ΔE* after thermal treatment was about 22. Humans can distinguish four to seven colors that can be created by this method. © 2004 Wiley Periodicals, Inc. Col Res Appl, 29, 312–316, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20027     

Comprehensive study of polymer fiber surface modifications Part 1: high‐fluence UV‐excimer‐laser‐induced structures

Recently, there has been great interest in physico‐chemical surface treatments for modifying polymer surfaces. Ultraviolet (UV)‐excimer‐laser irradiation of polymers is of particular interest. In this study, polyamide was irradiated by a 193 nm excimer laser with a fluence above its ablation threshold (high‐fluence). Morphological changes of the resulting samples were characterized by scanning electron microscopy (SEM) and tapping mode atomic force microscopy (TM‐AFM). Chemical modifications by laser treatment were studied by X‐ray photoelectron spectroscopy (XPS), time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and chemical force microscopy (CFM). Topographical results indicated that ‘ripple‐like’ structures of micrometer size were formed after laser irradiation. XPS and Tof‐SIMS results showed that bond scission occurred on the polymer surface under the action of high‐fluence. Changes in surface chemical properties of the laser‐irradiated polyamide were supported by CFM experiments. Copyright © 2004 Society of Chemical Industry     

Surface of cellulosic materials modified with functionalized polyethylene coupling agents

The interfacial adhesion between a wood fiber and a plastic matrix strongly influences the performance of wood‐fiber‐reinforced thermoplastic composites. Fiber surface modification with coupling agents is generally needed to induce bond formation between the fiber and polymer matrix. This study investigated the chemical reactions between cellulosic materials and functionalized polyethylene coupling agents. Both wood flour and cotton cellulose powder were treated with acrylic acid‐functionalized polyethylene and maleic anhydride‐functionalized polyethylene (maleated polyethylene) for surface modifications, and chemical changes resulting from these treatments were followed by a study of the Fourier transform infrared and X‐ray photoelectron spectroscopy spectra. Variations in the band intensities, oxygen‐to‐carbon ratios, and concentrations of unoxidized carbon atoms were related to changes that occurred on the surfaces of modified cellulosic materials. The experimental results indicated that chemical bonds between the hydroxyl groups of the cellulosic materials and the functional groups of the coupling agents occurred through esterification reactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 278–286, 2003     

Synergistic effect of hindered amine light stabilizers/ultraviolet absorbers on the polyvinyl chloride/powder nitrile rubber blends during photodegradation

The photostability of hindered amine light stabilizer (HALS) and ultraviolet absorber (UVA) on the blends of plasticized poly (vinyl chloride) (PVC) and powder nitrile rubber (NBR) has been studied with a Xenon Test Chamber. The digital photos, color differences, attenuated total refection‐Fourier transform infrared (ATR‐FTIR) spectra and mechanical properties of the blends have been determined. HALS combined with UVA effectively protects PVC/NBR blends from yellowing and restrains the decrease of elongation at break of the blends. The synergistic phenomenon is ascribed to the different photostable mechanisms of HALS and UVA at different photo aging stages. The color of PVC/NBR control sample quickly changes into yellow at the first 400 h of irradiation, due to the polyenes structures that induced by the double bonds of butadiene in NBR. From 400 to 800 h, crosslinking dominates and the amount of polyenes decreases, resulting into the decrease of color change. At the early stage of irradiation, chain‐scission of polymer takes the predominant place, and the tensile strength decreases. But during the latter stage, crosslinking takes the predominant place and the tensile strength increases slightly. HALS and UVA have a little effect on the maintaining of elongation at break of PVC/NBR blends. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

Urethane dimethacrylate oligomers for dental composite matrix: Synthesis and properties

Two urethane poly(ethylene oxide) dimethacrylates based on polyether diol of variable length (M_n: 300 and 1000 g/mol), isophorone diisocyanate and 2‐hydroxyethyl methacrylate, were synthesized and characterized to be used as comonomers for dental composites. The polymerization process initiated with benzoyl peroxide/amine or camphorquinone/tertiary amine couple was followed by a combination of FTIR spectroscopy and fluorescence technique using a pyrene probe for the in situ monitoring of microscopic changes in the polymeric systems. Difference in the polymerization kinetics of the oligomers and low‐molecular‐weight monomer is presented in connection with the chemical structure of the urethane dimethacrylate, taken together with another partners (bisGMA, TEGDMA, filler) with effect on the mobility and reactivity of the formed polymeric network. The results suggest a higher reactivity of the oligomeric forms and are in agreement with the fluorescence measurements induced of the pyrene molecule, whosemonomer fluorescence emission significantly increased with irradiation time as the network formation occurred. Measurements of the contact angle showed the maintenance of the hydrophilic nature of these resins, while the values of polymerization shrinkage and diametral tensile and compressive strengths of the three specimens indicated that the incorporation of dimethacrylate urethane oligomers in the organic matrix (18 wt%) led to materials with good properties. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Preparation of chlorinated poly(vinyl chloride)‐g‐poly(N‐vinyl‐2‐pyrrolidinone) membranes and their water permeation properties

Chlorinated poly(vinyl chloride) (CPVC) membranes for microfiltration processes were prepared with the combined process of a solvent evaporation technique and the water‐vapor induced‐phase‐inversion method. CPVC membranes with a mean pore size of 0.7 μm were very hydrophobic. These membranes were subjected to surface modification by ultraviolet (UV)‐assisted graft polymerization with N‐vinyl‐2‐pyrrolidinone (NVP) to increase their surface wettability and decrease their adsorptive fouling. The grafting yields of the modified membranes were controlled by alteration of UV irradiation time and NVP monomer concentration. The changes in chemical structure between the CPVC membrane and the CPVC‐g‐poly(N‐vinyl‐2‐pyrrolidinone) membrane and the variation of the topologies of the modified PVC membranes were characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, and field emission scanning electron microscopy. According to the results, the graft yield of the modified CPVC membrane reached a maximum at 5 min of UV exposure time and 20 vol % NVP concentration. The filtration behavior of these membranes was investigated with deionized water by a crossflow filtration measurement. The surface hydrophilicity and roughness were easily changed by the grafting of NVP on the surface of the CPVC membrane through a simultaneous irradiation grafting method by UV irradiation. To confirm the effect of grafting for filtration, we compared the unmodified and modified CPVC membranes with respect to their deionized water permeation by using crossflow filtration methods. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3188–3195, 2003     

Friction and wear of fiber reinforced polyimide composites in electron or proton irradiation

The polyimide (PI) composites reinforced with carbon fibers, glass fibers, and aramid fibers were fabricated by means of a hot‐press molding technique and irradiated by electron or proton for a certain time. The friction and wear behavior after irradiation, sliding against GCr15 steel balls, were evaluated in a ground‐based simulation facility using ball‐on‐disk tribosystem. The change of the chemical composition of the radiated surface was examined by X‐ray photoelectron spectroscopy. The worn morphologies and radiated surfaces of the materials were observed by scanning electron microscope to reveal the wear mechanism. Experimental analysis indicated that the chemical composition of the materials changed and an irradiated layer was formed at the surface. This irradiation layer had an important effect on the friction and wear behavior of the PI composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40774.     

2种不同激光对钛宝石辐照作用的研究

分别采用波长为193 nm的ArF准分子激光与波长为800 nm、脉冲宽度为120 fs的飞秒激光对温梯法生长的钛宝石进行辐照,并对辐照前后的吸收谱、荧光谱及电子顺磁共振(EPR)谱进行了检测。2种不同辐照的结果表明:218 nm及266 nm吸收峰并不是完全由同一种色心所引起的。通过对比不同品质因数(FOM)值的钛宝石样品在420 nm处的荧光谱,发现准分子激光辐照后420 nm处荧光强度降低,表明样品中Ti~(4 )离子浓度降低。而在飞秒激光辐照下荧光强度增大,即Ti~(4 )浓度增大。根据2种激光的波长,功率密度及辐照方式的差异对于2种辐照产生不同结果做出了解释。