Radiation Crosslinking Research Articles

Effects of gamma irradiation on properties of PLA/flax composites

Polylactic acid (PLA) is a well-known renewable and biodegradable polymer but is still limited by its low heat distortion temperature and brittleness. In this study, a PLA/flax composite containing flax fiber strands (5 wt%) was prepared through melt-compounding process followed by gamma irradiation at doses ranging from 0 to 20 kGy in the presence of a small amount of triallyl isocyanurate (TAIC) as cross-linking agent. The gel fraction of the composite was tested, and the datum showed that the gel fraction sharply increased first, and then slightly decreased with increasing irradiation dose. Gamma irradiation induced cross-linking of the polymer to form a three-dimensional network in the PLA/flax composite system. Irradiated composite could only swell instead of dissolving completely in chloroform, and the swollen morphology correlated with irradiation dose. The thermal stability of the PLA/flax composite was characterized using thermogravimetric analysis (TGA) temperature, and dimensional stability. Overall, irradiation modification improved the thermal resistance and dimensional stability of PLA composites. The mechanical property tests of the irradiated composites revealed increased tensile and impact strengths, reduced elongation-at-break, and unchanged tensile modulus. The analysis of water absorption of the composite demonstrated that the irradiation cross-linking induced no obvious effect on water absorption. Irradiation cross-linking modification cannot change the hydrophilicity or hydrophobicity of PLA composites. Overall, these findings look promising for future use in reinforcement and improvement of the thermal resistance of PLA/flax composites.

Radiation-Stimulated Transformation of the Reflectance Spectra of Diazoquinone–Novolac Photoresist Films Implanted with Antimony Ions

We measure the reflectance spectra of 1.8 µm-thick FP9120 photoresist films doped with antimony ions and deposited by centrifugation on the surface of p-type silicon wafers (ρ = 10 Ω cm) with a (111) orientation. Implantation leads to a decrease in the refractive index of the photoresist due to the radiation crosslinking of Novolac resin molecules and a decrease in the molecular refraction and density of the photoresist. In the opacity region of the photoresist film, an increase in the reflection coefficient is observed with an increase in the implantation dose.

Radiation crosslinking of pigmented coating material by UV LEDs enabling depth curing and preventing oxygen inhibition

LED light sources emit in a small wavelength region, e.g. in the blue light and UV-A. These LEDs can be applied for the radiation curing via radical polymerization, which is a growing sector in the coating industry. LEDs will in prospect substitute mercury arc lamps as the light sources, but development of higher intense LEDs and also in the UV-B or UV-C range is still in progress. In this report the efficiency of initiator systems was analyzed for the photopolymerization of UDMA. The chosen systems are usually used in the coating industry and others were invented in the dentistry and holography. The aim is the depth curing of urethane dimethacrylate (UDMA) with the help of UV LEDs at 365 nm, 395 nm, and 405 nm. The overlap of the absorbance of the initiator systems and the emission of the LED is discussed regarding the reactivity in the top layer and a thickness up to 20 mm hereby giving insights in the influence of the light source and the reactivity or spectral properties of the initiator system on the photopolymerization process. Surprisingly, the initiator systems like Ivocerin, and HABI-mercapto, which are unusual as initiators for the curing of coatings, show a high efficiency. Even pigmented and filled systems are curable up to a depth of 4–20 mm, respectively. Furthermore, applying a UV-C LED at 278 nm and using these initiators also decrease the tackiness on the surface caused by oxygen inhibition.

Electron beam crosslinking of alginate/nanoclay ink to improve functional properties of 3D printed hydrogel for removing heavy metal ions

A printable nanocomposite hydrogel was fabricated with intercalation of alginate into clay galleries followed by irradiation crosslinking graft copolymerization acrylic acid to remove inorganic micropollutants from wastewater. In this regard, nanocomposite-based ink was treated by electron beam irradiation (5–60 kGy), and then irradiated inks were printed using an extrusion-based printer. Structural investigates showed that ink suspension formed a crosslinked network upon irradiation, which could preserve its shape during printing and maintain 3D printed architecture. No additional post-print crosslinking was required due to the formation of free radical and remaining in printed hydrogels as shown by electron spin resonance. Printed hydrogels treated with 5 and 60 kGy irradiation experienced instrumental changes, while functional properties of 15–45 kGy irradiated samples were unaffected upon printing. Losing crystallinity and thermal instability of hydrogels after printing were inhibited through irradiation crosslinking. Metal ion adsorption capacity showed that crosslinked printed hydrogels effectively removed heavy metal ions with high-capacity and fast-responsive. Moreover, metal ions adsorption by printed hydrogels was not selective, thus they can be used to remove various metal ion pollutants from wastewater.

A lightweight, thermal insulation and excellent weatherability foam crosslinked by electron beam irradiation

Thermal insulation and excellent weatherability microcellular foams based on lightweight polymer are successfully developed from chlorinated polyethylene rubber/polyvinyl chloride (CM/PVC) compounds through electron beam irradiation cross-linking and chemical foaming technology. The effect of electron beam irradiation on the blends of CM/PVC foam prepared with different compositions starting from 70:30 to 50:50 (CM:PVC) with varied radiation doses from 30 to 70 kGy and varied chemical blowing agent contents from 10 to 20 phr has been studied. The aim was to investigate the influence of the different blending ratio, the chemical blowing agent content and the irradiation dose on physical and mechanical properties and morphology of the cellular structure in the produced foams. Thermal conductivity of CM/PVC compounds foams achieved in this study is as low as 0.0374W/mK.

Elongation behaviour of filled semi-crystalline polymers in thermoforming

ABSTRACT Thermoforming, besides injection moulding and extrusion, belongs to the most important processes of polymer processing. Thin sheets are formed to parts in a so-called stretch-forming process. The properties of the finally formed parts depend on the sheet properties. Amorphous polymers such as polystyrene and polymethylmethacrylate are examples for most popular polymers used in thermoforming because of their wide temperature ranges suitable for processing with thermoforming. Crystalline polymers or reinforced amorphous polymers have a smaller forming window compared to these amorphous polymers but offer several other advantages. For the processing of most crystalline polymers, modifications of the thermoforming process as well as the materials themselves are necessary. This study analyses the influence of fillers on the elongation behaviour of polyeythlene. Furthermore, the interaction between fillers and cross-linking is investigated in thermoforming experiments as well as microscopical analysis. The general aim is to expand the process related knowledge on material behaviour to qualify more semi-crystalline materials for processing in technical thermoforming applications. In this study, the enormous benefit of radiation crosslinking on the elongation behaviour during thermoforming of filled systems could be presented. Subsequent crosslinking of the filled systems enable the thermoforming of filled films, which could not be processed without irradiation.

Preparation and optimization of thorium selective ion imprinted nonwoven fabric grafted with poly(2-dimethylaminoethyl methacrylate) by electron beam irradiation technique

2-dimethylaminoethyl methacrylate (DMAEMA) was grafted onto PP/PE non-woven fabrics (NWF) using pre-radiation graft polymerization technique and subsequent mutual radiation crosslinking with divinylbenzene (DVB). The ion-imprinted polymer (IIP) was synthesized by DVB crosslinking with DMAEMA and thorium complex through radiation. Non-imprinted polymer (NIP) was prepared with the same conditions but utilizing pure DMAEMA instead of DMAEMA-Thorium complex. The NWF, DMAEMA-grafted-NWF, IIP and NIP were characterized with Field Emission Scanning Electron Microscopy (FESEM), Fourier Transformed Infrared Spectroscopy (ATR-FTIR), Thermogravimetric Analyzer (TGA), X-ray photoelectron spectroscopy (XPS), and X-ray Diffraction (XRD). The grafting process parameters were optimized prior to radiation crosslinking with DVB. The effects of DMAEMA concentration and reaction temperature as a function of different irradiation doses were investigated in order to attain optimal grafting conditions. The effects of DVB concentration, process temperature and radiation dosage on the degree of crosslinking were examined. In addition, the effects of crosslinking percentage, initial thorium concentration and concentration of imprinted thorium to the selectivity of IIP and NIP were also determined. The thorium selectivity of both IIP and NIP was measured using batch mixed ions system by inductively coupled plasma mass spectrometry (ICP-MS) analysis. Instead of simultaneous grafting and crosslinking process in bulk along with imprint template, this current study conciliates all grafting, imprint template and crosslinking process independently. Thus, the originality of the research is attributed to individuality grafting and crosslinking technique using ion beam irradiation to obtain IIP of high thorium selectivity without compromising the chemical and physical properties of the adsorbent.

Nano-Mechanical Properties of Surface Layers of Polyethylene Modified by Irradiation.

This study’s goal was to describe the influence of a wide range of ionizing beta radiation upon the changes in surface layer mechanical properties and structural modifications of selected types of polymer. Radiation crosslinking is a process whereby the impingement of high-energy electrons adjusts test sample structures, thus enhancing the useful properties of the material, e.g., hardness, wear-resistance, and creep, in order that they may function properly during their technical use. The selected polymers tested were polyolefin polymers like polyethylene (Low-density polyethylene LDPE, High-density polyethylene HDPE). These samples underwent exposure to electron radiation of differing dosages (33, 66, 99, 132, 165, and 198 kGy). After the crosslinking process, the samples underwent testing of the nano-mechanical properties of their surface layers. This was done by means of a state-of-the-art indentation technique, i.e., depth-sensing indentation (DSI), which detects the immediate change in the indentation depth associated with the applied force. Indeed, the results indicated that the optimal radiation dosage increased the mechanical properties by up to 57%; however, the beneficial levels of radiation varied with each material. Furthermore, these modifications faced examination from the structural perspective. For this purpose, a gel test, Raman spectroscopy, and crystalline portion determination by X-ray all confirmed the assumed trends.

UV-Initiated Crosslinking Reaction Mechanism and Electrical Breakdown Performance of Crosslinked Polyethylene.

The ultraviolet (UV) irradiation crosslinking reactions of polyethylene and the electronic properties of photo-initiators and reaction products are theoretically investigated by the first-principles calculations. The crosslinked polyethylene (XLPE) materials are prepared in experiments that employ the UV-initiated crosslinking technique with different photon-initiation systems. Infrared spectrum and the alternating current dielectric breakdown strength of UV-initiated XLPE are tested to explore the effect of reaction products on the breakdown characteristics in combination with the electron structure calculations. The theoretical calculations indicate that the 4-hydroxybenzophenone laurate, which is compatible with polyethylene, can effectively initiate crosslinking reactions of polyethylene molecules under UV photon excitation and will produce reaction by-products from carbonyl radicals; as a macromolecular auxiliary crosslinker, the monomer or homopolymer of dioleyl-2,2′,4,4′-tetraallyl isocyanurate can form chemical connections with multiple polyethylene molecules acting as a crosslinking node in a photon-initiated reaction process. The carbonyl, hydroxyl, or ester groups of reaction by-products are capable of capturing hot electrons to prevent polyethylene molecules from impact ionization, and thus will increase the breakdown electric field. The macromolecular auxiliary crosslinker and the macromolecular photon initiator as well as its reaction by-product can convert the energy of their captured high-energy electrons into heat, which can act as a voltage stabilizer. The molecule characterization of infrared spectra demonstrates that the characteristic absorption peaks of the carbonyl in the macromolecular photon initiator and the allyl in the macromolecular auxiliary crosslinking agent are gradually decreasing in intensity as the crosslinking reaction proceeds, which is consistent with the conclusion from theoretical calculations. Compared with the small molecular photon-initiation system generally used in the photon-initiated crosslinking process, the higher dielectric breakdown field of XLPE being prepared by utilizing a macromolecular photon-initiation system is in good agreement with the calculation results of electronic affinity and ionization potential. The consistent results of the experiments and first-principles calculations elucidate the fundamental mechanism of the UV-initiation crosslinking technique and suggest a prospective routine to improve the insulation strength for developing high-voltage XLPE insulating materials.

In Vitro Wear Performance of X-ray Cross-Linked Vitamin E Blended Polyethylene

The most common radiation cross-linking methods are electron-beam and Gamma-irradiation. Gamma-irradiation has a very low dose rate and e-beam serious penetration limitations. X-ray exhibits an excellent penetration capacity with a moderate dose rate. The objective of the study was the investigation of the wear behavior of vitamin E blended Ultrahigh Molecular Weight Polyethylene highly cross-linked by X-ray as an alternative cross-linking technology. We hypothesized that using same dose and irradiation temperature the wear behavior would be equivalent regardless of the radiation source.Hip wear simulation was performed with five different polyethylene acetabular inserts articulating with 40 mm diameter cobalt‑chromium heads. Two X-ray doses of 80 and 100 kGy and two irradiation temperatures each, i.e. room temperature and 100 °C, were considered. The reference was Vitelene®, a vitamin E stabilized polyethylene cross-linked by e-beam with 80 kGy at 100 °C. The inserts were subjected to artificial aging for 2 weeks prior to test.Increasing both the dose and the irradiation temperature led to an improved wear performance.X-ray showed the ability to improve the wear resistance of polyethylene in the same range as e-beam, as both are ionizing irradiation. SignificanceHighly cross-linked polyethylene has been established and taken over 80–100% of polyethylene usage in Total Hip Arthroplasty [1–3]. The goal is to retain its mechanical properties, oxidative stability and superior wear resistance over time, which is crucial in order to reduce the incidence of periprosthetic osteolysis and increase the service time over the second implantation decade [4]. Vitamin E stabilized polyethylene has been successfully introduced showing very good results at 5 years [5–7]. X-ray irradiation stands out by its worthwhile characteristics like high penetration capacity and moderate dose rate which extend the treatment possibilities of polyethylene and the preservation of its properties in the long term.

Enhanced electromechanics of morphology-immobilized co-continuous polymer blend/carbon nanotube high-range piezoresistive sensor

This study reports the development of novel piezoresistor which offer excellent sensitivity for strain measurements, can be used for the detection of high compressive stress and have low creep and fatigue characteristics. Morphology immobilized composites of hard-soft polyolefin blends with co-continuous (co-PEP) and dispersed (d-PEP) morphology were prepared by melt compounding polyolefin blends with Multiple-Walled Carbon Nanotubes (MWCNT) followed by radiation crosslinking. In comparison to d-PEP/MWCNT composites, co-PEP/MWCNT composite exhibited superior electromechanics, in terms of strain sensing range and gauge factor, along with low hysteresis. Most importantly, d-PEP did not exhibit compressive stress-dependent piezoresistivity whereas co-PEP showed reversible piezoresistivity in the range 25 kPa–1 MPa, which is considerably higher than the highest stress-sensing limit typically observed in MWCNT based systems. Fractal dimension analysis of MWCNT network using non-linear rheology revealed that co-PEP/MWCNT composites exhibit soft-aggregates contact breakage and had a much milder dependence on MWCNT volume fraction than binary composites. The cyclic and creep measurements confirmed excellent recovery under static and dynamic conditions, revealing the high potential of such material for standalone stress sensors for robotics, human–machine interfacing, and intelligent transport monitoring.

An increase of the mechanical strength and hardness of polymeric materials radiation-crosslinked by X-ray radiation from an gaseous electric discharge

The problem of investigation of mechanical and electrophysical properties of polymeric materials crosslinked by X-ray radiation from a gaseous electric discharge is considered. The effect of radiation crosslinking on the mechanical strength and hardness of polymers is presented by the example of samples of various thicknesses (from 0.08 mm to 10 mm) of LDPE and HDPE made using crosslinking technology by X-ray radiation from a barrier gaseous electric discharge proposed in [1]. Experimental data obtained on samples of low molecular weight LDPE-107-02K and high molecular weight HDPE-271-82K made in the form of dumbbell, cut in accordance with GOST IEC 60811-2-1 from PE plates, are considered. To study the electrophysical properties and the depth of semi-absorption of X-ray radiation from gaseous electric discharge, LDPE and HDPE samples in the form of disks of different thicknesses were used.The depth of penetration of X-ray radiation from a gaseous discharge into LDPE-107-02K and HDPE-271-82K was estimated.Comparative studies of changes in the electrophysical properties of mechanical strength and hardness of cable LDPE under the influence of X-ray radiation from gaseous discharge and under the influence of an electron beam are carried out.It is shown that the mechanical strength and hardness of LDPE and HDPE can be increased by at least 30% and 60% respectively via radiation crosslinking by X-ray from a gaseous discharge.

Green preparation of anti-inflammation an injectable 3D porous hydrogel for speeding up deep second-degree scald wound healing.

Scalds are one of the most common injuries and the 4th cause of trauma globally. Alginate has emerged as a promising scald wound dressing. Herein, we present a facile applicable strategy for electron beam (EB) radiation crosslinking gelatin, alginate, and carboxymethyl cellulose (CMC) into an injectable three-dimensional (3D) porous hydrogel (3D-PH) with a double crosslinked network for reliable deep second-degree scald wound healing. In addition, the injectable 3D-PH stimulated proliferation and migration of dermal fibroblasts in vitro and the deep second-degree scald wound healing process is accelerated in vivo. Most importantly, in vitro results revealed that the injectable 3D-PH stimulated cell proliferation via inducing the expression of Ki-67, and suppressed inflammatory signals as indicated by the downregulation of inflammatory factors (IL-6, TNF-α) in L929 cells. We further demonstrated that the 3D-PGH accelerated the wound healing process of deep second-degree scald in vivo. This study indicated the injectable 3D-PH with a double crosslinked network could be applied as a multifunctional injectable scald wound dressing material for anti-inflammation, necrotic tissue-removal, and wound closure. These findings suggest that the injectable 3D-PH may be conducive to the evolution of new pharmaceuticals for burn wound healing.

Selectivity of Copper by Amine-Based Ion Recognition Polymer Adsorbent with Different Aliphatic Amines.

This paper investigates the selectivity of GMA-based-non-woven fabrics adsorbent towards copper ion (Cu) functionalized with several aliphatic amines. The aliphatic amines used in this study were ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA). The non-woven polyethylene/polypropylene fabrics (NWF) were grafted with glycidyl methacrylate (GMA) via pre-radiation grafting technique, followed by chemical functionalization with the aliphatic amine. To prepare the ion recognition polymer (IRP), the functionalized amine GMA-grafted-NWF sample was subjected to radiation crosslinking process along with the crosslinking agent, divinylbenzene (DVB), in the presence of Cu ion as a template in the matrix of the adsorbent. Functionalization with different aliphatic amine was carried out at different amine concentrations, grafting yield, reaction temperature, and reaction time to study the effect of different aliphatic amine onto amine density yield. At a concentration of 50% of amine and 50% of isopropanol, EDA, DETA, TETA, and TEPA had attained amine density around 5.12, 4.06, 3.04, and 2.56 mmol/g-ad, respectively. The amine density yield decreases further as the aliphatic amine chain grows longer. The experimental condition for amine functionalization process was fixed at 70% amine, 30% isopropanol, 60 °C for grafting temperature, and 2 h of grafting time for attaining 100% of grafting yield (Dg). The prepared adsorbents were characterized comprehensively in terms of structural and morphology with multiple analytical tools. An adsorptive removal and selectivity of Cu ion by the prepared adsorbent was investigated in a binary metal ion system. The IRP samples with a functional precursor of EDA, the smallest aliphatic amine had given the higher adsorption capacity and selectivity towards Cu ion. The selectivity of IRP samples reduces as the aliphatic amine chain grows longer, EDA to TEPA. However, IRP samples still exhibited remarkably higher selectivity in comparison to the amine immobilized GMA-g-NWF at similar adsorption experimental conditions. This observation indicates that IRP samples possess higher selectivity after incorporation of the ion recognition imprint technique via the radiation crosslinking process.

The Influence of Ionizing Beta Radiation on the Flammability Index and Ignition Temperature of Thermoplastic Materials

Irradiation of polymeric materials is a modern method of modifying their final properties (for example, improvements in mechanical, thermal and chemical properties). The main used types of radiation to modify polymers include ionic and ionizing radiation. Due to its properties, ionization beta (electron) radiation is the most widely used. The interaction of ionizing radiation with polymeric materials manifests as radiation cross-linking, which is a result of recombination of migrating polymer radicals into the amorphous region. In this type of radiation, electrons are generated under high vacuum using a hot cathode. Electrons emitted from the cathode are then accelerated in the electrostatic field that arises between the cathode and the anode. The depth of penetration into the material rises with increasing energy of electrons. This study examines the influence of ionizing beta radiation on the flammability index and ignition temperature of thermoplastic materials.

Effect of Beta Radiation on the Quality of the Bonded Joint for Difficult to Bond Polyolefins.

Bonding is increasingly being used, and it is an ever-evolving method for creating unbreakable bonds. The strength of adhesive bonds determines, to a significant extent, the possible applications of this technology and is influenced by many factors. In addition to the type of adhesive used, the characteristics of the surface layers play a significant role; therefore, significant attention is paid to their adjustment and modification. Radiation crosslinking is one of the most important methods for modifying polymer properties. Currently, the most frequently used type of radiation for polymer crosslinking is beta minus (β−) radiation, which affects not only mechanical but also surface properties, chemical and temperature resistance, and surface layer characteristics of polymers. This study investigated the effect of β− radiation on the surface layer properties of low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP) and the effects of surface-layer modification on the ultimate tensile strength of bonded joints. Based on the results, we concluded that β− radiation significantly changes the properties of the tested surface layers, increases the surface energy, and improves the adhesiveness of bonds. Consequently, the final strength of the LDPE, HDPE, and PP bonds increases significantly.

A triple‐shape memory material fabricated by in situ crosslinking of poly(butylene adipate‐co‐terephthalate)/ε‐polycaprolactone via electron‐beam irradiation and its triple‐shape memory effects

ABSTRACTIn this work, we fabricated a triple‐shape memory polymeric material though in situ crosslinking of poly(butylene adipate‐co‐terephthalate)/ε‐polycaprolactone blends induced by electron beam irradiation. The intrinsic property of irradiation crosslinking, crosslinking rule in this heterogeneous system, formation of interfacial bridge molecular, and the resulted interfacial strength were investigated. No obvious interfacial slips were observed in tensile test, and the elongation at break was above 900%. The high‐temperature relaxation and recovery experiments at nonlinear region confirmed the excellent hyperelasticity and recovery ratios (Rr) can be as high as 95% for samples irradiated above 96 kGy. The mismatch between heating rate and relaxation kinetics resulted in both instable temporary shapes and heating‐mode dependent recovery behavior during the recovery process. Self‐stability of the temporary shape at middle temperature was also emphasized in view of the phenomenon that the second Rr was above 100% in our experiments. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48588.

Synthesis of Superabsorbent Polymer based Glucomanan-Polyacrylate by Gamma Irradiation

Materials with potential of fast absorption of water or liquid have emerged as very interesting objects for researches. Superabsorbent polymer is a cross linked polymer which has ability to absorb water hundreds to thousands of times the dry weight because it has hydrophilic groups. Owing to this characteristic this polymer gets attention for many applications, one of these is diapers. Superabsorbent polymer was synthesized from the mixture of glucomannan-pottasium acrylic-acrylamide solution by irradiation crosslinking with doses irradiation 10 kGy. It was found that SAP showed super swelling properties in water (880 g/g) at short time (15 minutes) and in real urine has a good swelling 110 g/g. Acrylamide was able to increase the swelling ratio in real urine. Therefore, it can be candidate as thin diapers with high sorption. The result of FTIR spectra confirmed that the crosslinking occurs in the hydrogels and SEM images of hydrogels showed large numbers of pores from SEM examination Keywords: Superabsorbent polymer; Acrylic acid; Acrylamide; Glucomannan; Irradiation

Further discussion on the reaction behaviour of triallyl isocyanurate in the UV radiation cross-linking process of polyethylene: a theoretical study.

Further theoretical investigation on the reaction behaviour of triallyl isocyanurate (TAIC) in the UV radiation cross-linking process of polyethylene (PE) is accomplished by density functional theory for high voltage cable insulation materials. The reaction potential energy information of the 13 reaction channels at B3LYP/6–311 + G(d,p) level are identified. These have been explored that the TAIC take part in the reaction behaviour on ground state during UV radiation cross-linking process and TAIC intra-molecular isomerization reaction itself. In addition, the results show that the effect of multiplication and acceleration for the cross-linking reaction of trimethylopropane trimethacrylate (TMPTMA) would be better than that of TAIC. It has further clarified the reasons why UV radiation cross-linking reaction of PE had been initiated by benzophenone (Bp), and the TAIC or TMPTMA needed to take part. The results obtained in the present study could directly guide both the optimization of UV radiation cross-linking PE process and the development of the insulation material of high-voltage cable in real application.

Effects of UVA+UVB Solar Radiation Levels and Cross-Linking on Animal Model with Bowman’s Layer: Chicken

Effects of UVA+UVB Solar Radiation Levels and Cross-Linking on Animal Model with Bowman’s Layer: Chicken