Study of Humidity and UV Wavelength Effects on Degradation of Photo-Irradiated Polyethylene Films Using DMA

Plastic bags, mostly made of polyethylene, cause pollution as solid waste due to their nondegradable nature. Accelerated degradation, as a solution to mitigate the menace, can be achieved through moisture enhanced photolysis. This study evaluated the effect of three relative humidity environments, i.e., 25%, 40%, and 60% RH, at a constant temperature of 55°C. The effect was studied for ultraviolet (UV) irradiated and nonirradiated samples of polyethylene (PE) films processed under conventional ways. Photodegradation was initiated using ultraviolet irradiation in the ranges (200–300) nm and (300–400) nm for two hours and the effects of subsequent humidity treatment analyzed. Dynamic mechanical analysis was used to measure the dynamic storage modulus to monitor degradation. For nonirradiated samples, there was essentially no change in storage modulus at the three relative humidity environments after 550 hrs. Irradiation in the (300–400) nm range showed faster degradation than for the (200–300)nm range with the highest drop in storage modulus being 67% after 550 hrs. Raising the humidity from 25% to 40% and 60% RH resulted in 41%, 62%, and 67% drop of storage modulus, respectively, at the 550 hrs.     

35MeV/uAr离子辐照聚酯膜引起的效应研究

采用多种手段研究了 35Me V/u的 Ar离子辐照聚酯 (PET)膜产生的微观结构变化 .结果表明 ,辐照使聚酯的化学键断裂并产生了炔端不饱和基团和自由基 .断键主要发生在乙二醇残留物、苯环的对位和酯的 C— O键上 .随着吸收剂量的增加 ,材料的结晶度逐渐降低 ,由原始的41 .7%减至最高辐照量时的 1 5.0 % .研究发现 ,聚脂的非晶化转变截面与电子能损呈线性关系 ;断键和非晶化效应主要取决于样品的吸收剂量 ,并存在一个约 4.0 MGy的阈值.Stacked polyethylene terephthalate films were irradiated with 35 MeV/u Ar ions at room temperature. The ion induced effects were studied by ultraviolet visible spectrometer, Fourier transform infrared spectroscopy, X ray diffractometer, X ray photoelectron spectroscopy, electron spin resonance spectroscopy and differential scanning calorimetry. Bond breaking and the formation of alkyne end groups and free radicals were observed. The bond breaking processes occurred mainly...     

红外光吸收研究35MeV/u Ar离子辐照半晶质聚酯膜引起的效应

35MeV/u Ar离子在室温下辐照了多层堆叠的半晶质聚酯膜,采用傅立叶转换的红外光吸收技术分析和研究了由辐照引起的化学键断裂及其对离子剂量、离子在样品中的平均电子能量损失和吸收剂量的依赖性.结果表明,辐照导致聚酯膜中发生了明显的化学键断裂,断键过程主要发生在反式构型的乙二醇残留物和苯环的对位上,苯环的基本结构在辐照中变化较小.断键不仅强烈地依赖于离子的照射剂量,而且还跟样品中电子能量沉积密切相关,明显的断键发生在4.0MGy以上的吸收剂量.     

紫外-真空紫外漫反射板的研究

选用在紫外－真空紫外波段反射率较高的铝作基底材料,通过光学研磨加工和光学镀膜处理制成漫反射板;建立了紫外－真空紫外波段漫反射特性测试研究装置,利用该系统进行漫 反射板余弦特性、双向反射比分布函数的测试。结果表明,该漫反射板反射比ρ（ｏ／ｄ）在３１５ｎｍ处为４９％;在正入射情况下,双向反射比分布函数在１５℃￣４０℃范围内偏差优于１１％。     

紫外转化的PPV薄膜电致发光性质的研究

PPV是一种常用的高荧光效率的黄绿色的电致发光共轭聚合物,因为PPV不易溶解于有机溶剂,所以在有机电致发光(OLEDs)中PPV薄膜的制备通常是PPV的预聚体旋涂成膜,然后在高温、真空条件下转化成PPV薄膜。这种高温转化制膜的方法无法对其进行掺杂,限制了PPV在OLED中的应用。文章利用紫外光照射,PPV预聚体薄膜在室温和真空条件下转化成PPV薄膜,它与热处理得到的PPV薄膜的光致发光(PL)和拉曼(Raman)光谱一致;利用这种方法制备了非掺杂和红色荧光染料掺杂的有机电致发光器件,实现了以PPV为主体和能量给体的不同染料的掺杂发光,并获得绿色和橙色的电致发光。电致发光器件的发光效率和发光强度还有待进一步提高。     

等离子体制取羟自由基降解苯酚溶液及其历程的UV研究

研究了利用强电离放电产生等离子体方法制取羟基自由基氧化降解高浓度苯酚废水。当羟基自由基浓度达到1 037 mg·L-1时,初始浓度为1 215 mg·L-1的废水降解率达99.11%;初始浓度为8 853 mg·L-1的废水苯酚浓度下降到6 250 mg·L-1,1 mg羟基自由基可处理苯酚2.5 mg。在同样羟自由基浓度下,苯酚初始浓度越小,去除率越高;但初始浓度越高,处理的绝对量越大。阐述并解释了不同降解阶段废水pH值、电导率与羟基自由基浓度变化的关系。随着羟自由基浓度的增大,废水酸碱性由接近中性逐渐转为酸性,浓度越大,酸性越强;继续增大羟自由基浓度,变化渐趋平缓。随着羟自由基的通入,电导率有一个微小的降低阶段然后开始上升,说明苯酚不断的被氧化为有机酸。通过紫外图谱和色谱分析了降解中间产物,表明氧化初始阶段邻苯二酚、对苯二酚和苯醌是其中重要的化合物。     

Effects of mesoporous structure and UV irradiation on in vitro bioactivity of titania coatings

Mesoporous titania coatings (MTCs) with a pore size of 4.75 nm were prepared on Ti6Al4V substrates by a sol-gel process, and then irradiated with UV light at room temperature for 2 h. The effects of mesoporous structure and UV irradiation on the in vitro bioactivity were investigated. Simulated body fluid (SBF) tests reveal that the MTCs exhibit a high apatite-forming ability, which may be attributed to the following reasons: (i) the BET surface area of the MTCs is ∼190 m²/g, resulting in a greater density of Ti-OH groups than that without mesoporous structure; (ii) theoretical analysis reveals that the mesoporous structure can improve the driving force and nucleation rate of apatite precipitation in SBF. As compared with the MTCs, the UV-irradiated coatings do not exhibit any change in phase components and surface morphologies. However, the apatite-forming ability is higher on the UV irradiation coatings than on the MTCs because of the increase of Ti-OH groups and the improvement of wettability after UV irradiation. In addition, the investigation of the MG63 cell proliferation on the both substrates was performed. The results indicate that the MTCs before and after UV irradiation exhibit a good biocompatibility and are fit for the MG63 cell proliferation.     

Degradation Studies of Polyolefins Incorporating Transparent Nanoparticulate Zinc Oxide UV Stabilizers

Coated and dispersed nanoparticulate zinc oxide is shown to improve ultra violet (UV) stability of polypropylene and high-density polyethylene without changing its characteristic absorption spectrum in the visible region (400–800-nm). The performance of these nanoparticulate UV stabilizers is compared to conventional hindered amine light stabilizers (HALS). QUV accelerated weathering is used to simulate long-term exposure. Positron annihilation lifetime spectroscopy (PALS) is used to provide an indication of physical and chemical changes due to accelerated weathering and is shown to have potential for detecting changes well before other techniques. Visual observation, optical microscopy, carbonyl index, yellowness index and PALS indicate that nanoparticulate zinc oxide gives superior resistance to UV degradation compared to organic HALS at appropriate loading levels.     

Experimental Study of the Influence of Thickness and Wavelength on the Ultraviolet Light Scattering of Polyethylene Films

A study of the influence of thickness and wave-length on the ultraviolet scattering of polyethylene films is reported in this paper. The scatter of samples was measured by considering the difference between absorbances values obtained with the sample placed in two positions at different distance from the detector in a UV/Vis Spectrophotometer.

The present work suggests that a linear relationship exists between absorbance and thickness film for the two sample positions, and also between the difference of these absorbances and wavelength. From the obtained equations it is possible to normalize scattering values for a given wavelength and a given thickness, and in this way experimental errors are minimized. This procedure represents a simple way for characterize optically these materials and, analogously, other transparent or translucent polymeric films.     

UV辐射光谱的光电测量研究

为了设计出符合要求的紫外产生材料和更好地对紫外光谱进行测量，提出了以原子材料为基础产生紫外光谱和采用紫外传感器测量紫外光谱的方法。这在对抗紫外制导方面具有十分重要的研究和实用价值。根据相关理论，重点对原子紫外光谱，尤其是碱金属原子核外电子的能量跃迁进行了分析和计算，列出了计算的谱线数据。介绍了目标紫外光谱的测量原理。在选用合适的紫外材料激发后，采用双光栅单色仪和紫外传感器进行测量。最后，给出了紫外传感器对紫外辐射的测量实验结果和测量曲线。     

UV light induced surface modification of HDPE films with bioactive compounds

The development of different techniques for surface modification of polymers becomes popular in a last decade. These techniques preserve useful bulk polymer properties unchanged, while the activation of the polymer surface offers more possibilities for polymer applications.In this work, a new, one-step method for bio-activation of HDPE (high density polyethylene) surface by UV irradiation is presented. HDPE films coupled with selected active compound and a photoinitiator was treated by UV lamp, emitting light at 254 nm.For surface functionalization of HDPE films, the following compounds were employed: 2-aminopyridine (AP), N¹-(2-pyridylaminomethyl)-1,2,4-triazole (TA) and benzocaine (BC). The influence of irradiation time on the extent of surface changes was investigated. The modified polymer surfaces were investigated by Fourier transformed infrared (FTIR) and Raman spectroscopy, scanning electron microscopy (SEM) and contact angle measurements, demonstrating successful functionalization of HDPE surface.     

Patterning of nanoparticulate transparent conductive ITO films using UV light irradiation and UV laser beam writing

Indium tin oxide (ITO) thin film is one of the most widely used as transparent conductive electrodes in all forms of flat panel display (FPD) and microelectronic devices. Suspension of already crystalline conductive ITO nanoparticles fully dispersed in alcohol was spun, after modifying with coupling agent, on glass substrates. The low cost, simple and versatile traditional photolithography process without complication of the photoresist layer was used for patterning ITO films. Using of UV light irradiation through mask and direct UV laser beam writing resulted in an accurate linear, sharp edge and very smooth patterns. Irradiated ITO film showed a high transparency (∼85%) in the visible region. The electrical sheet resistance decrease with increasing time of exposure to UV light and UV laser. Only 5 min UV light irradiation is enough to decrease the electrical sheet resistance down to 5 kΩ□.     

Mechanical Properties and Solid-State Structure of Photodegraded Polyoxymethylene and Effect of UV Stabilizers Modification

Ultraviolet (UV) light exposure can lead to photodegradation of polyoxymethylene (POM), resulting in a change of its physical and chemical properties. Benzophenone UV absorber (UV-9), benzotriazole light stabilizer (UV-327), and hindered amine light stabilizer (LD-622) were used as UV stabilizers to improve the photostabilization of POM. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) were employed to characterize POM before and after aging. The change of its solid-state structure during the aging process was investigated. The surface molecular weight and the mechanical properties of modified POM after UV aging were also determined. The results showed that the degradation of amorphous molecules mainly occurred at the surface, while crystalline reorganization occurred in the interior part of the sample as a result of the UV irradiation, both of which led to an increase of the crystallinity. After UV irradiation for 1000 h, the elongation at break and notched Charpy impact strength were only 16.6% and 27.4% of the initial sample, respectively. However, 1%–3% of the additives could reduce the chain scission and restrain the recrystallization of POM after UV irradiation. Furthermore, mechanical properties were maintained to a certain degree by adding the UV stabilizers.     

Development and Validation of UV Spectrophotometric Method to Study Stress Degradation Behaviour of Rizatriptan Benzoate

Rizatriptan benzoate is a 5HT 1B/1Dreceptor agonist which is prescribed for the treatment of migraine.In the present study new,simple,specific ultraviolet spectrophotometric method for rizatriptan benzoate was developed and validated.Forced degradation studies were carried out in acidic,alkaline and neutral pH conditions.The absorbance maxima peak was found to be 224 nm and linearity was observed in the concentration range of 0.5~2.5μg·mL-1 with regression coefficient value of 0.998 8.The method was validated and found to be precise.The percent recovery for rizatriptan benzoate was found to be 98.576±0.202.The bulk drug was found to be stable in neutral and acidic pH conditions but got degraded in 1N NaOH solution.     

UV照射大肠杆菌对其吸收光谱的影响

探讨了样品池溶液及分光光度计内置紫外光对大肠杆菌吸收光谱测定的影响。发现样品池溶液(2.8 mL双蒸水+0.1 mL生理盐水+0.1 mL LB培养基)较为合理,既给细菌提供了有利的生存环境,又对细胞的紫外吸收影响较小;研究同时发现在257 nm波段150 s内细胞吸收强度基本没有变化,说明内置的紫外光不会影响试验测定结果。在此基础上,研究了UV照射0,20,40,60,80,120 s大肠杆菌吸收光谱的变化情况。结果显示随着UV照射剂量的增加,大肠杆菌吸收光谱存在一个先降后升再降的现象。该现象反映了辐射中细胞损伤死亡和修复存活的生物学效应。该研究从光谱学角度探讨了UV对大肠杆菌细胞的损伤作用,对利用光谱技术研究细胞的辐射损伤、死亡和修复具有一定参考意义。     

The influence of UV irradiation on the surface of chitosan films

The surface properties of chitosan films before and after UV-irradiation (λ = 254 nm and 248 nm, respectively) were investigated using the technique of scanning electron microscopy (SEM) and by means of contact angle measurements allowing the calculation of surface free energy. Moreover, in order to determine the film mass changes, quartz crystal microbalance (QCM) measurements were performed. Measurements of the contact angle for diiodomethane (D), formamide (F) and glycerol (G) on the surface of chitosan films were made. The chemical and structural changes during UV irradiation were studied by FTIR-ATR spectroscopy.The contact angle and the surface free energy were altered by UV irradiation of chitosan films. The microscopy images have shown that the KrF excimer laser irradiation caused visible damages on the surface in comparison with the surface exposed to the mercury UV lamp. The surface modification of chitosan films can be achieved using both, the low intensity UV lamp and the excimer laser.     

红外紫外双色光谱的产生

本文给出了在红外光谱多外利用热受激后的原子材料产生紫外光谱的方法。文中给出了计算数据和实验结果。     

聚乙烯薄膜材料的红外光谱研究

由于红外吸收光谱法具有许多突出的优点,因此它在许多领域有广泛的应用。在薄膜、合成纤维、橡胶、塑料等高聚物的研究方面,用于单体、聚合物、添加剂的定性、定量和结构分析。一般高聚物的红外光谱中谱带的数目很多,而且不同种类的物质其光谱很不相同,特征性很强。此外红外光谱法的制样和实验技术相对比较简单,它适用于各种物理状态的样品。本实验研究以高聚物薄膜材料做样品,对样品高聚物进行红外光谱分析,分析表明,本实验所用样品高聚物成分为聚乙烯材料,这个实验结果也表明,用红外光谱法鉴定高聚物的组成非常有效。红外光谱法用于定量组分分析,与其它测量方法相比,具有制样简单方便、重复性好和测量精度高的特点。     

On the Effects of UV Radiation on the Release Ability of Glucose Embedded in Hydroxypropyl Cellulose Films

New drug delivery systems based on hydroxypropyl cellulose (HPC) and different percents of glucose were prepared and characterized to check their suitability as UV resistant patches. The spectral absorption properties of the HPC and HPC-glucose blends before and after UV irradiation were analyzed. The surface polarity and hydrophilicity were correlated with the morphology of the films and analyzed with respect to the UV exposure time and the embedded amount of glucose. The effects of UV radiation on in vitro evaluation of glucose release from the HPC films are reported. The mechanism involved in the drug release process, evaluated using the Korsmeyer-Peppas equation, was dependent on the introduced amount of glucose and less on the UV exposure time. A more polar, smoother, and less dense surface releases the glucose over larger periods of time, making the system with lower percents of glucose more adequate for the pursued purpose.