Analysis Techniques of Polymeric Encapsulant Materials for Photovoltaic Modules: Situation and Perspectives

AbstractThe properties of the encapsulant are critical to the long-term performance of photovoltaic (PV) modules under the influence of sunlight including UV, elevated temperature, humidity and diffusion of oxygen. Encapsulation process represents about 40% of the whole PV module cost. The introduction of new non-EVA encapsulant material type ″Low-Cost, High-Performance″ should provide a solution to outdoor yellowing degradation problems. The emerging encapsulant materials exhibit a good compatibility with emerging PV solar cells for long term durability. This new generation of encapsulant materials has the advantage to improve the PV module performances and long term durability for specific climate like desert regions. This scientific contribution presents an overview of the different encapsulant materials currently on the market, the general requirements of the emerging encapsulant materials and characterizations techniques for degradation, diagnostic and reliability lifetime estimation in the framework of Algerian renewable energy strategy

Fourier Spektroskopische Untersuchungen im Mittleren und Fernen Infrarotbereich an Co 60 bestrahlten und thermisch belasteten ultrahochmolekularen Polyethylen Proben

Fourier Spektroskopische Untersuchungen von hochmolekularem Polyethylen HMW PE und ultrahochmolekularem Polyethylen UHMW PE im Mittleren und Fernen Infrarotbereich können Veränderungen der molekularen Strukturen nachweisen, die durch Co60 amp; 947; Strahlung und Rekristallisationsprozesse initiiert werden. UHMW PE und HMW PE sind im gewählten IR Bereich unterscheidbar. Die integrale Absorption der B1u Gitterschwingungen im Fernen Infrarotbereich THz Bereich ermöglichen die quantitative Beschreibung des Kristallinitätsgrades und dessen Abbau. Die Bildung ungesättigter Vinylengruppen und der Abbau ungesättigter Methylengruppen können im Mittleren Infrarotbereich nachgewiesen werde

THz and mid IR Fourier Transform Spectroscopy on Polyethylene irradiated with gamma Co60 radiation

THz and mid IR spectroscopy of high molecular PE HMW and ultra high molecular PE UHMW reveals modifications of the molecular structure induced by amp; 947; Co60 radiation. UHMW PE and HMW PE can be distinguished. The integral absorption in the B1u THz region can quantitatively describe the amorphization of crystallinity. The formation of trans vinylene unsaturations and the decay of vinyl can be followed by mid IR spectroscop

ADDITIVE MANUFACTURING OF PERSONALIZED WETSUITS

Additive manufacturing (AM) provides opportunities to customize parts with precise control of geometry and materials. An application for the Navy is the fabrication of user-tailored wetsuits with superior fit, as well as enhanced thermal and mechanical properties required for dives at cold temperatures and high pressures. The goal of this project is to investigate AM for the fabrication of wetsuit parts. A 3D scanner was used to generate a digital model of a hand, which was modified with a modeling tool to form a glove and sliced for printing. The glove was 3D printed using fused filament fabrication with multiple methods and materials, including thermoplastic polyurethane elastomer (TPU), polyvinyl alcohol polymer (PVA), and polylactic acid (PLA). PLA was initially used to determine appropriate settings for the other materials. A fully TPU-printed glove most closely resembled a wetsuit with an excellent fit. TPU printed at 100% infill proved to be stiffer than neoprene, which might be advantageous for higher external pressures. Alternatively, a water-soluble PVA part was printed to use as a scaffold and a neoprene gel was applied to the outside, which left a thin shell of neoprene upon dissolution of PVA in water. This shell had the flexibility of a traditional wetsuit, but lacked thickness, which would require multiple applications of the gel. The results suggest a combination of these approaches can be used for producing next-generation personalized wetsuits for the Navy.Ensign, United States NavyApproved for public release. Distribution is unlimited

Relation between dielectric and mechanical losses in ferroelectric poly(vinylidene fluoride - hexafluoropropylene) films

The temperature dependences of dielectric permittivity and elastic modulus of poly(vinylidene fluoride - hexafluoropropylene) (P(VDF-HFP)) are compared and explained by use of structural data obtained by differential scanning calorimetry and X-ray analysis. Special emphasis is put on the effect of uniaxial stretching which renders the polymer ferroelectric. It is shown that dielectric and mechanical relaxations at the glass transition (a relaxation) are closely related and not significantly affected by stretching. It is further confirmed that stretching destroys the non-polar spherulitic crystalline structure and produces relatively small-sized polar crystallites. This manifests in the disappearence of the so-called c relaxation which is associated to molecular motions within the spherulitic crystalline lamellae. However, there are discrepancies between dielectric and mechanical losses above the glass transition which point towards a still not described structural trans ition

Discoloration Effects of High Dose gamma Irradiation and Long Term Thermal Aging of U HMW PE

Two polyethylene types with ultra-high (UHMW-PE) and high molecular weight (HMW-PE) used as neutron radiation shielding materials in casks for radioactive waste were irradiated with doses up to 600 kGy using a 60Co gamma source. Subsequently, thermal aging at 125°C was applied for up to one year. Degradation effects in the materials were characterized using colorimetry, UV-Vis spectroscopy, IR spectroscopy, and DSC. Both materials exhibited a yellowing upon irradiation. The discoloration of UHMW-PE disappeared again after thermal aging. Therefore, the yellowing is assumed to originate from annealable color centers in the form of free radicals that are trapped in the crystalline regions of the polymer and recombine at elevated temperatures. For the antioxidant-containing HMW-PE, yellowing was observed after both irradiation and thermal aging. The color change was correlated mainly to decomposition products of the antioxidant in addition to trapped radicals as in UHMW-PE. Additionally, black spots appeared after thermal aging of HMW-PE