Photovoltaics module interface: General purpose primers

The interfacial chemistry established between ethylene vinyl acetate (EVA) and the aluminized back surface of commercial solar cells was observed experimentally. The technique employed is called Fourier Transform Infrared (FTIR) spectroscopy, with the infrared signal being reflected back from the aluminum surface through the EVA film. Reflection infrared (IR) spectra are given and attention is drawn to the specific IR peak at 1080/cm which forms on hydrolytic aging of the EVA/aluminum system. With this fundamental finding, and the workable experimental techniques, candidate silane coupling agents are employed at the interface, and their effects on eliminating or slowing hydrolytic aging of the EVA/aluminum interface are monitored

Interfacial bonding stability

Interfacial bonding stability by in situ ellipsometry was investigated. It is found that: (1) gamma MPS is an effective primer for bonding ethylene vinyl acetate (EVA) to aluminum; (2) ellipsometry is an effective in situ technique for monitoring the stability of polymer/metal interfaces; (3) the aluminized back surface of silicon wafers contain significant amounts of silicon and may have glass like properties

Anticorrosion studies

The aging behavior of chemically bonded interfaces between metals and pottants, such as ethylene vinyl acetate (EVA) was studied using the Dow Corning primer systems. It was observed that the primers seem to function as anticorrosive agents on metal surfaces. It was demonstrated that EVA, and the A-11861 EVA/glass primer stops corrosion of the aluminum used on the back surfaces of crystalline silicon solar cells. However, this same treatment does not work for the aluminum on the back surfaces of amorphous silicon solar cells

Chemical Bonding Technology: Direct Investigation of Interfacial Bonds

This is the third Flat-Plate Solar Array (FSA) Project document reporting on chemical bonding technology for terrestrial photovoltaic (PV) modules. The impetus for this work originated in the late 1970s when PV modules employing silicone encapsulation materials were undergoing delamination during outdoor exposure. At that time, manufacturers were not employing adhesion promoters and, hence, module interfaces in common with the silicone materials were only in physical contact and therefore easily prone to separation if, for example, water were to penetrate to the interfaces. Delamination with silicone materials virtually vanished when adhesion promoters, recommended by silicone manufacturers, were used. The activities related to the direct investigation of chemically bonded interfaces are described

Elastic and thermodynamic properties of the shape-memory alloy AuZn

The current work reports on the elastic shear moduli, internal friction, and the specific heat of the B2 cubic ordered alloy AuZn as a function of temperature. Measurements were made on single-crystal and polycrystalline samples using Resonant Ultrasound Spectroscopy (RUS), semi-adiabatic calorimetry and stress-strain measurements. Our results confirm that this alloy exhibits the shape-memory effect and a phase transition at 64.75 K that appears to be continuous (second-order) from the specific heat data. It is argued that the combination of equiatomic composition and a low transformation temperature constrain the chemical potential and its derivatives to exhibit behavior that lies at the borderline between that of a first-order (discontinuous) and a continuous phase transition. The acoustic dissipation does not peak at the transtion temperature as expected, but shows a maximum well into the low-temperature phase. The Debye temeprature value of 219 K, obtained from the low-temperature specific heat data is in favorable agreement with that determined from the acoustic data (207 K) above the transition.Comment: 25 pages, 6 figures, submitted to Phys. Rev.

Energetics of Nanomaterials

This project, "Energetics of Nanomaterials," represents a three-year collaboration among Alexandra Navrotsky (UC Davis), Brian Woodfield and Juliana Boerio-Goates (BYU), and Frances Hellman (UC Berkeley). It's purpose has been to explore the differences between bulk materials, nanoparticles, and thin films in term of their thermodynamic properties, with an emphasis on heat capaacities and entropies, as well as enthalpies. the three groups have brought very different expertise and capabilities to the project. Navrotsky is a solid-state chemist and geochemist, with a unique Thermochemistry Facility emphasizing enthalpy of formation measurements by high temperature oxide melt and room temperatue acid solution calorimetry. Boerio-Goates and Woodfield are calorimetry. Hellman is a physicist with expertise in magnetism and heat capacity measurements using microscale "detector on a chip" calorimetric technology that she pioneered. The overarching question of our work is "How does the free energy play out in nanoparticles?", or "How do differences in free energy affect overall nanoparticle behavior?" Because the free energy represents the temperature-dependent balance between the enthalpy of a system and its entropy, there are two separate, but related, components to the experimental investigations: Solution calorimetric measurements provide the energetics and two types of heat capacity measurements the entropy. We use materials that are well characterized in other ways (structurally, magnetically, and chemically), and samples are shared across the collaboration

Heat capacity from 5 to 350 K and thermodynamic properties of cesium nitrate to 725 K

The low-temperature heat capacity (5 to 350 K) of CsNO3 was determined by adiabatic calorimetry. No anomalies were observed in this temperature region, the curve of heat capacity against temperature having the normal sigmoid shape. These measurements yielded the thermodynamic properties at 298.15 K: Cp[deg]=(96.47+/-0.19)J K- mol-; S[deg]=(153.95+/-0.31)J K- mol-; {H[deg](T) - H[deg](O)} =(20046+/-40)J mol-; {G[deg](T) - H[deg](O)}/T =(86.71+/-17)J K- mol-.These measurements have been combined with published high-temperature heat capacities to give the thermodynamic properties of CsNO3 to 725 K.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24563/1/0000844.pd

The influence of inspiratory muscle work history and specific inspiratory muscle training upon human limb muscle fatigue

This article has been made available through the Brunel Open Access Publishing Fund and is available from the specified link - Copyright @ 2006 The Authors.The purpose of this study was to assess the influence of the work history of the inspiratory muscles upon the fatigue characteristics of the plantar flexors (PF). We hypothesized that under conditions where the inspiratory muscle metaboreflex has been elicited, PF fatigue would be hastened due to peripheral vasoconstriction. Eight volunteers undertook seven test conditions, two of which followed 4 week of inspiratory muscle training (IMT). The inspiratory metaboreflex was induced by inspiring against a calibrated flow resistor. We measured torque and EMG during isometric PF exercise at 85% of maximal voluntary contraction (MVC) torque. Supramaximal twitches were superimposed upon MVC efforts at 1 min intervals (MVCTI); twitch interpolation assessed the level of central activation. PF was terminated (T-lim) when MVCTI was < 50% of baseline MVC. PF T-lim was significantly shorter than control (9.93 +/- 1.95 min) in the presence of a leg cuff inflated to 140 mmHg (4.89 +/- 1.78 min; P = 0.006), as well as when PF was preceded immediately by fatiguing inspiratory muscle work (6.28 +/- 2.24 min; P = 0.009). Resting the inspiratory muscles for 30 min restored the PF T-lim to control. After 4 weeks, IMT, inspiratory muscle work at the same absolute intensity did not influence PF T-lim, but T-lim was significantly shorter at the same relative intensity. The data are the first to provide evidence that the inspiratory muscle metaboreflex accelerates the rate of calf fatigue during PF, and that IMT attenuates this effect

Thermodynamics of thallium alkanoates I. Heat capacity and thermodynamic functions of thallium(I) n-hexanoate

The sub-ambient heat capacity of thallium(I) n-hexanoate is characterized by transitions at 203.5 and 208.3 K which show Cp, m/R maxima of about 400 and 2500 and ([Delta]Sm/R)'s of 1.03 and 1.07. Both appear to be essentially first order and show typical under-cooling phenomena. The heat capacities are in excellent accord with the d.s.c. values of Fernandez-Martin, Lopez de la Fuente, and Cheda over the common range of super-ambient values. At T = 298.15 K the values of {Smo(T)-Smo(0)}/R, {Hmo(T)-Hmo(0)}/R, and -{Gmo(T)-Hmo(0)}/RT are 39.06, 5880 K, and 19.33. Smoothed thermodynamic functions are tabulated through melting.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25683/1/0000237.pd