Polyethylene (PE), is a polymer formed by carbon-carbon single bonds, is a very stable material with a very slow degradation rate. In this paper, polyethylene films bag type were exposed to UV-B radiation (320-280 nm) at different exposure times (2 to 12 days). The UV radiation effects on PE samples were characterized using infrared spectroscopy with attenuated total reflectance (ATR). The vinyl group formation indicates the PE degradation. These chemical groups have IR absorption in 900-1300 cm-1; additionally the degree of crystallinity increase with the increasing of the exposure time. The experiment showed significant changes in PE molecular structure.
Laser provides a high controllable and localized spot for soldering joint formation and this is a valuable tool in Sn/Pb
Soldering process on electronic industry, in recent years, laser beam welding has become an emerging welding
technique, the use of laser in welding area is a high efficiency method. A 60 Watts CO2 continuous laser was used on
this study, during welding experimental results indicated the laser could significantly improve speed and weld quality. In
this work, the welding interactions of CO2 laser with Sn/Pb wire have been investigated in details through varying the
energy ratios of laser. And at the same time, the effect of distance from laser spot to material.
In this work we quantified the effective UV radiation dose in orange and colorless polyethylene samples exposed to
weather in the city of Aguascalientes, Ags. Mexico. The spectral distribution of solar radiation was calculated using
SMART 2.9.5.; the samples absorption properties were measured using UV-Vis spectroscopy and the quantum yield was
calculated using samples reflectance properties. The determining factor in the effective UV dose is the spectral
distribution of solar radiation, although the chemical structure of materials is also important.
This work carries out a simulation of the absorption spectra on the IR of an untinted textile fiber manufactured with
polyacrylonitrile (PAN), obtained by calculating the Molecular Orbitals (MOs) and their associated energies based on the
semiempirical (AM1) Hartree-Fock (HF) model and compared with the experimental results obtained from a PAN textile
fiber with blue pigment by means of an IR FTIR Avatar Nicolete spectrophotometer.
The degradation of weather exposed linear low density polyethylene (LLDPE) specimens, with and without pigments, in
Aguascalientes City, Ags. Mexico, during 269 days, was studied. Spectroscopic methods, ultraviolet (UV) spectroscopy
and colorimetry, were used to determine the degradation of the specimens. The material used is not pure since they are
samples of finished product that contain additives such as anti-oxidants, stabilizers, catalysts. One of the samples
contains orange color pigment and the other sample is colorless. The plots describing the absorption bands attributable to
the polymeric material show a similar profile in both samples. The bands attributable to pigment do show a considerable
decrease in absorbance. The results suggest that the orange pigment has been degrading, as it can also be observed in the
color change, while the polymeric material doesn't show any degradation.