Crosslinking of PVC formulations treated with UV light. II. Color formation and viscoelastic properties

Abstract

Two wire coating PVC formulations stabilized with Ca/Zn systems and one stabilized with a traditional lead compound were prepared. All three formulations contained trimethylolpropane trimethacrylate (TMPTMA) as a crosslinking agent and Irgacure 819 as a UV photoinitiator. Small specimens of hot‐pressed materials with 1.0 and 1.5 mm thicknesses were irradiated with UV light for 10 days, while monitoring changes at different time intervals. The presence of TMPTMA in the samples influenced the coloration of the lead‐stabilized formulation, while the others experienced the usual color formation after UV treatment, as seen by Yellowing Index measurements and corroborated by the evaluation of fluorescence spectra. The elastic modulus (E′) determined by DMA was shown to be sensitive to surface changes associated with crosslinking, while the loss modulus (E″) determined by DMA and the complex modulus (E*) obtained by TMA were shown to be sensitive indicators of bulk property changes. J. VINYL ADDIT. TECHNOL., 13:189–194, 2007. © 2007 Society of Plastics Engineers

A Quantitative Spectroscopic Study of the Bleaching Phenomena in Plasticized Formulations Containing PVC Exposed to Outdoor Conditions

“…Particularly for comparative purposes, there is an evident advantage when describing the PAB in a given system by using one unique curve (“master curve”) instead of a family of curves. This advantage has also been exploited when the Yellowness index (YI) has been used to describe the degrading behavior of different samples [33,34,35]. Unfortunately, there was not any numerical relationship correlating the YI of a given sample with the concentrations of each one of the different polyenes contained in it; in fact, it is very probable that there is not a univocal relationship among a given YI value and the different P n values.…”

Effect of the combination of a benzophenone‐type ultraviolet absorber with thermal stabilizers on the photodegradation of poly(vinyl chloride)

“…4 [8,9]. When organic calcium complex stabilizers are added to PVC individually to inhibit photodegradation, they can act by substituting active chloride as well as by scavenging HCl, which has an autocatalytic effect in the presence of oxygen [24][25][26]. In this case, the addition of a mixture of Chimassorb 81 and an organic calcium complex stabilizer to PVC film can provide a double barrier to protect the polymer from photodehydrochlorination.…”

Effect of relatively nontoxic thermal stabilizers on photodegradation of poly(vinyl chloride)

“…And excess zinc soaps used will result in ''zinc burn'' reaction. Liquid calcium series stabilizers used in our experiments are prepared by adding organic compounds to the traditional Ca/Zn stabilizers, which can effectively restrain the ''zinc burn'' to endow PVC films good initial color stability as well as a little long-term stability since Ca/Zn substitutes the main-chain active chloride as following reaction [21].…”

“…Fourier transform infrared absorption spectra of PVC films with different thermal stabilizers. spectrum in the range of 1550-1850 cm 21 appears on the infrared spectra of PVC after UV irradiation, and takes absorbance peak at 1721 and 1771 cm 21 . This broad band can be attributed to carboxylic, aldehyde, ketone, aand b-chloroketone, and so on [16,33,34].…”