Formation mechanism of microvoids and microcracks of poly(vinyl chloride) under an artificial aging environment

Abstract

Degradation behaviors of both the unplasticized and plasticized poly(vinyl chloride) (UPVC and PPVC) under an artificial accelerating aging condition were extensively studied. The dependence of mechanical properties, average molecular weight (MW), and surface morphology of the earlier PVC on aging time was investigated by tensile tests, gel penetrate chromatogram (GPC), and scanning electron microscope (SEM), respectively. Fourier transform infrared and ultraviolet (UV)–visible spectroscopy were used to evaluate the probable formation of both the oxygen‐containing groups and the conjugated sequences during aging. The results reveal that UPVC is much easier to be degraded than PPVC under the same testing conditions. The irradiated surface is detected to change from an even topology into a rough topology initially, and then follows the appearance of many voids even cracks in the SEM morphology. During the aging process, oxygen‐containing groups and conjugation of PVC molecular chains around the cracks are observed, and noticeably increase with aging time. However, visible difference of the corresponding MWs of PVC before and after aging is not detected. Moreover, a novel degradation mechanism nearly related to the formation of microvoids and microcracks based on the cohesion energy of groups along PVC molecular chains is developed and semiquantitatively discussed. It is detected that the formation of microvoids and microcracks is attributed to both the thermodynamic changes of PVC backbone during the aging and the aggregation of oxygen‐containing groups with relatively large volumes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Synthesis of a Stable Solid Acid Catalyst from Chloromethyl Polystyrene through a Simple Sulfonation for Pretreatment of Lignocellulose in Aqueous Solution

“…The formation of C−OH group during the sulfonation process is consistent with the result of Tyufekchiev's study [21] . The absorption peak from 3100 to 2850 cm −1 is attributed to the C−H bond stretching vibration of solid acid surface saturation [32] . The absorption peak from 1600–1500 cm −1 is the C=C stretching vibration of aromatic hydrocarbons, and the peak at 1250 cm −1 is the stretching vibration peak of S=O [33] …”

Cracks, microcracks and fracture in polymer structures: Formation, detection, autonomic repair

“…PVC that has been processed for long periods and/or high temperature demonstrates less resistance to UV damage [10].This may be due to the increase in the degree of degradation of macromolecular compounds as a result of processing temperature and time. Thermodynamic analysis for PVC has shown that the generation and growth of microvoids ( both in number and length) which is followed by formation of cracks is a result of relaxation of residual energy, creation of polar groups and the adjustment of conformation of macromolecular chains [121]. UV radiation has enough energy to break the carbon and oxygen bonds in polymers and to build volatile fragments.…”

Aging and Degradation of Printed Materials

“…Changes on the surface, for example, the analysis of microcracks, can be done with a scanning electron microscope (SEM) (Xiang et al, 2012). However, it is not as popular in the case of thermal, photo, or oxidative degradation as for analysis of surface after treatment or for biodegradation influence studies.…”

“…Influence of plasticizers added to PVC on the effect of artificially accelerated aging simulating environmental conditions was studied by Xiang et al (2012). Influence of plasticizers added to PVC on the effect of artificially accelerated aging simulating environmental conditions was studied by Xiang et al (2012).…”

“…Influence of plasticizers added to PVC on the effect of artificially accelerated aging simulating environmental conditions was studied by Xiang et al (2012). In longer artificial aging, the topology of PVC films is changed, the voids or even cracks appear on the surface (Xiang et al, 2012). In addition, these compounds are susceptible to microbial degradation (Jakubowicz, 2001;Kaczmarek & Bajer, 2008).…”