Degradation assessment of LDPE multilayer films used as a greenhouse cover: Natural and artificial aging impacts

Abstract

This article focuses on the assessment and understanding of the mechanism of natural and artificial aging processes of a triple‐layer film made of low‐density polyethylene (LDPE) used as greenhouse cover. The film material contains color dye and ultraviolet–A (UV–A) and infrared (IR) stabilizers and antioxidant. The combined effect of temperature variations and UV–A radiations, of the natural and artificial aging, on the physical properties (free surface energy and yellow color measurements), mechanical behavior (tensile tests), thermal stability (TGA and DSC analysis), and structural stability (FTIR analysis) was investigated. The natural aging was conducted on a greenhouse, located in northern Algeria, over a period of 7 months. However, the artificial aging was performed at four different agricultural greenhouse simulating conditions of temperature and UV–A radiation (namely, at 40°C, 40°C with UV–A, 50°C, and 50°C with UV–A) for periods of aging up to 5486 h (7.6 months). The results revealed that, the maximum loss of the yellow color additives occurs at 2981 h under the natural aging process and at 2440, 1096, 1340, and 121 h under the four artificial aging conditions, respectively. There was an observed increase in the films free surface energy and a significant degradation in the mechanical properties with aging time. This can be correlated with the film material structural changes. The natural aging of the film in North Africa is almost equivalent to artificial aging at 40°C. The concurrent effect of temperature and UV–A radiations induced polymer chains scission leading to faster degradation in the film material and consequently a reduction in its durability and service lifetime. The results show also that the measured parameters are directly related to the limit of use criterion for evaluating the lifespan of agricultural greenhouse LDPE covers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Investigation of the changes in physical properties of PES/PVC fabrics after aging

“…The maximum strain is sensitive to large temperature jumps. Researchers have measured that the maximum elongation at break (%) decreased when the aging temperature was increased. As we can see from Figure (a,b), PVC‐coated polyester fabric had increased breaking strength, and the elongation at break decreased, as the effect of aging increased stiffness.…”

“…The process of artificial aging was simulated based on standards LST EN 1297:2003, LST EN 1296:2004, and ISO 9142:2003, experimentation of other researchers, and geographic location. Geographic, latitudinal, and other atmospheric variations will contribute to variability of natural sunlight.…”

Aging and Degradation of Printed Materials

“…Sometimes, wettability measurements of the aged material are also used consisting mainly of the measurement of surface free energy, which describes unbalanced intermolecular forces (Dehbi et al, 2012;Rabek, 1995). Decreasing the value of these parameters means the formation of chemical crosslinks and decrease in the free volumes.…”

“…Both uniaxial and biaxial orientation have the impact on degradation due to the changes in polymer morphology which influence the rate of oxidation (Rabek, 1996). The light has a negative effect on the mechanical properties of the LDPE film and also causes a color change in the material (Dehbi et al, 2012). The light has a negative effect on the mechanical properties of the LDPE film and also causes a color change in the material (Dehbi et al, 2012).…”

Consequences of stratospheric ozone depletion and climate change on the use of materials

“…Dependence of solar UV radiation damage to greenhouse films on the dose of solar UV-B radiation is of interest in developing lifetime assessments. Dehbi and colleagues 77,78 reported a U-shaped (nonlinear) dependence of yellow discoloration with duration of exposure for LDPE greenhouse films, in both natural and accelerated weathering. However, this form of dose-response behaviour is unexpected and atypical and is likely an artifact of the layered structure of the film.…”