Studies Report
GLOBAL PLASTIC SA DE CV
Thermal aging and UV Polyethylene Film with additive Oxodegradable.
Responsible: Dr. Roberto Cantu Benavides
Participants: TLQ M. Concepción González Cantú
Saltillo Coahuila,
Background
The Global Plastic Company Inc. CIQA requested a proposal to study the stability behavior of the atmosphere of a film of low density polyethylene containing an additive which promotes the degradability of the resin;
The CIQA prepared the proposal considering the interests of the company, which involved a project that sought to evaluate the thermal and UV degradation polyethylene film and accelerated environmental conditions, evaluating the presence of oxidative stress resistance and to obtain a correlation of these properties and be able to predict the life of the film. This involved 4 stages: thermal degradation, UV degradation accelerated environmental degradation and environmental correlations-accelerated. The company developed the first two stages, which were developed using the following experimental work.
Experimental Methodology
a) .- .- Thermal degradation of film pieces were cut, with and without the additive, which were placed in an oven with air circulation TMI brand at a temperature of 60 ± 2 ° C for a period of time of 90 days. Samples were taken every 10 days to assess the target 9 points. Photographs were taken of the aged samples, both thermal and photochemically.
b) .- Accelerated UV Degradation .- The UV light treatment was performed in a chamber of artificial accelerated weathering QUV Q-Panel, following the ASTM D-4329. For the present study, UVA-340 nm lamps, with cycles of UV / Condensation of 8 / 4 hrs at 60/50 ° C, for 42 days. Samples were taken every 7 days for a total of six points over the target.
c) .- Evaluation .- mechanically treated samples, in oven or under UV light were assessed on his property in tensile strength and elongation. The monitoring of the property was performed on a universal Instron machine model 4301, according to ASTM D-882 with a test speed of 20 in. / min and separation of jaws 1 in. Each point of evaluation consisted of 6 samples and the result is the average of the six evaluations.
d) .- Infrared Spectroscopy (FTIR) .- The determination of oxidation of the samples was performed in a spectrophotometer Fourier transform infrared Nicolet model Magna 550 mark, with 25 scans at a resolution of 4 cm-1. Rates were calculated by measuring the height of carbonyl band of oxidation at 1714 cm-1 with respect to a stable band at 728 cm-1.
Results and Discussion
Figure 1 shows the results of stress tests to rupture obtained for the thermally aged samples.
Figure 1 .- Tension at break for films thermally aged
He noted that the sample without the additive (white) has a fluctuating values with perhaps a small sequential decline of the property during the time interval evaluated, while the additive polyethylene remains stable at the beginning and suffers a sudden drop at 14 days of thermal aging, so that at 48 days of treatment was no longer possible to continue the assessment of property for failure to maintain equipment in the sample.
On the other hand, the maximum elongation obtained for these same samples thermally aged in Figure 2. The property loss is more noticeable than the breakdown voltage, since the sample containing the additive has a total loss of this property within 42 days of heat treatment and the target has no apparent changes, fluctuating only results .
Figure 2 .- Maximum Elongation movies thermal aging.
These same samples were evaluated on their level of oxidation, Figure 3 shows the carbonyl indices thermally aged films, which shows that the sample without the additive or blank sample, in a barely perceptible increase their level of oxidation in 90 days of heat treatment, while the sample containing the additive Oxodegradable within 14 days of thermal aging begins his untimely increase in the level of oxidized compounds in the film, reaching very high levels as far as the 48 days where it was decided and no problems continue to manipulate evaluation samples.
Figure 3 .- Index carbonyls (1725 / 728 cm-1) for thermally aged films
On the other hand, the same films were aged in a QUV accelerated aging chamber with ultraviolet light. Figure 4 shows the results of stress at break of the samples treated under this condition, which shows that UV light has a significant effect in both films, although it is clear that the sample without additive (white) needs 12 days treatment to reduce their property in half, while adding the additive requires less than 6 days for a similar fall.
Figure 4 .- Tension at break of films with UV light aging
In the same test was assessed the maximum deformation obtained in these films and Figure 5 shows the values throughout the treatment applied. There is a stability property for the first 4 days for the blank sample, and then fall to 14 days sequentially evaluated. On the other hand, the sample containing the additive Addiflex begins to lose its property to elongate since starting treatment with ultraviolet light, supporting only 7 days to lose it completely.
Figure 5 .- The maximum elongation for films with UV light aging
These same samples were also evaluated on their level of oxidation during ultraviolet light treatment, Figure 6 shows the trends we observed for the blank and the sample with the additive Oxodegradable. It notes that while the sample blank (no additive) in a sequential increase its oxidation level with respect to time of treatment, the sample with the additive is stable for three days of treatment after an increase unexpectedly values, obtaining the top in just 9 days. The behavior is almost the same as observed during heat treatment, with only differences in the time supported by the material in both environments (heat and UV light).
Figure 6 .- Index carbonyls (1725 / 728 cm-1) for films with UV light aging
Samples were also checked with the naked eye to evaluate the consistency and color during treatment in all cases when the mechanical property was evaluated more than half of the initial material was very difficult to handle, that fell apart in their hands. With regard to color, no noticeable changes were observed, as can be seen in Figures 7-10.
Figure 7 .- Thermal Aging film without additive
Figure 8 .- Thermal Aging Oxodegradable additive film.
Figure 9 .- UV aging film without additive
Figure 10 .- Aging UV additive Oxodegradable movie.
Conclusions
The sample of polyethylene film containing the additive Oxodegradable, thermal and photochemically treated with UV light initiates the process of loss of mechanical properties at very short time, with respect to film sample without the additive: The same applies to the content of oxidation of the films, evaluated the rate of carbonyls by FTIR. On the other hand, the coloring material is not very visible during the evaluation period in this work.
A tempting
Dr. Robert Cantu Benavides
Transformation Processes
Note: This report relates solely to the material samples provided by Global Plastic. SA DE CV