Polyolefin degradation
Sara Zarei; Gholam-Reza Nejabat; Mohammad-Mahdi Mortazavi; Soheyl KhajehPour-Tadavani
Abstract
Varying amounts of an amorphous poly(1-hexene) (PH, Mv 1.7×106 Da) were added to an LLDPE matrix containing 3% w/w Addiflex oxo-biodegradable additive (HES-W) and extruded and converted into films. Then the effect of presence of PH was investigated on microstructure, thermal and tensile behavior ...
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Varying amounts of an amorphous poly(1-hexene) (PH, Mv 1.7×106 Da) were added to an LLDPE matrix containing 3% w/w Addiflex oxo-biodegradable additive (HES-W) and extruded and converted into films. Then the effect of presence of PH was investigated on microstructure, thermal and tensile behavior of polymer films before and after 6 weeks of ultra violet irradiation (UVR). Due to UVR, viscosity average molecular weight (Mv) of the sample without PH decreased from 9.6×104 to 4.6×103 Da and for the sample containing 3% w/w PH from 11.3×104 to 3.0×104 Da, also carbonyl index (CI) of the sample without PH increased from 0 to 28.7 while for the sample containing 3% w/w PH increased from 1.8 to 30.4. Moreover, differential scanning calorimetry (DSC) showed that crystallinity of the sample without PH increased from 34.4% to 36.9% and from 28.7% to 32.1% for the sample containing 3% w/w PH. Thermal gravimetric analysis (TGA) showed lower decomposition temperature for the samples containing PH. The elongation-at-break decreased from 723.0% to 88% for the sample without PH and from 410% to 10% for the sample containing PH. Atomic force microscopy (AFM) indicated smoother surfaces for samples containing 3% w/w PH before and after UVR. Although, the aforementioned results showed that the presence of limited amounts of PH in the LLDPE matrix deteriorated thermal and mechanical properties of the matrix, it hindered the oxo-biodegradablity of the matrix by opposing assimilation process perhaps due to high Mv and/or gelation.
Polyolefin degradation
Soheyl Khajehpour-Tadavani; Gholam-Reza Nejabat; Mohammad-Mahdi Mortazavi
Abstract
Crystallinities of high-density polyethylene (HDPE) films containing various amounts of an oxo-biodegradable additive (HES-W) were investigated immediately after preparation and 6 weeks after ultraviolet (UV) irradiation (λ=254 nm). HDPE granules were mixed with oxo-biodegradable masterbatch in ...
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Crystallinities of high-density polyethylene (HDPE) films containing various amounts of an oxo-biodegradable additive (HES-W) were investigated immediately after preparation and 6 weeks after ultraviolet (UV) irradiation (λ=254 nm). HDPE granules were mixed with oxo-biodegradable masterbatch in a twin-screw extruder and the extrudates were converted into films with thicknesses of 35±5 micrometers. The films were exposed to UV light for 6 weeks. Crystallinities of the films are investigated by X-ray diffraction spectroscopy (XRD) and differential scanning calorimetry (DSC). The XRD results show that upon UV exposure, the crystallinities of the films enhance. The DSC thermograms have confirmed the XRD results and also show a decrease in melting points of the samples after UV exposure. Further investigations on viscosity average molecular weights (Mv) of the samples show that their Mv decrease sharply after UV exposure. Scanning electron microscopy (SEM) shows clear cracks on the samples surfaces after 6 weeks exposure to UV irradiation. Investigating the functionalities of the polymers through Fourier transform infrared spectroscopy (FTIR) show the emergence of carbonyl peaks after UV irradiation so that the carbonyl index of the samples increases. It is concluded that maximum oxo-biodegradation enhancement of the HDPE film samples can be achieved by using a specific amount of the oxo-compound (3 wt%); furthermore the crystallinities of the samples show considerable enhancement after UV exposure which can be due to better packing ability of low molecular weight chains along with probable dipole-dipole attractions between the carbonyl groups on different newly formed short polar chains.
