Study On Characteristic Of Degradation Of Polyethylene Blending With Ethers

In this paper, the characteristic of degradation of low-density polyethylene(LDPE) and its blend with the ethers (PEG400, sorbitol ether or glycerol ether)under the environment either the UV irradiation or low temperaturethermo-oxidation have been studied respectively. The contents of the gel and thecarboxyl group, the carbonyl index and samples morphology have beeninvestigated. Some results have been found as follows:1. The results of the photo-oxidation degradation experiment showed that thedegree cross-linking of LDPE increased in initial with the increasing of ether,but after irradiation 60 days, the degree of degradation of LDPE increasing wasnot proportional with the increasing of the ether. The effect of degradation wasbest as the ether's content is 1%, which the intrinsic viscosity of its LDPEdecreased from 67.57, 67.46, 68.02Pa·s to 34.89, 23.49, 28.62Pa·s, respectively.In the low temperature thermo-oxidation experiments it can be found that thedegree of LDPE didn't increased proportionably with the increasing of ether. Asthe ether's content is 0.5%, the effect of degradation was best, which after beingheated 60 days, the intrinsic viscosity of its LDPE decreased from 67.38,67.59, 67.66Pa·s to 35.47, 27.47, 22.14 Pa·s, respectively.2. Prolonged UV irradiation time, the intrinsic viscosity of LDPE and the content of gel increased firstly, and then decreased gradually, but the content ofcarboxyl increased gradually. After irradiation 60 days and blending with 1%PEG400, sorbitol ether and glycerol ether, respectively, the intrinsic viscosity ofthe LDPE decreased from 67.57, 67.46, 68.02Pa·s to 34.89, 23.49,28.62Pa·s,respectively, the gelatin content was 5.84%, 0.92%, 2.44%, the carboxyl groupcontent was 1.29%, 1.10%, 0.96%, and the carbonyl index was 1.45, 5.08, 4.45,respectively at that time. Some holes were observed in the surface of samplesafter photo-oxidation degradation with the scanning electron microscopy (SEM).3. Prolonged heated time, the intrinsic viscosity of LDPE blended with differentethers increased firstly, and then decreased gradually, but the content ofcarboxyl increased gradually. After being heated 60 days, with 0.5% differentethers, the intrinsic viscosity of its LDPE decreased from 67.38, 67.59,67.66Pa·s to 35.47, 27.47, 22.14Pa·s, respectively, the carboxyl group contentreached 0.92%, 1.45%, 1.24%, and the carbonyl index reached 1.72, 2.31, 2.47,respectively. With the SEM, it can be seen some holes at the surface of samplesafter low temperature thermo-oxidation degradation.4. The influence of different ethers (PEG400, sorbitol ether and glycerol ether)on characteristic of the LDPE degradation under the condition either the UVirradiation or the low temperature thermo-oxidation has been studied. Under UVirradiation, compare with other two ethers, the sorbitol ether has the bestdegradation accelerating effect on the LDPE. After irradiation 60 days, theintrinsic viscosity of the LDPE blended with 1% sorbitol ether decreased from 67.46Pa·s to 23.49Pa·s, the gelatin content and the carboxyl group contentreached 0.92%, 1.10%, respectively. In the low temperature thermo-oxidationdegradation experiments, the glycerol ether has the best degradation acceleratingeffect on the LDPE. As the content of glycerol ether is 0.5%, the intrinsicviscosity of its LDPE decreased from 67.66 Pa·s to 22.14Pa·s, the carboxylgroup content reached 1.24%.