The Molecular Classification Of Pe And The Odor Effect Study Of Oxidation Of Different Molecular Weight Polyethylene

Polyethylene has more and more applications, it has been widely used in drinking water buckets, and milk bottles, bottle caps and other food and beverage packaging. With the increasingly fierce market competition, the downstream manufacturers of drinking water pay more attention to the odor of packaging materials. At present, China’s "food packaging polyethylene resin analysis of hygienic standard"(GB / T5009.58-2003) specifies the sampling method, loss on drying, residue on ignition methodological standards and n-hexane extracts, but the odor of polyethylene is not been specified. However, the evaluation of the odor is mainly depended on artificially taste at a certain temperature, environmental conditions and time. Because evaluators and the environment are different, the evaluation results are different,and probably may cause disputes.In this paper, it has established a method of drinking water odor evaluation, The method is to analyze the organic matter in water by using solid phase micro-extraction combined with GC-MS analysis. In this paper, the extraction conditions were analyzed, it turned out that the detection limit can reach 1 μg/m L. Compared with other method, the method is simple, short time-consuming, and can be used for most analysis of organic matter. Analysis of water samples before and after polyethylene bottles can be seen that the organic matter comes from the water bottles, organic compounds can migrate to the water from the bottle packaging. The results showed that the type of volatile organic compounds in water is mainly hydrocarbons, carbonyl compounds, alcohols, benzene, etc.The odor o f drinking water mainly comes from bottle packaging, so the studies of polyethylene body will be very important. The researchers at home and abroad agree that the organic matter is mainly caused by the oxidation of low molecular weight polyethylene and the se organic compounds can migrate from bottle packaging to the water. But for how much of molecular weight polyethylene can oxidize during processing, less domestic and foreign have researched. This paper has established a method of molecular weight fractionation of polyethylene, the polyethylene classified into different molecular weight polyethylene, and then under processing conditions, different weight polyethylene has been studied. And then the analysis of its oxidation at 200 ℃, determine how much molecular weight polyethylene can be oxidized in processing conditions, which is the innovation of this article.This paper established a method for classification of molecular weight polyethylene. And, the polyethylene has been successfully classified into 6 kinds of different molecular weight polyethylene, and its molecular weight is determined by GPC. The molecular weight of the test results is 7793, 5176,3022,1702,1249,650. In the oxidization analysis of the different molecular weight polyethylene, it can be seen 1702,1249,650 these three kinds of molecular weight polyethylene can oxide at the processing temperature of 200 ℃, which can generate some carbonyl compounds analyzed by GC-MS and the infrared spectrum analysis. And, 7793,5176,3022 these three kinds of molecular weight polyethylene cannot oxide at 200 ℃. Eventually, the molecular weight of polyethylene that can be oxidized is under 1700,and the molecular weight of polyethylene that can not be oxidized is above 3000. Therefore, drinking water bottles should contain as little as possible with the polyethylene that under 1700 molecular weight, so as not to affect water quality.