The Characterization Of Ultra High Molecular Weight Polyethylene And The Researches On Strutural Change Of The Raw Materials During The Production Of UHMWPE Fiber

The raw materials for Ultra high molecular weight polyethylene fiber of dry spinning play a key role in the properties of fiber. But, at present only the second chemical additive plant in Beijing and Shanghai Research institute of Chemical industry can provide materials for UHMWPE fiber.The characterization methods and system of special material for UHMWPE fiber has not been set up and unified interiorly. Based on the current situation, the special materials for high-performance UHMWPE fiber by dry spinning were researched in this thesis.In order to meet the needs of the manufacture of high-performance UHMWPE fiber by dry spinning, finding the methods to characterize UHMWPE, then establishing the trusted system of characterization of UHMWPE fiber.The particle size distribution of raw materials was measured by analysis of microscope graphics software statistical. High temperature gel permeation chromatography is not suitable for molecular weight determination of UHMWPE, and the molecular weight distribution index can be used as approximate relative references. D 4020-01a standard was chose for basic methods. Uriah type viscometer method was employed to determine the viscosity molecular weight, which manifested there is a significant positive correlation between the particle size of raw materials and the viscosity molecular weight.The larger particles size, the higher viscosity molecular weight.The difference viscosity molecular weight vaule between the large and the small particle size of raw materials can reach 0.56 million. The pretreated swelling and high temperature dissolving were used to measure the molecular weight of different UHMWPE fiber.The molecular weight of UHMWPE fiber made by us and Dyneema (?) SK75 are all about 200 million. The infrared spectrometry based on the data processing of NMR was used to determine the degree of branching (CH3/1000C) which can be used as a relative simple method to characterize the degree of branching of UHMWPE raw materials. Melting and swelling DSC is the comprehensive reflection of the structural feature of UHMWPE, which can be used as the characterization methods to monitor the raw material and the basis for determination of swelling and dissolution. Raw material particle size distribution should also be the basis for the determination of swelling process.