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Surface Modification of PP and Its Surface In-situ Initiating Alloying of St under the Action of Low Temperature Plasma

Author: DiJinJiang
Tutor: MaGuiQiu
School: Tianjin University
Course: Materials Science
Keywords: polypropylene polystyrene plasma surface modification in-situ alloy miscibility
CLC: TQ320
Type: Master's thesis
Year: 2009
Downloads: 65
Quote: 2
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Abstract


A new method was investigated to prepare PP/PS in-situ alloy on the basis of low temperature plasma surface modification. A comprehensive understanding of the alloy’s structure has been obtained by means of scanning electron microscopy(SEM), differential scanning calorimeter (DSC), wide-angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS) .Through the calculation of surface contact angle and surface tension , the optimal parameter for Ar plasma surface treatment on PP film was obtained, and after that X-Ray Photoelectron Spectroscopy(XPS) was used to characterize the content of elements and groups on PPP(Plsasma treated PP surface). Further more, the exact species of the groups have been characterized with the help of Fourier Transform Infrared Spectroscopy (FTIR), which are carbonyl groups, carboxyl groups and peroxys groups. Moreover, the content of free radicals on PPP surface was calculated by means of DPPH, the results show that the content of free radicals was firstly determined by discharging voltage.After low temperature plasma surface treatment , active groups (mostly peroxys groups) on PPP can initiate polymerization of vinyl monomers at some certain temperature , and at the same time, free radicals may become the places where graft polymerizations happen. It shows that St monomers polymerize fastly under the synergistic effect of surface initiation and thermal polymerization , and the viscosity-average molecular weight as well as conversion are higher than single thermal polymerization. What’s more , the results showed the grafting ratio of PS on PPP reached up to 4.32%.PPP particles will dissolve in PS after two hours’polymerization , and the reaction products are solid .By mixing different ratio of PP and PS at some certain condition, it-situ alloys were obtained. In this thesis , the pre-polymerization temperature of PPP and St to prepare alloys were set at 100℃and 120℃and later discussions were carried out between these two series.SEM results show that two phases are homogeneously dispersed after mixing , and the test of Tg and Tm0 also indicate that miscibility between PP and PS was improved to some extent . Further more , it was safe to conclude that SAXS is also an effective way to investigate miscibility of blends.

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CLC: > Industrial Technology > Chemical Industry > Synthetic resins and plastics industry > General issues
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