| As the rapid development of science technology and society, the update rate of electronicproducts accelerated, leading to a huge amount of electronic waste. Printed circuit boards areessential compoments to all kinds of electronic products and causing a severe environmentalcontanmination. Most of the attention of current study was paid on the recycle of metalelements contained in the wasted printed circuit boards, while, as for the wasted printedcircuit boards basement (WPCBB) of high value, the cineration and filling treatments werethe common method, which resulted in a serious waste of resource and gread danger to theenvironment.In this paper, firstly, the ingrediants and morphology of wasted printed circuit boardsbasement (WPCBB) were studied. Then the PP/WPCBB composites were prepared bymelting blending, with WPCBB after surface treated as reinforcing material and PP as thematrix resin, implementing the high-value reuse of wasted resource as well as reducing theenvironmental pollution.The main studying contents are as follows:1. Characterization of WPCBB’s ingrediants and morphologyWPCBB’s ingrediants and morphology were charactered via infrared spectroscopy(FT-IR), thermogravimetric analysis (TG), muffle sintering and scanning electron microscope(SEM). Results showed that WPCBB is consisted of glass fiber, epoxy resin, phenolic resinand so forth; it coule be acquired that the length of glass fiber was between180～360μm andthe diameter of glass fiber was about7μm, with average draw ratio being40, which meansthat it can be used as reinforcing material for PP.2. Effect of WPCBB contents on the mechanica land dynamic properties of PP/WPCBBcompositesThe mechanical properties of composites first increased the decreased as the addition ofWPCBB increased. Optimum mechanical properties could be achieved when WPCBB contentis20%, with impact strength being4.5KJ/m~2，flexural strength62.47MPa，tensile strength 54.5MPa，increased by70%,50%and30%respectively, compared with pure PP.DMA results showed that, in the measuring temperature range, both the storage modulus(M′) and loss modulus (M″) of composites were greater than that of pure PP. A decliningtendency of M′was observed with the rising temperature. Meanwhile, slight decreasing trendsof both the loss factor tanδ and the glass transition temperature Tg were observed.3. Effect of WPCBB contents on the rheological property of PP/WPCBB compositesThe fall of melting index of compostites as the WPCBB contents was witnessed, whilethe viscosity rose with the increasing WPCBB contents. The composites were stillpseudoplastic fluid. The non-Newtonian index of composites showed a decrease as theWPCBB contents, which was reverse to the relationship between the non-Newtonian index ofcomposites and temperature, meaning deviating from Newtonian fluid more and more. Underthe same shearing stress, the flow activation energy first declined and then rose with theWPCBB. The minimum value of flow activation energy could be seen when the WPCBBcontent was20%. Moreover, the viscosities of composites were more sensitive to the changeof shearing stress rather than the change of temperature.4. Effect of WPCBB contents on the crystallization behaviour of PP/WPCBB compositesThe crystal form transformed from single type, α crystal, to two types, α and βcrystalsand the sphaerocrystal structure were damaged by the addititon of WPCBB. The phenomenonof the Black Cross’s extinction was unconspicuous and the quantity of the sphaerocrystalincreased accompanied with the decrease of size. Furthermore, both the degree and rate ofPP’s crystallization were increased by WPCBB as well as the crystallization startingtemperature, which means that the WPCBB played a role in the heterogeneous nucleationThe kinetics of isothermal and non-isothermal crystallization of PP and PP/WPCBBcomposites could be described by the Avrami equation and Mo method by which the relevantkinetic parameters of composites can also be achieved respectively. |
PDF Full Text Request