The Mechanical Properties of Some Polymer Composites Based on Natural Rubber

This paper presents the development and characterization of polymer composites based on natural rubber, crosslinked using two types of vulcanization systems, as follows: the classical method using sulfur and curing accelerators and the method using peroxide in the presence of a polyfunctional monomer - trimethylolpropanetrimethacrylate. The composites were made with 0 parts to 100 parts rubber (phr) and 40 phr filler content. The physical-mechanical characteristics of resulting composites depend on the crosslinking method and on the composition. The mechanical parameters of materials were derived by processing the transmissibility curves, derived for samples with known dimensions and density. The main vibration frequencies and the quality factor, derived in the vicinity of resonances, allow to derive the elasticity and internal damping of materials.

Synthesis and Characterization of Branched Poly(Ethylene Terephthalate)

Linear and branched poly (ethylene terephthalate) were prepared by using terephthalic acid, ethylene glycol as main raw materials and pentaerythritol as polyfunctional monomer through melt polycondensation method. The samples were characterized with respect to intrinsic viscosity and differential scanning calorimeter (DSC). The results show that the low branched poly (ethylene terephthalate) could be obtained by the addition of tertrafunctional pentaerythritol through common melt polycondensation process.

Compatibilization Effect of Polyfunctional Monomers on PP/TPU Blends

This paper mainly researched how polyfunctional monomers affect the Compatibilization of PP/TPU blends. With triallylisocyanurate (TAIC) and trimethylolpropane triacrylate (TMPTA) which belong to polyfunctional monomers as compatibilizers, various PP/TPU blends were prepared via melt mixing by using a twin-screw extruder. It is investigated that the effect of polyfunctional monomer on the mechanical properties, morphology and melt flowing behavior of the blends. The results show that the compatibility of PP/TPU is improved by adding moderate TAIC or TMPTA, and the compatibilization effect of TMPTA is superior to TAIC, especially when the content of monomers is 3 phr.

Encapsulation of Nanometer CaCO3 by Polymer Network

Stearic acid coated nanometer CaCO3 was encapsulated by polystyrene (PS) network via emulsion polymerization, where a polyfunctional monomer trimethyol propane trimethacrylate (TMPTMA) or divinyl benzene (DVB) was used as crosslinker. The feed modes of monomer and initiator are investigated. Batch mode is shown to be more convenient than semi-continuous mode in view of network perfection. With the amount of crosslinkers increased from 1 wt% to 7 wt%, the percentage of unextractable PS is high (not lower than 95%) for all samples in the system of TMPTMA, while this value decreases sharply from 74% to 3% in the system of DVB. The yield in the system of DVB is higher than that of TMPTMA. With increased amount of CaCO3, encapsulation ratio can be varied from 5.2 to 2.6, while the yield and unextractable PS decrease. FT-IR spectra of the products after extraction indicate tight encapsulation between PS and CaCO3, and TEM photographs of composite particles give direct evidence of encapsulation.