Papers by Keyword: Branching

Abstract: This research aimed to recycle polyethylene terephthalate (rPET) from drinking water bottles using a commercial multi-functional chain extender (Joncryl®ADR4468) with low content, to improve the properties of low molecular weight recycled PET, giving it a long chain with branching structure. The effects of the chain extender on the structural change, viscosity, thermal properties and thermal stability of modified recycled PET (modified-rPET) were studied by using Fourier transform infrared (FTIR) spectrometer, a rotational rheometer, a differential scanning calorimeter (DSC) and thermogravimetric analysis technique (TGA). The results indicate that the chain extender can increase the molecular weight and modify the structure of rPET to a long chain with branching structure and improve the viscosity. Furthermore, the thermal properties and thermal stability analysis from this research could be great evidence to support the assumption that the use of low dose of Joncryl®ARD4468 could turn the molecular structure of rPET into long chain with branching structure, without gel, perfectly.

Abstract: 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.

Abstract: This paper presents a Cohesive Zone Model (CZM) approach for investigating dy- namic failure processes in homogeneous and Functionally Graded Materials (FGMs). The failure criterion is incorporated in the CZM using both a ßnite cohesive strength and work to fracture in the material description. A novel CZM for FGMs is explored and incorporated into a ßnite element framework. The material gradation is approximated at the element level using a graded element formulation. A numerical example is provided to demonstrate the eácacy of the CZM approach, in which the inàuence of the material gradation on the crack branching pattern is studied.