In this research, the influences of adding talc mineral particles of 10 μm particle size on the shrinkage and the mechanical properties of injection molded polypropylene (PP)/talc composites were investigated. PP has a crystalline molecular structure and hence it possesses nonisotropic shrinkage along and across the flow directions. Addition of the talc mineral filler to PP induced an isotropic shrinkage in the molded part because of the nonisotropic shape of talc particles. The results of experiments indicated that the maximum flexural strength, maximum impact strength, and isotropic shrinkage were achieved by adding 10, 20, and 30 by weight percent of talc respectively. By incorporating of 10 wt% of talc particles into the PP matrix, the tensile strength was hardly affected but the occurrence of cold drawing phenomena in the tensile test was hindered considerably. The flake‐shape structure of talc filler played an important role in determining the molded part shrinkage and mechanical properties. POLYM. ENG. SCI., 47:2124–2128, 2007. © 2007 Society of Plastics Engineers

This research studies the properties of poly (butylene terephthalate) (PBT)-based systems toughened with thermoplastic polyurethane (TPU; 10, 20, and 30 wt%) and reinforced with multiwalled carbon nanotubes (CNTs; 0.1, 0.2, and 0.3 wt%). Different compositions prepared via melt mixing. Morphology studies showed good compatibility between the two polymeric phases in PBT/TPU. The addition of TPU to PBT reduced crystallization rate and melt temperature, while inclusion of CNTs had nucleation effect and increased the degree of crystallinity, crystallization, and melt temperatures. The existence of TPU in PBT caused significant enhancement in notch-impact resistant. The inclusion of CNTs to PBT/TPU blend led to the substantial improvements in tensile and flexural strengths and moduli. Dynamic mechanical thermal analysis revealed that the incorporation of CNTs into PBT/TPU enhanced storage modulus and heightened glass transition temperature. The storage modulus of PBT/TPU/CNT nanocomposite containing 0.5 wt% CNT was comparable with that of pure PBT particularly at high temperatures.

Poly(butylene terephthalate) (PBT) nanocomposites reinforced with different weight fractions of montmorillonite (MMT), and nanoprecipitated calcium carbonate (NPCC) were prepared by a two‐step melt compounding method. X‐ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses were employed to explore the effect of nanofiller inclusion on the crystalline structure of PBT nanocomposites. The mobile amorphous fraction (MAF) and the rigid amorphous fraction (RAF) were first measured using the specific heat capacity (Cp) and melting enthalpy data. However, the contributors to total RAF, including interfacial RAF (RAFint) and crystalline RAF (RAFc), could not be discerned using only DSC. A novel and simple method was hence developed by employing a combined DSC‐dynamic mechanical thermal analysis (DMTA) approach (CDDA) to disentangle the RAF components and determine the fractions of constrained volume constituents. To validate the results, the MAF calculated by CDDA were compared to those of DSC. The values obtained using CDDA were relatively higher, owing to the more significant sensitivity of this approach to polymer chain mobility.

No abstract

The condition of the interfacial area and interphase region in a nanocomposite can significantly affect its mechanical performance. In this research, the tensile performance of a POM/CaCO3 nanocomposite, including the modulus of elasticity and tensile strength, are analysed using different mathematical models and the Ansys FEM software. The mechanisms of the plastic deformation and crazing of the POM/CaCO3 nanocomposite were investigated using FEM. Furthermore, the effects of interface adhesion and the interphase property on interfacial debonding, as well as tensile properties, were analysed. The tensile strength of the nanocomposite could not be greater than that of bulk POM because of the failure which was initiated from the matrix. By stiffening the interphase and increasing the adhesion between nanoparticle and polymer, the nanocomposite's elastic modulus and strength were increased. Two toughening mechanisms, including plastic deformation and crack initiation, were observed in the POM/CaCO3 nanocomposite. The high interfacial adhesion of the matrix to the particles led to the formation and propagation of crazes along the extension load in the POM matrix. The tensile strengths of different nanocomposites were over-predicted by the Pukanszky model, while the moduli magnitudes estimated by the Ji mathematical model were less when compared to those determined by FEM.