Designing biobased hyperbranched polyesters from vegetable oil has been attracting considerable interests from academic industrial communities.Herein, a novel fully biobased hyperbranched polyester (HBPE) was prepared by self-condensation of AB 2 -type bioderived monomer based on methyl ricinoleate (MR), a castor oil-derived renewable chemical. The reaction conditions were optimized to obtain the AB 2 -type monomer in a high conversion ratio (up to 87%). The self-condensation of AB 2 -type monomers was carried out in the presence of two kinds of transesterification catalysts (Ti(OBu) 4 versus Zn(Ac) 2 ), among which Ti(OBu) 4 was found to be more efficient one and yield higher molecular weights in the range of 5800$11,500 g/mol. The resulting HBPEs were characterized in terms of Fourier transform infrared spectroscopy, nuclear magnetic resonance, differential scanning calorimetry, and thermogravimetric analysis. The degree of branching was calculated to be 0.33$0.39.Thermal analysis revealed that the as-prepared HBPEs were amorphous with tunable glass transition temperatures ranging from À44.8 to À24.6 C. All the prepared HBPEs exhibited good thermal stability with the maximum onset decomposition temperature (T onset ) up to 294.6 C. These structural features and properties of resulting biobased HBPEs enabled them to act as a potential 'greener' additive for polymers.biodegradable, biopolymers and renewable polymers, polyesters, thermoplastics Pengjia Shan and Hengyu Lu contributed equally to this work.

To describe uncured rubber melt flow, a modified Phan–Thien–Tanner (PTT) model was proposed to characterize the rheological behavior and a viscoelastic one-dimensional flow theory was established in terms of incompressible fluid. The corresponding numerical method was constructed to determine the solution. Rotational rheological experiments were conducted to validate the proposed model. The influence of the parameters in the constitutive model was investigated by comparing the calculated and experimental viscosity to determine the most suitable parameters. The uncured rubber viscosity was 3–4 orders larger than that of plastic and did not have a visible Newtonian region. Compared with the Cross-Williams-Landel-Ferry (Cross-WLF) and original PTT models, the modified PTT model can describe the rheological characteristics in the entire shear-rate region if the parameters are set correctly.