查看更多>>摘要：Poly(butylene adipate-co-terephthalate)(PBAT)is a promising biodegradable flexible polymer but suffers from slow crystallization rate,making it less attractive for some applications like the injection-molded products in comparison with low-density polyethylene(LDPE).This work aimed to accelerate the crystallization of PBAT by adding a self-assembly nucleating agent octamethylenedicarboxylic dibenzoylhydrazide(OMBH).PBAT/OMBH composites with various OMBH contents(0 wt％,0.5 wt％,0.7 wt％,1 wt％,2 wt％,3 wt％and 5 wt％)were prepared through melt-mixing.The effect of OMBH on the crystallization behavior,morphologies and mechanical properties of PBAT was investigated.The highest nucleation efficiency value of 59.6％was achieved for PBAT with 0.7 wt％OMBH,much higher than that of 22.7％for PBAT with 0.7 wt％talc.Atomic force microscopy results showed that OMBH formed fine fibers and induced the formation of transcrystalline layers of PBAT.Fourier trans-form infrared spectroscopy(FTIR)combined with two-dimensional correlation spectra suggested that the intermolecular dipole-dipole N-H…O=C interactions but not hydrogen bond between OMBH and PBAT promoted the crystallization of PBAT in the initial period of crystal-lization.The presence of OMBH did not change the crystal form of PBAT but had positive contribution in enhancing its crystallinity and mechani-cal properties.This work is essential for preparing PBAT with high crystallization rate,enhancing its potential applications in injection-molded products.
查看更多>>摘要：High speed sintering,a new powder-bed fusion additive manufacturing technology,utilizes infrared lights(IR)to intensely heat and melt polymer powders.The presence of defects such as porosity,which is associated with particle coalescence,is highly dependdent on the level of energy input.This study investigate the influcence of energy input on porosity and its subsequent effects on the mechanical properties and mi-crostructures of PEBA parts.The parts were manufactured with a variety of lamp powers,resulting in a range of energy input levels spanning from low to high.Subsequebtly,they underwent testing using Archimedes'method,followed by tensile testing.The porosity,mechanical characteris-tics,and energy input exhibit a strong correlation;inadequate energy input was the primary cause of pore formation.Using the reduced IR light power resulted in the following outcomes:porosity,ultimate tensile strength,and elongation of 1.37％,7.6 MPa,and 194.2％,respectively.When the energy input was further increased,the porosity was reduced to as low as 0.05％and the ultimate tensile strength and elongation were in-creased to their peak values of 233.8％and 9.1 MPa,respectively.
查看更多>>摘要：In unit cell simulations,identification of ordered phases in block copolymers(BCPs)is a tedious and time-consuming task,impeding the advancement of more streamlined and potentially automated research workflows.In this study,we propose a scattering-based automated identification strategy(SAIS)for characterization and identification of ordered phases of BCPs based on their computed scattering patterns.Our approach leverages the scattering theory of perfect crystals to efficiently compute the scattering patterns of periodic morphologies in a unit cell.In the first stage of the SAIS,phases are identified by comparing reflection conditions at a sequence of Miller indices.To confirm or refine the iden-tification results of the first stage,the second stage of the SAIS introduces a tailored residual between the test phase and each of the known can-didate phases.Furthermore,our strategy incorporates a variance-like criterion to distinguish background species,enabling its extension to multi-species BCP systems.It has been demonstrated that our strategy achieves exceptional accuracy and robustness while requiring minimal compu-tational resources.Additionally,the approach allows for real-time expansion and improvement to the candidate phase library,facilitating the de-velopment of automated research workflows for designing specific ordered structures and discovering new ordered phases in BCPs.
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