Improving the Compatibility of Biodegradable Poly (Lactic Acid) Toughening with Thermoplastic Polyurethane (TPU) and Compatibilized Meltblown Nonwoven

Poly (Lactic Acid) (PLA) is a biodegradable polymer which originates from natural resources such as corn and starch, offering excellent strength, biodegradability, nevertheless its inherent brittleness and low impact resistance properties have limited its application. On the other hand, Thermoplastic Polyurethane (TPU) has high toughness, durability and flexibility, which is one of the most potential alternatives for enhancing the flexibility and mechanical strength of Poly (Lactic Acid) (PLA) by blending it with a compatibilizer. With the aim to improve the mechanical and thermal properties of Poly (Lactic Acid) (PLA) meltblown nonwovens, The Thermoplastic Polyurethane (TPU) was melt blended with Poly (Lactic Acid) (PLA) at the different corresponding proportions for toughening the Poly (Lactic Acid) and the corresponding PLA/TPU MBs (meltblown nonwovens) were also manufactured. Joncryl ADR 4400 is mixed into the PLA matrix during processing. It was found that Joncryl had a much higher chain extension that substantially increased the molecular weight of the PLA matrix. SEM study revealed that Joncryl ADR 4400 is a good compatibilizer. Moreover, in this study, the crystallization, thermal and rheological behaviors of the corresponding PLA and TPU blends were also investigated. PLA/TPU MBs were also characterized by morphology and mechanical properties. The rheological property of the PLA/TPU meltblown nonwoven revealed that the viscosity is increasing as the amount of TPU is increasing in the blend, PLA/TPU meltblown nonwovens exhibited excellent mechanical properties;they are soft, elastic, and have certain tensile strength. New materials have potential applications in the medical and agricultural fields. Joncryl ADR 4400 compatibilized blends showed higher strength than simple PLA/TPU blends at the same PLA/TPU ratio.

热塑性聚氨酯增韧聚乳酸及其熔喷非织造材料研究

聚乳酸(PLA)生物可降解熔喷非织造材料因其超细纤维结构和环境友好性而体现出有力的市场竞争力,但PLA由于其本身力学韧性不足,限制了拓展应用。文章以高流动性热塑性聚氨酯(TPU)为PLA的增韧材料,采用熔融共混法制备熔喷非织造用PLA/TPU复合母粒,对其相结构形态、热-结晶性能、热稳定性和晶型结构变化进行研究,进一步制备了PLA/TPU熔喷非织造材料。结果表明:PLA与TPU为不相容体系,TPU对PLA的结晶过程和晶型结构几乎无影响,但使PLA的热稳定性有所下降。TPU共混质量比在20%以内,PLA/TPU的熔喷加工性较佳,PLA/TPU熔喷非织造材料相比单一PLA熔喷材料体现出更好的强度和拉伸延展性。

Effect of Sintering Temperature on Structural and Magnetic Properties of Ni_0.55Zn_0.45Fe₂O₄Ferrites

The effect of frequency and sintering temperature on initial permeability of Ni0.55Zn0.45Fe2O4 ferrites have been studied by using an impedance analyzer. The samples were prepared by conventional double sintering ceramic technique using oxide nanoparticles of grain size 30 - 50 nm. Single phase spinal structure has been confirmed for the prepared samples by X-ray diffraction. As the sintering temperatures increase from 1160℃ to 1300℃, the permeability gradually increases. The increase of permeability is ascribed to the increase of density and grain size. Grain size is expected to grow with the increase of sintering temperature. Ferrites with large average grain size posses higher initial permeability. The Curie temperatures determined from temperature dependence of permeability of the samples sintered at different temperatures are found to be Tc = (321 ± 1)℃ and independent of sintering temperature. At Ts = 1300℃, Tc is found to increase substantially which can be explained by the fact that Zn has evaporated from the surface layer.