No abstract

As plastic pollution becomes more serious, we need to find out eco‐friendly materials to alleviate the pollution. Polylactide (PLA) and poly (butylene adipate‐co‐terephthalate) (PBAT) will be one of the most attractive materials to replace those undegradable materials. However, few studies research the segregated conductive PLA/PBAT/MWCNTs nanocomposites. Herein, PLA/PBAT/MWCNTs nanocomposites with the segregated structure were successfully fabricated firstly. The MWCNTs are selectively dispersed in the continuous PBAT phase. The nanocomposite with segregated structure owns excellent electric conductivity. When the content of MWCNTs is 0.41 vol%, the electrical conductivity of composites with segregated structure is 9.43 × 10−4 S/m, which is about 5 orders higher than the nanocomposites without the segregated structure (1.75 × 10−10 S/m). The segregated nanocomposite with 2 wt% (1.18 vol%) MWCNTs owns excellent electromagnetic interference (EMI) of 24 dB, while the ordinary structure of composite is only 17 dB.

In order to obtain the automatic simulation generation of traditional handmade batik patterns in a computer, this paper proposes the automatic generation method of batik flower patterns based on fractal geometry. Firstly, we analyze the fractal characteristics of batik flowers and design an automatic flower generation algorithm based on a two-dimensional iterated function system (IFS) and a curve function. The algorithm forms a complete flower pattern. Secondly, a nonlinear function is defined and the flower pattern is introduced into the nonlinear function to iterate and change. On this basis, we present an automatic generation method of different distribution patterns for flower patterns which obtains the most effective range of each parameter value for each function. Finally, in order to verify the feasibility of the automatic generation method of batik flower patterns, we develop an automatic generation experiment system for batik patterns via an interactive way of working. The results show that the user or designer can quickly and automatically simulate a series of flower patterns by changing the relevant parameter values, realizing the digitization and innovative design of the pattern and enriching the batik pattern base.

The formation of dense and complete conductive networks in the electromagnetic interference (EMI) shielding composite is the basis for its excellent EMI shielding performance. In this work, biodegradable poly (lactic acid)/poly (butylene succinate)/multi‐walled carbon nanotubes (PLA/PBS/MWCNTs) nanocomposites with segregated structures were successfully prepared via melt blending. Due to the successful preparation of segregated structures and the fact that MWCNTs were mainly dispersed in the PBS phase, an ultralow percolation value of 0.071 vol% was achieved in biodegradable PLA/PBS/MWCNTs nanocomposites. When the MWCNTs content is 0.499 vol%, the electrical conductivity of the PLA/PBS/MWCNTs nanocomposites with segregated structures is around 7.15 × 10−3 S/m, which is about 6 orders of magnitude higher than that of the PLA/PBS/MWCNTs nanocomposites with normal structures. When the MWCNTs content increased to 2.0 wt%, the average EMI shielding effectiveness (SE) of segregated structures remained stable at 27.56 dB, which can effectively block 99.82% of the microwave radiation. Furthermore, as suggested in the EMI shielding analysis, the EMI shielding of PLA/PBS/MWCNTs nanocomposites is mainly through absorption shielding, so there will be no secondary environmental pollution. This study provides a practical and universal method to prepare biodegradable conductive polymer composites with ultralow percolation threshold and excellent EMI SE.

Owing to the thermomechanical degradation and impurities, the high‐value utilization of waste packaging plastics is still a great challenge. In this work, we confirmed that the major sort of impurity in waste polyethylene (PE) packing films is calcium carbonate. Consequently, PE/poly(ethylene‐co‐1‐octene)‐maleic anhydride (rPE/POE‐g‐MAH) and poly(ethylene‐co‐1‐octene) (rPE/POE) composites were recycled using a custom‐made three‐screw extruder, who can supply intensive shear flow during extrusion. The POE‐g‐MAH is detected to be filled between PE and inorganic impurities, and the compatibility is improved through chemical reactions. As mechanical test manifested, the rPE/POE‐g‐MAH blends present higher tensile strength and elongation at break than the rPE/POE blends at the same composition. The reason for such improved toughness of composite was explained in detail through the tensile fracture surface analysis. Rheology test further shows that POE‐g‐MAH improves the compatibility of matrix and impurities. In summary, this article provides a sustainable route for enhancing the poor ductility of recycled express bags in a simple and economical way, which could pave an avenue for high‐value utilization of waste packaging plastics. At the same time, it also provides new solutions for material selection in packaging, construction, agriculture and other fields.

Due to the white pollution, the recycling of waste plastics has attracted more and more attention. In this research, waste polypropylene/Ethylene‐octene elastomer/nano‐SiO2 composites (wPP/POE/SiO2) were melt‐blended using an Eccentric Rotor Extruder (ERE) dominated by elongational flow field and a Torque Rheometer (TR) dominated by shear flow field, respectively. The micromorphology, mechanical, crystallization, thermal and rheological properties of wPP/POE/SiO2 blends were studied. Compared to the blends fabricated by TR, the wPP/POE/SiO2 blends with different compositions fabricated by ERE showed higher tensile strength, flexural strength, and modulus. Particularly, without sacrificing the tensile strength, the notched impact strength of the wPP/POE/SiO2 blends fabricated by ERE increased to 13.53 kJ/m2, a factor of 3 times larger than that of neat wPP. The enhancement of impact strength of the wPP/POE/SiO2 blends fabricated by ERE could be ascribed to the good dispersion of POE under elongational flow and the increase of PP crystallinity. The finding from this work provides an efficient way to recycle wPP.

The rapid development of polymer blends and nanocomposites has put forward new requirements for the mixing performance of extruders. In comparison with shear flow field, extensional flow field has been shown to have unique advantages in improving dispersive mixing performance and reducing energy consumption. However, building an extensional flow field in a conventional single-screw extruder remains challenging. In this work, a new mound-shaped extensional mixing element (M-EME) was designed based on the geometric characteristics of a sine curve. To investigate the effect of this M-EME on the mixing properties of a conventional single-screw extruder, a numerical simulation analysis of this M-EME was performed. The results showed that the proportion of the region with a mixing index greater than 0.55 in the M-EME was higher than 43 %, and that the highest mixing index of the M-EME reached around 0.9, confirming the dominance of the extensional flow field in the M-EME. Moreover, it was observed that the changes in amplitude and period of the sine function have no significant effect on the distribution of the mixing index. The findings from this work provide a viable way to generate extensional flow fields in conventional screw extruders.