Short glass fiber (SGF) reinforced polyamide 6 (PA6) composite is an important thermoplastic engineering plastic with excellent properties such as high toughness, high strength, self-lubrication and corrosion resistance. However, due to the characteristics of difficult to disperse and easy to break of the fibers during processing, the application range of the PA6/SGF composite is limited. An innovative twin-eccentric rotor extruder (TERE), which can generate continuous elongation flow, is applied to fabricate the PA6/SGF composites in different fiber content and rotor speed. The fiber length remains good and the fibers are well dispersed in the polymer matrix so that the residual fibers after burn-off form a network interlock structure. That is, the TERE based on continuous elongational flow not only disperses the glass fibers effectively, but also reduces the fiber breakage. Under the action of elongation flow field, the fiber agglomerates undergo a periodic convergence-divergience effect, which forces the fiber agglomerates to separate from each other and disperse homogeneously in the polymer matrix. Interestingly, the charpy impact strength of the composites prepared by the TERE is about double that prepared by the twin-screw extruder (TSE) at each fiber content, which can be attributed to the more efficient fiber dispersion and longer fiber retention length. The thermal oxygen aging property, fatigue property, and creep property analysis also indicate that the TERE has a better dispersion effect than the TSE, and the fibers retain a longer length in the PA6 matrix, thereby providing more excellent service properties.

Nowadays, the improvement of injection molding technology development research is in great demand due to the limitation of convenient injection molding for structural engineering applications. For injection-molded products, oriented structure is ubiquitous. To promote the formation of oriented structure, exert a positive impact on the final mechanical properties of polymer products, an advanced injection molding process is used to achieve multiple shear melt in this work. Based on our previous work about melt multi-injection molding technology, to investigate the influence about oriented structure of composites attracted by higher shear stress, iPP/MWCNTs and iPP/β-NA composites were studied. Compared to traditional injection-molded samples, the addition of MWCNTs impede the formation of oriented structure. For iPP/β-NA composites, the higher flow shear stress inside the mold wall increase the overall crystallinity but restrain the growth of β-crystal.

In recent years, researchers are paying more attention to high efficiency, high process stability and eco-friendly nanofiber fabrication techniques. Among all of the nanofiber fabrication methods, electrospinning including solution electrospinning and melt electrospinning is the most promising method for nanofiber mass production. Compared to solution electrospinning, melt electrospinning could be applied in many areas such as tissue engineering and wound dressings due to the absence of any toxic solvent involvement. Capillary melt electrospinning generates only one jet with low efficiency. Hence, we have proposed polymer melt differential electrospinning (PMDES) method, which could produce multiple jets with smallest interjet distance of 1.1 mm from an umbrella shape spinneret, thus improving the production efficiency significantly. Many techniques such as material modification, suction wind, and multistage electric field were proposed to refine the fibers and nanofibers with average diameter of about 300 nm were obtained. Scale up production line of PMDES with capacity of 300–600 g/h was established by arraying umbrella shape spinnerets. PMDES is a promising technology to meet the requirements of nanofiber production in commercialization.

Compared with the traditional three-platen injection molding machine, the two-platen injection molding machine has many potential advantages such as space and material saving, uniform clamping force, etc. Internal circulation clamping system is the key to realize energy-saving and high speed clamping for small and medium types of two-platen injection molding machines. This paper presented an internal circulation clamping system with supplementary volume. Compared with the other internal circulation clamping systems, the new system with supplementary volume could not only confirm the uniform tension force on tie bars for dramatic increase of service life but also improve energy-saving. In order to estimate the properties of the new system, the models of two different hydraulic clamping systems were established by using AMESim. The displacement of the moving platen, the pressure of the clamping cylinder, and the energy consumption of the hydraulic clamping system were all calculated and analyzed.

Composites based on poly (trimethylene terephthalate) (PTT)/acrylonitrile butadiene styrene (ABS) blend with maleic anhydride grafted PTT (PTT-g-MA) as a compatibilizer and carbon nanotubes (CNTs) as reinforcers were prepared via melt-mixing, and the mechanical, electrical, and barrier properties of the as-fabricated composites were evaluated. Scanning electron microscopy (SEM) characterization of the cross-section of the composites after tensile test showed improved phase stability in the presence of the compatibilizer PTT-g-MA. The toughness of the composites was also improved with the addition of the compatibilizer and CNTs. Electrical conductivity tests were carried out and the results showed that CNT-reinforced composite exhibited significantly increased conductivity. Since barrier properties are very sensitive to structural changes, the oxygen transmission rate (OTR) of the composites was measured and the results showed that the composites possess a much high oxygen barrier compared to that of the neat PTT or ABS.

In this study, we prepare series of low-density polyethylene (LDPE)/recycled polyethylene terephthalate (RPET) blends using melt extrusion. The effects of RPET content on the crystallization behavior and thermal conductive properties of the resultant blends were investigated using DSC, XRD, DMTA, TGA, etc. RPET was found to exert nucleating effect on the melt crystallization of LDPE without changing LDPE's crystal form. A four-parameter model (FPM) was adopted coupled with an in-situ temperature measurement to further disclose the solidification kinetics of LDPE in the presence of RPET. Among three thermal conduction models, the Agari model presented a reasonable prediction of thermal conductivity as a function of LDPE loading. A coefficient of cooling rate (CCR) is proposed and can be applicable as an indicator for thermal conductivity (λ) of the polymer blends.