In this study, biaxially oriented polyamide 6/polyketone/graphene oxide (PA6/PK/GO) films were prepared by melt blending then simultaneously biaxially stretched process, with the aim of obtaining high barrier properties films and improvements in their mechanical properties. The oxygen transmission rate of biaxially oriented PA6/PK/GO film significantly decreased with addition of polyketone and GO. It is surprising that the biaxially oriented process can excellently improve the barrier properties of biaxially oriented PA6/PK/ GO film. For example, there was 94.7% OTR reduction of the film containing 20 wt% PK and 0.08 wt% GO compared with PA6 film at a stretching ratio of

The main purpose of this work was to investigate the linear tearing properties of PA6/MXD6 films prepared by simultaneous biaxial stretching. The compatibility between PA6 and MXD6 and the thermal properties of the PA6/MXD6 composites were also investigated. The results showed that the tearing deviation of the blending films decreased from 100 to 3.8% when the MXD6 blend ratio increased from 0 to 25%, but the deviation increased when the MXD6 blend ratio continue to increase. It means that the PA6/MXD6 films with addition of 25 wt% MXD6 exhibited the best linear tearing properties. The differential scanning calorimetry results revealed that the addition of MXD6 reduced the melting temperature from 227.5 to 224.8°C and crystallization temperature of PA6 from 179.3 to 175°C due to the benzene ring structure of MXD6. The dynamic mechanical analysis results indicated that MXD6 exhibits favorable compatibility with PA6. In addition, it was found that the barrier properties of the biaxially oriented PA6/MXD6 films were extremely improved with the increase of MXD6 content.

The yield strength of a metallic technological surface with biaxial residual stresses may be determined using X-ray stress analysis techniques. Shot peening can increase the superficial proof stresses of a spring steel treated in the hard state, even though there is a considerable decrease in the half width of the X-ray diffraction profile. It can therefore be concluded that for a metallic material in the hard state, the half width parameter of the X -ray interference lines at the surface does not correctly reflect static strength.

PLA is widely used in the field of disposable products for its good transparency, high strength, high modulus, and good processing performance. However, the crystallization rate and crystallinity of PLA are weak. In actual production, the PLA products that are typically obtained are amorphous with poor heat resistance, which greatly limits the application range of PLA products. Finding an effective nucleating agent to improve the transparency of PLA has been a hot topic in research. This study found that Cerium fluoride (CeF3) can effectively improve the crystallinity of PLA/CeF3 (P/F) films. When the content of CeF3 in PLA was 1 wt %, the retention ratio of visible light transmittance was 82.36%, the crystallinity was 29.8%, and the tensile strength was 59.92 MPa. Compared to pure PLA, the crystallinity of P/F1 increased by 56% and tensile strength increased by 8.76%. This study provided an alternative scheme that maintained the PLA film’s transparency and improved the crystallinity of PLA, which significantly expanded the application of PLA.

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In this study, cerium based DOPO derivative (Ce@DDP) was synthesized by hydrothermal method, and its effects on flame retardancy, thermal stability, and mechanical properties of intumescent flame retardant polypropylene (PP) are investigated. When addition of 17 wt% of intumescent flame retardants (IFR) and 1 wt% of Ce@DDP, the results indicate that the peak heat release rate (PHRR) and peak smoke production rate (PSPR) of the resulted PP composite is reduced by 62.0% and 42.3%, respectively. Meanwhile, the vertical burning rating reaches UL94 V-0, and the limiting oxygen index (LOI) is 33.8%. Furtherly, the Ce@DDP significantly improves the thermal stability and char formation ability of PP/IFR. Notably, Ce@DDP exhibits better synergistic flame retardant and mechanical strength for PP/IFR than CeO 2 . Finally, it was speculated that there was dilution effect and radical quenching effect in gas phase, and catalytic carbonization effect in condensed phase of IFR/Ce@DDP system, and the combined action of the these aspects led to high-efficiency flame retardant.DOPO derivative, flame retardancy, intumescent flame retardant, polypropylene, rare earth | INTRODUCTIONPolypropylene (PP) has excellent mechanical properties, high performance, easy processing and good chemical resistance. [1][2][3] It is widely used in automobile, wire, cable, electronic, electrical and building materials, etc. However, PP is a flammable material, it burns with flammable dripping and releases smoke and toxic gases, these disadvantages restrict its applications. Thus, the flame retardant research of PP is of great significance to expand its practical applications.Recently, intumescent flame retardants (IFR) have attracted more attention in flame retardant PP due to their advantages in terms of low toxicity, low smoke, and anti-dripping. 4 During combustion process, IFR undergoes a series of chemical reactions such as esterification, aromatic cyclization, expansion and curing to form an expanded char layer, which acts as a barrier and slows down the transfer of heat and substances. 5 Nevertheless, on the one hand, the traditional IFR has poor water resistance and is easy to migrate to the polymer surface during processing; on the other hand, the

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As the main encapsulation material, epoxy resin has an urgent need to obtain higher thermal conductivity. So how to improve the thermal conductivity of epoxy resin is very important. In this work, a novel strategy is proposed that the irregular alumina (i-Al 2 O 3 ) and the round plate boron nitride (h-BN) are integrated into epoxy resin to enhance the thermal conductivity. When the total amount of filler is 40%, and the volume ratio of auxiliary filler h-BN and the basic filler i-Al 2 O 3 is 6: 34，The thermal conductivity of the epoxy composites is significantly increased 709% higher than that of pure epoxy resin. The roles of the main filler i-Al 2 O 3 and the auxiliary filler h-BN in epoxy composites system were investigated. A possible mechanism was established that the h-BN connects i-Al 2 O 3 to generate the heat conduction network. The blending of irregular particles and round plate method proposed in this work is a new avenue, which meets the need of industrialized design and fabricating, making an achievement of obtaining a kind of epoxy composites with a high thermal conductivity and excellent comprehensive properties.