While the stress relaxation is a common phenomenon for polymers, its effect on the stress/strain accelerated aging of the hydrogenated nitrile butadiene rubber (HNBR) cannot be ignored. In this paper, the aging tests of HNBR at various temperature and strain levels were performed. To consider the influence of relaxation behavior during the accelerated aging process under external strains, a modified time-temperature-strain superposition principle considering stress relaxation (TTSSP-R) was proposed. With the general Maxwell model and the constructed master curve of relaxation modulus, the effect of stress relaxation on accelerated aging can be described. It was demonstrated that the proposed TTSSP-R approach provides an accurate evaluation of physical aging of HNBR with the consideration of stress relaxation. It could help the material designer to better understand the long-term performance and reliability of rubber components.

For high-value use of recycled polyethylene terephthalate (r-PET) resource and simultaneous development of high performance isotactic polypropylene (PP) materials, the blends of r-PET with PP and its compatibilized versions were prepared. PP-g-MA, POE-g-MA and EVA-g-MA with same functional group, as well as their mixtures, were used as compatibilizer. The crystallization behavior, mechanical properties and microphotographs of r-PET/compatibilizer, r-PET/PP bleds and its compatibilized versions were characterized. The results indicated that addition of compatibilizer decreased the tensile and flexural strength of r-PET and slightly improve its impact strength. The introduction of r-PET to PP matrix increased the tensile and flexural strength of PP. The tensile and flexural strength of compatibilized r-PET/PP are dependent on the kinds of compatibilizers. Addition of PP-g-MA improved the tensile and flexural strength of r-PET/PP blends and introduction of POE-g-MA or EVA-g-MA increased the impact strength of r-PET/PP blends. Effect of compatibilizer and its mixtures and r-PET content on the mechanical properties of compatibilized r-PET/PP blends is discussed. The r-PET/PP blends with high strength and toughness can be obtained by compatibilization of the mixtures of PP-g-MA and POE-g-MA (or EVA-g-MA). This investigation provides an effective method to use the r-PET to prepare high performance PP blends with low cost and high-value.

In this paper, identification system of plastic solid waste (PSW) based on near-infrared (NIR) reflectance spectroscopy in combination with Support Vector Machine (SVM) was presented. A device applied to obtain NIR spectra of plastics in the detection platform was developed. After pre-processing (normalized, 1st derivative and smooth), the repeatability of spectral absorption features was improved, which would assist the identification. A “principal component analysis (PCA)SVM” identification method was proposed to identify polypropylene (PP), polystyrene (PS), polyethylene (PE), poly(methyl methacrylate) (PMMA), acrylonitrile butadiene styrene (ABS) and polyethylene terephthalate (PET) among plastics, and its identification accuracy can reach 97.5%. The type of samples could clearly be identified and the shape of samples could also be roughly discerned. It is clearly shown that this system can achieve good identification results while reducing costs considerably, which has great potential in industrial recycling.

The aging behaviors of PMMA in liquid scintillator at different temperatures of 30 °C, 40 °C, 50 °C and 55 °C under static tensile stress were experimentally investigated with dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC), and the service life of the PMMA was predicted on the basis of the time-temperature superposition approach. The results showed that the higher the aging temperature, the faster the tensile strength of PMMA decreased. Acceleration of aging can be realized by applying high temperatures, and a master curve can be constructed using the time-temperature superposition concept. The linear behavior of the plot of the shift factors versus the inverse aging temperature indicated that the aging mechanism was consistent with Arrhenius's law, and the lifetime of PMMA was predicted to be 25 years at 20 °C.

To solve the problems of low precision and molding efficiency of 3D printing technology at present, the concept of “3D copying” intelligent manufacturing is put forward for the first time considering the important demands and background knowledge of intelligent manufacturing, which integrates the research works of the author's team in the field of precision injection molding and melt differential 3D printing technology of polymer. Supported by the National Natural Science Foundation of China and the key R & D projects, the core principle and technical route of 3D copying technology have been preliminarily explored. Three key aspects of the scientific and technical issues are discussed, namely, target product's virtual design or 3D modeling, 3D printing of mould, intelligent injection molding. 3D copying technology can realize the rapid, high precision and large quantity replication of samples. It is expected to become a new trend of modern manufacturing intelligent development, and has a broad application prospect.