Investigation on crosslinking behaviors of NBR/PVC filled with anhydrous copper sulfate particles by dynamic mechanical analysis

Research on the Design and Performance of Plant Volatile Organic Compounds Water Removal Device Based on Optimized Filler Ratio

This study focuses on the development and optimization of a water removal device for biogenic volatile organic compounds (BVOCs) from plant emissions. BVOCs play a crucial role in various ecological processes and have potential therapeutic effects on human health. However, it is challenging to accurately detect and analyze BVOCs due to their very low concentrations and interference by water vapor. This study systematically evaluates different filler materials and ratios to alleviate water vapor interference while maintaining BVOCs' integrity. The experimental results demonstrate that the combination of MgSO4 + Na2SO4 mixed filling and CuSO4 layered filling in a 3:3:1 ratio can effectively improve the collection efficiency and detection accuracy of BVOCs. Meanwhile, the effectiveness of the device in improving the detection of volatile compounds in plant samples is also confirmed by the VOC verification experiments on Michelia maudiae and Cinnamomum camphora tree species after mechanical damage. The experimental results show that the device is effective in improving the detection of volatile compounds in plant samples. The findings provide a powerful technical means for exploring the role of BVOCs in environmental monitoring and scientific research.

Kinetics of thermal oxidative degradation of poly (vinyl chloride) containing Ca and Sn at low temperature

Calcium metal soap and polyol (dipentaerythritol) additives are replacing or partially replacing organotin in poly(vinyl chloride) (PVC) heat stabilizers due to their low cost, nontoxicity and safety. Therefore, investigating the low-temperature thermal oxidative degradation of stabilized plasticized PVC from the source is essential for recycling. This work uses isothermal thermogravimetry to investigate the thermal degradation process and isothermal discoloration of PVC/calcium metal soap/dipentaerythritol/organotin soft products with excellent heat resistance at 453-503 K and under air atmosphere. The chemical kinetics method is used to fit a single equation model of mass loss and time during the thermal oxidation degradation of PVC, and the kinetic equation obtained is: -ln(1 - α) = 3.83 × 10³exp (-6834.4/T)t. When the temperature is 453-503 K, the calculation results are basically consistent with the experimental data and are independent of the heating rate and temperature changes. In addition, the isothermal discoloration of different PVC materials was tested under air atmosphere at 468 K. The results show that when the test material is PVC/calcium metal soap/dipentaerythritol/organotin, the heat aging time to become completely blackened is longer than that of the blank sample, which indicates a strong interaction occurs between Sn, Ca and dipentaerythritol complexes and PVC molecules, inhibiting the release of hydrogen chloride. At the same time, in order to recover PVC and prevent it from carbonization, if the temperature is set to 486 K, the thermal oxidation degradation time of PVC should be less than 130 min.

Chemical and physical properties of self-crosslinked poly(vinyl chloride)/nitrile rubber nanocomposites prepared by melt-mixing process

In this article, poly(vinyl chloride) (PVC)/acrylonitrile butadiene rubber (NBR)/clay nanocomposites were melt-mixed using the computerized Brabender plasticorder. During preparation of the nanocomposites self-crosslinking (crosslinking without aid of any crosslinking agent) occurs and affects all properties of a sample. The extent of crosslinking reaction depends on the processing temperature, rotor speed and mixing temperature and it increased with increasing each of mixing parameters. The mechanism of the self-crosslinking reaction was examined by the Fourier transform infrared spectroscopy test. The morphology of the materials was characterized using X-ray diffraction and scanning electron microscope. The swelling test and tensile test were applied to distinguish the effects of self-crosslinking phenomena on physical properties of NBR/PVC nanocomposites. Dynamic mechanical thermal analysis tests of nanocomposites were also performed to study the physical properties, such as glass transition temperature (T g). The results showed that the crosslinking reaction made a material more strong with high modulus and tensile strength. Thus, it can be deduced that crosslinks convert the NBR/PVC nanocomposites to stiffer materials that are less penetrable by the solvent. The results drawn from the loss tangent (tan δ) curves of nanocomposite samples can be used as further evidence for the above conclusions.