Molecule Dynamics Simulation of the Effect of Oxidative Aging on Properties of Nitrile Rubber

The effects of oxidative aging on the static and dynamic properties of nitrile rubber at the molecular scale were investigated by molecular dynamics simulation. The aged nitrile rubber models were constructed by introducing hydroxyl groups and carbonyl groups into rubber molecular chains to mimic oxidative aging. The static and dynamic properties of the unaged and aged nitrile rubber under different conditions were evaluated by mean square displacement, self-diffusion coefficients, hydrogen bond, fractional free volume, radial distribution function, cohesive energy density and solubility parameter. The results show that the elevated temperature intensified significantly the mobility of rubber molecular chains and fractional free volume, while the compressive strain displayed the opposite effect resulting in packing and rearrangement of rubber chains. The introduction of hydroxyl groups and carbonyl groups enhanced the polarity, intermolecular interactions, the volume and rigidity of molecular chains, implying weaker mobility of molecular chains as compared to unaged models. The compressive strain and oxidative aging both decreased the fractional free volume, which inhibited gaseous and liquid diffusion into the rubber materials, and slowed down the oxidative aging rate. This study provides insights to better understand the effect of molecular changes due to oxidative aging on the structural and dynamic properties of rubber materials at the molecular level.

Synthesis of Low Temperature Resistant Hydrogenated Nitrile Rubber Based on Esterification Reaction

Hydrogenated Nitrile Rubber (HNBR) is widely used in aerospace, petroleum exploration and other fields because of its excellent performances. However, there remains a challenge of balancing the oil resistance and the low temperature resistance for HNBR. In this work, a series of grafted carboxyl nitrile rubber (XNBR) was prepared by the esterification reaction between active functional groups (–COOH) of XNBR and alkanols of different molecular chain lengths (C8H17OH, C12H25OH, C16H33OH, C18H37OH) or Methoxypolyethylene glycols (MPEG) of different molecular weights (Mn = 350, 750, 1000). The structure and low temperature resistance of as-obtained grafted polymers were characterized by Fourier Transform Infrared (FTIR), 1H-NMR and Differential scanning calorimetry (DSC). It was found that the glass transition temperatures (Tg) of grafted XNBR were significantly decreased. MPEG grafted polymers with better low temperature resistance were then selected for hydrogenation. As-prepared hydrogenated XNBR grafted with MPEG-1000 (HXNBR-g-1000) showed the lowest Tg of −29.8 °C and the best low temperature resistance. This work provides a novel and simple preparation method for low temperature resistant HNBR, which might be used potentially in extremely cold environments.

Effect of Ground Vulcanizate Modification Methods on Properties of Oil-Petroleum-Resistant Rubber

In this paper, the influence of the modification method applied to ground vulcanizate (GV) on the properties of elastomeric compositions based on nitrile rubber is discussed. Modified GV has been mixed with the elastomeric composition, which is used for the manufacturing of oil-petroleum-resistant rubber products.The work takes into consideration two types of GV with different chemical nature. The first GV type is rubber crumb produced from end-of-life tires. The second GV type was obtained from rubber wastes based on nitrile rubber. Three methods of the modification are compared in the research: mechanical activation in a planetary ball mill, swelling in a Polyethylene glycol (PEG-400) medium, and the mechano-chemical transformation of GV with PEG-4000. It is shown that depending on the dosage addition of GV modified with PEG-4000 reduce the compression set up for (16.1±0.7%), the strength decreases only by 2.1–8.3%, and the elongation at break increases by 0.8–10.3% compared to rubber without additives.

Design and Control of an Automated SCARA Robotic Arm with a Pneumatic Soft Gripper

The paper focuses on the design, analysis and control of an automated 3 DOF SCARA robotic manipulator with an end effector made of asymmetric flexible pneumatic bellow actuator (AFPBA). The manipulator is made for use in the poultry industry and therefore tested in its ability to detect, pick and place eggs. The links of the manipulator are made using acrylonitrile butadiene styrene (ABS) and the end effector is made using nitrile rubber. A neural network derived from the VGG-16 and YOLO architecture is then implemented to detect and localize eggs. The predicted values were then used to calculate the inverse kinematics of the manipulator.

Pengaruh Variasi Insulator Saluran Chilled Water Terhadap Performansi Prototype Mini Water Chiller

The high heat transfer rate from the environment to the chilled water pipe will affect the performance of the mini water chiller prototype, so it is necessary to insulate the chilled water pipe using the right insulator to optimize the performance of the mini water chiller prototype. Therefore, this study aims to determine the effect of the chilled water pipe insulator variations: nitrile rubber expanded and polyurethane foam on the optimal temperature and cooling rate of the mini water chiller prototype cabin. The method used in this study is an experimental method with a variation of the insulator as independent variables and the optimal temperature also cooling rate of the mini water chiller prototype cabin as the dependent variables. The testing process was carried out 20 times repetition of data collection on each variation using a stopwatch, thermo gun, thermostat, ampere pliers, a bulb, and a water heating element as a tool in research. In addition, it expanded nitrile rubber and polyurethane foam spray as research material. The results obtained from this study showed that the average optimal temperature achievement of the mini water chiller prototype with polyurethane foam insulator was 11.242◦C, and with the nitrile rubber expanded insulator was 11.250◦C. Otherwise, the average cooling rate of the mini water chiller prototype cabin with polyurethane foam insulator variation was 0.001421◦C, while in the variation of nitrile rubber expanded it was 0.001032◦C, which indicates that there is an effect of chilled water pipe insulator variations on the performance of the mini water chiller prototype.