Development and Aging Behaviour of Solvent-Based Polychloroprene Rubber Nano-Adhesive Using Multiwall Carbon Nanotubes

Polychloroprene (PC) based contact adhesives are widely used in various applications;however, there is a possibility to improve the properties of PC adhesive. Modifications of polymers can enhance the properties of the material, e.g. increase in thermal stability, compatibility, rigidity, physical response, flexibility and improve the polymer process ability. In the current study, improved formulation of solvent-based adhesive was developed, and the properties were further enhanced by the addition of nano-reinforcement of multiwall carbon nanotubes (MWCNTs). The addition of nano-reinforcement was optimized to obtain improvement in the bond strength and also to enhance its resistance at a high temperature (~100°C). This paper discusses the uniform dispersion of MWCNTs during the synthesis of polychloroprene solvent-based adhesive, thereby improving its structural properties. Incorporation of MWCNTs-solvent-based adhesives resulted in a 20% - 35% improvement in 180° peel strength determined on flexible substrates such as canvas, leather. The reinforced based adhesive also exhibited improved thermal stability and weather resistance compared with unreinforced adhesive. The MWCNTs- solvent-based contact adhesives is a potential candidate in an industrially relevant branch of adhesives commonly used in structural applications, e.g., footwear, plastic, leather, automobile, construction industries, etc.

Constitutive model of viscoelastic dynamic damage for the material of gas obturator in modular-charge howitzer

In order to investigate the mechanical response behavior of the gas obturator of the breech mechanism,made of polychloroprene rubber(PCR), uniaxial compression experiments were carried out by using a universal testing machine and a split Hopkinson pressure bar(SHPB), obtaining stress-strain responses at different temperatures and strain rates. The results revealed that, in comparison to other polymers, the gas obturator material exhibited inconspicuous strain softening and hardening effects;meanwhile, the mechanical response was more affected by the strain rate than by temperature. Subsequently, a succinct viscoelastic damage constitutive model was developed based on the ZWT model, including ten undetermined parameters, formulated with incorporating three parallel components to capture the viscoelastic response at high strain rate and further enhanced by integrating a three-parameter Weibull function to describe the damage. Compared to the ZWT model, the modified model could effectively describe the mechanical response behavior of the gas obturator material at high strain rates. This research laid a theoretical foundation for further investigation into the influence of chamber sealing issues on artillery firing.

DEVELOPMENT OF SYNCHRONOUS BELT JACKET FABRIC AND ITS PERFORMANCE

Jacket covering fabric is one of the critical materials for the production of synchronous beltswhich are widely used for positive drive in various departments of industry. The successful de-velopment of textured yarn jacket fabric by our lab has filled a domestic vacancy in this respect.In this paper the processing of textured yarn jacket fabric is briefly outlined, its characteristicsexplained and its performance test results given.

Studies on Physical Chemistry of Rubber-Rice Husk Ash Composites

Nowadays an alternate source of filler from renewable and plant derivatives are being thought of in rubber industries due to their reliability,environmental and economic benefits.Rice Husk Ash(RHA)a byproduct of the rice milling industry is obtained on partial and as well as full combustion of the rice husks.This ash is a good source of silica,silicates and needle shaped carbon and hence can be used as filler for cements.In the present study,a detailed investigation was carried out to understand the RHA as reinforcing material using mechanical properties and fractography using SEM.The rubbers studied were natural rubber(NR),poly chloroprene(CR)and ethylene propylene diene monomer(EPDM).Interestingly,the RHA added NR stock on open mill mixing generated considerable amount of static charges.The properties of NR were found to be as good as regular formulations.EPDM compounds behaved well during mixing.But the properties were found to be poor.CR-RHA compounds were found to result in higher viscosity and the properties were not as good.The SEM studies showed surprisingly cohesive failure as evidenced with the presence of flow lines and the fibrous filler(RHA)remains embedded in the matrix regardless of the chemistry of the repeating unit,NR,EPDM and the chlorine containing monomer inCR.