Ageing of rocket insulator compound based on EPDM

Dynamically cured poly(vinyl chloride)/nitrile butadiene rubber (PVC/NBR), thermoplastic elastomers (TPEs) were melt mixed at 150°C at 50 rev.min.-1 with a Brabender Plasticorder. Curatives concentration was varied from 0 to 1 phr in order to study the effect of dynamic curing on the oil resistance of the plastified formulations. The compounds were characterized in respect to their mass swell, tensile properties, tear strength and hardness. The PVC/NBR formulations have been exposed to air and oil under otherwise identical conditions. The influence of oil and thermo-oxidative ageing on the mechanical properties were characterized at room temperature and 100°C. It was found that at ambient temperature the samples immersed in oil possessed similar properties to those that were exposed to air. Profound enhancement in mechanical properties were observed for both environments at 100°C. The observed scenario has been attributed to the increase in the degree of curing which was accompanied by a steady reduction in % mass swell with increased sulfur loading. The excellent mechanical behavior of the PVC/NBR TPEs even after immersing the samples in oil at 100°C evidenced for the good oil resistance of the materials.

Oil Resistance of Dynamically Vulcanized Poly(Vinyl Chloride)/Nitrile Butadiene Rubber Thermoplastic Elastomers

Rubbers are long-chain molecules which are plastic in nature in the raw or unvulcanized state. Vulcanization is an irreversible process by which the predominantly plastic rubber is converted to predominantly elastic and a three-dimensional network structure through the anchoring between two polymer chains. Chemically, this is done by an intermolecular cross-linking reaction. Cross-linking increases the retractive force and reduces the amount of permanent deformation remaining after removal of the deforming force. These links between polymer chains may be chains of sulfur atom or atoms, carbon-carbon bonds, polyvalent metal ions, etc., depending on the nature of the vulcanizing system. Properties of elastomers depend on how efficiently this cross-linking has been achieved and also which types of cross-linking agents are used. For example, the retractive force resisting a deformation is proportional to the number of network supporting polymer chains per unit volume of elastomers [1]. Again the stre...

Mixed Cross-Link Systems in Elastomers

The article contains sections titled: 

1.	Emulsion Styrene - Butadiene Rubber (E-SBR)	
1.1.	Properties, Grades, and Application	
1.2.	Basic Chemistry and Production Processes	
1.3.	Producers and Production Capacities	
2.	Chloroprene Rubber (CR)	
2.1.	Properties, Grades, and Applications	
2.2.	Basic Chemistry and Production Processes	
2.3.	Producers and Production Capacities	
3.	Nitrile Rubber (NBR)	
3.1.	Properties, Grades, and Applications	
3.2.	Basic Chemistry and Production Processes	
3.3.	Producers and Production Capacities	
4.	Emulsion Polybutadiene (E-BR)	
4.1.	Properties and Applications	
4.2.	Basic Chemistry and Production Processes	
4.3.	Producers and Production Capacities	
5.	Acrylate Rubber (ACM)	
5.1.	Properties, Grades, and Applications	
5.2.	Basic Chemistry and Production Processes	
5.3.	Producers and Production Capacities	
6.	Fluororubbers	
6.1.	Chemical Composition and Properties	
6.2.	Vulcanization	
6.3.	Production Processes	
6.4.	Producers, Production, Capacities, and Markets

Rubber, 4. Emulsion Rubbers

The battle against the COVID-19 pandemic counters the waste management system, as billions of single-use face masks are used per day all over the world. Proper disposal of used face masks without jeopardizing the health and the environment is a challenge. Herein, a novel method for recycling of medical face masks has been studied. This method incorporates the nonwoven polypropylene (PP) fiber, which is taken off from the mask after disinfecting it, with acrylonitrile butadiene rubber (NBR) using maleic anhydride as the compatibilizer, which results in a PP–NBR blend with a high percentage economy. The PP–NBR blends show enhanced thermomechanical properties among which, 70 wt % PP content shows superior properties compared to other composites with 40, 50, and 60 wt % of PP. The fully Atomistic simulation of PP-NBR blend with compatibilizer shows an improved tensile and barrier properties, which is in good agreement with the experimental studies. The molecular dynamics simulation confirms that the compatibility between non-polar PP and polar NBR phases are vitally important for increasing the interfacial adhesion and impeding the phase separation.

https://pubs.acs.org/doi/pdf/10.1021/acsomega.1c04913

Experimental and Simulation Studies on Nonwoven Polypropylene–Nitrile Rubber Blend: Recycling of Medical Face Masks to an Engineering Product

Considerable advances have been made in NBR technology and still more are possible. The heat resistance of NBR has been raised so that it will with-stand 150°C in air for short periods, instead of 120°C. There is potential in the polymer backbone for still greater stability. It has been demonstrated that the ozone resistance of NBR can be improved by blending with EPDM, but the optimum blend has not yet been developed. The use of PVC to improve the ozone resistance of NBR is now much better understood. Crosslinked NBR has been developed as a non-migratory plasticizer which improves embossing characteristics of PVC and PVC-ABS blends. This, in turn, led to the production of NBR powders which may be used to speed up compounding on conventional equipment and permit rubber to be compounded in equipment generally used for fabricating plastics. Powder black masterbatches of NBR are now being evaluated in industry. Another new product form is liquid NBR, generally with reactive end groups. This is alrea...

H. A. Pfisterer

Papers

Advances in Nitrile Rubber Technology