A Novel Biocidal Elastomer

2001 ◽  
Vol 74 (2) ◽  
pp. 331-337 ◽  
Author(s):  
D. B. Elrod ◽  
J. Gibb Figlar ◽  
S. D. Worley ◽  
Royall M. Broughton ◽  
J. R. Bickert ◽  
...  
Keyword(s):  
Chemical Process ◽  
Triblock Copolymer ◽  
Protective Clothing ◽  
Food Packaging ◽  
Formation Reaction ◽  
Surgical Gloves ◽  
Chemical Company ◽  
Elastomeric Material ◽  
Elastomeric Materials ◽  
Shell Chemical

Abstract Biocidal elastomeric materials have been produced by a three-step chemical process on commercial elastomers which are composed of a styrene/ethylene-butylene/styrene triblock copolymer. The commercial elastomeric material employed was Kraton®G, produced by the Shell Chemical Company in Houston, Texas. The three-step process involved a Friedel-Crafts acylation of the styrene blocks of the elastomer, followed by a hydantoin ring formation reaction, and subsequent halogenation with chlorine or bromine. Both raw and processed elastomeric materials were studied. The biocidal efficacies of the materials were demonstrated using several species of bacteria. A few applications for the technology may include prevention of disease by biocidal surgical gloves, condoms, protective clothing, food packaging, and the prevention of biofouling in elastomeric tubing.

scholarly journals Fracture of Elastomeric Materials by Crosslink Failure

2018 ◽  
Vol 85 (8) ◽  
Author(s):  
Yunwei Mao ◽  
Lallit Anand
Keyword(s):  
Free Energy ◽  
Failure Mode ◽  
Chain Scission ◽  
Progressive Damage ◽  
Central Feature ◽  
Single Chain ◽  
Elastomeric Material ◽  
Damage And Fracture ◽  
Elastomeric Materials ◽  
Covalent Crosslinks

If an elastomeric material is subjected to sufficiently large deformations, it eventually fractures. There are two typical micromechanisms of failure in such materials: chain scission and crosslink failure. The chain scission failure mode is mainly observed in polymers with strong covalent crosslinks, while the crosslink failure mode is observed in polymers with weak crosslinks. In two recent papers, we have proposed a theory for progressive damage and rupture of polymers with strong covalent crosslinks. In this paper, we extend our previous framework and formulate a theory for modeling failure of elastomeric materials with weak crosslinks. We first introduce a model for the deformation of a single chain with weak crosslinks at each of its two ends using statistical mechanics arguments, and then upscale the model from a single chain to the continuum level for a polymer network. Finally, we introduce a damage variable to describe the progressive damage and failure of polymer networks. A central feature of our theory is the recognition that the free energy of elastomers is not entirely entropic in nature; there is also an energetic contribution from the deformation of the backbone bonds in a chain and/or the crosslinks. For polymers with weak crosslinks, this energetic contribution is mainly from the deformation of the crosslinks. It is this energetic part of the free energy which is the driving force for progressive damage and fracture of elastomeric materials. Moreover, we show that for elastomeric materials in which fracture occurs by crosslink stretching and scission, the classical Lake–Thomas scaling—that the toughness Gc of an elastomeric material is proportional to 1/G0, with G0=NkBϑ the ground-state shear modulus of the material—does not hold. A new scaling is proposed, and some important consequences of this scaling are remarked upon.

Gun Liner Emplacement Using Elastomeric Materials

2010 ◽  
Author(s):  
Robert H. Carter ◽  
David M. Gray
Keyword(s):  
Refractory Metal ◽  
Outer Diameter ◽  
Elastomeric Material ◽  
Elastomeric Materials ◽  
Residual Internal Stress ◽  
Inner Diameter ◽  
Bond Strengths ◽  
Frictional Bond ◽  
Load Frame ◽  
Metal Liner

The development of a process to emplace a refractory metal liner inside a gun tube is described. The process consists of filling the liner with an elastomeric material and then slipping this arrangement into the gun tube whose inner diameter is close to the outer diameter of the liner. The ends of the liner are plugged with plastic disks and pressure is applied to the elastomeric material by a load frame. This pressure can produce a residual internal stress within the steel gun tube that produces a frictional bond between the liner and gun tube. Initial efforts have resulted in bond strengths over 3 ksi (21 MPa). In addition, by tailoring the degree of lubrication between the elastomeric material and the liner, a graded autofrettage can be produced in the steel gun tube.

Eponate 12, a new epoxy resin: Comparisons with EPON 812 and observations on its use for general biological electron microscopy

1987 ◽  
Vol 45 ◽  
pp. 628-629
Author(s):  
J.A. Mascorro ◽  
G.S. Kirby
Keyword(s):  
Electron Microscopy ◽  
Epoxy Resin ◽  
Flow Rate ◽  
Epoxy Resins ◽  
Physical Characteristics ◽  
Past Study ◽  
Chemical Company ◽  
Shell Chemical

Many epoxy resins have been introduced during the last several years as replacements for Epon 812 since the Shell Chemical Company discontinued production of this popular embedding resin. In a past study, the present investigators examined several of the “replacement” resins for physical characteristics such as viscosity, flow rate, density, mass weight, and hardness of the polymerized medium. In addition, other equally important parameters including sectioning and infiltrating character as well as stain-ability and section strength subsequent to beam and vacuum conditions also were evaluated. The present work follows a similar rationale and seeks to determine this same information for Eponate 12, an epoxy resin designated as a true generic replacement for the formerly available Epon 812 product.For purposes of physical comparisons, Eponate 12 was tested against a sample of original Shell Epon 812 still maintained in our laboratory.

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