Silicone Elastomers - June 2010

This month we're looking at Silicone Elastomers.

Silicone Elastomers are fundamentally important materials in the world of healthcare, pharmaceuticals, automotive, electrical and food contact applications amongst others. This is due to their impressive range of properties, including biocompatibility, heat resistance and inertness. These adaptable materials are also finding exciting new applications, including replacing glass and other transparent polymers in lens and light guidance systems. All types of Silicone Elastomers are subject to further development work in terms of compounding and processing to develop even better properties, making them ideal for even more functions.

Abstracts

Please see below a selection of abstracts highlighted in the June Newsletter. These are records which relate to Silicone Elastomers that have been recently added to the Polymer Library.

Click on the 7-digit accession numbers to find out about ordering a copyright-cleared full text copy of the items shown.

1062082 - SILICONE ELASTOMERS IN MEDICAL APPLICATIONS - REDUCTION OF FRICTION WITH LSR TOP COAT
The characteristics of liquid silicone series Silopren LSR 4000 are described and end-use applications thereof in the medical field are demonstrated. The use of a biocompatible liquid silicone rubber topcoat, LSR Top Coat TP3719, to reduce silicone rubber friction is demonstrated and possible applications of this topcoat in the medical industry are indicated. 2 refs.
Rubber Fibres Plastics International, 5, No.2, March 2010, p.62-65, ISSN: 1863-7116
Ledig B

1061681 - FORMATION OF SILICONE ELASTOMER NETWORKS FILMS WITH GRADIENTS IN MODULUS
We describe the formation of soft material substrates with position-dependent modulus. Two strategies have been employed in the preparation of such materials. In the first method, we create modulus gradient structures by inter-diffusing two (or more) formulations of silicone elastomers (SE), comprising mixtures of poly(dimethylsiloxane) (PDMS) and poly(vinylmethylsiloxane) (PVMS) with varying molecular weight and content of PDMS, and cross-link them thermally in order to form SE networks. With this method, the resultant substrates exhibit shallow modulus gradients that extend over a few centimetres in length. The second technique is based on employing ultraviolet (UV)-based cross-linking of mercapto-terminated PVMS chains across transparency lithographic masks. We demonstrate that the shape and ''sharpness'' of the modulus on the substrate depends solely on the position-dependent transparency of the mask to the UV light. As a part of the study we provide detailed material characterisation of networks formed by the PDMS-PVMS and PVMS-SH chains. 38 refs. Copyright (c) 2010 Elsevier Ltd.
Polymer, 51, No.3, 2010, p.763-773, ISSN: 0032-3861, DOI: 10.1016/j.polymer.2009.11.070
Crowe-Willoughby J A; Weiger K L; Ozcam A E; Genzer J

1061586 - DEVELOPMENT OF A HIGH PERFORMANCE HYBRID EPOXY SILICONE RESIN FOR COATINGS
The synthesis of novel high temperature vulcanisation and room temperature vulcanisation organic-inorganic epoxy-silicone hybrid resins by curing of a thermally stable aminosilicone resin, derived from diethoxydimethylsilane and gamma-aminopropyldiethoxymethylsilane with a different proportions of commercial poly(ethylene glycol) bisphenol A epoxy resin and toluene diisocyanate is described. Surface coatings based on the products on steel and glass substrates were characterised by scratch hardness, pencil hardness, adhesion, solvent resistance, acid and alkali resistance, FTIR and TGA, and the effects of composition on cure characteristics, chemical resistance, mechanical and thermal properties are discussed in terms of the fabrication of heat resistant coatings. 12 refs.
Pigment and Resin Technology, 39, No.2, 2010, p.96-100, ISSN: 0369-9420, DOI: 10.1108/03699421011028680
Bajpai P; Bajpai M

1061463 - PREPARATION AND CHARACTERIZATION OF GAMMA-IRRADIATED CROSSLINKED SILICONE RUBBER/ORGANOATTAPULGITE COMPOSITES (downloadable pdf available)
Silicone rubber (SR)/organoattapulgite (OAT) composites were prepared with gamma-irradiation crosslinking at a dose range varied from 30 to 300 kGy. Natural fibrillar silicate attapulgite (AT) was modified by silane coupling agent, and the obtained OAT was used as reinforcing fillers in SR. The effect of irradiation doses on the degree of crosslinking of SR/OAT composites was determined by solvent swelling method. It was found that the molecular weight between crosslinks (Mc) reduced with the increase in irradiation doses. Moreover, the addition of OAT to SR matrix promoted an increase in the crosslinking density of the composites because of the presence of the active crosslinking sites of OAT. The mechanical properties of the SR/OAT composites including tensile strength, elongation at break, and Shore A hardness subjected to various irradiation doses were studied. The experimental results showed that the tensile strength, elongation at break, and Shore A hardness were all improved significantly in the presence of OAT, which indicated that OAT was an alternative reinforcing filler of SR. In addition, the effect of various irradiation doses on the mechanical properties of SR and SR/OAT composites was also investigated. 23 refs.
Polymer Composites, 31, No.3, 2010, p.405-410, ISSN: 0272-8397, DOI: 10.1002/pc.20817
Song L; Fang S; Zhan J; Hu Y; Wu J

1061274 - DYMAX. UV/VISIBLE LIGHT-CURING SILICONE (short article)
DYMAX Cure-Point 9440-A/B, a UV/visible light-curable silicone potting and sealing material, designed for applications where fast cure, enhanced thermal performance and room-temperature shadowed-area cure are required, is briefly described. The product is for use in providing protection to electronic components and circuitry.
Adhesives and Sealants Industry, 17, No.1, Jan.2010, p.39, ISSN: 1070-9592

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