A-HV Fluoroelastomers - Technical Information

Nov 2, 2026

Viton™ A-HV is a high-viscosity bisphenol AF curable fluoroelastomer dipolymer engineered to deliver vulcanizates with high tensile strength and superior compression-set resistance. The information outlines key features, typical seal and gasket applications, and a detailed product composition and physical characterization. Guidance covers curing system options, mixing and extrusion practices, low-temperature cure windows, and oven post-curing requirements to maximize mechanical properties.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages6

Reading Time15 min

AccessFree to download

Introduction

Features

Product Description

Chemical Composition and Physical Data

Curing Systems for Viton™ A-Types

Processing

Mixing

Extruding

Curing

Safety and Handling

A-HV Fluoroelastomers Technical Information Introduction Viton™ A-HV is a high viscosity fluoroelastomer dipolymer that provides vulcanizates with high tensile strength and best resistance to compression set compared to other Bisphenol AF curable types. Features • Bisphenol AF and Diamine Curable • High Tensile Strength • Low Compression Set Typical applications include compression molded seals, O-rings, gaskets, and oil-field parts, such as packers. Product Description | Chemical Composition | Dipolymer of hexafluoropropylene, vinylidene fluoride | | --- | --- | | Physical Form | Sheet | | Appearance | White to tan | | Odor | Negligible | | Mooney Viscosity, ML 1 + 10 at 149 °C (300 °F) | 100 | | Specific Gravity | 1.82 | | Storage Stability | Excellent | | Fluorine,% | ~66 | Curing Systems for Viton™ A-Types The A-types of Viton™ can be cured with Viton™ Curative Masterbatches (No. 20 and 30), Curative No. 50, or with diamines—Viton™ Curative Nos. 1 (VC-1) or 3 (VC-3) . Typical formulations and physical properties for compounds using Curatives No. 20, No. 30, and No. 50 are found in Table 1. A comparison of A-HV to A-500 and A-700 can be found in Table 2. For additional information on curing Viton™, see technical bulletin “Viton™ Curatives No. 20, No. 30, and No. 50.” Processing Mixing Perhaps the most important aspect of mixing Viton™ is to use equipment free of contamination from other polymer mixes. Residual oil s and sulfur or sulfur-containing chemicals can have ruinous effects on mixing and curing characteristics of Viton™ compounds. Viton™ compounds should be mixed on a mill or in an internal mixer that has adequate cooling capacity; not only to prevent stock scorch, but also to prevent sticking of the mix to rolls or rotors. All powdered ingredients should be premixed—this ensures good dispersion and prevents sticking, which occurs if magnesia is added by itself early in the mix. The use of Viton™ Curative No. 1 (VC-1) results in fairly scorchy compounds. For this reason, VC-1 should be added last when mill mixing and on the drop mill when using an internal mixer. Depending on the acid acceptor and filler systems used, re-milling compounded stock after a minimum of 24 hr often improves physical properties of vulcanizates. Extruding High viscosity A-types like A-HV typically provide a better extrudate surface when processed through a hot die— 100–140 °C (212–284 °F) . The use of 1–1.5 phr of a process aid, such as VPA No. 2 or carnauba wax, markedly improves the surface and definition of extrudates. When using a process aid, it is best to keep the feed zone cool relative to the die and head areas of the extruder to avoid stock slippage and loss of feed. Curing Compounds may be cured at temperatures as low as 160 °C (320 °F); but, when using Curative Masterbatches, 170 °C (338 °F) is a minimum temperature to use if practical cure times are desired. These are guidelines for a simple, compression-molded part; in transfer molding or compression molding, where the stock flows significantly, enough shear heat may result to shorten“expected” cure times significantly. To attain maximum physical properties, cured parts of Viton™ must also be oven post-cured for 24 hr at a temperature between 200–260 °C (392–500 °F) . In general, property values will reach 80–90% of maximum in 12 hr at 232 °C (450 °F) . Parts thicker than 6 mm (0 .25 in) should be step post-cured to avoid internal fissuring. Starting at 125 °C (257 °F), the heat can then be increased hourly to the final desired post-cure temperature. For more information, see technical bulletin “Viton™ Fluoroelastomers—Oven Post-Curing of Parts.” Safety and Handling Before handling or processing Viton™ A-HV, read and be guided by the suggestions in the technical bulletin,“Handling Precautions for Viton™ and Related Chemicals.” Table 1. Viton™ A-HV Compared to E-45 | Compound \# CSG0244-10 CSG0244-11 CSG0244-06 CSG0244-07

FAQs

What are the main performance benefits of Viton™ A-HV?

Viton™ A-HV provides vulcanizates with high tensile strength and best resistance to compression set compared with other bisphenol AF curable types.

Which curing systems can be used for Viton™ A-Types, including A-HV?

A-types of Viton™ can be cured using Viton™ Curative Masterbatches (No. 20 and 30), Curative No. 50, or diamines such as Viton™ Curative Nos. 1 (VC-1) or 3 (VC-3).

What post-curing conditions are recommended to achieve maximum properties?

Cured parts of Viton™ should be oven post-cured for 24 hr at 200–260 °C. Property values generally reach 80–90% of maximum in about 12 hr at 232 °C, and thicker parts (over 6 mm) should be step post-cured to avoid internal fissuring.

Nov 2, 2026

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