Vulkollan rubbers

Landel used a commercial material called Vulcollan 18/40 to study the rubber-to-glass transition of a polyurethane. This material is described as being prepared from a low molecular weight polyester which is extended and crosslinked. .. by reacting it with naphthalene-1,4-diisocyanate and 1,4-butanediol. The polyester. .. is prepared from adipic acid and a mixture of ethylene and propylene glycols. Draw the structural formula of a portion of the cross-linked polymer which includes the various possible linkages that this description includes. Remember that isocyanates react with active hydrogens use this fact to account for the cross-linking.  [c.67]

By careful formulation it is possible to produce polyurethane rubbers with a number of desirable properties. The first rubbers were prepared by Pinten in Germany in about 1940. Known as I-Gummi, they were produced by reacting a polyester with a di-isocyanate. These products had a high tensile strength and abrasion resistance but low tear strength and poor low-temperature properties. Subsequently the variables in the formulation were systematically investigated by Bayer, Muller and co-workers and this led to the advent of the Vulkollan rubbers. Today three types of solid polyurethane rubber may be recognised, namely  [c.784]

Polyurethane rubbers in general, and the Vulkollan types in particular, possess certain outstanding properties. They can have higher tensile strengths than any other rubber and have excellent tear and abrasion resistance. They tend to have a high hardness and a low resilience and in fact may be regarded as somewhat intermediate between conventional rubbers and flexible thermoplastics. The urethane rubbers also show outstanding resistance to ozone and oxygen (features lacking with the diene-rubbers) and to aliphatic hydrocarbons. Reversible swelling occurs with aromatic hydrocarbons. One disadvantage of the materials is that hydrolytic decomposition occurs with acids, alkalis and the prolonged action of water and steam.  [c.788]

Some typical properties of a Vulkollan-type polyurethane cast rubber and a black-reinforced polyurethane rubber processed by conventional techniques are compared with black-reinforced natural and nitrile rubbers in Table 27.2  [c.788]

Plastics materials (1999) -- [ c.784 , c.787 , c.791 , c.794 ]