Properties of Baypren®

 

Crystallization

A key distinguishing feature of the raw polymers is their tendency to crystallize. While virtually all liquids – water, for example – have a clearly defined temperature at which they undergo spontaneous crystallization on cooling (solidification point), some high molecular- weight products, such as natural rubber and a number of synthetic rubber grades, do not have a clearly defined crystallization point. Instead, they harden slowly as the temperature falls. In case of these rubber grades, this behavior is caused by a partial orientation of the macromolecules (crystallization). This hardening overlaps  the increase in hardness that results from a drop in temperature (thermoplasticity). Hardening due to crystallization is a fully reversible process that can be performed by subjecting the crystallized material to heat or dynamic stress. Unvulcanized polymers and compounds display a strong tendency to crystallize. Vulcanization, however, considerably slows down the extent of hardening resulting from crystallization in rubber articles. The  tendency of the polymers to crystallize can be influenced by appropriately controlled production processes. For this reason, rubber articles made from Baypren® grades with a low tendency to crystallize display virtually no  increase in hardness due to crystallization even after exposure to low temperatures for long periods. In contrast, polymers with a particularly pronounced tendency to crystallize display a clear increase in hardness even after a relatively short time.

 

Modification

The properties of Baypren® vulcanizates are influenced by the type of modification of the raw polymer.

 

Effect of pre-crosslinking

  • Reduction of the elastic resilience (snappiness) of the raw rubber and uncured compound
  • Reduction of the die swell
  • Improvement in calendering behavior
  • Improvement of the surface smoothness of injection-molded articles
  • Improvement of the dimensional stability, e.g. of uncured profiles

 

Effect of sulfur modification

  • Facilitates mastication of the rubber, permitting the production of soft compounds with good building tack
  • Only MgO/ZnO required for vulcanization
  • Better tear resistance than standard grades
  • Better adhesion to fabrics than standard grades
  • Lower storage stability of raw polymers
  • Lower aging resistance of vulcanizates

 

Effect of XD (xanthogen disulfide) modification

  • Lower elasticity (less “nerve”) means easier processing(by calendering or extrusion)
  • Better mechanical properties than M-modified grades in thesame formulation
  • Higher filler loadings possible
  • Dampers, which you can rely on