Selecting Natural Rubber Latex Compounds for Slingshot Bands

Student:  I am a PhD student in organic chemistry. My hobby is sling shooting, there are many slingshot clubs and tournaments in Europe.

Over the last years, it has become more and more difficult to find rubber sheetings that are suitable to craft long lasting slingshot bands from. I believe that the modern vulcanization packages which are used to create most latex sheeting offer advantages in the manufacturing process, but diminish the dynamic properties of the product.

I therefore want to conduct a few experiments in my laboratory, and ideally come up with a possibility to start small-scale production of a rubber sheeting that can supply us sling hooters with good rubber bands - and would be very grateful if you could answer me two questions:

- Am I right to assume that rubber with long sulfur crosslink chains has a better rebound elasticity than rubber types made with strong sulfur donors?

-Does prevulcanisation of the latex affect break elongation and resilience of the final product?

John Woon (Senior Latex Consultant): Generally, polysulphidic crosslinks (i.e. long sulphur crosslinks) give higher tension set and hence lower elasticity. On the other hand, with an EV system (Efficient vulcanization) with the use of sulphur donors, one gets better elasticity. However, EV system gives lower tensile strength. Hence it is advisable to take the middle road, i.e. Semi-EV system.

Generally PV gives higher elongation at break and lower resilience compared to a good postvulcanisable latex compound. However, the actual elasticity properties also depend on the curative recipes used for making the prevulcanised laetx (PV).