NEW MEDICAL TENSILE TESTING OF RUBBER LOOPS
26 July 2006 - Lloyd Instruments

Lloyd Instruments can offer a versatile system for tensile testing of circular rubber products, featuring a special motorised ring grip in conjunction with a universal materials testing system such as the LRXPlus. This powerful combination can be used to test O-rings, and other rubber products such as condoms and surgical/medical gloves.

The motorised grip can accommodate bands up to 20 mm wide. The grip consists of two anvils mounted on shafts to allow rotation. The lower anvil is driven by a small electric motor and is mounted to the lower anchor pin of the testing machine. The upper anvil is mounted to the loadcell of the testing machine and is free to rotate.

The lower anvil speed can be adjusted between 0 and 20 RPM. The sample is placed over both anvils and rotated by the electric motor while a tensile load is applied by the testing machine. In this way stress in the sample is equalised through its length. The grip can be used for applied forces up to 10 kN.

Tensile measurements can be used to monitor the quality and uniformity of latex condoms, since they indicate that the latex has been formulated and vulcanized correctly. For these products a 20 mm-wide sample is cut from the mid-section of the condom. Three properties of latex are typically measured: the force required to break the latex ring, the percentage elongation before breaking and the tensile breaking strength. Tests can be repeated on condoms that have been oven-conditioned to simulate ageing. Tests can also be carried out on other circular rubber materials such as cross sections cut from the fingers of rubber gloves.

The LRXPlus is a single column instrument that can be used for material testing applications up to 5 kN (1124 lbf). Fast (8 kHz) sampling rates allow detailed measurement and analysis, benefiting research as well as production applications. Special 'creep' and 'relaxation' programmes accompany tensile, compression, flexural and cycling modes to fulfil a wide range of test applications. The addition of Lloyd Instruments’ powerful NEXYGEN MT materials test and data analysis software and Ondio application builder software allows full automation of the tests, collection of data and presentation of results.

http://www.lloyd-instruments.co.uk

More News:
  • For July 2006
  • From Lloyd Instruments
  • For Materials Characterisation and Testing