A polymer suitable for use in a thin film hinge (living hinge) comprising from about 0.1 to about 5 weight % of a C.sub.4-8 comonomer and the balance ethylene, said composition having a density as determined according to ASTM D 792 from about 0.945 to about 0.965 g/cm.sup.3; a melt index as determined according to ASTM D1238 (2.16 kg/190 C.) from about 10 to about 20 g/10 min; a weight average molecular weight (Mw) from about 45,000 to about 55,000 g/mol; a polydispersity from about 2.5 to about 3.1 and when molded into a strip having a length of about 13 cm and gross thickness from about 50 to about 70 mil (about 1 to about 2 mm) and completely bent over end to end four times to create a thinned region or crease having a thickness from about 15 to about 30 mil (about 0.3 to about 0.7 mm) tested by bending and releasing the deformed thinned region of the strip through a radius of curvature from about 180 to about 190 about a rounded plate goes through not less than 500 cycles without breaking.

A test apparatus (12) and a method of testing a sample (30) are disclosed. The method comprises receiving a test sample (30) within a test chamber (14), the test chamber (14) containing two or more iron saturation elements (2) separated by a spacer (16); and filling the test chamber (14) with a test solution, the iron saturation elements (2) being arranged to saturate the test solution with iron. Each iron saturation element (2) is shaped such that it has a predetermined surface area such that the ratio of the volume of the test solution to the surface area of the iron saturation elements (2) and the test sample (30) exposed to the test solution can be calculated.

Polyethylene living hinges used in snap top lids for condiments and the like may be electron bean irradiated to partially crosslink the polyethylene to produce a hinge having an improvement in the number of opening and closing cycles until failure of not less than 30%. The irradiated lids may be used in place of polypropylene lids for condiment containers.

A mechanical testing system for deformable samples, such as gels or tissues, is disclosed. The system includes a container for holding a liquid, and a floatable platform configured to float on the liquid. The platform includes attachments for connecting to a deformable sample and a force sensor assembly. The system allows for the application of unidirectional tension to the sample and the measurement of the resulting force by the force sensor assembly. The design of the system minimizes off-target forces and sample vibration, and allows for submerged testing and simultaneous imaging of the sample. The system is particularly suitable for testing small, soft materials such as extracellular matrix polymers.