Polypropylene Homopolymer and Copolymer Impact Performance Differences
Polypropylene impact copolymers sacrifice flexural modulus to gain sub-zero toughness through dispersed ethylene-propylene rubber domains in an isotactic matrix.
Instrumentated Drop Weight
Meaning
Dynamic testing equipment captures the complete force-deflection curve during a strike to evaluate the toughness of plastic sheets or finished parts. Unlike simple pendulum tests, instrumentated drop weight provides a continuous record of the energy absorbed from the moment of contact to final failure. The data gathered helps engineers understand the transition between ductile and brittle behavior under realistic strike conditions.
Measurement Precision
Sensors mounted on the striker tip or the support base record force at microsecond intervals. This high-speed acquisition allows the instrumentated drop weight to distinguish between the energy required to start a crack and the energy required to propagate it. Such granularity is necessary for selecting resins for automotive bumpers or safety equipment.
Data Output
Results typically include peak force and total energy absorbed by the specimen. Load curves show whether the material yielded gradually or failed suddenly without deformation.
Failure Analysis
Visual inspection of the puncture site combined with the recorded data reveals the specific failure mode of the polymer. Brittle failures show clean cracks with little energy absorption, while ductile failures involve stretching and whitening of the material. Instrumentated drop weight remains the standard for assessing thin-walled packaging and heavy-duty structural components.