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Particles cannot be rendered by default, and they always need an object attached (see → "Particle Rendering"). Currently it is not possible to render particle instances with motion blur.
Rigid and Elastic
Both deformer types do not support motion blur at the moment (fix is underway)Motion blur with these deformer is only supported when the affected geometry is cached or baked. Take a look at this → page for a workflow description.
Thinking Particles
RealFlow | Cinema 4D's particles can be turned into → Thinking Particles under Fluid > Particles. These converted particles contain the original velocity information for motion blur effects:
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