If you're a materialist and you think there is no afterlife then I don't believe there would be a void. There's no mechanism for "you" to perceive a void or perceive time.

Its the difference between:

"I see nothing when I close my eyes" (actually you 'see' darkness over time)

and...

"I see nothing through my elbow" (You really don't see anything through your elbow because the capacity for it just doesn't exist.)

Even our basic perception of time is mediated by the structure of our brains... and without that there's no difference between one second and a trillion^trillion years.