Fujiya Instruments has released a free electric guitar library for Native Instruments Kontakt. The Junk Guitar Free instrument includes 500 samples and comes with many articulations.
Junk Guitar Free contains a monophonic mode for riffs and guitar solos, a polyphonic mode with a general mechanism, and a chord mode containing four types of chords.
In monophonic mode, once you press a key, it continues to sound the sample until the next note or stop noise. This is close to the actual guitar playing style, it is suitable for guitar solos and riffs. Polyphonic mode is the most standard mode.
Make sure to check the list of Kontakt Freebies at Rekkerd for many more free downloads.