to disintegrate /dɪˈsɪntəˌgreɪt/ /dɪsˈɪntɪgreɪt/
to break up /breɪk ʌp/ /breɪk ʌp/
to break down /breɪk daʊn/ /breɪk daʊn/
to crumble /ˈkrʌmbəl/ /ˈkrʌmbl/
to come apart /kʌm əˈpɑrt/ /kʌm əˈpɑːt/