#, ~ syllabic and morphological boundaries

re~serve = rɪ'zərv
re#serve = ri'sərv (as in re serve that beer)

re~sist = rɪ'zɪst
re#sist = ri'sɪst


Voicing of the consonant depends on the nature of boundary--whether it is a formative boundary or not (cf. C.-J. Bailey).

Affixation has consequences for the sound patterns of the words: one group of affixes don't change the phonological form of the words; the other affects the phonological form.

That those affect phonological forms: formative affixes
That those don't are: word boundary affixes.

All inflectional suffixes (like -ment, -ly, -ness, and other prefixes) don't change the phonological form.

-ive, -ion are formative boundaries; they are added to the words after a boundary which doesn't mark the end of the phonological form of a word. In Eng and for the most part, formative boundary affixes are derived from Latin, and are used in word-formation processing involving the latinate-portion of Eng. vocabulary; while word boundary derivational affixes (like -ment, -ly, etc) are derived from Anglo-Saxon forms are used in word-formation processes involving the Anglo-Saxon portion of Eng. vocabulary (cf. Chomsky and Halle, The Sound Pattern of English)