This phenomenon is called 連濁 (rendaku). The basic rules for rendaku can be found in the following question, so please take a look at it first:

• Rules or criteria for 連濁: Voiced or unvoiced syllables in compound words

Now, in addition to the rules mentioned in the linked question, there is yet another rule (or "tendency") regarding rendaku: there are several kanji that tend to block rendaku for whatever reasons.

According to Mark Irwin, a prefix 片- (かた; meaning "part", "fragment") is one of such kanji, and many words that start with 片 somehow resist rendaku. See this presentation (PDF) for details.

• 片言 かたこと
• 片恋 かたこい
• 片時 かたとき
• 片袖 かたそで
• 片仮名 かたかな

Likewise, 御【お】-, 御【ご】-, 一【ひと】-, 二【ふた】-, 唐【から】- and so on tend not to accept rendaku:

• 御酒 おさけ
• 一葉 ひとは
• 唐傘 からかさ

Some kanji including -姫【ひめ】, -先【さき】, -浜【はま】 resist rendaku when it's the second component of a compound:

• 砂浜 すなはま
• 歌姫 うたひめ

Unfortunately, even researchers do not know why these kanji block rendaku. It may be worth remembering which kanji tends to block rendaku, but please keep in mind that there are many exceptions like 二葉（ふたば）. Ultimately, you have to remember each word individually.

This phenomenon is called 連濁 (rendaku). The basic rules for rendaku can be found in the following question, so please take a look at it first:

• Rules or criteria for 連濁: Voiced or unvoiced syllables in compound words

Now, in addition to the rules mentioned in the linked question, there is yet another rule (or "tendency") regarding rendaku: there are several kanji that tend to block rendaku for whatever reasons.

According to Mark Irwin, a prefix 片- (かた; meaning "part", "fragment") is one of such kanji, and many words that start with 片 somehow block rendaku. See this presentation (PDF) for details.

• 片言 かたこと
• 片恋 かたこい
• 片時 かたとき
• 片仮名 かたかな

Likewise, 御【お】-, 御【ご】-, 一【ひと】-, 二【ふた】-, 唐【から】- and so on tend not to accept rendaku:

• 御酒 おさけ
• 一葉 ひとは
• 唐傘 からかさ

Some kanji including -姫【ひめ】, -先【さき】, -浜【はま】 block rendaku when it's the second component of a compound:

• 砂浜 すなはま
• 歌姫 うたひめ

Unfortunately, even researchers do not know why these kanji block rendaku. It may be worth remembering which kanji tends to block rendaku, but please keep in mind that there are many exceptions like 二葉（ふたば）. Ultimately, you have to remember each word individually.