{"id":866,"date":"2026-06-24T09:16:11","date_gmt":"2026-06-24T09:16:11","guid":{"rendered":"https:\/\/oldhamcoupling.net\/acetal-vs-peek-vs-nylon-centre-disc-which-material-lasts-longest-in-your-application\/"},"modified":"2026-06-24T09:16:11","modified_gmt":"2026-06-24T09:16:11","slug":"acetal-vs-peek-vs-nylon-centre-disc-which-material-lasts-longest-in-your-application","status":"publish","type":"post","link":"https:\/\/oldhamcoupling.net\/vi\/acetal-vs-peek-vs-nylon-centre-disc-which-material-lasts-longest-in-your-application\/","title":{"rendered":"\u0110\u0129a trung t\u00e2m Acetal, PEEK hay Nylon: V\u1eadt li\u1ec7u n\u00e0o b\u1ec1n nh\u1ea5t trong \u1ee9ng d\u1ee5ng c\u1ee7a b\u1ea1n?"},"content":{"rendered":"

\u0110\u0129a trung t\u00e2m l\u00e0 b\u1ed9 ph\u1eadn hao m\u00f2n duy nh\u1ea5t trong kh\u1edbp n\u1ed1i Oldham, v\u00e0 v\u1eadt li\u1ec7u ch\u1ebf t\u1ea1o n\u00f3 quy\u1ebft \u0111\u1ecbnh h\u1ea7u h\u1ebft m\u1ecdi \u0111\u1eb7c t\u00ednh ho\u1ea1t \u0111\u1ed9ng th\u1ef1c t\u1ebf c\u1ee7a c\u1ee5m l\u1eafp r\u00e1p \u2014 tu\u1ed5i th\u1ecd, m\u00f4-men xo\u1eafn ch\u1ecbu \u0111\u01b0\u1ee3c, nhi\u1ec7t \u0111\u1ed9 ho\u1ea1t \u0111\u1ed9ng t\u1ed1i \u0111a, kh\u1ea3 n\u0103ng ch\u1ecbu \u0111\u1ef1ng h\u00f3a ch\u1ea5t v\u00e0 li\u1ec7u c\u00f3 c\u1ea7n b\u00f4i tr\u01a1n hay kh\u00f4ng. Tuy nhi\u00ean, vi\u1ec7c l\u1ef1a ch\u1ecdn v\u1eadt li\u1ec7u \u0111\u0129a l\u1ea1i l\u00e0 m\u1ed9t trong nh\u1eefng b\u01b0\u1edbc th\u01b0\u1eddng b\u1ecb b\u1ecf qua nh\u1ea5t trong vi\u1ec7c x\u00e1c \u0111\u1ecbnh th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt c\u1ee7a kh\u1edbp n\u1ed1i. Nhi\u1ec1u k\u1ef9 s\u01b0 th\u01b0\u1eddng m\u1eb7c \u0111\u1ecbnh s\u1eed d\u1ee5ng v\u1eadt li\u1ec7u m\u00e0 nh\u00e0 s\u1ea3n xu\u1ea5t cung c\u1ea5p theo ti\u00eau chu\u1ea9n m\u00e0 kh\u00f4ng \u0111\u1eb7t c\u00e2u h\u1ecfi li\u1ec7u l\u1ef1a ch\u1ecdn kh\u00e1c c\u00f3 ph\u00f9 h\u1ee3p h\u01a1n v\u1edbi \u0111i\u1ec1u ki\u1ec7n \u1ee9ng d\u1ee5ng c\u1ee7a h\u1ecd hay kh\u00f4ng.<\/p>\n

B\u00e0i vi\u1ebft n\u00e0y cung c\u1ea5p s\u1ef1 so s\u00e1nh chi ti\u1ebft, song song gi\u1eefa ba lo\u1ea1i v\u1eadt li\u1ec7u \u0111\u0129a trung t\u00e2m kh\u1edbp n\u1ed1i Oldham ph\u1ed5 bi\u1ebfn nh\u1ea5t \u2014 acetal (POM)<\/strong>, NH\u00ccN TR\u1ed8M<\/strong>, V\u00e0 nylon gia c\u01b0\u1eddng s\u1ee3i th\u1ee7y tinh (PA66-GF)<\/strong> \u2014 tr\u00ean m\u1ecdi th\u00f4ng s\u1ed1 \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn tu\u1ed5i th\u1ecd v\u00e0 \u0111\u1ed9 tin c\u1eady th\u1ef1c t\u1ebf.<\/p>\n

\n \"So
V\u1eadt li\u1ec7u c\u1ee7a \u0111\u0129a trung t\u00e2m quy\u1ebft \u0111\u1ecbnh t\u1ed1c \u0111\u1ed9 m\u00e0i m\u00f2n, ph\u1ea1m vi nhi\u1ec7t \u0111\u1ed9 ho\u1ea1t \u0111\u1ed9ng, kh\u1ea3 n\u0103ng ch\u1ed1ng \u0103n m\u00f2n h\u00f3a h\u1ecdc v\u00e0 kh\u1ea3 n\u0103ng ch\u1ecbu momen xo\u1eafn \u2014 t\u1ea5t c\u1ea3 \u0111\u1ec1u r\u1ea5t quan tr\u1ecdng \u0111\u1ed1i v\u1edbi hi\u1ec7u su\u1ea5t kh\u00f4ng c\u00f3 \u0111\u1ed9 r\u01a1 trong th\u1eddi gian d\u00e0i.<\/figcaption><\/figure>\n

V\u00ec sao ch\u1ea5t li\u1ec7u \u0111\u0129a phanh quan tr\u1ecdng h\u01a1n ch\u1ea5t li\u1ec7u moay \u1ed1c<\/h2>\n

Trong m\u1ed9t kh\u1edbp n\u1ed1i Oldham \u0111\u01b0\u1ee3c thi\u1ebft k\u1ebf \u0111\u00fang c\u00e1ch, \u0111\u0129a trung t\u00e2m \u0111\u01b0\u1ee3c c\u1ed1 \u00fd thi\u1ebft k\u1ebf l\u00e0 b\u1ed9 ph\u1eadn m\u1ec1m nh\u1ea5t trong to\u00e0n b\u1ed9 c\u1ee5m. C\u00e1c r\u00e3nh tr\u00ean tr\u1ee5c \u2013 \u0111\u01b0\u1ee3c gia c\u00f4ng t\u1eeb h\u1ee3p kim nh\u00f4m ho\u1eb7c th\u00e9p kh\u00f4ng g\u1ec9 \u2013 c\u1ee9ng h\u01a1n nhi\u1ec1u so v\u1edbi b\u1ea5t k\u1ef3 \u0111\u0129a polymer n\u00e0o, v\u00e0 ch\u00ednh \u0111\u0129a l\u00e0 b\u1ed9 ph\u1eadn b\u1ecb m\u00e0i m\u00f2n nhi\u1ec1u nh\u1ea5t khi ti\u1ebfp x\u00fac v\u1edbi c\u00e1c r\u00e3nh n\u00e0y. \u0110\u00e2y l\u00e0 thi\u1ebft k\u1ebf c\u00f3 ch\u1ee7 \u0111\u00edch: m\u1ed9t \u0111\u0129a b\u1ecb m\u00f2n ch\u1ec9 c\u1ea7n thay th\u1ebf trong n\u0103m ph\u00fat; c\u00f2n m\u1ed9t tr\u1ee5c b\u1ecb m\u00f2n c\u1ea7n ph\u1ea3i thay th\u1ebf to\u00e0n b\u1ed9 n\u1eeda kh\u1edbp n\u1ed1i v\u00e0 c\u0103n ch\u1ec9nh l\u1ea1i tr\u1ee5c.<\/p>\n

Do \u0111\u00f3, v\u1eadt li\u1ec7u c\u1ee7a \u0111\u0129a kh\u1edbp quy\u1ebft \u0111\u1ecbnh t\u1ed1c \u0111\u1ed9 m\u00e0i m\u00f2n c\u1ee7a to\u00e0n b\u1ed9 kh\u1edbp n\u1ed1i. M\u1ed9t \u0111\u0129a qu\u00e1 m\u1ec1m so v\u1edbi m\u00f4-men xo\u1eafn truy\u1ec1n t\u1ea3i s\u1ebd nhanh ch\u00f3ng b\u1ecb m\u00e0i m\u00f2n, t\u1ea1o ra \u0111\u1ed9 r\u01a1 trong v\u00f2ng h\u00e0ng tr\u0103m gi\u1edd. M\u1ed9t \u0111\u0129a \u0111\u01b0\u1ee3c l\u1ef1a ch\u1ecdn \u0111\u00fang c\u00e1ch c\u00f3 th\u1ec3 ho\u1ea1t \u0111\u1ed9ng h\u00e0ng ngh\u00ecn gi\u1edd tr\u01b0\u1edbc khi c\u1ea7n thay th\u1ebf. L\u1ef1a ch\u1ecdn \u0111\u00fang v\u1eadt li\u1ec7u l\u00e0 c\u00e1ch hi\u1ec7u qu\u1ea3 nh\u1ea5t \u0111\u1ec3 k\u00e9o d\u00e0i tu\u1ed5i th\u1ecd c\u1ee7a kh\u1edbp n\u1ed1i gi\u1eefa c\u00e1c l\u1ea7n b\u1ea3o tr\u00ec.<\/p>\n

Acetal (POM): Ch\u1ea5t li\u1ec7u m\u1eb7c \u0111\u1ecbnh ph\u1ed5 bi\u1ebfn<\/h2>\n

Polyoxymethylene \u2014 \u0111\u01b0\u1ee3c b\u00e1n d\u01b0\u1edbi c\u00e1c t\u00ean th\u01b0\u01a1ng m\u1ea1i nh\u01b0 Delrin (DuPont) v\u00e0 Hostaform \u2014 l\u00e0 v\u1eadt li\u1ec7u \u0111\u0129a ti\u00eau chu\u1ea9n cho ph\u1ea7n l\u1edbn c\u00e1c \u1ee9ng d\u1ee5ng chuy\u1ec3n \u0111\u1ed9ng ch\u00ednh x\u00e1c. S\u1ef1 th\u1ed1ng tr\u1ecb c\u1ee7a n\u00f3 l\u00e0 ho\u00e0n to\u00e0n x\u1ee9ng \u0111\u00e1ng.<\/p>\n

C\u00e1c \u0111\u1eb7c t\u00ednh ch\u00ednh:<\/strong> Acetal c\u00f3 \u0111\u1ed9 \u1ed5n \u0111\u1ecbnh k\u00edch th\u01b0\u1edbc tuy\u1ec7t v\u1eddi, ngh\u0129a l\u00e0 \u0111\u0129a \u0111\u01b0\u1ee3c gia c\u00f4ng v\u1edbi dung sai ch\u1eb7t ch\u1ebd s\u1ebd duy tr\u00ec trong ph\u1ea1m vi dung sai \u0111\u00f3 trong to\u00e0n b\u1ed9 d\u1ea3i nhi\u1ec7t \u0111\u1ed9 ho\u1ea1t \u0111\u1ed9ng b\u00ecnh th\u01b0\u1eddng. H\u1ec7 s\u1ed1 ma s\u00e1t c\u1ee7a n\u00f3 v\u1edbi th\u00e9p v\u00e0 nh\u00f4m th\u1ea5p \u2014 trong kho\u1ea3ng t\u1eeb 0,1 \u0111\u1ebfn 0,3 t\u00f9y thu\u1ed9c v\u00e0o \u0111\u1ed9 ho\u00e0n thi\u1ec7n b\u1ec1 m\u1eb7t v\u00e0 t\u1ea3i tr\u1ecdng \u2014 \u0111\u00f3 l\u00e0 l\u00fd do t\u1ea1i sao \u0111\u0129a acetal ho\u1ea1t \u0111\u1ed9ng kh\u00f4 m\u00e0 kh\u00f4ng c\u1ea7n b\u00f4i tr\u01a1n v\u00e0 ho\u1ea1t \u0111\u1ed9ng nh\u01b0 v\u1eady trong th\u1eddi gian d\u00e0i m\u00e0 kh\u00f4ng t\u1ea1o ra nhi\u1ec7t \u0111\u00e1ng k\u1ec3. \u0110\u1ed9 b\u1ec1n n\u00e9n (kho\u1ea3ng 130 MPa) v\u00e0 \u0111\u1ed9 c\u1ee9ng c\u1ee7a n\u00f3 \u0111\u1ee7 cho c\u00e1c \u1ee9ng d\u1ee5ng m\u00f4-men xo\u1eafn nh\u1eb9 \u0111\u1ebfn trung b\u00ecnh.<\/p>\n

Ph\u1ea1m vi nhi\u1ec7t \u0111\u1ed9:<\/strong> Nhi\u1ec7t \u0111\u1ed9 ho\u1ea1t \u0111\u1ed9ng li\u00ean t\u1ee5c th\u01b0\u1eddng \u0111\u01b0\u1ee3c gi\u1edbi h\u1ea1n \u1edf m\u1ee9c 90\u2013100\u00b0C. V\u01b0\u1ee3t qu\u00e1 ph\u1ea1m vi n\u00e0y, acetal b\u1eaft \u0111\u1ea7u m\u1ec1m \u0111i \u0111\u00e1ng k\u1ec3, l\u00e0m gi\u1ea3m \u0111\u1ed9 b\u1ec1n n\u00e9n v\u00e0 \u0111\u1ea9y nhanh t\u1ed1c \u0111\u1ed9 m\u00e0i m\u00f2n. Trong c\u00e1c \u1ee9ng d\u1ee5ng m\u00e0 \u0111\u0129a ho\u1ea1t \u0111\u1ed9ng g\u1ea7n \u0111\u1ed9ng c\u01a1 n\u00f3ng ho\u1eb7c trong m\u00f4i tr\u01b0\u1eddng \u0111\u01b0\u1ee3c l\u00e0m n\u00f3ng, nhi\u1ec7t \u0111\u1ed9 c\u1ee7a \u0111\u0129a c\u00f3 th\u1ec3 v\u01b0\u1ee3t qu\u00e1 \u0111\u00e1ng k\u1ec3 nhi\u1ec7t \u0111\u1ed9 kh\u00f4ng kh\u00ed xung quanh \u2014 m\u1ed9t y\u1ebfu t\u1ed1 th\u01b0\u1eddng b\u1ecb \u0111\u00e1nh gi\u00e1 th\u1ea5p.<\/p>\n

Kh\u1ea3 n\u0103ng kh\u00e1ng h\u00f3a ch\u1ea5t:<\/strong> Acetal c\u00f3 kh\u1ea3 n\u0103ng ch\u1ed1ng l\u1ea1i h\u1ea7u h\u1ebft c\u00e1c hydrocarbon, d\u1ea7u, r\u01b0\u1ee3u v\u00e0 axit, baz\u01a1 lo\u00e3ng. N\u00f3 b\u1ecb t\u1ea5n c\u00f4ng b\u1edfi c\u00e1c axit oxy h\u00f3a \u0111\u1eadm \u0111\u1eb7c (axit nitric \u0111\u1eadm \u0111\u1eb7c, axit sulfuric), ki\u1ec1m m\u1ea1nh v\u00e0 m\u1ed9t s\u1ed1 dung m\u00f4i clo h\u00f3a. Trong b\u1ed1i c\u1ea3nh ch\u1ea5t l\u00e0m m\u00e1t m\u00e1y c\u00f4ng c\u1ee5, h\u1ea7u h\u1ebft c\u00e1c ch\u1ea5t l\u1ecfng c\u1eaft g\u1ecdt h\u00f2a tan trong n\u01b0\u1edbc v\u00e0 d\u1ea7u b\u00f4i tr\u01a1n nh\u1eb9, acetal ho\u1ea1t \u0111\u1ed9ng t\u1ed1t.<\/p>\n

Ph\u00f9 h\u1ee3p nh\u1ea5t cho:<\/strong> \u1ee8ng d\u1ee5ng trong \u0111i\u1ec1u khi\u1ec3n \u0111\u1ed9ng c\u01a1 servo v\u00e0 \u0111\u1ed9ng c\u01a1 b\u01b0\u1edbc \u1edf t\u1ea3i tr\u1ecdng v\u00e0 t\u1ed1c \u0111\u1ed9 v\u1eeba ph\u1ea3i, k\u1ebft n\u1ed1i b\u1ed9 m\u00e3 h\u00f3a, tr\u1ee5c m\u00e1y CNC, d\u1ee5ng c\u1ee5 ph\u00f2ng th\u00ed nghi\u1ec7m, m\u00e1y \u0111\u00f3ng g\u00f3i v\u00e0 b\u1ea5t k\u1ef3 \u1ee9ng d\u1ee5ng chuy\u1ec3n \u0111\u1ed9ng ch\u00ednh x\u00e1c \u0111a n\u0103ng n\u00e0o \u1edf nhi\u1ec7t \u0111\u1ed9 m\u00f4i tr\u01b0\u1eddng b\u00ecnh th\u01b0\u1eddng.<\/p>\n

Nylon gia c\u01b0\u1eddng s\u1ee3i th\u1ee7y tinh (PA66-GF): B\u01b0\u1edbc ti\u1ebfn v\u01b0\u1ee3t b\u1eadc cho \u0111i\u1ec1u ki\u1ec7n kh\u1eafc nghi\u1ec7t h\u01a1n<\/h2>\n

Nylon 66 \u0111\u01b0\u1ee3c gia c\u01b0\u1eddng b\u1eb1ng 30% s\u1ee3i th\u1ee7y tinh l\u00e0 l\u1ef1a ch\u1ecdn n\u00e2ng c\u1ea5p t\u1ef1 nhi\u00ean khi acetal b\u1eaft \u0111\u1ea7u b\u1ed9c l\u1ed9 nh\u1eefng h\u1ea1n ch\u1ebf c\u1ee7a n\u00f3 \u2014 \u0111\u1eb7c bi\u1ec7t l\u00e0 khi c\u1ea7n kh\u1ea3 n\u0103ng ch\u1ecbu momen xo\u1eafn cao h\u01a1n ho\u1eb7c nhi\u1ec7t \u0111\u1ed9 ho\u1ea1t \u0111\u1ed9ng cao h\u01a1n m\u00e0 kh\u00f4ng c\u1ea7n chuy\u1ec3n sang s\u1eed d\u1ee5ng PEEK \u0111\u1eaft ti\u1ec1n.<\/p>\n

C\u00e1c \u0111\u1eb7c t\u00ednh ch\u00ednh:<\/strong> Vi\u1ec7c gia c\u01b0\u1eddng b\u1eb1ng s\u1ee3i th\u1ee7y tinh l\u00e0m t\u0103ng c\u01b0\u1eddng \u0111\u1ed9 b\u1ec1n n\u00e9n l\u00ean kho\u1ea3ng 180\u2013200 MPa \u2014 cao h\u01a1n kho\u1ea3ng 50% so v\u1edbi acetal kh\u00f4ng pha tr\u1ed9n \u2014 v\u00e0 l\u00e0m t\u0103ng \u0111\u00e1ng k\u1ec3 \u0111\u1ed9 c\u1ee9ng v\u00e0 kh\u1ea3 n\u0103ng ch\u1ed1ng bi\u1ebfn d\u1ea1ng d\u1ebbo c\u1ee7a v\u1eadt li\u1ec7u d\u01b0\u1edbi t\u1ea3i tr\u1ecdng k\u00e9o d\u00e0i. \u0110\u1ed9 b\u1ec1n cao h\u01a1n n\u00e0y cho ph\u00e9p \u0111\u0129a nylon pha s\u1ee3i th\u1ee7y tinh ch\u1ecbu \u0111\u01b0\u1ee3c m\u00f4-men xo\u1eafn cao h\u01a1n v\u1edbi c\u00f9ng k\u00edch th\u01b0\u1edbc v\u1eadt l\u00fd nh\u01b0 \u0111\u0129a acetal, ho\u1eb7c n\u00f3i c\u00e1ch kh\u00e1c, \u0111\u1ea1t \u0111\u01b0\u1ee3c tu\u1ed5i th\u1ecd s\u1eed d\u1ee5ng l\u00e2u h\u01a1n \u1edf c\u00f9ng m\u1ee9c m\u00f4-men xo\u1eafn b\u1eb1ng c\u00e1ch gi\u1ea3m \u1ee9ng su\u1ea5t ti\u1ebfp x\u00fac tr\u00ean c\u00e1c m\u1eb7t m\u1ed9ng.<\/p>\n

Ph\u1ea1m vi nhi\u1ec7t \u0111\u1ed9:<\/strong> Ho\u1ea1t \u0111\u1ed9ng li\u00ean t\u1ee5c \u1edf nhi\u1ec7t \u0111\u1ed9 kho\u1ea3ng 120\u2013130\u00b0C, v\u1edbi c\u00e1c \u0111\u1ec9nh nhi\u1ec7t ng\u1eafn h\u1ea1n l\u00ean \u0111\u1ebfn kho\u1ea3ng 150\u00b0C. \u0110i\u1ec1u n\u00e0y mang l\u1ea1i kh\u1ea3 n\u0103ng ch\u1ecbu nhi\u1ec7t \u0111\u00e1ng k\u1ec3 so v\u1edbi nh\u1ef1a acetal trong c\u00e1c \u1ee9ng d\u1ee5ng g\u1ea7n \u0111\u1ed9ng c\u01a1 n\u00f3ng ho\u1eb7c trong m\u00f4i tr\u01b0\u1eddng c\u00f3 nhi\u1ec7t \u0111\u1ed9 xung quanh t\u01b0\u01a1ng \u0111\u1ed1i cao, ch\u1eb3ng h\u1ea1n nh\u01b0 v\u1ecf m\u00e1y m\u00f3c v\u00e0o m\u00f9a h\u00e8.<\/p>\n

Kh\u1ea3 n\u0103ng kh\u00e1ng h\u00f3a ch\u1ea5t:<\/strong> Nylon 66 d\u1ec5 b\u1ecb h\u00fat \u1ea9m h\u01a1n acetal \u2014 trong m\u00f4i tr\u01b0\u1eddng \u1ea9m \u01b0\u1edbt, n\u00f3 c\u00f3 th\u1ec3 h\u1ea5p th\u1ee5 t\u1edbi 3% n\u01b0\u1edbc theo tr\u1ecdng l\u01b0\u1ee3ng, g\u00e2y ra hi\u1ec7n t\u01b0\u1ee3ng gi\u00e3n n\u1edf k\u00edch th\u01b0\u1edbc c\u00f3 th\u1ec3 \u0111o \u0111\u01b0\u1ee3c. \u0110\u1ed1i v\u1edbi c\u00e1c \u1ee9ng d\u1ee5ng y\u00eau c\u1ea7u \u0111\u1ed9 ch\u00ednh x\u00e1c kh\u00f4ng c\u00f3 khe h\u1edf, n\u01a1i dung sai kh\u1edbp m\u1ed9ng v\u00e0 r\u00e3nh l\u00e0 r\u1ea5t quan tr\u1ecdng, t\u00ednh nh\u1ea1y c\u1ea3m v\u1edbi \u0111\u1ed9 \u1ea9m n\u00e0y l\u00e0 m\u1ed9t nh\u01b0\u1ee3c \u0111i\u1ec3m ti\u1ec1m t\u00e0ng. Nylon kh\u00f4ng pha tr\u1ed9n c\u0169ng b\u1ecb t\u1ea5n c\u00f4ng b\u1edfi c\u00e1c axit m\u1ea1nh; c\u00e1c lo\u1ea1i nylon pha tr\u1ed9n s\u1ee3i th\u1ee7y tinh c\u1ea3i thi\u1ec7n kh\u1ea3 n\u0103ng kh\u00e1ng h\u00f3a ch\u1ea5t ph\u1ea7n n\u00e0o nh\u01b0ng kh\u00f4ng b\u1eb1ng acetal ho\u1eb7c PEEK v\u1ec1 m\u1eb7t n\u00e0y.<\/p>\n

\u0110\u1eb7c t\u00ednh m\u00e0i m\u00f2n:<\/strong> Nylon gia c\u01b0\u1eddng s\u1ee3i th\u1ee7y tinh c\u00f3 ma s\u00e1t v\u1edbi kim lo\u1ea1i cao h\u01a1n m\u1ed9t ch\u00fat so v\u1edbi acetal, \u0111i\u1ec1u n\u00e0y c\u00f3 ngh\u0129a l\u00e0 \u0111\u0129a t\u1ea1o ra nhi\u1ec7t nhi\u1ec1u h\u01a1n m\u1ed9t ch\u00fat tr\u00ean m\u1ed7i \u0111\u01a1n v\u1ecb c\u00f4ng tr\u01b0\u1ee3t. Tr\u00ean th\u1ef1c t\u1ebf, s\u1ef1 kh\u00e1c bi\u1ec7t n\u00e0y nh\u1ecf \u1edf t\u1ed1c \u0111\u1ed9 b\u00ecnh th\u01b0\u1eddng, nh\u01b0ng \u1edf t\u1ed1c \u0111\u1ed9 cao k\u1ebft h\u1ee3p v\u1edbi \u0111\u1ed9 l\u1ec7ch tr\u1ee5c \u0111\u00e1ng k\u1ec3, \u0111\u1eb7c t\u00ednh nhi\u1ec7t c\u1ee7a nylon gia c\u01b0\u1eddng s\u1ee3i th\u1ee7y tinh k\u00e9m thu\u1eadn l\u1ee3i h\u01a1n so v\u1edbi acetal.<\/p>\n

Ph\u00f9 h\u1ee3p nh\u1ea5t cho:<\/strong> C\u00e1c b\u1ed9 truy\u1ec1n \u0111\u1ed9ng servo c\u00f3 m\u00f4-men xo\u1eafn cao, n\u01a1i v\u1eadt li\u1ec7u acetal d\u1ec5 b\u1ecb m\u00e0i m\u00f2n, c\u00e1c \u1ee9ng d\u1ee5ng trong m\u00f4i tr\u01b0\u1eddng nhi\u1ec7t \u0111\u1ed9 t\u01b0\u01a1ng \u0111\u1ed1i cao, t\u1ef1 \u0111\u1ed9ng h\u00f3a c\u00f4ng nghi\u1ec7p trong \u0111i\u1ec1u ki\u1ec7n kh\u00f4ng \u1ea9m \u01b0\u1edbt.<\/p>\n

\n \"L\u1ef1a
M\u1ed7i lo\u1ea1i v\u1eadt li\u1ec7u \u0111\u0129a chi\u1ebfm m\u1ed9t v\u1ecb tr\u00ed kh\u00e1c nhau tr\u00ean ph\u1ea1m vi hi\u1ec7u su\u1ea5t \u2014 vi\u1ec7c l\u1ef1a ch\u1ecdn \u0111\u00fang \u0111\u00f2i h\u1ecfi ph\u1ea3i ph\u00f9 h\u1ee3p gi\u1eefa \u01b0u \u0111i\u1ec3m c\u1ee7a v\u1eadt li\u1ec7u v\u1edbi c\u00e1c y\u00eau c\u1ea7u ch\u1ee7 y\u1ebfu c\u1ee7a \u1ee9ng d\u1ee5ng.<\/figcaption><\/figure>\n

PEEK: S\u1ef1 l\u1ef1a ch\u1ecdn cao c\u1ea5p d\u00e0nh cho m\u00f4i tr\u01b0\u1eddng \u0111\u00f2i h\u1ecfi kh\u1eaft khe<\/h2>\n

Polyether ether ketone l\u00e0 m\u1ed9t lo\u1ea1i nh\u1ef1a nhi\u1ec7t d\u1ebbo k\u1ef9 thu\u1eadt c\u00f3 hi\u1ec7u su\u1ea5t kh\u00e1c bi\u1ec7t so v\u1edbi acetal v\u00e0 nylon. C\u00e1c \u0111\u1eb7c t\u00ednh c\u01a1 h\u1ecdc \u1edf nhi\u1ec7t \u0111\u1ed9 cao, kh\u1ea3 n\u0103ng kh\u00e1ng h\u00f3a ch\u1ea5t v\u00e0 t\u00ednh t\u01b0\u01a1ng th\u00edch sinh h\u1ecdc khi\u1ebfn n\u00f3 tr\u1edf th\u00e0nh v\u1eadt li\u1ec7u \u0111\u0129a \u0111\u01b0\u1ee3c l\u1ef1a ch\u1ecdn khi m\u00f4i tr\u01b0\u1eddng \u1ee9ng d\u1ee5ng v\u01b0\u1ee3t qu\u00e1 kh\u1ea3 n\u0103ng ch\u1ecbu \u0111\u1ef1ng c\u1ee7a acetal ho\u1eb7c nylon. Chi ph\u00ed cao h\u01a1n \u0111\u00e1ng k\u1ec3 c\u1ee7a n\u00f3 ch\u1ec9 \u0111\u01b0\u1ee3c bi\u1ec7n minh khi nh\u1eefng \u0111i\u1ec1u ki\u1ec7n kh\u1eafc nghi\u1ec7t \u0111\u00f3 th\u1ef1c s\u1ef1 t\u1ed3n t\u1ea1i.<\/p>\n

C\u00e1c \u0111\u1eb7c t\u00ednh ch\u00ednh:<\/strong> \u0110\u1ed9 b\u1ec1n n\u00e9n c\u1ee7a PEEK v\u01b0\u1ee3t qu\u00e1 200 MPa \u1edf nhi\u1ec7t \u0111\u1ed9 ph\u00f2ng v\u00e0 \u2013 \u0111i\u1ec1u quan tr\u1ecdng \u2013 n\u00f3 v\u1eabn gi\u1eef \u0111\u01b0\u1ee3c ph\u1ea7n l\u1edbn \u0111\u1ed9 b\u1ec1n n\u00e0y \u1edf nhi\u1ec7t \u0111\u1ed9 l\u00ean \u0111\u1ebfn 200\u00b0C. T\u00ednh \u1ed5n \u0111\u1ecbnh nhi\u1ec7t n\u00e0y c\u00f3 ngh\u0129a l\u00e0 m\u1ed9t \u0111\u0129a PEEK trong m\u00f4i tr\u01b0\u1eddng n\u00f3ng (g\u1ea7n \u0111\u1ed9ng c\u01a1 qu\u00e1 n\u00f3ng, b\u00ean trong bu\u1ed3ng x\u1eed l\u00fd ho\u1eb7c ho\u1ea1t \u0111\u1ed9ng \u1edf nhi\u1ec7t \u0111\u1ed9 m\u00f4i tr\u01b0\u1eddng cao) v\u1eabn duy tr\u00ec \u0111\u01b0\u1ee3c \u0111\u1ed9 \u1ed5n \u0111\u1ecbnh v\u1ec1 k\u00edch th\u01b0\u1edbc v\u00e0 kh\u1ea3 n\u0103ng ch\u1ecbu t\u1ea3i, trong khi \u0111\u00f3 acetal s\u1ebd b\u1ecb m\u1ec1m v\u00e0 b\u1eaft \u0111\u1ea7u bi\u1ebfn d\u1ea1ng.<\/p>\n

Ph\u1ea1m vi nhi\u1ec7t \u0111\u1ed9:<\/strong> C\u00f3 th\u1ec3 ho\u1ea1t \u0111\u1ed9ng li\u00ean t\u1ee5c \u1edf nhi\u1ec7t \u0111\u1ed9 l\u00ean \u0111\u1ebfn 250\u00b0C, v\u00e0 ch\u1ecbu \u0111\u01b0\u1ee3c nhi\u1ec7t \u0111\u1ed9 ng\u1eafn h\u1ea1n l\u00ean \u0111\u1ebfn 300\u00b0C. PEEK c\u00f3 th\u1ec3 ch\u1ecbu \u0111\u01b0\u1ee3c nhi\u1ec1u chu k\u1ef3 ti\u1ec7t tr\u00f9ng b\u1eb1ng n\u1ed3i h\u1ea5p (h\u01a1i n\u01b0\u1edbc 134\u00b0C) m\u00e0 kh\u00f4ng b\u1ecb thay \u0111\u1ed5i k\u00edch th\u01b0\u1edbc \u2014 m\u1ed9t \u0111\u1eb7c t\u00ednh m\u00e0 kh\u00f4ng c\u00f3 v\u1eadt li\u1ec7u \u0111\u0129a th\u00f4ng th\u01b0\u1eddng n\u00e0o kh\u00e1c c\u00f3 th\u1ec3 s\u00e1nh \u0111\u01b0\u1ee3c. \u0110i\u1ec1u n\u00e0y l\u00e0m cho n\u00f3 tr\u1edf th\u00e0nh l\u1ef1a ch\u1ecdn b\u1eaft bu\u1ed9c cho c\u00e1c thi\u1ebft b\u1ecb y t\u1ebf c\u1ea7n ti\u1ec7t tr\u00f9ng.<\/p>\n

Kh\u1ea3 n\u0103ng kh\u00e1ng h\u00f3a ch\u1ea5t:<\/strong> PEEK c\u00f3 kh\u1ea3 n\u0103ng ch\u1ed1ng ch\u1ecbu v\u01b0\u1ee3t tr\u1ed9i v\u1edbi h\u1ea7u h\u1ebft c\u00e1c h\u00f3a ch\u1ea5t c\u00f4ng nghi\u1ec7p \u2014 axit \u0111\u1eadm \u0111\u1eb7c (bao g\u1ed3m axit sulfuric v\u00e0 nitric \u1edf nhi\u1ec7t \u0111\u1ed9 v\u1eeba ph\u1ea3i), baz\u01a1 m\u1ea1nh, hydrocarbon, ketone, ester v\u00e0 h\u1ea7u h\u1ebft c\u00e1c dung m\u00f4i h\u1eefu c\u01a1. Ngo\u1ea1i l\u1ec7 \u0111\u00e1ng k\u1ec3 duy nh\u1ea5t l\u00e0 m\u1ed9t s\u1ed1 dung m\u00f4i halogen h\u00f3a v\u00e0 axit sulfuric n\u1ed3ng \u0111\u1ed9 r\u1ea5t cao tr\u00ean 150\u00b0C. Trong m\u00f4i tr\u01b0\u1eddng s\u1ea3n xu\u1ea5t d\u01b0\u1ee3c ph\u1ea9m v\u1edbi c\u00e1c ch\u1ea5t t\u1ea9y r\u1eeda m\u1ea1nh, PEEK v\u1ec1 c\u01a1 b\u1ea3n l\u00e0 v\u1eadt li\u1ec7u polymer duy nh\u1ea5t kh\u1ea3 thi cho \u0111\u0129a.<\/p>\n

Kh\u1ea3 n\u0103ng ch\u1ed1ng b\u1ee9c x\u1ea1:<\/strong> PEEK v\u1eabn gi\u1eef \u0111\u01b0\u1ee3c c\u00e1c \u0111\u1eb7c t\u00ednh c\u1ee7a n\u00f3 sau khi ti\u1ebfp x\u00fac v\u1edbi li\u1ec1u chi\u1ebfu x\u1ea1 gamma \u0111\u1ec3 kh\u1eed tr\u00f9ng, trong khi nhi\u1ec1u lo\u1ea1i polymer kh\u00e1c, bao g\u1ed3m c\u1ea3 acetal, l\u1ea1i b\u1ecb ph\u00e2n h\u1ee7y. \u0110\u1ed1i v\u1edbi c\u00e1c thi\u1ebft b\u1ecb y t\u1ebf \u0111\u01b0\u1ee3c kh\u1eed tr\u00f9ng b\u1eb1ng chi\u1ebfu x\u1ea1 gamma, \u0111\u0129a PEEK l\u00e0 ti\u00eau chu\u1ea9n \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng.<\/p>\n

C\u00e2n nh\u1eafc v\u1ec1 chi ph\u00ed:<\/strong> Nguy\u00ean li\u1ec7u th\u00f4 PEEK c\u00f3 gi\u00e1 cao h\u01a1n kho\u1ea3ng 20 \u0111\u1ebfn 50 l\u1ea7n so v\u1edbi acetal t\u00ednh theo kilogram. \u0110\u1ed1i v\u1edbi m\u1ed9t \u0111\u0129a kh\u1edbp nh\u1ecf, \u0111i\u1ec1u n\u00e0y d\u1eabn \u0111\u1ebfn m\u1ed9t kho\u1ea3n ph\u00ed ch\u00eanh l\u1ec7ch \u0111\u00e1ng k\u1ec3 nh\u01b0ng kh\u00f4ng qu\u00e1 l\u1edbn \u2014 th\u01b0\u1eddng g\u1ea5p 3 \u0111\u1ebfn 8 l\u1ea7n gi\u00e1 c\u1ee7a m\u1ed9t \u0111\u0129a acetal t\u01b0\u01a1ng \u0111\u01b0\u01a1ng. Kho\u1ea3n ph\u00ed ch\u00eanh l\u1ec7ch n\u00e0y ho\u00e0n to\u00e0n h\u1ee3p l\u00fd khi m\u00f4i tr\u01b0\u1eddng th\u1ef1c s\u1ef1 y\u00eau c\u1ea7u c\u00e1c \u0111\u1eb7c t\u00ednh c\u1ee7a PEEK; tuy nhi\u00ean, \u0111\u00f3 l\u00e0 m\u1ed9t kho\u1ea3n chi ph\u00ed kh\u00f4ng c\u1ea7n thi\u1ebft trong c\u00e1c \u1ee9ng d\u1ee5ng c\u00f4ng nghi\u1ec7p th\u00f4ng th\u01b0\u1eddng, n\u01a1i acetal ho\u1ea1t \u0111\u1ed9ng t\u1ed1t.<\/p>\n

Ph\u00f9 h\u1ee3p nh\u1ea5t cho:<\/strong> C\u00e1c thi\u1ebft b\u1ecb y t\u1ebf c\u1ea7n kh\u1eed tr\u00f9ng, s\u1ea3n xu\u1ea5t d\u01b0\u1ee3c ph\u1ea9m v\u1edbi h\u00f3a ch\u1ea5t CIP\/SIP m\u1ea1nh, m\u00f4i tr\u01b0\u1eddng c\u00f4ng nghi\u1ec7p nhi\u1ec7t \u0111\u1ed9 cao, ph\u00f2ng s\u1ea1ch b\u00e1n d\u1eabn y\u00eau c\u1ea7u kh\u1ea3 n\u0103ng t\u01b0\u01a1ng th\u00edch sinh h\u1ecdc theo ti\u00eau chu\u1ea9n ISO 10993, v\u00e0 b\u1ea5t k\u1ef3 \u1ee9ng d\u1ee5ng n\u00e0o m\u00e0 \u0111\u1ed9 \u1ed5n \u0111\u1ecbnh k\u00edch th\u01b0\u1edbc l\u00e2u d\u00e0i d\u01b0\u1edbi t\u00e1c \u0111\u1ed9ng \u0111\u1ed3ng th\u1eddi c\u1ee7a nhi\u1ec7t v\u00e0 h\u00f3a ch\u1ea5t l\u00e0 r\u1ea5t quan tr\u1ecdng.<\/p>\n

B\u1ea3ng so s\u00e1nh tr\u1ef1c ti\u1ebfp<\/h2>\n
\n
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
T\u00e0i s\u1ea3n<\/th>\nAcetal (POM)<\/th>\nNylon PA66-GF30<\/th>\nNH\u00ccN TR\u1ed8M<\/th>\n<\/tr>\n<\/thead>\n
C\u01b0\u1eddng \u0111\u1ed9 n\u00e9n<\/td>\n~130 MPa<\/td>\n~180 MPa<\/td>\n~200 MPa<\/td>\n<\/tr>\n
Nhi\u1ec7t \u0111\u1ed9 li\u00ean t\u1ee5c t\u1ed1i \u0111a<\/td>\n90\u2013100\u00b0C<\/td>\n120\u2013130\u00b0C<\/td>\n250\u00b0C<\/td>\n<\/tr>\n
ti\u1ec7t tr\u00f9ng b\u1eb1ng n\u1ed3i h\u1ea5p<\/td>\nKH\u00d4NG<\/td>\nKH\u00d4NG<\/td>\n\u0110\u00fang<\/td>\n<\/tr>\n
Ch\u1ea1y kh\u00f4 (kh\u00f4ng b\u00f4i tr\u01a1n)<\/td>\nXu\u1ea5t s\u1eafc<\/td>\nT\u1ed1t<\/td>\nT\u1ed1t<\/td>\n<\/tr>\n
H\u1ea5p th\u1ee5 \u0111\u1ed9 \u1ea9m<\/td>\nR\u1ea5t th\u1ea5p (<0,25%)<\/td>\nCao (2\u20133%)<\/td>\nR\u1ea5t th\u1ea5p (<0,5%)<\/td>\n<\/tr>\n
Kh\u1ea3 n\u0103ng kh\u00e1ng h\u00f3a ch\u1ea5t<\/td>\nT\u1ed1t<\/td>\nV\u1eeba ph\u1ea3i<\/td>\nXu\u1ea5t s\u1eafc<\/td>\n<\/tr>\n
Kh\u1ea3 n\u0103ng ch\u1ed1ng b\u1ee9c x\u1ea1 gamma<\/td>\nNgh\u00e8o<\/td>\nV\u1eeba ph\u1ea3i<\/td>\nT\u1ed1t<\/td>\n<\/tr>\n
T\u00ednh \u1ed5n \u0111\u1ecbnh v\u1ec1 k\u00edch th\u01b0\u1edbc<\/td>\nXu\u1ea5t s\u1eafc<\/td>\n\u0110\u1ed9 \u1ea9m v\u1eeba ph\u1ea3i<\/td>\nXu\u1ea5t s\u1eafc<\/td>\n<\/tr>\n
Kh\u1ea3 n\u0103ng ch\u1ecbu m\u00f4-men xo\u1eafn (t\u01b0\u01a1ng \u0111\u1ed1i)<\/td>\n1.0\u00d7<\/td>\n1,4\u00d7<\/td>\n1,6\u00d7<\/td>\n<\/tr>\n
Chi ph\u00ed \u0111\u0129a t\u01b0\u01a1ng \u0111\u1ed1i<\/td>\n1\u00d7<\/td>\n2\u20133\u00d7<\/td>\n5\u20138\u00d7<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

C\u00e1c tr\u01b0\u1eddng h\u1ee3p \u0111\u1eb7c bi\u1ec7t: UHMW-PE, v\u1eadt li\u1ec7u composite PTFE v\u00e0 \u0111\u0129a kim lo\u1ea1i<\/h2>\n

Ngo\u00e0i ba v\u1eadt li\u1ec7u ch\u00ednh, hai l\u1ef1a ch\u1ecdn b\u1ed5 sung xu\u1ea5t hi\u1ec7n trong c\u00e1c \u1ee9ng d\u1ee5ng chuy\u00ean bi\u1ec7t:<\/p>\n

UHMW-PE (Polyethylene c\u00f3 tr\u1ecdng l\u01b0\u1ee3ng ph\u00e2n t\u1eed c\u1ef1c cao):<\/strong> V\u1eadt li\u1ec7u n\u00e0y c\u00f3 h\u1ec7 s\u1ed1 ma s\u00e1t th\u1ea5p nh\u1ea5t so v\u1edbi c\u00e1c v\u1eadt li\u1ec7u \u0111\u0129a th\u00f4ng th\u01b0\u1eddng kh\u00e1c v\u00e0 kh\u1ea3 n\u0103ng ch\u1ed1ng m\u00e0i m\u00f2n v\u01b0\u1ee3t tr\u1ed9i \u1edf \u00e1p su\u1ea5t ti\u1ebfp x\u00fac th\u1ea5p. Tuy nhi\u00ean, n\u00f3 m\u1ec1m h\u01a1n acetal (\u0111\u1ed9 b\u1ec1n n\u00e9n th\u1ea5p h\u01a1n, kho\u1ea3ng 35\u201350 MPa), \u0111i\u1ec1u n\u00e0y h\u1ea1n ch\u1ebf \u0111\u00e1ng k\u1ec3 kh\u1ea3 n\u0103ng ch\u1ecbu momen xo\u1eafn. \u200b\u200bPh\u00f9 h\u1ee3p nh\u1ea5t cho c\u00e1c kh\u1edbp n\u1ed1i t\u1ed1c \u0111\u1ed9 th\u1ea5p, t\u1ea3i tr\u1ecdng r\u1ea5t nh\u1eb9 trong c\u00e1c \u1ee9ng d\u1ee5ng th\u1ef1c ph\u1ea9m ho\u1eb7c v\u1ec7 sinh, n\u01a1i ho\u1ea1t \u0111\u1ed9ng \u00eam \u00e1i, y\u00ean t\u0129nh v\u00e0 gi\u1ea3m thi\u1ec3u sinh h\u1ea1t l\u00e0 t\u1ed1i quan tr\u1ecdng. Nhi\u1ec7t \u0111\u1ed9 ho\u1ea1t \u0111\u1ed9ng t\u1ed1i \u0111a th\u1ea5p \u2014 kho\u1ea3ng 80\u00b0C \u2014 \u0111i\u1ec1u n\u00e0y c\u00e0ng h\u1ea1n ch\u1ebf ph\u1ea1m vi \u1ee9ng d\u1ee5ng c\u1ee7a n\u00f3.<\/p>\n

\u0110\u0129a kim lo\u1ea1i (nh\u00f4m ho\u1eb7c th\u00e9p t\u00f4i c\u1ee9ng):<\/strong> \u0110\u1ed1i v\u1edbi c\u00e1c \u1ee9ng d\u1ee5ng c\u00f4ng nghi\u1ec7p n\u1eb7ng, n\u01a1i y\u00eau c\u1ea7u m\u00f4-men xo\u1eafn v\u01b0\u1ee3t qu\u00e1 kh\u1ea3 n\u0103ng ch\u1ecbu t\u1ea3i c\u1ee7a b\u1ea5t k\u1ef3 \u0111\u0129a polymer n\u00e0o trong k\u00edch th\u01b0\u1edbc kh\u1edbp n\u1ed1i hi\u1ec7n c\u00f3, c\u00e1c \u0111\u0129a kim lo\u1ea1i v\u1edbi r\u00e3nh trung t\u00e2m \u0111\u01b0\u1ee3c b\u00f4i tr\u01a1n cung c\u1ea5p kh\u1ea3 n\u0103ng ch\u1ecbu m\u00f4-men xo\u1eafn cao h\u01a1n t\u1eeb 3 \u0111\u1ebfn 5 l\u1ea7n so v\u1edbi \u0111\u0129a polymer t\u01b0\u01a1ng \u0111\u01b0\u01a1ng. Tuy nhi\u00ean, c\u0169ng c\u00f3 nh\u1eefng nh\u01b0\u1ee3c \u0111i\u1ec3m \u0111\u00e1ng k\u1ec3: kh\u1edbp n\u1ed1i c\u1ea7n \u0111\u01b0\u1ee3c b\u00f4i tr\u01a1n th\u01b0\u1eddng xuy\u00ean, m\u1ea5t \u0111i \u0111\u1eb7c t\u00ednh c\u00e1ch \u0111i\u1ec7n c\u1ee7a \u0111\u0129a polymer, t\u1ea1o ra nhi\u1ec1u ti\u1ebfng \u1ed3n v\u00e0 rung \u0111\u1ed9ng h\u01a1n, v\u00e0 \u0111\u00f2i h\u1ecfi s\u1ef1 c\u0103n ch\u1ec9nh tr\u1ee5c ch\u00ednh x\u00e1c h\u01a1n. Kh\u1edbp n\u1ed1i Oldham b\u1eb1ng \u0111\u0129a kim lo\u1ea1i l\u00e0 s\u1ea3n ph\u1ea9m chuy\u00ean d\u1ee5ng cho c\u00e1c h\u1ec7 th\u1ed1ng truy\u1ec1n \u0111\u1ed9ng c\u00f4ng nghi\u1ec7p t\u1ed1c \u0111\u1ed9 th\u1ea5p \u0111\u1ebfn trung b\u00ecnh, m\u00f4-men xo\u1eafn cao, trong \u0111\u00f3 \u01b0u \u0111i\u1ec3m ch\u00ednh c\u1ee7a kh\u1edbp n\u1ed1i l\u00e0 kh\u1ea3 n\u0103ng x\u1eed l\u00fd \u0111\u1ed9 l\u1ec7ch ngang l\u1edbn trong m\u1ed9t thi\u1ebft k\u1ebf nh\u1ecf g\u1ecdn.<\/p>\n

\n \"H\u01b0\u1edbng
Vi\u1ec7c l\u1ef1a ch\u1ecdn v\u1eadt li\u1ec7u \u0111\u0129a ph\u00f9 h\u1ee3p ngay t\u1eeb \u0111\u1ea7u s\u1ebd tr\u00e1nh \u0111\u01b0\u1ee3c c\u00e1c chu k\u1ef3 thay th\u1ebf s\u1edbm v\u00e0 \u0111\u1ea3m b\u1ea3o kh\u1edbp n\u1ed1i ho\u1ea1t \u0111\u1ed9ng h\u1ebft tu\u1ed5i th\u1ecd thi\u1ebft k\u1ebf.<\/figcaption><\/figure>\n

H\u01b0\u1edbng d\u1eabn l\u1ef1a ch\u1ecdn: N\u00ean ch\u1ecdn v\u1eadt li\u1ec7u n\u00e0o cho \u1ee9ng d\u1ee5ng n\u00e0o?<\/h2>\n

B\u1eaft \u0111\u1ea7u v\u1edbi acetal tr\u1eeb khi m\u1ed9t trong nh\u1eefng \u0111i\u1ec1u ki\u1ec7n sau \u0111\u00e2y x\u1ea3y ra:<\/strong><\/p>\n