Cong nghipp rimg
>/ ANH HirdNG CUA XU" LY THUY - NHIET DEN MQT SO TINH CHAT CO HOC CUA GO BACH DAN {Eucalyptus urophylla) Nguyin van Dien^ Ph^m Van Chirong^, Le Xuan Phirong^
ThS. Tntdng Dpi iwc Ldm nghipp PGS.TS. Tnrdng Dgi Itpc Ldm nghipp TS. Trudng Dpi hpc Lain nghiep
TOM T A T
Phuong phip xu ly ihiiy nhi?t cho go da va dang dugc nhieu nuoc trSn the gi<ji ap dyng nhim nang cao muc dich sur dyng go. Phuong phdp n&y uu dilm lon la 6n dinh kfch thiroc. giam kha nang hiit dm va hut nuoc. mau sac go thay d6i tir nSu nhgt den nSu \km cho g5 gi6ng voi m^u sac ciia rngt s6 g6 quy, cai thi^n d6 bin sinh hgc cho g6, c6ng ngh§ v i thiSt bi kh6ng qud phiic tap, an toin v i ih§n thign voi m6i tnrong. Tuy nhifin, nhugfc diem cua g6 sau khi xir ly ton ih^l kh6i lugmg, ti'nh chat ca hgc giam \k g5 xii ly de bj mit, tdch vk ehe. VI the, mot trong nhimg xu huomg chii yeu trong viec nang cao chdt lugng g6 da va dang dugc cac nhk khoa hoc trgn the gioi quan tam la xii ly nhi?t cho go. Trong bai vik n&y tac gia trinh bay kdt qua xu ly g6 bang phuong phdp thiiy - nhi?l din mgt so Ifnh chat co hgc ciia g6 B^ch Akn (Eucalyptus urophylla S.T. Blake). Ket qua nghiSn ciiu cho thdy, Xli ly thliy - nhi?t vdi s\r thay dfii cdc ehe dg nhu nhi^t dg (MO^C; i60°C vd 180°C) vk thai gian (2 gio; 3 gio vd 4 gio) Idm cho ti'nh chat co hgc ciia go giam khi nhi^t dg v^ th6i gian thai gian tdng: Dg ben uon ttnh (MOR):
tir 105,83 MPa con 52.38 MPa (giam 50,5% so voi mau chua xti ly). Dg bin nen dgc thd (COM//): tir 65.86 MPa c6n 42,18 MPa (gidm 35,95% so v6i mlu chua xii ly), Dp bin nen ngang tho theo chieu xuyfin tam (COM ±R);
til 8,90 MPa c6n 5,02 MPa (giam 43,58% so vdi mau chua xu ly), Dg bin nen ngang tilp tuyin (COM ±T): tir 7,92 MPa cdn 5,26 MPa (giam 33,37% so vdi mdu chua xii ly).
Tir khda: Bpch ddn, dp ben uon tlnlt, dp ben nen dpc, d0 bin nen ngang th& theo chieu xuyen ldm, dp ben nen ngang th&theo chieu tiep tuyen, xdrl^ thuy - nhift.
I. DAT VAN DE danh gifi 1^ thSn thi?n vol moi tnrofng, c6ng G6 Bach d^n \h mpt loai cay uu ti6n rung nghe vii thi§t bj dtm gian va chi phf gia thanh trong, uu di^m cSy Bach d&n co khfi nang tang cho c5ng nghe thfip ciing la ly do tfie gia chgn truong nhanh, g6 c6 mhx sfic dep, cuong do co phuong phfip nay dk xu i^ cho gd B^ch dan.
IJ cao ..., nhugc diem cua gS Bach dfin co nhieu Tir nhijng nam 1915, bfio cfio cua Tiemann npi iJmg sufit ngiim nen khi su dung go de bi [10] da de cgp den, g6 sau khi sfiy cr nhiet dp cong venh, nut, tfich, tre... (3 cac nuoc Chau Au 150°C trong th6i gian 4h, ti'nh hiit fim gifim 10- nhu Hh Lan, Phfip, Due, Phiin Lan da thigt lap 25%, nhung cuong d0 cila g6 cilng co sir giam dupc 5 cong ngh$ xit ly nhi?t dien hinh nhu: nh?. Den nam 1937, trong bfio cfio cua Stamm c5ng nghe su dyng nuac, hoi nuac ho|ic khong va Hansen [9] the hi?n, xii 1^ nhi?t trong dieu khf (PlatoWood) ciia Hfi Lan, cong ngh? sti kien co cfic loai chat khf bao v?, dp am bao h6a dyng hai nuoc, khf N2 (Le Bois Perdure vfi cua go, ti 1? co rut, gian na ciia go deu gifim Rectification) cua Phfip, xu ly bfing hai nudc xuong. Nhihig nam gan day cac tfie gia Holger (ThermoWood) cua Phan Lan, cong nghe siJr Militz va Soke Tjeerdsma (PLATO- dung dfiu thuc v^t (OHT- Oil Heat Treatment) PROCESS) (2006) da trinh bfiy phuang phfip cua Diic. Xli 1^ nhi?t su dung nuoc hofic hoi xii ly thiiy nhiet theo c6ng nghe Plato [2], The (xii 1^ thliy - nhiet) uu difim rfit lan cua phuang Plato technology (PLATO®-WOOD: 2006) phfip nfiy lfi dfim bfio tfnh on dinh kfch thuoc [3]: Tu nfim 1995 mpt dpi ngii ky su Plato da [8], thfinh phfin h6a hpc [4], thay doi dupc mau phfit trien cong nghe lfin dau tien trong phong sfic g6 [1] khong sir dung hoa ehfit hay bat ky thf nghiem ciia Hofing gia Hfi Lan. Nhiet dp va ehfit xi5c tfie nfio nen lam cho phuong phap duac fip suat trong qua trinh nfiy la lap trinh cfin t h ^
TAP CHf KHOA HOC VA CONG NGHE L A M NGHIfiP SO 4-2014 91
Cong nghipp rdng
va phu hpp cho timg loai cua cac loai go dupc sii dung. C^c lofii go duac xii 1;^ da dugc kiem tra de thiet lap su phu hgp va dieu kien qufi trinh toi uu ciia no. Dieu nfiy da tgo nSn mgt san pham go on dinh kfch thuac va ben, pham vi ciia cfic iing dung san phfim go (hang rao khu vuan, g6 op tuang vfi khung, khuon cua), tiep theo tir nhirng nfim 2000 hang tram cong ty sail xuat vfi cfic du fin dfi dugc thuc hien tai Hfi Lan, Bl va Diic, vi the khang dinh va phfin finh tiem nfing kinh te ciia cua cong nghe nfiy [3]. Quy trtnh Plato sii dung cfic giai doan khfic nhau, giai doan 1 lfi giai doan xii ly vfi ket hgp lien tuc buac thiiy nhiet phfin vfi giai doan 2 la giai dogn sfiy da t\i (curing). Muc dfch ciia giai dogn 1 lfi tfie dpng ctia thiiy nhiet phan trong ket qua xii ly Plato, s^r xufit hi?n ciia bi6n d6i cfic thfinh phan h6a hpc khfic nhau, su dung sir hi?n di?n ciia dp am doi dao trong thfinh t6 bfio go de thliy nhi?t phSn nhfim hoa tan cfic ehfit chiet suat vfi tien thuy phan hemicellulose vfi lignin, hgn ehe cfic phfin iing ciia cac ehfit khdng mu6n, nhi?t dp xii ly trong giai dogn nfiy tir ISO^C - igO^C trong moi truang hoi nudc, gifii dogn 2 la giai dogn sfiy da tu nhfim ddng ran cfic ehfit vfi kSt hgp cfic ehfit lgi vdi nhau thfinh mpt chat mdi, nhiet dp ciia giai doan nfiy tir 150°C - \9iPC trong moi trudng khong khf kh6 [2]. Theo k6t qua nghien cihi ctia cong ngh? Plato [3] thi cfic tfnh ehfit co hpc c6 mpt chiit thay doi so vdi g6 khong xii 1^: Cfic mo dun dfin hdi (MGE) dugc tang len (0-10%), dp bin udn tmh (MOR) lfi gifim nhe (5-20%). tdn thfit khdi lugng (WL) rfit ft so vdi cfic phuang phfip xii ly nhiet khfic. Nhin chung, tinh chat co hpc ciia trong edng nghe Plato®
Wood Ifim cho sfin phfim gd xu ly phii hgp cho vi?c sii dyng vfio cac cong trinh dd mdc ndi ngogi that, dd go trong vudn vfi cac cong trinh doi hdi tfnh chju nudc cao cua go.
Ket qua nghien ciiu cua Hiroshi Jinno (1993), Misato Noriraoto vfi Joeseph Gril cho
thfiy xu ly go d 180°C tir 3 gid - 10 gid vdi ip sufit thudng Ifim cho cudng dp, vfi dgc biet \\
md dun dfin hoi ciia go tfing nhe [5]. Kamdem va cgng su (2002), nghien cuu xii ly nhi?t tfing siic de khfing sinh hgc ciia go. Kamdem et al cho rfing, viec xii ly nhiet cho gd gifim mo dun dan hdi (MOE) khoang 10 - 50%. Nghien cmi chi ra rang, khi tfing nhiet dp vfi thdi gian xii 1^
md dun dfin hdi trong go Sdi gifim xudng [6].
Cho dfin nay, cfic cdng trinh nghien ciiu vfi xij iy thliy nhifit d Viet Nam con hgn chfi, chira ling dyng nhieu trong sfin xuat vfi nghien ciiu.
Trong bai viet nfiy, tac gifi trinh bfiy ket qua vg budc dfiu nghien ciiu "Anh hudng ciia xu ly thliy - nhifit dfin mgt sd tfnh chat co hpc ciia go Bgch dfin" gdp phan xfiy d\mg vfio cdng ngh?
xii ly thliy nhi?t cho vat lieu go ndi chung vfi gd Bach dfin ndi ridng.
ILVATLI|UVAPHUONGPHAPNGHIE3VCI^
2.1. Vat li^u nghien ctiu
Go Bach dfin (Eucalyptus urophylla S.T.
Blake) cd dp tudi tir 10 ddn 15 tudi khai thac tai Ba VI - Ha Ngi, tifin hfinh xe theo kich thudc 25 X 40 X 600 mm (xuyfin tfim x tifip tuyen x dpc thd) de Ifim mfiu thii cfic tfnh chit vfit ly ciia go sau khi xii 1^ thiiy - nhi§t, cfic mfiu Xli ly thiiy - nhifit vfi mau ddi chiing dugfC cfit tren ciing mpt thanh gd xe cd dfic vfi ldi dfi so sfinh tuang doi vfi Ifiy tri sd trung binh cfic mau xu ly vfi chua xii ly, sau dd kilm tra cfic tfnh ehfit cua go, do a m ciia go tnidc khi xii ly bien dpng tir: 25 - 30 %. X\x 1^ thuy - nhiet bfing may SUMPOT d cfic ehe dg nhi?t dp (140"C; 160°C; 180**C) vfi thdi gian (2 gi6;
3 gid vfi 4 gid). Sau do cfit mau theo tifiu chufin thii cfic tfnh ehfit: dg bfin uon tmh 20x20x300mm (xuyfin tam x tifip tuyen x dpc thd), do bfin nen dpc vfi nen ngang thd 20 x 20 X 30 mm (xuyen tam x tifip tuyfin x dpc thd);
sd mau 10/chfi dg xtr ly trong timg tfnh ehfit dl kifim tra, dfinh gifi kfit qufi thyc nghifim.
92 TAP CHI KHOA HQC v A CONG NGHE L A M NGHIEP SO 4-2014
Cdng nghidp rung 2.2. Phinmg phap nghien cihi a) Stf do quy trinh thirc nghiem
Mau gd thf nghiem (Bach dfin Uro)
Thiet bi xii ly thiiy - nhipt (Sumpot)
Giai doan 1: Xu ly thiiy - nhipt (nhipt dp, thdi gian)
Giai doan 2: Sfiy da tu (nhipt dp duy tri: 140**C, thdi gian duy tri: 3 gid);
dOdmgd: 12%.
Lfim ngupi tu nhifin (nhi|t dp mdi trudng)
- Mau go Bach dan Uro chua xic ly ihiiy nhiet (doi chirng).
- So lupng: 10 mau/che do.
:^^:.
- Mau gd Bach dan Uro xir ly Ihuy - nhiet (nhiet do (T): 140"C va thai gian ( r ): 2; 3 va 4 gid).
- So lugng: 10 mau/che do.
- Mau gd Bach dan Uro xii' ly thuy - nhiet (nhiet dp (T): 160V va thdi gian ( r ) : 2; 3 va 4 gid).
- Sd lirgng: 10 mau/che do.
- Mau go Bach dan Uro xii' ly thliy - nhiet (nhiet dp (T). 180"C va ihdi gian ( r ): 2; 3 va 4 gid).
- So lirong: 10 mau/che dp.
Kiem tra tfnh chat gd xir 1^ vfi ddi chiing
- Dg bfin uon iTnh (MOR).
- Dd bfin nen dpc thd (COM//).
- Dp bfin nen ngang thd theo chifiu xuyen tfim (COM _LR).
- Dp ben nen ngang tiep tuyfin ( C O M - L T ) .
Bang 01. Che dp xirly thOy - nhift cho gd B^h tdn Nhiet dg (°C) 140 160 Thoi gian (gio) 2 3 4 2 3 4 2
180
3 4
Xii ly thiiy - nhiet la xii ly qua 2 giai doan:
Giai dopn 1: Gd dugc xir ly trong mdi trudng nudc d nhifit dp cao lam hda tan mpt sd ehfit chifit sufit, phfi hiiy hemicellulose, tien
than phfin hiiy lignin vfi cellulose.
Giai dopn 2: Gd sau khi xii ly trong mdi trudng nudc, dfi rao roi tien hfinh say. Khi do cac ehfit bi tan trong giai doan 1 dugc da tu lai TAP CHf KHOA HQC VA C 6 N G N G H E L A M NGHIEP S 6 4-2014 93
Cdng nghipp rdng hinh thfinh cfiu true radi trong go.
b) Tieu chuan va phiromg phap Idfim tra tinh chit v&t ly cua go
- Dp ben uon tinh
Tieu chufin kiem tra: theo tifiu chufin qude te ISO 3133:1975 va ISO 3349:1975 (TCVN 8048-3:2009).
Kfch thude mfiu: 20 x 20 x 300 mm.
Dung lugng mau: 10 mfiu/chfi dp.
Dyng cy kifim tra: Thudc kep dp chfnh xfic 0,01mm, mfiy thu tfnh ehfit co ly QTEST 25.
Quy trinh kiem tra: Mfiu sau khi gia cdng xong xic ly mau den dp am cfin bang vdi mdi trudng khong khi thudng (12%). Khi mau dfi xu 1;^ ve dp am thfing bfing tien hfinh do kfch thudc mau sau dd tifin hfinh xfic djnh gidi han ben nfin dpc dugc thirc hipn trfin mfiy thii ca hpc QTEST 25.
Cdng Ihiic xac djnh:
2 b.h^ "
Trong dd:
Pmax - lyc phfi hogi mau , N;
1 - khofing cfich gdi, mm;
b, h - chifiu rpng vfi chifiu cao mfiu, mm;
oi2 - gidi han bfin uon ttnh d dp fim thang bfing (12%);
Ow - gidi hgn bfin uon ttnh d dp fim thf nghi?m, N/mm^;
ct - h§ sd difiu chinh dp fim Ifiy bfing 0,02;
W - dp am luc thf nghipm, %.
- Dp ben nen dpc thd
Tieu chufin kiem tra: tieu chufin qudc tfi ISO 3132-1975 (TCVN 363-70).
Kieh thudc mfiu: 20 x 20 x 30 mm.
Dung lugng mfiu: 10 mfiu/chfi do.
Dyng cy kifim tra: Thudc kpp dp chfnh xfic 0,01mm, mfiy thii tfnh ehfit ca IJ QTEST 25.
Quy trinh kifim tra: Mfiu sau khi gia cong xong xu ly mau dfin dg fim efin bfing vdi mdi Irudng khdng khf thudng (12%). Khi mlu da Xli ly vfi dg fim thfing bfing tifin hanh do kich
thudc mfiu sau do tifin hfinh xfic dinh gidi han bfin nen dpc duac thue hien trfin mfiy thir co hpc QTEST 25.
Cdng thiic xfic dinh:
P
*^H.—~7", o-,2 = o-Jl + a(U'-12)],N/mm^
Trong dd:
Pmax - luc phfi buy mfiu, N;
a, b - kfch thudc tiet dien ngang cua mau, mm;
oi2 -gidi han ben nfin dpc thd d dp fim thfing bfing (12%);
Ow . gidi han bfin nfin dpc thd d dp fim thf nghipm, MPa;
a - hp sd dieu chinh dp fim lay bfing 0,04.
- Dp ben nen ngang thd"
Tieu chuan kiem tra: theo tifiu chufin TCVN 8048-5:2009.
Kfch thudc mfiu: 20 x 20 x 30 mm.
Dung lupng mlu: 10 mau/clfg.i^.
Dyng cy kiem tra: Can dien tir dp chfnh x^c
± 0,0lg, tu sfiy nhiet dp tdi da 300'^C cd dp chfnh xfic ±0,1°C.
Quy trinh kiem tra: Mau sau khi gia cdng xong Xli IJ' mau dfin dp am can bfing vdi mdi trudng khdng khi thudng (12%). Khi mlu da Xli ll? vfi dp fim thfing bfing tidn hfinh do kfch thudc mfiu sau dd tien hfinh xfic djnh gidi han ben n6i\ ngang thd dugc thvrc hi^n tren may thic ca hgc QTEST 25.
Cdng thuc xac dinh:
p
<^. = 7. 0-12 = <y„, [l + a{W - 1 2 ) ] , N/mm^
Trong dd:
P - l\rc phfi hiiy mfiu, N;
a-chieu r^ng cua mfiu, mm;
1- chifiu dfii mlu, mm;
ai2 - gidi hgn ben nen ngang thd d dp fim thfing bfing (12%);
<Jw - gidi han bfin nen dpc thd d dp am thf nghipm (MPa);
W - do am ldc thf nghiem (%);
a - h$ sd didu chinh do fim lay bfing 0,035.
94 TAP CHI KHOA HQC VA C 6 N G NGH? L A M NGHIEP S 6 4-2014
Cong nghipp rimg
IIL KET QUA NGHIEN CU*U
3.1. Anh hu&ng cua ehe dp xir ly thuy - nhiet den dp ben uon ttnh gdBpch dan
Tir ket qua nghien ciiu va sau khi xii ly thdng ke ta dugc kfit qua ghi trong bfing 02.
D|c trung thong ke
DC
Bang 02. Bp ben uon tmh cua gd Bach ddn (MPa) Che d$ x4 ly nhift d? (T) v4 thM gian (T ) 140°C- 140°C- 140°C 160°C- 160°C 160°C 180°C
2 gia 3 gid - 4 gio 2 gid - 3 gio - 4 gid - 2 gid 180°C - 3 gid
180°C - 4 gid X
s s%
p%Min Max C(95%)
105,83 2,09 6,60 20,68 97,57 118,25 4,72 Ghi chti: Y :
95.62 1,93 6,11 17,05 85,68 102,73
4,37
91,86 86,89 1,81 1,72 5,73 5,42 15,79 14,09 84,28 79,99 100,06 94,08 4,10 3,88 Gia tri trung binh mau; S: Sa
80,91 1,90 6,01 20,09 69,93 90,02 4,30
hsm 75,83 0,98 3,08 11,18 68.70 79,88 2,21 ciia uoc
72,45 61,96 1,26 1,26 4,00 3,97 12,02 11,63 67,12 56,30 79,15 67,93 2,86 2,84 luQFng vdi do tin
56,81 1,64 5,20 14,70 51,67 66,37 3,72 cay 95%.
52,38 1,38 4,37 11,22 47,49 58,70 3,13
so cua so trung binh mau; S%: He so bifin dpng; P%: He sd chfnh xfic; Min: Tri so c\rc tieu; Max: Tri so c\rc dai; C(95%): Sai so cue
Tir kfit qufi d bfing 02, ta xay dung dupc dd thj finh hudng cua ehe dp xii ly vdi dp ben udn tmh ciia go Bach dan:
ANH HLf&NG cCiA C H £ D 0 XO* LY THCIY - NHi$T D £ N D O B £ N U 6 N TTNH G O B A C H D A N (MPB)
* *
Che dp xi> ly (nhi^t dp vi thai gian)
Hinh 01. Bi^u dd quan hpgiua ehe dp xdrly vdi dp bin uon tinh Nh^n x6t:
Qua qufi trinh th\rc nghiem ta thay dp ben u6n tmh ciia go Bach dan da xii 1^ thuy - nhifit so vdi go Bach dan chua xur ly gifim tir 105,83 MPa cdn 52,38 MPa (giam 50,5% so vdi mfiu chura xii 1;?) vfi giam dfin d cfic chfi dp xii IJ' khi nhipt dp tfing va thdi gia tfing, cy thfi nhu sau:
- Xii ly thuy nhipt d nliiet 140°C thdi gian lfi 2 gid, 3 gid vfi 4 gid dp ben uon tuih cua gd Bach dan giam dfin tir 95,62 MPa dfin 86,89 MPa.
- Xu ly thuy nhipt d nhiet dp 160"C thdi gian Xli ly lfi 2 gid, 3 gid vfi 4 gid dp bfin udn llnh cua gd Bach dfin giam tir 80,91 MPa dfin 72,45 MPa%.
- Xu ly thuy nhifit d nhiet dO ISO^C thdi gian xu ly 2 gid, 3 gjd vfi 4 gid dp bfin uon tinh cua go Bach dfin gifim tir 61,96 MPa dfin 52,38 MPa.
Difiu nfiy cd thfi gifii thfch khi gd dugc xii ly thuy nhifit su phan gifii do tac dgng ciia nhifit TAP CHf KHOA HQC v A C 6 N G N G H f L A M N G H I E P SO 4-2014 95
Cong nghipp rung
dp cua cfic polyme tren vach te bfio, dfic biet la hemixenlulo tir nhimg chuoi dai chudi thfinh nhung chuoi ngan han, dan dfin khfi nang chiu uon gifim xu6ng. Mat khfic, nhiet dp cao, thdi gian xu ly dfii thi dp bfin udn tmh cfing gifim lfi do trong qufi trtnh xii 1^ thuy nhiet cfic chat chifit sufit trong gd bi logi bd ra ngofii, hemixenlulo bi phfin huy, gd trd lfin rdng xdp khdi luong thfi tich gifim lfim cho lifin ket giua Bang 03. Dp ben nin dpc thd
cac mixen xenlulo bi long leo, do do dp bfin udn tmh bj giam xudng. Dac biet la d chi d^
nhifit dp ISO^C thdi gian xii ly la 2 gid, 3 gio va 4 gid dp bfin udn ttnh ciia gd Bgch dfin da xir ly thliy - nhiet bi gifim manh.
3.2. Anh hu&ng cda chi dp xu ly thuy - nhipt din dp ben nen dpc thd go Bpeh ddn
Tir kfit qua nghien ciiu vfi sau khi xir IJ thdng kfi la dugc ket qufi ghi trong bfing 03.
(COM//) cua gdBpchddn(%) trinig
th6ng ke
Che d§ \w Iy nhi?t dp (T) va thdi gian (T )
140''C 140''C- \A{fC leO^C- 160"C IbO^C ISO^C 180"C 180"C - 2 gid 3 gid - 4 gid 2 gid - 3 gid - 4 gid - 2 gid - 3 gid - 4 gicr X
s s%
p%
Min Max
C(95%)
65.86 1,15 3,64 9,45 60,99 70,44 2,61
62,33 0,74 2,34 7,30 57,89 65,19 1,68
59,80 0,87 2,76 8,45 55,10 63,56 1,97
57,11 1,32 4,16 12,66 50,96 63,62 2,98
55,58 0,82 2,60 8,61 50,88 59,49 1,86
53,46 1,32 4,17 10,98 46,97 57,95 2,98
51,88 1,65 5,21 15,14 43,24 58,38 3,72
48,97 0,71 2,24 6,77 46,23 53,00 1,60
45,35 1,14 3,61 12,10 36,46 48,56 2,58
42,18 0,75 2,39 7,00 39,06 46,06 1,71 Tir ket qua d bang 03 la xay dung dugc dd
thi quan hp giita nhifit dg vfi thdi gian ddi vdi
dd ben nen dgc thd:
ANH HUeyNG COA CHe D O XO" L V T H O Y - NHI$T D ^ N D 0 B t N NEN D p c T H O G 6 BACH D A N (MPa)
* rft 3 *
140.3 140-* 160.Z 160.3 i s f M lBO-2 Ch6 d$ xu- li^ (nh)9t d9 v4 t h « gian)
Hinh 02. Biiu dd quan h(gitia ehe dp xu ly vii d^ ben nen dpc thi (COM//) Nhan xet:
Qua kk qua nghien cira cho thjy (bang 03) SII anh hudng ciia nhi?t dp xu ly thiiy nhi?t cho go Bgch d^n den dp ben nen doc r3t ro ret con thdi gian anh hudng rit ft d cung chS dp nhiet
dp. Dp bSn nen dpc thd (COM//) giam tir 65,86 MPa c6n 42,18 MPa (giam 35,95% so vcri mau chua xu ly), cu the 6 cac chS dp nhu sau:
- Xir ly thuy nhi#t o nhiet 140°C thoi gian 112 gio, 3 giir va 4 gio dp bSn nen dpc tho cua g§
TAP c m KHOA H p c VA CONG NGHE LAM NGHIEP SO 4-2014
Cdng nghipp rirng
Bach dan gifim dfin tir 62,33 MPa dfin 57,11 MPa (d chfi dp 4 gid so vdi 2 gid thi gifim 8.39%).
- Xii ly thuy nhiet d nhiet dg IdO^C thdi gian xir \f lfi 2 gid, 3 gid vfi 4 gid dp bfin nen dpc thd cua gd Bach dfin gifim tii 55,58 MPa den 51,88 MPa (d chi dp 4 gid so vdi 2 gid thi gifim 6,66%).
- Xii ly thuy nhipt d nhiet do 180°C thdi gian xu 1^ 2 gid, 3 gjd vfi 4 gid dp bfin nfin dpc thd ciia g5 Bgch dan gifim tir 48,97 MPa ddn 42,18 MPa (d ehe dp 4 gid so vdi 2 gid thi gifim 13,86%).
Nhiet dp finh hudng ro net nguyfin nhfin lfi dudi su tfie ddng cua nhipt dp cao thi cac polyme vach te bfio bi phfin huy, nhifit dp cfing cao thi thanh phan pentose bi phfin buy cfing manh lfim cho do bfin ndn dgc thd gifim.
3.3. Anh hudng cua ehe dp xir ly thdy - nhiet den dp ben nen ngang th& theo chieu xuyen tdm vd tiep tuyen go Bgch ddn
a) Dp ben nen ngang xuyen tdm Tit kfit qua nghifin ciiu vfi sau khi xir ly thdng kfi ta dugc kfit qufi ghi trong bang 04.
Bang 04. Dp bin nen ngang thd theo chieu xuyen tdm (COM 2g) cua gd Bpch ddn (%) Dac
t r i m g t h o n g ke X
S S%
P%
Min Max C(w%)
BC 8,90 0,13 0,40 1,23 8,29 9,52 0,29
140"C - 2 gicr
8,51 0,15 0,47 1,32 7,83 9,14 0,34
Che 140°C -
3gi6 8,03 0,17 0,55 1,76 7,23 8,99 0,39
d9 xii- ly nhi^t do (T) va th6i gian (T) MO'C
- 4 gio 7,70 0,20 0,64 1,77 6,78 8,55 0,46
160°C- 2gi6 6,76 0,17 0,55 1,60 6,18 7,78 0,39
160°C - 3 giir 6,36 0,23 0.73 2.42 5,44 7,86 0,52
leo'c
- 4 gia 6,18 0,09 0,29 0,99 5,73 6,72 0,21
180°C - 2 giir 5,35 0,08 0,27 0,82 5,00 5,82 0,19
180"C - 3 gio 5,19 0,09 0,29 0,92 4,60 5,51 0,21
180°C -4 giir 5,02 0,16 0,50 1,66 4,55 6,21 0,36 Tir kfit qua d bfing 04 tfie gifi xfiy dyng dugc vdi dp ben nen ngang thd theo chieu xuyfin dd thi quan he giiia nhipt do vfi thdi gian doi tam:
A N H H U ^ N G CClACHe o O xO- L V T H O Y - N H I $ T O ^ N B p B t N N^N NGANG THd' THEO CHI^U XUY^N TAM G d B/iCH DAN (MPa)
i=i=S ft-A
140-2 140-3 140-4 160-2 160-3 160-4 180-2 180-3 180-4 C)i4 d$ xi> ly (nhift d$ vi thM gian)
Hinh 03. Bieu do qaan hp giira ehe dp xir ly vdi COM J^
h) Dp bin nen ngang tiep luyen thdng kfi la dugc ket qufi ghi trong bang 05.
Tir kel qua nghien ciiu va sau khi xu If
TAP CHf KHOA HQC VA CONG NGHE LAM NGHIEP S 6 4-2014 97
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Bing 05. Bp bin nen ngang thi theo chieu tiip tuyin (COM Jj) cua f 5 Bpch ddn (%) Die
trimg thong DC
ke
Ch6 do x t ly nhiet d? (T) va thoi gian (T ) MO'C
-2 giir
140°C- 140"C 160''C- 160°C 160°C 180°C 180°C 180"c 3 giii - 4 gia 2 gia - 3 giir - 4 giir - 2 gio - 3 giir - 4 gio X
s s%
p%
Min Max
Ci95%)
7,92 0,14 0,44 1,46 7,31 8,77 0,31
7,35 0,11 0,34 1,07 6,76 7,83 0,24
7,11 0,06 0,18 0,49 6,89 7,39 0,13
6,82 0,08 0,26 0,75 6,40 7.16 0.18
6,52 0,11 0,36 1,32 5,65 6,97 0,26
6,31 0,09 0,29 0,92 5,81 6,74 0,21
6,01 0,05 0,15 0,46 5,85 6,30 0,11
5,59 0,07 0,22 0,59 5,29 5,87 0,16
5,39 0,03 0,10 0,29 5,24 5,53 0.07
5,26 0,04 0,14 0.41 5,10 5,51 0,10 Tir ket qufi d bfing 05 tfie gifi xfiy dung
dugc dd thi quan hp giiia nhipt dp vfi thdi
gian ddi vdi do ben nen ngang thd theo chieu tiep tuyen:
A N H HutiTNG C O A C H ^ D O xir L Y T H D Y < N H I ^ T Q £ N D O B £ N N ^ N NGANG T H d THEO CHlEU TlfiP TUY^N GO BACH B A N (MPa)
i ^ i l s A
140-2 140.3 140.4 160-2 i e 0 - 3 160-4 1BD-2 180-3 160-4 Chi d$ xi> iy(nh)9t d$ V6 th^l gian)
Hinh 05. Biiu do quan h^gidn chi dp xu ly vdi COM J.r Nh^n x6t:
Khi nhi$t dp va thiri gian tang, thg hi?n a 9 chS d§ Xli 1^ thuy nhiet thi do bSn nen ngang theo chieu xuyen tam va ti6p tuy^n co xu huong giam dan so voi mlu doi chimg (mau cliua Xli ly), qua kk qua nghien ciiu cho thdy do ben nin ngang tha theo chiSu xuySn tam (COM I R ) : tir 8,90 MPa con 5,02 MPa (giam 43,58%
so voi mau chua xii ly), dp b6n n6n ngang tiep tuySn (COM XT): tii 7,92 MPa cim 5,26 MPa (giam 33,37% so vod man chua xii IJ).
CSn cii vio bang 04; bang 05. d6 thi hinh 03 v^ do thi 05, ta thSy xu ly thuy nhi$t g6 Bach dta o nhi$t dp 140°C; 160°C; 18D°C, thiri gian
Xli 1^ 2giir, 3 giir va 4 gio dp bSn nen ngang th6 giam din Idii nhiet dp vJ thiri gian xil ly tang, dp ben nen ngang xuyen tam giam (o chg do 140»C - 2 giir va ISO'C - 4 gia) tir 8,51 MPa dgn 5,02 MPa (40,96%), dp bgn nin ngang tho tigp tuyen giam (a chg dp 140°C - 2 gicr vi 180°C - 4 gia) tir 7,35 MPa dgn 5,26 MPa (28,36%). Nguyen nhSn duoi t^c dpng cua nhi?t do lim cho polyme vach te bio bi thuy phSn, nhiet dp cang cao thai gian xii ly dii se Iim xenlulo ciia g6 Bach din bi thuy phan din dgn cau triic vich tg bao long leo v i tao phan irng ngit cic msich lien Icgt cua cic phin hi trong go dieu do se lim cho dp ben nen ngang tho giam.
98 T ^ c m KHOA HQC VA CONG N G H $ LAM N G H I E P SO 4-2014
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Tom lai: Khi nhiet do vfi thdi gian xir Iy tfing lam cho qua trinh xu 1;^ thiiy - nhiet hinh thfinh nen mgt sd axft hofi tan nhu: axit formic vfi axit axetic tir qua trinh phan huy hemixelulo. Ngofii ra cac axit nfiy tac ddng vfio xelulo va lam giam do polyme (cfit mach xelulo) dfin tdi do bdn ca hgc gifim [7].
IV. K E T LUAN
Ket qua nghifin ciiu Cdng nghe xu ly thuy - nhift cho gd Bach dan thong qua chfi do xii ly nhi?t do (140''C; IdO^C vfi 180°C) va thdi gian (2 gid; 3 gid vfi 4 gid), tfie gifi di ddn mgt sd kfit luan: Dg bfin udn tinh (MOR): tic 105,83 MPa cbn 52,38 MPa (gifim 50,5% so vdi mau chua xd ly), Dg ben nen dpc thd (COM//): tir 65,86 MPa cdn 42,18 MPa (gifim 35,95% so vdi mfiu chua xii ly), Do bfin nfin ngang thd theo chieu xuydn tam (COM I R ) : tu 8,90 MPa cdn 5,02 MPa (gifim 43,58% so vdi mau chua xOr ly), Dg ben nfin ngang tifip tuyen (COM I T ) : tir 7,92 MPa cbn 5,26 MPa (gifim 33,37%
so vdi mau chua xir ly). Dieu dd, cd thfi minh chiing rang su finh hudng nhift dg vfi thdi gian ciia phucmg phfip xu ly thiiy - nhifit dfi lam gifim do ben ca hgc cua go Bach dan khi bifin sd nhifit do vfi thdi gian thay ddi.
TAI LIEU THAM KHAO
1. Andreja Kutnar, Milan Semek (2008), Reasons for colour changes durmg thermal and hydrothermal treatment of wood.
2. Andreas O. Rapp (2001), "Review on lieai treatments of wood", BFH The Federal Research Centre for Forestry and Forest Products Information and Documentation, D-21027 Hamburg, Germany, pp. 1-66
3. BV P. 1. (2006), "The Plato Technology".
4. Hill, C.A.S. (2006), Wood modification. Chemical, thermal and Other processes. John Wiley & Son
5. Hiroshi Jinno, Misaio Norimoto va Joeseph Gril (1993), Recent reseach on wood based, Materal-Society ofMateral-Science.
6. Kamdem, D. P., Pizzi, A., Jermannaud. A. (2002), Durability of heat-treated wood, Holz als Rohund
Werkstoff 60(1): 1-6.
7. Marc Borrega (2011), "Mechanisms affecting the structure and properties of heat-treated and high- temperature dried Norway spruce (Picea abies) wood".
Dissertaliones Forestales 134. 52 p, School of Forest Sciences - Faculty of Science and Forestry - University of Eastern Finland.
8. P. Rezayati Charani'*, J. Mohammad!
Rovshandeh^, B. Mohebby', O. Ramezani 4 "Influence of hydrothermal treatment an the dimensional stability of beech wood", Caspian J. Env. Sci. 2007, Vol. 5 No.2 pp.
125-131, The University of Guilan, Printed in LR. Iran.
9. Stamm A. and L. Hansen (1937), "Minimizing wood shrinkage and swelling: Effect of healing in various gases", Joumal of industnal and engmeenng chemistry, 29(7), pp. 831-833.
10. Tiemann H. D. (1915), "The effect of different methods of drying on the strength of wood". Lumber World Review, 28(7), pp. 19-20.
T^P CHI KHOA HQC VA CONG NGHE LAM NGHIEP SO 4-2014 99
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EFFECT OF THE HYDRO - THERMAL TREATMENT ON MECHANICAL PROPERTIES OF Eucalyptus urophyUa S.T. BLAKE WOOD
Nguyen Van Dien, Pham Van Chuong, Le Xuan Phuong SUMMARY
The hydro-thermal treatment of wood has been a lot of countries around the world to enhance application uses wood. This method is great advantage dimensional stability, reduced ability to absorb moisture and absorbs water, wood color changes from light brown to brown as the color of the wood similar to some of precious wood improve biological stability timber, technology and equipment is not too complicated, safe and friendly environment. However, the disadvantages of timber after handling mass loss, decreased mechanical properties and easy processing of wood cracking, splitting and splitting. So, one of the major trends in improving wood quality has been the world's scientists are interested in the heat treatment of wood. In this article the authors present the results of treatment of timber by hydraulic methods - thermal and mechanical properties of a number of eucalyptus wood (Eucalyptus urophylla ST Blake). The study results showed that hydro-processing - heal to change the temperature mode (HO^C, I60"C and 180''C) and time (2 hours, 3 hours and 4 hours) makes the mechanical properties of wood reduce the temperature and increase the time period: Module of rupture (MOR):
from 105.83 MPa was 52.38 MPa (reduced 50.5% compared to untreated samples). Compressive strength parallel to grain (COM//): from 65.86 MPa was 42.18 MPa (reduced 35.95% compared to untreated samples), Compressive stress perpendicular to grain (COM I R ) : from 8 90 MPa to 5.02 MPa (reduced 43.58% compared to untreated samples). Compressive stress perpendicular to grain (COM I T ) : from 7.92 MPa to 5.26 MPa longer (reduced 33.37% compared to untreated samples).
Keywords: Compressive strength parallel to grain, compressive stress perpendicidar to grain, compressive stress perpendicular to grain, hydro-thermal treatment. Eucalyptus urophylla S.T. Blake, module of rupture.
Ngudi phSn bi^n Ngfiy nhfin bai Ngfiy phfin b i | n Ngfiy quyet djnh d3ng
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