Cong nghiep rimg
ANH HLTOfNG CUA XU^ LY THUY - NHIET DEN MOT SO TINH CHAT CO HOC CUA GO BACH DAN (Eucalyptus urophylla)
N g u y e n V a n D i e n S P h a m V a n Chirffng^, L e X u a n P h u o n g ^ ThS. Trudng Dai hgc Lam nghiep
'PGS.TS. Trudng Dgi hoc LAm nghiep TS. Tnrdng Dgi hoc Lam nghiep
T O M T A T
Phucmg phap xii ly thiiy nhiet cho go da va dang dugc nhieu nuoc tren the gidi ap dung nham nSng cao muc di'ch sii dyng go. Phuong phap nay mi diem Ion la on d)nh kich ihuoc. giam kha nang hut am va hut nutjc, mau sac go thay doi tir nau nhat den nau lam cho go giong voi mau sac cua mpt so go quy. cai thien dg ben sinh hoc cho go, c6ng n g h | va thiet bj khong qua phiic tap, an toan va than thien vdi moi trudng. Tuy nhien, nhupc diem cua g6 sau khi xOf ly ton that khoi lirgng. linh chit ca hgc giam va go xii ly dl bi mil, tach va che. Vi ihl, mgt trong nhimg xu hudng chii yeu trong viec nang cao chat lugng go da va dang dugc cac nha khoa hgc tren the gidi quan tam 1^ xii ly nhiet cho gd. Trong bai viet nay tac gia trinh bay ket qua xit ly go bang phuong ph^p Ihiiy - nhiet den mgt sd tinh chat co hgc ciia gd Bach dan (Eucalyptus urophylla S.T. Blake), K^t qua nghien cihi cho thIy, xir ly thiiy - nhi?t vdi su thay d6i cac ch6 dg nhu nhiet do (140°C; leO^C va 180"C) va thdi gian (2 gid, 3 gid va 4 gid) lam cho tinh chat ca hoc cua gd giam khi nhiet do va thdi gian thdi gian lang: Dd b6n udn tinh (MOR) tir 105,83 MPa cdn 52,38 MPa (giam 50,5% so vdi mau chua xii ly), Do b€n nen dgc tho (COM//): tii 65,86 MPa con 42,18 MPa (giam 35,95% so vdi mlu chua xit I J), Dd ben nen ngang (hd iheo chieu xuyen tam (COM ±R):
tir 8,90 MPa cdn 5,02 MPa (giam 43,58% so vdi mlu chua xii iy). Do ben nen ngang tigp tuyen (COM J-T): tir 7,92 MPa con 5,26 MPa (giam 33,37% so vdi mlu chua xir ly)
Tir khoa: Bach ddn, dp ben udn link, do bin nen dpc, da ben nen ngang thd theo chieu xuyen tam, do ben nen ngang thd Iheo chieu tiep tuyen, xir ly Ihdy - nhiet.
I. DAT VAN DE
Gd Bach dan la mot loai cay uu tien rimg trdng, uu diem cay Bach dan cd kha nang tang trudng nhanh, gd cd mau sac dep, cudng dp co ly cao ..., nbugc diem ctia gd Bach dan cd nhieu ndi ung suat ngam ngn khi six dung gd de bi cong vSnh, nut, tach, tre... 6 cac nude Chau Au nhu Ha Lan, Phap, Due, Phan Lan da thiet lap dugc 5 cdng nghe xu ly nhiet dien hinh nhu:
cdng nghe su dung nude, hoi nude hoac khdng khi (PlaloWood) cua Ha Lan, cdng nghe sii dung hoi nude, khi N2 (Le Bois Perdure va Rectification) ciia Phap, xu ly bang hoi nude (ThermoWood) cua Phan Lan, cdng nghe sir dung dku thuc vat (OHT- Oil Heat Treatment) cua Due. Xir ly nhiet su dung nude hoac hoi (xu ly thuy - niiiet) uu diem rat ldn cua phuong phap nay la dam bao tinh dn dinh kich thudc [8], thanh phan hda hgc [4], thay ddi dugc mau s5c go [tj khdng sir dung hda chat hay bat ky chdt xuc tac nao nen lam cho phucmg phap dugc
danh gia la than thien vdi mdi trudng, cdng nghe va thiet bi don gian va chi phi gia thanh cho cdng nghe thap ciing la ly do tac gia chon phuang phap nay de xu 1^ cbo gd Bach dan.
Tir nhiing nam 1915, bao cao cua Tiemann [10] da de cap den, gd sau khi say d nhiet do ISO^C trong thdi gian 4h, linh hiit am giam 10- 25%, nhung cucmg do cua gd ciing cd su giam nhe. Den nam 1937, trong bao do cua Stamm va Hansen [9] the hien, xii ly nhiet trong dieu kien cd cac loai chat khi bao ve, do am bao hda ciia gd, ti le co riit, gian nd cua gd deu giam xudng. NhiJng nam gan day cac tac gia Holger Militz va Boke Tjeerdsma (PLATO- PROCESS) (2006) da trinh bay phuong phap xu ly thuy nhiet theo cdng nghe Plato [2], The Plato technology (PLATO®-WOOD: 2006) [3]: Tir nam 1995 mdt ddi ngii ky su Plato da phat trien cdng nghe Ian dau tien trong phdng thf nghiem cua Hoang gia Ha Lan. Nhiet do va ap suat trong qua trinh nay la lap trinh c4n than T ^ CHI KHOA HOC VA CONG NGHE LAM NGHIEP SO 4-2014 91
Cong nghiep rung
va phii hgp cho timg loai cua cac loai gd dugc sii dung. Cac loai gd dugc xu ly da dugc kiem tra de thiet lap su phii hgp va dieu kien qua trinh tdi uu ciia nd. Dieu nay da tao nen mdt san pham gd dn dmh kich thudc va ben, pham vi ciia cac ung dung san pham gd (hang rao khu vudn, gd dp tudng va khung, khudn cua), tiep theo tir nhimg nam 2000 hang tram cdng ty san xuat va cac du an da dugc thuc hien tai Ha Lan, Bi va Due, vi the khang dinh va phan anh tiem nang kinh te ciia ciia cdng nghe nay [3]. Quy trinh Plato sii dung cac giai doan khac nhau, giai doan 1 la giai doan xir ly va ket hop lien tuc budc thuy nhiet phSn va giai doan 2 la giai doan say da tu (curing). Muc di'ch cua giai doan 1 1& tac ddng ciia thuy nhiet phSn trong ket qua xu ly Plato, su xuat hien ciia bien ddi cdc thanh phan hda hgc khac nhau, sir dung su hien dien ciia do am ddi dao trong thanh te bao gd de thuy nhiet phan nham hoa tan cac chat chiet suat va tien thiiy phan hemicellulose va lignin, han che cac phan ung ciia cSc chat khdng mudn, nhiet do xii ly trong giai doan nay tir ISO^C - 190°C trong mdi trudng hoi nude, giai doan 2 la giai doan sdy da tu nhSm ddng ran cac chat va ket hop cac chat lai vdi nhau thanh mdt chat mdi, nhiet do cua giai doan nay tir ISO^C - 190^C trong mdi truimg khong khi khd [2]. Theo kdt qua nghien ciiu cua cdng nghe Plato [3] thi c^c tinh ch§t co hgc cd mgt chtit thay ddi so vdi gd khdng xu ly: Cac md dun dan hoi (MOE) dugc tang len (0-10%), do ben udn tinh (MOR) la giam nhe (5-20%), tdn that khoi lugng (WL) r5t it so vdi cac phuong phap xii ly nhiet khac. Nhin chung, tfnh chat co hgc ciia trong cdng nghS Plato®
Wood lam cho san pham go xu ly phti hgp cho viec sir dung vao cac cdng trinh dd mgc npi ngoai that, dd gd trong vudn va cac cdng trinh doi hdi tfnh chiu nude cao cua gd.
Ket qua nghian ciiu cua Hiroshi Jinno (1993), Misato Norimoto va Joeseph Gril cho
thay xii ly gd d 180 C til 3 gid - 10 gid vdi ap suat thuimg lam cho cuong do, va dac biet la md dun din hdi cua gd tang nhe [5]. Kamdem va cdng su (2002), nghien ciiu xu 1;^ nhiet tang SLTC de khang sinh hoc cua gd. Kamdem et al cho rang, viec xir ly nhiet cho gd giam md dun dan hdi (MOE) khoang 10 - 50%. Nghien ciiu chi ra rang, khi tang nhiet dp v i thdi gian xii ly md dun dan hdi trong gd Sdi giam xudng [6].
Cho den nay, cac cdng trinh nghien ciiu ve xu ly thuy nhiet d Viet Nam cdn ban che, chua irng dung nhieu trong san xuat va nghien ciiu.
Trong bai viet nay, tac gia trinh bay kel qua v^
budc dau nghien ciiu "Anh hudng ciia xii ly thdy - nhiet den mdt sd tfnh chat co hoc ciia gd Bach dan" gdp phan xay dung v^o cong nghe xii ly thiiy nhiet cho vat lieu gd ndi chung va gd Bach dkn ndi rieng.
ILVATLIEUVAKIirONGKIAP NGHIEN CUU 2.1. Vat lieu nghien cii-u
Gd Bach dan (Eucalyptus urophylla S.T.
Blake) cd dp tudi tir 10 d6n 15 tudi khai thac tai Ba Vi - Ha Npi, tiSn hanh xe theo kfch thudc 25 X 40 X 600 mm (xuyen tam x tilp tuyen x doc thd) dd lam man thir cac tfnh ch5t vat ly cua go sau khi xu ly thiiy - nhiet, cac mau xii ly thuy - nhiet va mau ddi chiing dugc cat tren cung mdt thanh gd xe cd dac va ldi de so s^nh tuong ddi va ISy tri sd trung binh cdc m§u xu ly va chua xii ly, sau dd kidm tra cac tinh chat ciia gd, do am cua gd trudc khi xu ly biSn dgng tir: 25 - 30 %. Xu ly thuy - nhiet b&ng may SUMPOT d cac cbg dp nhiet dp (140"C; I60^C; \S(fC) va thdi gian (2 gid;
3 gid va 4 gid). Sau do c§t m§u theo ti£u chuan thii cac tfnh chSl: dp b£n uon tinh 20x20x300mm (xuyen tSm x tiSp tuydn x dgc thd), dp ben nen dgc va nen ngang thd 20 x 20 x 30 mm (xuyen tam x tiep tuyen x dgc thd);
sd mau 10/che do xu ly trong timg tfnh chat de kiem tra, danh gia ket qua thuc nghiem.
92 TAP CHI KHOA HOC VA CONG NGHE LAM NGHIEP SO 4-2014
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2.2. Phuong phap nghien ciru a) Stf do quy trinh thuc nghiem
Mlu gd thf nghiem (Bach dan Uro)
Thiet bi xii ly thiiy - nhiet (Sumpot)
Giai doan 1: Xii ly tbiiy - nhiet (nhiet dp, thdi gian)
Giai doan 2: SSy da tu (nhiet dp duy tri: 140°C, thdi gian duy tri: 3 gid);
dd am gd: 12%.
/ Lam ngudi tu nhien
\ (nhiet do mdi trudng)
Kiem tra tfnh chat gd xir ly vh ddi chiing
- Mau gd Bach dan Uro chua xii ly thiiy nhiet (ddi chiing).
- Sd lugng: 10 mau/che do.
- Mau go Bach dan Uro xu ly thuy - nhiet (nhiet dp (T): 140°C va thai gian ( r ) . 2; 3 va 4 gid).
- Sd Urons: 10 mau/che dd.
- Mau go Bach dan Uro xtr ly thiiy - nhiet (nhiet dp (T): 160V va thdi gian (T): 2, 3 va 4 gid).
- Sd lircmo; 10 mau/che do.
- Mau gd Bach dan Uro xu ly thiiy - nhiet (nhiet dd (T): ISO^'C va thdi gian ( r ) : 2; 3 va 4 gid).
- So krone: 10 mau/che do
- Dp ben udn tinh (MOR).
- Dp ben nen dgc thd (COM//).
- Dp ben nen ngang thd theo chieu xuyen tam (COM _LR).
- Dp ben nen ngang tiep tuyen (COM I T ) .
n
Bang 01. Che dp xtr ly thuy - nhiet cho go Bgcli ddn Nhiet do (°C) 140 160
ThCTi gian (gicr) 2 3 4 2 3 4 2
180 3 4 Xii ly thiiy - nhiet la xii ly qua 2 giai doan:
Giai dogn 1: Gd dugc xir ly trong mdi trudng nude d nhiet dp cao lam hoa tan mdt sd chdt chik suat, ph^ hiiy hemicellulose, tien
than phan huy lignin va cellulose.
Giai doan 2: Gd sau khi xir ly trong mdi trudng nude, de rao rdi tiln hanh sdy. Khi do cac chat bi tan trong giai doan 1 dugc da tu lai T.\P CHI KHOA HOC VA CONG NGHE LAM NGHIEP SO 4-2014 93
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•- (T,„[l+a(W-I2)],N/mn hinh thanh cau tnic mdi trong gd.
b) Tieu chuan va phirorng phap kiem tra tinh chat vat ly ciia go
- Do ben uon tinh
Tieu chuan kiem tra: theo tieu chuan qudc te ISO 3133:1975 va ISO 3349:1975 (TCVN 8048-3:2009).
Kich thudc mau: 20 x 20 x 300 mm.
Dung lugng mau: 10 mau/che do.
Dung cu kiem tra: Thudc kep dp chinh xac 0,01mm, mdy thu tinh chSt co ly QTEST 25.
Quy trinh kiem tra: Mau sau khi gia cdng xong xii ly mSu den dp am can bang vdi mdi trudng khong khi thudng (12%). Khi mlu da xtr ly ve dp am thang bang tien hanh do kich thudc man sau dd tien hanh xac dinh gidi han ben nen dpc dugc thuc hien tren may thii co hoc QTEST 25.
Cdng thiic xac dinh:
_ 3 P^^J
^"''l h.h- ' Trong do:
Pmax - luc pha hoai mlu , N;
I - khoang each gdi, mm;
b, h - chieu rdng va chieu cao mau, mm;
oi2 - gidi ban ben udn tinh d dp am thang bang (12%);
Ow - gidi han ben uon tinh d dp 3m thi nghiem, N/mm";
a - he sd dieu chinh do km ISy bang 0,02;
W - dp am liic thi nghiem, %.
- Bg hen nen dgc tha
Tieu chuan kiem tra: tieu chuSn qudc t l ISO 3132- 1975 (TCVN 363-70).
Kich thudc mlu: 20 x 20 x 30 mm.
Dung lugng mlu: 10 mau/chl do.
Dung cu kiem tra: Thudc kep do chinh xac 0,01mm, may thii tfnh chk co ly QTEST 25.
Quy trinh kiim tra: Mlu sau khi gia cdng xong xtr ly mlu din dp Sm can bing vdi mdi trudng khong khf thudng (12%). Khi mlu da xtr ly ve do am thang b k g tiln hanh do kich
= o-,,[l + Q'(lV-12)],N/mm^
thudc mau sau do tien hanh xac dinh gidi han ben nen dpc dugc thuc hien tr§n mdy thu co hgc QTEST 25.
Cong thiic xac dinh:
P
" ab'
Trong do:
Pmax - iuc pha hiiy mau, N,
a, b - kfch thudc tiet dien ngang cua mau, mm;
ai2 -gidi ban ben nen dgc thd d dp am thang bang (12%);
Ow - gidi ban ben nen dpc thd d dp am thf nghiem, MPa;
a - he sd dieu chinh dp am lay bang 0,04.
- Do bin nen ngang th&
Tieu chuan kiem tra: theo tidu chuSn TCVN 8048-5:2009.
Kich thudc mau: 20 x 20 x 30 mm.
Dung luong mlu: 10 mau/cl^l.tf^- Dung cu kiem tra: Can dien tii do chfnh xac
± 0,01g, tu sly nhiet dp tdi da 3O0''C cd dp cbinhxac±0,l°C.
Quy trinh kiem tra: Mau sau khi gia cdng xong xii ly man den do am can bang vdi mdi trudng khdng khi thudng (12%). Khi mlu da xii ly vl dp Sm thang bang tiln hanh do kfch thudc mau sau do tien hanh xac dinh gidi han ben nen ngang thd dugc thuc hien tren may thir CO hpc QTEST 25.
Cdng thuc xac dinh:
p
cr. = , o-,2=o-Jl-i-a(lV-12)],N/mm^
axl Trong dd:
P - luc pha hiiy mlu, N;
a-chieu rdng ciia mlu, mm;
1- chieu dai mau, mm;
Oil - gidi ban ben nen ngang thd d dp lm thang biing (12%);
uw - gidi han ben nen dgc thd d dp am thf nghiem (MPa);
W - dp am liic thi nghiem (%);
a - he sd dieu chinh do am lay bang 0,035.
94 TAP CHI KHOA HOC VA CONG NGHE LAM NGHIEP SO 4-2014
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HI. KET QUA NGHIEN ClTU
3.7. Anh huang cua che do xu ly thdy - nhiet den dg bin uon tinh gdBgch ^n
Tir ket qua nghien ciiu va sau khi xii ly thdng ke ta dugc ket qua ghi trong bang 02.
Bang 02. Do bin udn tinh cua gd Bgch ddn (MPa) D a c
t r i m g t h o n g k e X S S%
P % Min Max Cnn,
D C
105,83 2,09 6,60 20,68 97,57 118,25 4,72
Ghi chii: X:
140°C - 2gicf
95,62 1,93 6,11 17,05 85,68 102,73 4,37
C h e do xir ly nhiet d o (T) va thoi gian ( Z") 140°C-
3 gia 91,86 1,81 5,73 15,79 84,28 100,06 4,10
MO'C - 4 g i c r 86,89 1,72 5,42 14,09 79,99 94,08 3,88
160°C- 2gicr 80,91 1,90 6,01 20,09 69,93 90,02 4,30 3 i a tri t r u n g b i n h m l u ; S: Sai h a n
160°C - 3 gio
75,83 0,98 3,08 11,18 68,70 79,88 2,21 c u a u a c
160°C - 4 gia 72,45 1,26 4,00 12,02 67,12 79,15 2,86
180°C - 2 gio
61,96 1,26 3,97 11,63 56,30 67,93 2,84 l u a n g vol dp tin
]80''C - 3 gia
56,81 1,64 5,20 14,70 51,67 66,37 3,72 cay 9 5 % .
180°C - 4 gio
52,38 1.38 4,37 11,22 47,49 58,70 3,13
sd cua sd trung binh mau; S%: He sd bien ddng; P%: He sd chfnh xac; Min: Tri sd cue tieu; Max: Tri sd cue dai; C(95%): Sai sd cue
Tu ket qua d bang 02, ta xay dung dugc do thi anb hudng ciia che do xii IJ' vdi do ben udn tinh ciia gd Bach dan:
A N H HifdNG COA C H ^ D O xCr LY THCIY - NHIET D ^ N D O B ^ N U 6 N TTNH Gd BACH DAN (MPa)
ft
Che d9 xi> ly (nhift da va thoi gian)
Hinh 01. Bieu do quan he Nhan xet:
Qua qua trinh thuc nghiem ta thay dp ben udn tinh ciia go Bach dan da xu ly thuy - nhiet so vdi go Bach dan chua xir ly giam tir 105,83 MPa con 52,38 MPa (giam 50,5% so vdi mlu chua xii ly) va giam dan d cac che dp xii 1^' khi nhiet do tang va thdi gia tang, cu the nhu sau:
- Xu ly thuy nhiet d nhiet MO^C thiri gian la 2 gid, 3 git^ va 4 gid dp ben uon tinh cua go Bach dan giam din tir 95,62 MPa den 86,89 MPa.
giira che dp xuly vdi do ben uon tinh - Xii ly thuy nhiet d nhiet do IdO^C thdi gian xu ly la 2 gid, 3 gid va 4 gid do ben udn tinh cua gd Bach dan giam tir 80,91 MPa den 72,45 MPa%.
- Xir ly thuy nhiet d nhiet dd 180°C thdi gian xii ly 2 gid, 3 gid va 4 gid dp ben uon tinh cua go Bach dan giam tir 61,96 MPa den 52,38 MPa.
Dieu nay cd the giai thfch khi gd dugc xii ly thuy nhiet su phan giai do tac ddng cua nhiet TAP CHI KHOA HOC VA CONG NGHE LAM NGHIEP SO 4-2014 95
Cong nghiep rirng
do ciia cac polyme tren vach te bao, dac biet la hemixenlulo tir nhiing chudi dai chudi thanh nhiing chudi ngan ban, dan den kha nang chiu udn giam xudng. Mat khac, nhiet dp cao, thdi gian xir ly dai thi dp ben udn tinh cang giam la do trong qua tnnh xii ly thuy nhiet cac chat chiet suat trong gd bi loai bd ra ngoai, hemixenlulo bi phan huy, gd trd len rdng xdp khdi lugng the tfch giam lam cho lien ket giira Bang 03. Dg ben nin dgc thd
cac mixen xenlulo bi ldng leo, do do dp bdn udn tinh bi giam xudng. Dac biet la d che do nhiet do I80°C thdi gian xir ly la 2 gid, 3 gid va 4 gid dp ben udn tinh ciia gd Bach dan da xu ly thiiy - nhiet bi giam manh.
3.2. Anh hu&ng cua che dp xut ly thuy - nhiet den dp ben nen dgc th&go Bach ddn
Tir ket qua nghien ciru va sau khi xii ly thdng ke ta dugc ket qua ghi trong bang 03.
(COM//) cua gdBgch ddn (%) Dac
trimg thong ke X
S
s%
p%Min Max Ci9.W|
DC 65,86
1,15 3,64 9,45 60,99 70,44 2,61
140°C -2 gio 62,33
0,74 2,34 7,30 57,89 65,19 1,68
Che 140°C-
3 gio 59,80 0,87 2.76 8,45 55,10 63,56 1,97
d§ xir ly nhiet do (T) va thoi gian (z 140°C
- 4 gia 57.11 1.32 4.16 12,66 50,96 63,62 2,98
160°C- 2 gio 55,58 0,82 2,60 8,61 50,88 59,49 1,86
I60°C - 3 gio 53,46
1,32 4,17 10,98 46,97 57,95 2,98
160°C - 4 gia 51,88
1,65 5,21 15,14 43,24 58,38 3,72
)
180°C -2 gia 48,97
0,71 2,24 6,77 46,23 53,00 1,60
180°C -3 gio 45.35
1,14 3,61 12,10 36,46 48.56 2,58
180"C - 4 gia 42,18
0,75 2,39 7,00 39,06 46,06 1,71 Tir ket qua d bang 03 ta xay dung dugc dd
thi quan he giiia nhiet dp va thdi gian ddi vdi
dp ben nen dgc thd:
A N H HLFdNG CCiA CH^ Dp Xl> LY THUY - NHIET O E N Dp B £ N N E N D P C T H a G 6 B A C H D A N (MPa)
I 30 J 20 cf 10
160-2 160-3 160-4
ly (nhift d$ v^ thoi gian)
Hinh 02. Bieu dd quan he giira chi dp xir ly vdi dp ben nen dgc thd (COM//) Nhan xet:
Qua k8t qua nghien ciiu cho thSy (bang 03) su anh hudng cua nhiet dp xii ly thuy nhiet cho gd Bach dan den dp ben nen dpc rat ro ret con thdi gian anh hudng rit ft d cung ch8 dp nhiet
dp. Dp ben n6n dgc thd (COM//) giam tir 65,86 MPa cdn 42,18 MPa (giam 35,95% so vdi mau chua xii ly), cu the d cac che do nhu sau:
- Xii ly thuy nhiet d nhiet WO^C thdi gian la 2 gid, 3 gid va 4 gid dp ben nen dgc thd ciia gd
96 TAP CHI KHOA HOC VA CONG NGHE LAM NGHIEP SO 4-2014
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Bach dan giam dan tir 62,33 MPa d^n 57,11 MPa (d che dp 4 gid so vdi 2 gid thi giam 8,39%).
- Xu ly thuy nhiet d nhiet do leO^C thdi gian xii ly la 2 gid, 3 gid va 4 gid dp b6n nen dpc thd cua gd Bach dan giam tir 55,58 MPa den 51,88 MPa (d che dd 4 gid so vdi 2 gid Ihi giam 6,66%).
- Xii ly thuy nhiet d nhiet dp 180°C thdi gian xu ly 2 gid, 3 gid va 4 gid dp bSn nen dgc thd ciia gd Bach dan giam tir 48,97 MPa den 42,18 MPa (d ch8 do 4 gid so vdi 2 gid thi giam 13,86%).
Niiiet do anh hudng rd net nguyen nhan la dudi su tac ddng ciia nhiet do cao thi cac polyme vach te bao bi phan buy, nhiet dd cang cao thi thanh phan pentose bi phSn buy ckng manh lam cbo dp ben nen dpc thd giam.
3.3. Anh huang cua che dp xir ly thuy - nhiet den dp ben nen ngang thd theo chieu xuyen tdm vd tiep tuyen go Bgch dan
a) Do ben nen ngang xuyin tdm Tir ket qua nghien ciiu va sau khi xii ly thdng ke ta dugc ket qua ghi trong bang 04.
Bang 04. Dp bin nen ngang thd theo chieu xuyen tdm (COM 1^ cua go Bgch dan ( Dac
trimg thong ke X
s s%
p%Mm Max
C<95%|
DC 8,90 0,13 0,40 1,23 8,29 9,52 0,29
140°C - 2 gia 8,51 0,15 0,47 1,32 7,83 9,14 0,34
Che do xir ly nhiet do (T) va thoi gian (T 140°C -
3 gio 8,03 0,17 0,55 1,76 7,23 8,99 0,39
140°C -4 gio 7,70 0,20 0,64 1,77 6,78 8,55 0,46
160°C- 2 gia 6,76 0,17 0,55 1,60 6,18 7,78 0,39
160°C - 3 gio 6,36 0,23 0,73 2,42 5,44 7,86 0,52
160°C -4 gio 6,18 0,09 0.29 0,99 5.73 6.72 0.21
)
180°C -2 gia 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 gia 5.02 0,16 0,50 1,66 4,55 6,21 0,36 Tu ket qua d bang 04 tac gia xay dung dugc vdi dp ben nen ngang thd theo chieu xuyen do thi quan he giira nhiet do va thdi gian ddi tam:
ANH H U ^ N G C U A C H ^ D O XLF LY T H U Y - NHIET D ^ N D O B £ N N E N NGANG T H Q T H E O C H I ^ U XUYEN TAM G D BACH DAN (MPA)
I
*
* Pfcffi * - *-
140-2 140-3 140-4 160-2 160-3 1G0-4 180-2 180-3 180-4 Che d p x i r l y {nhiet d o va t h o i g i a n )
'tiinhQ'i. Biiu do quan he giua chi dp xiely vdi COM J^
b) Do hen nen ngang tiep tuyen thdng ke ta dugc ket qua ghi trong bang 05.
Tir k6t qua nghien ciiu va sau khi xii ly
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Bang 05. Bg bin nen ngang thd theo chieu tiep tuyin (COM ±T) cda gd Bgch ddn ( Dac
trung thong ke
Che do xtr ly nhiet do (T) va thoi gian (T ) 140''C 140^0 -
- 2 gid 3 gid
140''C 160''C- 16ffC 160^C 1 SO^C 1 SO^C 1 SO^C - 4 gid 2 gid - 3 gid - 4 gid - 2 gid - 3 gid - 4 gid X
s s%
p%
Min Max C(95t)
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 qua d bang 05 tac gia xay dung
dupe dd thi quan he giira nhiet dp va thdi
gian ddi vdi do ben nen ngang thd theo chieu tiep tuyen:
ANH HlfdNG CO A C»6. OO XO" LY T H O Y - NHIgT D^N D 0 B^N NEN NGANG THO THEO CHlfeU Tl^P TUY^N G 6 BACH D A N (MPa)
II £ fr
140-2 140-3 140-4 160-2 160-3 160-1 180- Che do xi> ly (nhiet do va th6>i gian)
Hinh 05. Biiu dd quan hi giua chi dp xu ly vdi COM J.r Nh$n xet:
Khi nhiet do va thdi gian tang, th6 hien d 9 che dp xii IJ thuy nhiet thi dp ben nen ngang theo chieu xuyen tam va tiep tuyen cd xu hudng giam dan so vdi man ddi chung (mlu chua xir ly), qua ket qua nghien ciiu cho thay do ben nen ngang thd theo chi^u xuyen tam (COM 1 R ) : tir 8,90 MPa cdn 5,02 MPa (giam 43,58%
so vdi mau chua xii ly), dp ben nen ngang tidp tuygn (COM I T ) : tir 7,92 MPa cdn 5,26 MPa (giam 33,37% so vdi mau chua xu ly).
Can cii vao bang 04; bang 05, dd thi hinh 03 va dd thi 05, ta thay xu ly thuy nhiet go Bach dan d nhiet dp 140V; IdO^C; 180'*C, thdi gian
xu I;^ 2gid, 3 gid va 4 gid dp ben nen ngang thd giam dan khi nhiet do va thdi gian xu ly tang, do ben nen ngang xuyen tam giam (d che do MO^C - 2 gid va 180°C - 4 gid) tir 8,51 MPa ddn 5,02 MPa (40,96%), do hen nen ngang thd tiep tuyen giam (d ch6 do 140°C - 2 gid va ISO^'C - 4 gid) tir 7,35 MPa den 5,26 MPa (28,36%). Nguyen nhan dudi tac dgng ciia nhiet dp lam cho polyme vach te bao bi thuy phan, nhiet dp cang cao thdi gian xii ly dai se lam xenlulo ciia gd Bach dan bi thuy phSn dan den cau true v3ch te bao ldng leo va tao phan irng ngat cac mach lien ket ciia cac phan tii trong gd dieu do se lam cho do ben nen ngang thd giam.
TAP CHI KHOA HOC VA CONG NGHE LAM NGHIEP SO 4-2014
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Tdm lai: Khi nhiet do va thdi gian xii ly tang lam cho qua trinh xii ly thuy - nhiet hinh thanh nen mdt sd axit hoa tan nhu: axit formic va axit axetic tir qua trinh phan buy hemixelulo. NgoM ra cac axit nay tac ddng vao xelulo va lam giam dp polyme (ck mach xelulo) dSn tdi do ban co hpc giam [7].
IV. KET LUAN
Ket qua nghien ciiu Cdng nghe xii ly thiiy - nhiet cho gd Bach dan thong qua ch8 dp xir ly nhiet dp (140'*C; 160°C va 180''C) va thdi gian (2 gid; 3 gid va 4 gid), lac gia di den mdt so kdt luan: Dp b^n udn tmh (MOR): tir 105,83 MPa cdn 52,38 MPa (giam 50,5% so vdi mau chua xu ly). Do ben nen dgc thd (COM//): tir 65,86 MPa cdn 42,18 MPa (giam 35,95% so vdi mau chua xii ly), Do ben nen ngang thd theo chiSu xuyen tam (COM XR): tir 8,90 MPa cdn 5,02 MPa (giam 43,58% so vdi mSu chua xu ly). Dp ben nen ngang tiep tuyen (COM I T ) : tir 7,92 MPa cdn 5,26 MPa (giam 33,37%
so vdi mau chua xir ly). Dieu dd, cd the minh chimg rang su anh hudng nhiet dp va thdi gian cua phuong phap xu ly thuy - nhiet da lam giam dp ben co hpc ciia gd Bach dan khi bien so nhiet dp va thdi gian thay ddi.
TAI LIEU THAM KHAO
1. Andreja Kutnar, Milan Semek (2008), Reasons for colour changes during thermal and hydrolhennal trealment of wood.
2. Andreas O. Rapp (2001), "Review on heat treatments of wood", BFH The Federal Research Centre for Forestry and Foresl Products Information and Documentanon, D-21027 Hamburg, Germany, pp. 1-66
3. BV P. I. (2006), "The Plato Technology".
4. Hill, C.A.S. (2006). Wood modification. Chemical, thermal and other processes. John Wiley & Son
5. Hiroshi Jinno, Misato Norimoto va Joeseph Gril (1993), Recent reseach on wood based, Materal-Society of Materal-Science.
6. Kamdem, D. P., Pizzi, A,, Jermannaud, A (2002), Durability of heat-treated wood, Holz als Rohund
Werksioff60{l): 1-6.
7. Marc Borrega (2011), "Mechanisms affecting Ihe structure and properties of heat-treated and high- temperature dried Norway spruce (Picea abies) wood", Dissertaliones Foreslales 134. 52 p, School of Forest Sciences - Faculty of Science and Forestry - University of Eastern Finland.
8 P. Rezayati Charani'*, J. Mohammadi Rovshandeh^, B. Mohebby^, O. Ramezani 4 "Influence of hydrolhennal ireatnient on the dimensional siabilily oj beech wood", Caspian J. Env. Sci. 2007, Vol. 5 No.2 pp.
125-131, The University of Guilan, Printed inl R. Iran.
9. Stamm A. and L. Hansen (1937), "Minimizing wood shrinkage and swelling: Effect of heating in various gases". Journal of industrial and engineering chemistry, 29(7), pp. 831-833
10. Tiemann H. D. (1915), "The effect of differeni methods of drying on Ihe sirenglh of wood". Lumber World Review. 28(7), pp. 19-20.
TAP CHI KHOA HOC 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 moisiure and absorbs water, wood color changes from light brown lo 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 fnendly environment. However, Ihe 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 worid's scienUsls are interested in the heat treatment of wood. In this article the authors present the results of treatment of Umber 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 (140"C, 160''C and ISO^C) and time (2 hours, 3 hours and 4 hours) makes the mechanical properties of wood reduce Ihe 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 ±R): from 8 90 MPa to 5.02 MPa (reduced 43.58% compared to untreated samples). Compressive stress perpendicular to grain (COM XT)- from 7.92 MPa to 5.26 MPa longer (reduced 33.37% compared to untreated samples).
Keywords; Compressive strength parallel to grain, compressive stress perpendicular to grain, compressive stress perpendicular to grain, hydro-thermal treatment. Eucalyptus urophylla S.T. Blake, module of rapture.
Ngirtri phan bien Ngay nhan bai Ngay phan bien Ngay quyet dinh dang
PGS.TS. Cao Quoc An 15/7/2014 01/10/2014 20/10/2014
100 TAP CHi KHOA HOC VA CONG NGHE LAM NGHIEP SO 4-2014
