THÔNG TIN TÀI LIỆU
MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT MINISTRY OF EDUCATION AND TRAINING TRƯỜNVIETNAM NATIONAL UNIVERSITY OF FORESTRY LÊ NGỌCC PHAM LE HOA RESEARCH ON TREATMENT TECHNOLOGY OF NGOT BAMBOO (Dendrocalamus latiflorus)MATERIAL FOR PRODUCING BAMBOO SCRIMBER MAJORITY: FORESTRY PROCESSING TECHNOLOGY CODE: 9549001 SUMMARY OF ENGINEERING DOCTORAL THESIS HA NOI, 2021 Research work is completed at: Vietnam National Forestry Trường Đại học Lâm nghiệp Việt Nam University of Scientific instructors: Scientific instructor 1: Associate Professor, Dr Cao Quoc An Scientific instructor 2: Professor, Dr Tran Van Chu Chương Reviewer 1:…………………………………………… Reviewer 2:…………………………………………… Reviewer 3:…………………………………………… The defense will be taken in front of the Institutional Board of Thesis Evaluation at: Vietnam National University of Forestry At: … time, Date ….Month… Year 2021Thn The thesis can be found in the libraries: National Library; Vietnam National University of Forestry Library LIST OF PUBLICIZED ARTICLES, SCIENTIFIC WORKS RELATED TO THE THESIS Year of publication 2019 2021 Name of the scientific article Effects of pressing treatment of Mang Ngot (Dendrocalamus latiflorus) to mechanical characteristics of Bamboo scrimber materials Effect of temperature, treatment time and bamboo moisture to some basic properties of Ngot Bamboo (Dendrocalamus latiflorus) Journal name Journal of Forestry Science and Technology Journal of Forestry Science and Technology Author/Co -author Co-author Co-author ABSTRACT Official thesis title: "Research on treatment technology of Ngot bamboo (Dendrocalamus latiflorus) material for producing bamboo scrimber " I INTRODUCTION Dendrocalamus latiflorus is a fast-growing plant in the bamboo family Bamboo Sweet Bamboo also has advantages such as: large biomass ratio, large body Can be planted in concentrated forests or alone according to the smoke, easy to care for, exploit, transport However, bamboo has some disadvantages such as hydrophilic nature, dimensional stability and resistance to microorganisms, poor mold, low shelf life of bamboo Therefore, it is necessary to treat denaturation to reduce the above disadvantages and improve the properties and value of bamboo materials Sweet bamboo shoots are only exploited at the age of 3-4 years old because of this type of tree, people take bamboo shoots as the main, and the value of using bamboo stalks is not high At present, there are several treatment methods such as acetylation, chemical and heat treatment that have been applied Compared with previously reported methods, heat treatment for bamboo is an environmentally friendly bamboo protection method, which helps bamboo products enhance some physical and mechanical properties, increasing their use value use Through heat treatment, the microbial resistance, dimensional stability and weather resistance of the material are enhanced Pressed bamboo is a man-made composite product, it is made from bamboo materials in the form of bamboo or bamboo fibers that have been glued with high pressure When a large enough pressure is reached, the bamboo spokes or bamboo fibers will form a stable bond with each other These products are used as floor structures, beams, bridges Currently, in Vietnam and around the world, there have been many researches on material handling technology for block-pressed bamboo However, there is no research on processing technology for Mang Ngot bamboo materials used as raw materials for the production of block-pressed bamboo products For those reasons, I carried out the thesis: "Research on processing technology for denaturing bamboo materials Sweet bamboo shoots (Dendrocalamus latiflorus) used in the production of pressed bamboo products" II OBJECTIVES, RESEARCH CONTENTS AND METHODOLOGY 2.1 Research objectives 2.1.1 Theoretical objectives - On the basis of studying the relationship between temperature, time, and humidity of heat-treated bamboo to find out the change in structure, mechanical and physical properties of bamboo, thereby contributing to explain the processing mechanism calculated by thermal method for bamboo species in general and for sweet bamboo shoots in particular - Contributing to supplementing the theoretical basis of the technology of modification by heat method, as a basis for determining the parameters of heatmechanical treatment technology for bambo 2.1.2 Practical objectives - Determining the influence of heat treatment on the change of microscopic structure of whole bamboo and block pressed bamboo - Determine the influence of time, temperature and humidity on the quality of heat-modified bamboo - Determine the reasonable parameters in the process of modifying the stamped bamboo by heat method used to produce block pressed bamboo - Proposing the technological process to produce block-pressed bamboo from the heat-modified sweet bamboo material 2.2 Research content - Theoretical research - Determine the microscopic structure and some basic properties of bamboo rods - Study on the influence of technological parameters on the physical, mechanical, chemical composition and adhesive ability of denatured treated whole bamboo shoots - Study on the influence of technological parameters on the physical, mechanical and anti-fungal properties of block plywood using heat-modified hotrolled sweet bamboo shoots - Optimizing technological parameters to the properties of pressed bamboo using heat-modified hot-rolled sweet bamboo shoots - Test the results and optimize the processing parameters from which to propose the technological process of producing block pressed bamboo 2.3 Main research method - Experimental method The main method of the thesis is the empirical method, using the experimental design method to meet RMS surface and analyzing and evaluating the results by Design Expert 11.0 software Design method based on the following function: N = ^ x + 2x + 6cp (1.1) In which: N- experimental numbers, x- variables, cp- center point The distance from the center to the star point α = 2k / 4, where k is the input variable (k = 3), so α = , 6819 Experimental levels are arranged at levels (-α, -1, 0, 1, + α) The number of experiments was calculated according to formula (1.1) and processed by Design Expert 11.0 software to obtain the experimental mode in Table 1.1 Table 1.1 Experimental parameters with influencing factors Coding Modes Variables Real Variables Temperature Time Humidity C (Minutes) % A B C -1 -1 -1 140 60 15 -1 -1 180 60 15 -1 -1 140 180 15 1 -1 180 180 15 -1 -1 140 60 25 -1 180 60 25 -1 1 140 180 25 1 180 180 25 -α 0 126 120 20 10 +α 0 194 120 20 11 -α 160 19 20 12 +α 160 221 20 13 0 -α 160 120 12 14 0 +α 160 120 28 15 0 160 120 20 16 0 160 120 20 17 0 160 120 20 18 0 160 120 20 19 0 160 120 20 20 0 160 120 20 o The experiments in the model, the experimental results (Y) and the predicted model results (Y ') are shown through the correlation between the indicators function Y and the influence parameters xi: Y = bo + b1 x1 + b2 x2 + b3x3 + b12 x1 x2 + b13 x1 x3 + b23 x2 x3 + b11 x12 + b22 x22 + b33 x32 (1.2) In which: Y - norm functions (elasticity return, anti-expansion coefficient, specific gravity, mechanical properties ); xi- the coded value of the variables; bo free coefficient; bi - linear coefficients; bii: - quadratic coefficients Testing standards: (1) For bamboo sticks (1-1) Determination of chemical composition Determination of celluloses content (Standard T-210-OS-70) Determination of Lignin content (Standard T – 13 OS – 54) (1-2) Density - Test standard: GB/T15780-1995 of China for determining the physical and mechanical properties of bamboo (1-3) Radial expansion test - Applying test standards: TCVN 8048-15:2009 of Vietnam on testing the expansion of wood Applied to Bamboo because there is no standard to test the expansion of bamboo (1-4) Static flexural strength (MOR) - Test standard: GB/T15780-1995 of China for determination of mechanical and mechanical properties of bamboo (1-5) Determination of compressive strength along the grain ((σnd )) - Test standard: GB/T15780-1995 (1-6) Glue film slip resistance - Applicable standard: TCVN 8576:2010 (1-7) Methods for analysis of microscopic structure By field emission Scanning Electrion microscopy Microscope) S-4800 at the Institute of Materials Science, No 18C, Hoang Quoc Viet, Hanoi (2) For pressed bamboo blocks (2-1) Density: Test standard: LY/T 3194-2020 (2-2) Thickness swelling test: Test standard: LY/T 3194-2020 (2-3) Degree static flexural strength (MOR) - Test standard: LY/T 3194-2020 (2-4) Determination of compressive strength along the grain - Test standard: LY/T 3194-2020 (2-5) Method Determination of resistance to fungi: TCVN 10752:2015 Evaluation of the resistance of artificial composite boards to pure cultured basidiomycetes wood fungus; TCVN 10753: 2015 - Wood preservatives, method of determining effectiveness against wood-damaging fungi (2-6) Method of analyzing microscopic structure Method of analyzing structure of microscopy (SEM image): by Field emission Scanning Electrion Microscope S-4800 at the Institute Materials science 2.3 Meaning of Thesis 2.3.1 Scientific significance The thesis is a research work that provides the theoretical basis and the scientific nature of bamboo processing by high temperature - vacuum treatment for the purpose of using as block pressed bamboo 2.3.2 Practical significance The research results of the thesis are the scientific and practical basis for building a technological process of bamboo treatment by heat method in general, for the purpose of producing block plywood in particular III RESULTS AND DISCUSSIONS 3.1 Results of inspection and evaluation of the influence of heat treatment parameters on the quality of bamboo in the form of bars Table 3.1 Test results of Celluloses and Lignin content of bamboo sticks Celluoloses Lignin Temperature Time Humidity (oC) (Minutes) (%) TN1 140 60 15 49,32 0,02 25,22 0,11 TN2 180 60 15 32,32 0,17 32,32 0,17 TN3 140 180 15 45,14 0,18 29,21 0,23 TN4 180 180 15 43,13 0,09 31,78 0,23 TN5 140 60 25 50,82 0,06 27,15 0,00 TN6 180 60 25 49,22 0,06 29,14 0,06 TN7 140 180 25 47,45 0,04 31,07 0,05 TN8 180 180 25 45,54 0,14 33,45 0,02 TN9 126 120 20 49,81 0,07 26,44 0,04 TN10 194 120 20 43,95 0,02 32,71 0,08 TN11 160 19 20 51,98 0,06 27,05 0,22 TN12 160 221 20 45,42 0,08 32,58 0,02 TN13 160 120 12 46,75 0,07 26,73 0,16 TN14 160 120 28 50,12 0,17 32,32 0,94 TN15 160 120 20 48,11 0,12 30,30 0,17 52,01 0,07 25,21 0,24 Mode ĐC Content SD (%) Content SD (%) We can see that: - All treatment regimes have resulted in lower cellulose content than the control sample, the value of the control sample reached 52.01%; The mode with the most decisive factor to the radial expansion The temperature factor has a stronger influence than the time and humidity factor Y 𝑛3 = 157,80 - 0,4777A + 0,2244B - 0,8801C - 0,4300AB + 0,1500 AC- 0,3750 BC - 0,133A2 - 0,1043B2 - 0,2302C2 MOR A, B , C is a closely bound relationship, the parameters have a resonance relationship with each other The humidity and temperature factors have a stronger influence than the time factor Y 𝑛4 = 57,31 - 0,6152A + 0,3243B - 1,08C - 0,0175AB - 0,0375AC- Cylindrical compression 0,1075BC - 1,20A2 - 0,8867B2 - 0,00134C2 A, B, C are closely bound relations The temperature factor has a stronger influence than the time and humidity factor Temperature is a major determinant of longitudinal compressive strength Y 𝑛5 = 9,16 - 1,51A - 1,31B + 0,8804C + 0,1087AB + 0,0862AC- Lend tensile 0,0188BC + 0,2781A2 + 0,0536B2 + 0,0341C2 sliding glue the A, B, C are closely bound relations The temperature factor has the strongest influence, the time factor and the humidity factor have almost equal influence According to Table 3.2, we see: 3.1.3 Effect of treatment parameters on density + Mode gives the highest density: 0.61 g/cm3; Mode 12 for the lowest density 0.54 g/cm3; All treatment modes gave lower results than the control sample (0.62 g/cm3); The density of bamboo tends to decrease when the temperature is increased to 160oC, for 120 minutes, the humidity is 20%, and decreases sharply when it is increased to 180oC, for 180 minutes; 15% humidity 3.1.4 Effect of processing parameters on Static flexural strength (MOR) Bending strength 160.03 MPa in TN5 mode; Lowest static flexural strength of 152.73 MPa in TN12 mode; All treatment modes gave lower results than the value of the control sample (161.95 MPa); 10 3.1.6 Effect of processing parameters on longitudinal compressive strength Highest longitudinal compressive strength of 63.33 MPa in TN5 mode; Lowest longitudinal compressive strength 56.03 MPa in TN12 mode; All treatment modes gave lower results than the value of the control sample (65.06 MPa); 3.1.7 Effect of processing parameters on adhesive Film sliding tensile strength The highest adhesive film sliding strength is 13.20 MPa in TN5 mode; The lowest adhesive film slip strength of 5.95 MPa in TN12 mode; This mode gives a lower value of glue film sliding strength than the control sample, The remaining treatment modes give higher results than the control sample 3.1.8 The results of examining the microscopic structure of bamboo Microscopic Structure of the heat-treated bamboo sample in the experimental mode with the control sample, the bamboo samples were taken on the same bamboo stick of slat (a) Microscopic structure of the cross- (b) Cross-sectional microstructure of section of bamboo that has not been heat heat-treated bamboo treated Cross-sectional microstructure of untreated and heat-treated bamboo 11 (a)- Microscopic structure of radial (b)- Microscopic structure of the cross-section of unheated bamboo radial section of heat-treated bamboo Microscopic structure of the radial section of untreated and heat-treated bamboo (a)- Microscopic structure section of unheated bamboo of tangential (b)- Microscopic structure of tangential section of heat-treated bamboo Microstructure of tangential cross-section of untreated and heat-treated bamboo Figure 3.1 Microscopic structure of untreated and heat-treated bamboo sticks General comment: The results show that, with the increase of heat treatment temperature and prolongation of time while the humidity is low, there will be hydrolysis of the lost cellulose content in bamboo In case of cracks when observed in bamboo rays, in parenchymal cell walls and intermediate layers of bamboo, and in larger vascular pores, bamboo fibers are broken The results show the feasibility of using modified bamboo materials as composite materials from bamboo and this is also the same result as Qin (2010) 12 3.2 Results of testing and evaluating the influence of heat treatment parameters on the quality of pressed bamboo Table 3.3 Test results of properties of block pressed bamboo H Tem Mode pera ture (oC) Ti me (Mi nut es) u mi Dens dit ity y (g/c ( m3) Expa SD SD nding (Expa (Dens thick nding ity) ness( thick %) ness) % Longitudin MOR (MPa) SD al (MOR compressiv ) e strength (MPa) SD Longitudinal compressive strength) ) TE1 140 60 15 1,06 0,019 6,71 0,035 131.65 2719 65,94 0,637 TE2 180 60 15 0,95 0,016 6,79 0,038 114.91 1914 64,35 0,502 TE3 140 180 15 1,03 0,016 6,75 0,046 130.95 1686 66,16 1083 TE4 180 180 15 0,96 0,010 6,73 0,024 114.94 2480 66,36 2442 TE5 140 60 25 0,95 0,019 5,34 0,036 115.93 3863 64,14 1089 TE6 180 60 25 0,95 0,014 5,34 0,037 115.93 3271 64,14 1718 TE7 140 180 25 0,96 0,017 5,35 0,031 115.04 2807 64,23 1278 TE8 180 180 25 0,94 0,015 5,21 0,036 111.16 3066 62,25 1493 TE9 126 120 20 0,97 0,029 5,97 0,070 114.97 2137 66,18 1008 TE10 194 120 20 0,93 0,017 6,07 0,070 110.62 2440 62,06 1316 TE11 160 19 20 0,94 0,017 5,91 0,054 111.38 2632 62,18 1381 TE12 160 221 20 0,97 0,017 6,08 0,069 114.77 3708 66,18 2323 TE13 160 120 12 1,05 0,036 9,31 0,043 131.76 2613 67,17 1526 TE14 160 120 28 1,03 0,019 7,36 0,034 125.97 1398 67,18 1418 TE15 160 120 20 1,11 0,019 8,93 0,078 136.73 2878 74,21 2747 TE16 160 120 20 1,08 0,028 8,89 0,089 137.28 2209 74,23 2711 TE17 160 120 20 1,11 0,024 8,72 0,050 138.12 3204 74,31 0,712 TE18 160 120 20 1,01 0,014 8,96 0,099 137.26 1539 74,22 1204 TE19 160 120 20 1,10 0,011 8,86 0,057 137.68 3851 74,25 1042 TE20 160 120 20 1,12 0,026 8,07 0,062 138.15 1779 74,23 1653 0,86 0,020 9,69 0,040 109.78 2791 60,72 1952 ĐC 13 The Relationship between three factors: temperature, time, humidity and the influence of these three factors on the quality of block plywood is shown in the equation correlate: Equation correlate Y 𝑒1 = 1,10 - 0,0196A + 0,0022B - 0,0176C + 0,0025AB + 0,0200AC – 0,0025BC - 0,0535A2 - 0,0517B2 - 0,0217 C2 Density A and B, A and C are non-binding, B and C have resonance The factors of temperature and time have a stronger influence than the factor of humidity Temperature has the strongest effect on density Ye2 = 8,77 + 0,0026A + 0,0158B - 0,9119C - 0,0212AB 0,0338AC -0,0038BC- 1,17A2 - 1,18B2 - 0,0003C2 A, B, and C are closely related relationships The humidity factor Thickness has a stronger influence than the time and temperature factors in swelling terms of first-order relationship Considering the quadratic relationship, the humidity factor has less influence than the temperature and time factors The factors of temperature and time have almost equal influence Static flexural strength (MOR) Y 𝑒3 = 157,50- 3,53A + 0,2615B - 3,54C + 0,1312AB + 0,038AC - 0,0988BC - 8,49A2-8,39B2-2,81C2 (3.8) The equation for the relationship A, B, C is a closely constrained relation The temperature and time factors have an equal influence and have a stronger influence than the humidity factor Y 𝑒4 = 74,25 - 1,05A + 0,5211B - 0,5853C - 0,0237AB - Longitudinal 0,0737AC- 0,0087BC - 3,66A2 - 3,64B2 - 2,58C2 A, B, C compressive are closely tied relationships, the importance of factors A, B is strength equal and greater than C Considering the influence of factors according to the first-order relationship, temperature and time are weak Time has a greater influence than humidity 14 3.2.1 Effect of processing parameters on density Mode 20 gave the highest density results: 1.12 g/cm3 ; Mode 10 gives the lowest density of 0.93 g/cm3; All treatment modes gave higher results than the control sample (0.86 g/cm3); 3.2.2 Effect of processing parameters on thickness swelling Mode has a temperature treatment parameter of 180oC, resulting in the lowest thickness swelling of 5.21%; Mode 13 results in swelling to the highest thickness of 9.31% All modes gave lower results than the control sample (9.69%) The thickness swelling increased slightly when the parameters of temperature, rise time and bamboo moisture decreased However, the thickness swelling tends to decrease when the temperature exceeds the threshold of 160 oC and the time exceeds the level of 120 minutes 3.2.3.Effect of processing parameters on static Flexural strength The highest static flexural strength is 138 MPa in TE20 mode; Lowest static flexural strength 110.62 MPa in TE10 mode All treatment modes gave higher results than the value of the control sample (109.78 MPa) We see that the static flexural strength of block-pressed bamboo increases with increasing temperature and processing time, but decreases when the temperature exceeds 160 oC and the time exceeds 120 minutes, the time is prolonged; High temperature (greater than 180 oC), long time (greater than 180 min) and low bamboo humidity (below 15%) will cause the static flexural strength to decrease markedly 3.2.4 Effect of processing parameters on the compressive strength along the grain The highest longitudinal compression strength of 74.31 MPa in TE17 mode; Lowest longitudinal compression strength of 56.03 MPa in TE10 mode; All treatment modes gave lower results than the value of the control sample (60.72MPa); The compressive strength of pressed bamboo increases with 15 increasing temperature and processing time, but will decrease when the temperature exceeds 160 oC and the time exceeds 120 minutes, the time is prolonged; High temperature (greater than 180 oC), long time (greater than 180 min) and low humidity of bamboo (less than 15%) will cause a marked decrease in compressive strength 3.2.5 Optimizing heat treatment parameters to physical and mechanical properties of block-pressed bamboo For optimization, select input and output parameters according to table 3.30 and get results according to table 3.4 after processing with Design software Expert 11 Table 3.4 Input and output variable target range for optimal planning Name Target Temperature Within A: Within High Value Value level level Below Above 140 180 1 60 180 1 15 25 1 Importance Range B: Time Within C: Low Humidity Within Range Within Within Range Density Largest 0.93 1.12 1 Thickness Swelling Smallest 5.21 11.31 1 Static Largest 110.62 138.15 1 Largest 62.06 1 flexural strength (MOR) Longitudinal 74.31 compressive strength 16 After the analysis of the only 01's best option is to be optimism with parameters like after: temperature (153,1oC), Time (123,26 minute) and humidity 19,91% 3.2.6 Lab test positive for fungal antifungal From the optimal mode, with the processes, temperature (153,14oC), Time (123,26 minute) and humidity 19,91% I'm working on antifungals for the bamboo tumor The results of anti-fungal fungus Daedalea quercina (L.) Perbamboo mass spectrum treatment and no heat processing I see the DSI readings of the bamboo model forcing the temperature of the maximize mode, 90, 96 and the bam6 pressure patterns don't apply to the temperature to the 80,84 It also shows that the fungus of the bamboo hepatic strain forces the masses to apply the temperature from the bamboo tumor to no heat 3.2.7 The test results of the bamboo microscope are controlled At cross section: Structure of micrographs of cross-sectional Cross-sectional microstructure of heatunheated block treated block pressed bamboo pressed bamboo At the radial face 17 Microscopic structure of radial cross- Microstructure of the radial surface of section of unheated block pressed heat-treated block-pressed bamboo bamboo At the tangent section Microscopic structure of tangential Microscopic structure of tangential section of unheated block pressed surface of heat-treated block-pressed bamboo bamboo Figure 3.2 Results of examining the microscopic structure of bamboo block pressed with raw materials of untreated heat-treated bamboo and heattreated bamboo General comment: The results show that, with the increase of heat treatment temperature and prolongation of time While low humidity then in bamboo causes cracks as observed 18 in bamboo rays, between fibers and fiber bundles, in parenchymal cell wall and intermediate cell layer of bamboo, and large vascular pores more, bamboo fiber is broken, when there is pressure on parenchymal cells, vascular pores and bamboo fibers are compressed to different degrees, cell wall is folded or even crushed, PF glue easily penetrate into cracks, vascular holes, even parenchymal cells, due to high temperature treatment, parenchymal cells are expanded, thereby making block-pressed bamboo have a higher solidity than the undamaged sample handle 3.3 Testing and Proposing Procedures 3.3.1.Testing for Optimal Results The test results of the optimal regime affecting bamboo properties are shown in Table 3.5 Table 3.5 Optimal mode test results Optimum Indicator mode Test results Erro 1,1 1,09 1,0092 8,65 8,66 0,9988 187,78 186,25 1,0082 74,21 73,13 1,0148 results Density (g/cm3) Thickness Expansion (%) MOR (MPa) Compression Strength (MPa) Based on table 3.5 it is found that the error between the experimental mode and the optimal mode is recommended to reach a low error value of no more than 2% The confidence level is 98% This result is completely reliable and applicable to production With this result, compared with the results of BWG's pressed bamboo products 19 (information on BWG's website) shows that the specific weight of the thesis product has a lower value (1.09 compared to BWG's website) with 1.1), swelling has the same value - Proposing the production process of block-pressed bamboo using heatmodified sweet bamboo Technological diagram Bamboo sweet aged from to 4, choose a length of 3m in the range of the stem (from (Stage 1) 1.3 m from the base to the top) Creating - Cut the tube into to parts to create the bamboo size bamboo stick ruler with a width of 100 embryos mm - Rolled and planed to a thickness of 12 mm (Stage 2) Bamboo drying - Drying the shaved bamboo to a moisture content of 19-20% Regularly check the humidity - After drying, it is immediately transferred to the heat treatment stage to denature heat High temperature treatment for bamboo in a (Stage 3) High vacuum environment with the following treatment parameters: Treatment temperature temperature: 153 oC; Processing time: treatment about hours (123 minutes); Vacuum pressure: 0.1 Ba (Stage 4) Temperature 20±3 oC, humidity 65±5%, 20 Stabilizatio time days n of bamboo (Stage 5) Dip glue and cold press (Stage - Dip PF (Phenol Formadehyde) glue for 10 to 15 minutes Drying glued bamboo to 15% moisture - Pressing blocks by cold pressing method: Pressing pressure is 75 MPa 6) Drying heat: Drying temperature, drying Drying curing time of 4.5 minutes / 1mm thickness curing (about 15 hours) (Stage 7) Let the bamboo press the block in an Stabilizing environment with a temperature of 20±3 the pressed oC, a humidity of 65±5%, for days bamboo Unload the mold Figure 3.4 Technological diagram for the production of heat-modified blockpressed bamboo 21 CONCLUSIONS AND RECOMMENDATIONS Conclusion Thesis: "Study on processing technology of bamboo materials Sweet bamboo shoots used in the production of pressed bamboo products" achieved the following results: (1) Influence of processing parameters heat on the quality of bamboo sticks - Temperature, heat treatment time and bamboo humidity have a clear influence on the density, radial expansion, static flexural strength and longitudinal compressive strength of bamboo materials Sweet bamboo shoots Specifically: Density and radial expansion decrease with increasing temperature, increasing processing time and reducing bamboo moisture; Static flexural strength, longitudinal compressive strength and film shear strength increased slightly with increasing temperature and curing time - When the processing temperature is higher than 160oC, the time is longer than 120 minutes and the humidity is below 15%, the static flexural strength, longitudinal compressive strength and film sliding strength tend to decrease slightly; When the temperature is higher than 180oC, the curing time is longer than 180 minutes and the humidity is below 12%, the static flexural strength, compressive strength and sliding strength of the adhesive film tend to decrease sharply - The microscopic structure of heat-treated bamboo has many changes compared to untreated bamboo Larger vascular pores and soft tissue cells, more cracks appeared in the heat-treated bamboo This is the most favorable factor for the subsequent penetration of PF resin into the microstructure of bamboo thereby forming a bond very high crosslinking of thermoset polymers in block pressed bamboo (2) Effect of heat treatment parameters on the quality of pressed bamboo The temperature, heat treatment time and bamboo humidity have a clear influence 22 on the density, radial expansion, static flexural strength and longitudinal compressive strength of pressed bamboo shoots Specifically: Bamboo pressed blocks from heat-treated materials have higher results in static flexural strength and longitudinal compression than in block-pressed bamboo samples with raw materials that have not been heat treated However, when the temperature is higher than 180 oC, the processing time is longer than 180 minutes and the humidity is below 12%, the static flexural strength and longitudinal compressive strength of block-pressed bamboo tend to decrease sharply - Optimum parameters of heat treatment for bamboo: Temperature (153.14 oC), Time (123.26 minutes) and bamboo humidity 19.91% The vacuum pressure is 0.1 Bar - Both heat-treated and non-heat-treated block-pressed bamboo samples have good antifungal properties ie the DSI index is lower than the lowest standard DSI index of 89.4 The DSI index of the heat-treated block-press bamboo sample in the optimal mode reached 70.96 and that of the non-heat-treated block-pressed bamboo sample reached 80.84 The anti-fungal ability of the heat-treated block-pressed bamboo sample was better than that of the non-heat-treated block-pressed bamboo sample - The quality of pressed bamboo is achieved through the following criteria: Specific weight is 1.09 g/cm3, swelling thickness is 8.66%; Static flexural strength is 136.25 MPa, longitudinal compressive strength is 73.13 MPa (3) The process of producing block pressed bamboo The thesis has given the process of producing block pressed bamboo from Sweet Bamboo material including stages in which the implementation of the stages is clearly described Recommendations (1) In order to orient a suitable processing solution for block pressed bamboo, it is necessary to study the processing ability of bamboo on common machines 23 (2) The thesis has not evaluated a number of criteria such as, the adhesion of the glue circuit, the natural durability, the jewelry ability of the block pressed bamboo, so it is necessary to have other works to separate research on these issues this topic (3) There should be objective assessments on the economic efficiency of using modified block-pressed bamboo with popular planted forest woods such as Acacia, Pine (4) On the basis of the results of the thesis, which still exists without studying the solute composition of sweet bamboo, it is necessary to have studies on the structure and chemical composition of bamboo before and after when processed more intensively (5) Implement research and application of raw materials processing technology Sweet bamboo used in the production of block-pressed bamboo products into production and popularized products on the market 24 ... tangential section of heat-treated bamboo Microstructure of tangential cross-section of untreated and heat-treated bamboo Figure 3.1 Microscopic structure of untreated and heat-treated bamboo sticks... of heat-treated block-pressed bamboo bamboo Figure 3.2 Results of examining the microscopic structure of bamboo block pressed with raw materials of untreated heat-treated bamboo and heattreated... flexural strength, compressive strength and sliding strength of the adhesive film tend to decrease sharply - The microscopic structure of heat-treated bamboo has many changes compared to untreated
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