Study on the manufacturing and properties of gas barrier multilayers films and applications

r even though PE-g-MAH has low viscosity. The results also showed that when increasing the content of PE-g-MAH compatibilizer, the torque of the polymer blend increased. 3.1.1.3. Mechanical properties of PE/EVOH polyme blends Effects of PE/EVOH ratio on mechanical properties of PE/EVOH polymer blends with and without PE-g-MAH compatibilizer were presented in Table 3.1. Table 3.1. Effect of the composition ratio on the mechanical properties of PE/EVOH polymer blend PE/EVOH ratio PE-g-MAH compatibilizer (%) Tensile strength (MPa) Elongation at break (%) 100/0 0 29.5 1005.4 90/10 19.6 765.7 80/20 15.8 420.3 70/30 12.4 256.2 60/40 10.1 148.5 50/50 7.6 89.6 0/100 25.2 17.1 90/10 4 24.5 359.2 80/20 26.4 389.3 70/30 28.3 404.9 60/40 27.1 367.5 50/50 25.5 315.8 7 In samples without PE-g-MAH compatibilizer, both tensile strength and elongation at break of the polyme blend samples decreased with increasing EVOH content. This is because PE and EVOH have differences in nature, chemical structure, polarity, surface interaction energy ... so the low adhesion between PE and EVOH leads to agglomeration of a large EVOH amount in the PE matrix. In the presence of a compatibilizer, the mechanical properties of the polymer blends were significantly improved. Tensile strength and elongation at break increased because PE-g-MAH acted as an effective compatibilizer between EVOH dispersion phase and PE matrix. Adding PE-g-MAH increased the dispersion of EVOH and increases the adhesion between phases to enhance the mechanical properties of polymer blends. The results also showed that in the presence of 4% compatibilizer, when the EVOH content increased from 10-30%, the tensile strength and elongation at break increased. Tensile strength was significantly improved when increasing EVOH content in polymer blends possibly due to high tensile strength of EVOH. However, when the EVOH content was > 30%, the mechanical properties of the polymer blends decrease because the tensile strength was strongly influenced by the phase interaction between PE and EVOH. This showed that when the EVOH content increased, the binding capacity of PE and EVOH decreased. The effect of the PE-g-MAH content on the mechanical properties of the PE/EVOH polymer blends was presented in Table 3.2. Table 3.2. Effect of PE-g-MAH content on mechanical properties of PE/EVOH 70/30 polymer blend PE-g-MAH content (%) Tensile strength (MPa) Elongation at break (%) 0 12.4 256.2 2 25.6 379.8 4 28.3 404.9 6 26.5 416.3 8 24.1 420.4 10 23.9 418.5 The results showed that the tensile strength of the polymer blends increased when the content of compatibilizer increased from 0-4%. However, when the PE-g-MAH content continued to increase to > 4%, the tensile strength of the polymer blend decreased and then stabilized. Elongation at break increased when the PE-g-MAH content increased to 6%, then almost unchanged. However, when the PE-g-MAH content continued to increase, the mechanical properties of the polymer blend samples decreased. 8 3.1.1.4. Surface morphology of PE/EVOH polymer blends SEM images of fracture surface of PE/EVOH polymer blends without and with PE-g-MAH compatibilizer wre shown in Figure 3.6 and Figure 3.7. a) PE/EVOH 90/10 b) PE/EVOH 80/20 c) PE/EVOH 70/30 d) PE/EVOH 60/40 e) PE/EVOH 50/50 Fig. 3.4. SEM images of fracture surface of PE/EVOH polymer blends without PE-g-MAH compatibilizer a) PE/EVOH 90/10 b) PE/EVOH 80/20 c) PE/EVOH 70/30 d) PE/EVOH 60/40 e) PE/EVOH 50/50 Fig. 3.5. SEM images of fracture surface of PE/EVOH polymer blends with 4% PE-g-MAH compatibilizer SEM images of fractured surface of the polymer blends showed that in the polyme blends without compatibilizer (Fig. 3.4), the phases dispersed unevenly, forming distinct phase separation regions, the dispersion of EVOH in PE matrix was quite large and coarse. With polymer blends containing compatibilizer, when the EVOH content increased from 10-30%, the component polymers had good dispersion and compatibility with each other. 9 However, when increasing EVOH content in polymer blend from 40-50%, the compatibility between EVOH and LLDPE phases becomes worse. 3.1.1.5. Differential scanning calorimetry (DSC) of PE/EVOH polymer blends DSC curves of PE/EVOH polymer blends with 4% PE-g-MAH compatibilizer at different PE/EVOH ratios were summarized in Table 3.3. Table 3.3. Effect of the LLDPE/EVOH ratio on thermal properties of polymer blends LLDPE/EVOH ratio Tg ( o C) Tm ( o C) Tc ( o C) Polyme blend LLDPE EVOH LLDPE EVOH 100/0 -20.7 121.8 - 104.8 - 90/10 -14.5 121.3 182.1 104.7 161.9 80/20 -2.4 120.4 182.7 104.6 161.3 70/30 6.32 122.0 183.0 102.5 159.2 60/40 6.5 và 38.5 120.7 184.0 103.8 161.1 50/50 6.0 và 38.8 122.3 184.2 104.3 160.9 0/100 40 - 184.4 - 162.3 The results showed that at 4% PE-g-MAH compatibilizer, when increasing the EVOH content from 0-30%, a Tg in the range Tg of EVOH (Tg = 40 o C) and Tg of LLDPE (Tg = -20.7 o C). This proves that in the presence of a PE-g-MAH compatibilizer, at 10-30% EVOH, the two polymers had good compatibility with each other. When the EVOH content continued to increase from 40-50%, two Tg values appeared in the range of Tg of the two component polymers. However, there was a shift in Tg of LLDPE to Tg of EVOH. This proves that at the EVOH content of 40–50%, in the presence of a PE-g-MAH compatibilizer, there was partial compatibility between the two polymers. The results also showed that the melting temperature Tm of LLDPE in polymer blends did not change much when the EVOH content increased. However, when increasing the EVOH content, the Tm value of EVOH in the polymer blends increased slightly but was smaller than the Tm value of EVOH resin. Crystallization temperature (Tc) of LLDPE in blends is almost unchanged. Meanwhile, when increasing EVOH content, Tc value of EVOH in polymer blend decreased slightly compared with Tc of EVOH resin. 3.1.2. Study on preparation of PA6/EVOH polyme blends To study preparation of polymer blend PA6/EVOH, polymer blend samples were prepared at different ratios of PA6/EVOH 100/0, 90/10, 80/20, 75/25, 50/50 and evaluate the properties of the polymer blend samples. 3.1.2.1. Viscosity of PA6/EVOH polyme blends The effect of the components rate on the torque of PA6/EVOH polymer blends were presented in Fig. 3.10. 10 Fig. 3.10. Curves of mixing torque versus time for PA6, EVOH, PA6/EVOH polyme blends The results showed that the torque in the molten equilibrium of PA6/EVOH polymer blends was lower than EVOH and higher than PA6. In addition, when increasing the EVOH content in the polymer blend, the torque in the molten equilibrium of the polymer blends increased. This may be due to the interaction between the organizational groups in the polymer blend, namely the amino groups of PA6 and the hydroxyl groups of EVOH. When EVOH increased, the number of hydrogen bonds between hydroxyl groups and amine groups increased, increased the intermolecular and intermolecular bonds leading to an increase in torque. 3.1.2.2. Mechanical properties of PA6/EVOH polymer blends Effects of the PA6/EVOH ratio on the mechanical properties of the polymer blends wre presented in Table 3.5. Table 3.5. Mechanical properties of PA6/EVOH polymer blends PA6/EVOH ratio (%) Tensile strength (MPa) Elongation at break (%) 100/0 60.4 29.5 90/10 58.7 42.5 80/20 52.6 58.6 75/25 48.6 74.2 50/50 32.4 68.4 0/100 25.1 17.2 The results showed that the tensile strength of PA6/EVOH polymer blends decreased when the EVOH content increased. However, the elongation at break increased when the EVOH content increased from 0-25%, when the EVOH content increased to higher than 25%, the elongation at break decreased. 3.1.2.3. Surface morphology of PA6/EVOH polymer blends Morphology of fracture surface of PA6/EVOH polymer blends was 11 shown in figure 3.11. PA6/EVOH 90/10 PA6/EVOH 80/20 PA6/EVOH 75/25 Fig. 3.11. SEM images of fracture surface of PA6/EVOH polymer blend Observing the fracture surface SEM images of the PA6/EVOH polymer blends, it was found that the fracture surface was relatively smooth, difficult to distinguish the morphology of the two phases PA6 and EVOH after mixing. This demonstrates a good dispersion of the two phases together. Surface morphology of the polymer blends after soaking in dioxane solution was shown in Figure 3.12. PA6/EVOH 90/10 PA6/EVOH 80/20 PA6/EVOH 75/25 Fig.3.12. SEM images of PA6/EVOH polyme blends after soaking in dioxane solution The results showed that with samples containing low EVOH content (Fig. 3.12a), there was no EVOH dispersion zone in the PA6 substrate. When the EVOH content increased (Fig.3.12 (b), (c) and (d)), the corrosive EVOH regions appear and the number of these eroded regions increases and the size of the regions were larger as EVOH the content in polymer blends increased.. 3.1.2.4. Differential scanning calorimetry (DSC) of PA6/EVOH polymer blends Effect of PA6/EVOH ratio on thermal properties (crystallization temperature Tc, melting temperature Tm and glass transition temperature Tg) of PA6/EVOH polymer blends was presented in Table 3.6. The results showed that the melting temperature of PA6 in the PA6/EVOH polymer blends decreased from 226.3 o C to 207.1 o C when the EVOH content increased from 0-50%, and the molten heat absorption process of EVOH was not observed. Crystallization temperature of PA6 decreased from 193 o C to 170 o C when the EVOH content increased to 50%. This indicated the formation of 12 intermolecular and intramolecular hydrogen bonds and chemical interactions between two polymers that form block copolymers (consisting of EVOH blocks and PA6 blocks). Table 3.6. DSC analysis results of polymer PA6, EVOH and PA6/EVOH polymer blends PA6/EVOH ratio Thermal properties of polyme blends Tc ( o C) Tm ( o C) 100/0 193.0 226.3 90/10 189.2 218.1 80/20 185.0 214.8 75/25 181.1 213.3 50/50 170.4 207.1 0/100 162.3 184.4 3.2. Study on preparation of gas barrier multilayer films based on polyme blends of EVOH and evaluate the lifetime of films 3.2.1. Study on preparation of PE/PE-EVOH/PE gas barrier multilayer films 3.2.1.1. Effect of PE-g-MAH compatibilizer content on properties of PE/PE- EVOH/PE gas barrier multilayer films To evaluate the effect of PE-g-MAH compatibilizer content in layer 1 and layer 3 on the properties of the PE/PE-EVOH/PE multilayer film, PE/PE- EVOH/PE multilayer film with layer 2 (PE/EVOH polymer blend) accounted for 15% in volume, layer 1 and layer 3 (LLDPE/PE-g-MAH polymer blend) accounted for 85% in volume were prepared. The PE-g-MAH compatibilizer contents in layer 1 and layer 3 were 0-8%. 3.2.1.1.1. Effect of PE-g-MAH compatibilizer content on surface morphology of PE/PE-EVOH/PE gas barrier multilayer films SEM images of the fracture surface of the PE/PE-EVOH/PE 3-layer films with the PE/EVOH polymer blend content of 15% with and without the compatibilizer was shown in Figure 3.16. Fig.3.16. SEM images of the fracture surface of the PE/PE-EVOH/PE films a) without PE-g-MAH; b) with 2% PE-g-MAH; c) with 4% PE-g-MAH SEM image of the fracture surface of the PE/PE-EVOH/PE films containing the PE-g-MAH compatibilizer showed that with 2% of the compatibilizer, the phase separation between layers was still relatively clear, (b) (a) (c) 13 but when the content of compatibilizer increased to 4%, it was difficult to observe the division between layers, showing good adhesion between the layers. It can be explained that the EVOH layer requires sufficient amount of PE-g-MAH to develop covalent bond through the reaction between the anhydride group of PE-g-MAH and hydroxyl groups of EVOH on the interphase surface between LLDPE and EVOH. 3.2.1.1.2. Effect of PE-g-MAH compatibilizer content on mechanical properties of PE/PE-EVOH/PE multuilayer films Effect of PE-g-MAH content on the mechanical properties of PE/PE- EVOH/PE multilayer films was shown in fig. 3.17. Fig.3.17. Effect of PE-g-MAH content on the mechanical properties of PE/PE-EVOH/PE films The results showed that when adding 2% PE-g-MAH, the tensile strength of the multilayer films decreased slightly, then the tensile strength increased slightly when the PE-g-MAH content reached 4% and was almost unchanged if the content of PE-g-MAH continues to increase. Thus, it can be seen that PE-g-MAH had unsinificantly affect on the mechanical properties of the PE/PE-EVOH/PE multilayer films. 3.2.1.1.3. Effect of PE-g-MAH compatibilizer content on oxygen transmission rate (OTR), water vapor transmission rate (WVTR) of PE/PE- EVOH/PE multilayer films The effect of the PE-g-MAH content on the permeability of the PE / PE-EVOH / PE multilayer film is summarized in Table 3.8. Table 3.8. The oxygen and water vapor tranmisison rate of the PE/PE- EVOH/PE multilayer films with different PE-g-MAH contents (15% of PE/EVOH) Transmission rate The content of PE-g-MAH (%) 0 2 4 6 8 Oxygen transmission rate (ml/m 2 .ngày) 3.01 3.22 3.26 4.58 5.64 Water vapor transmission rate (g/m 2 .ngày) 6.87 6.85 6.89 6.86 7.01 400 450 500 550 600 650 10 15 20 25 30 35 0 2 4 6 8 E lo n g at io n a t b re ak ( % ) T en si le s tr en g th ( M P a) PE-g-MAH content Độ bền kéo đứt Độ dãn dài khi đứt Tensile stength Elongation at break 14 The results showed that when the PE-g-MAH content increased from 0 - 4%, the oxygen transmission rate of the PE/PE-EVOH/PE film was almost unchanged. However, at the PE-g-MAH content> 6%, the oxygen transmission rate increased. The results also showed that the water vapor transmission rate of the films was not affected by the PE-g-MAH content. 3.2.1.2. Effect of PE/EVOH polyme blend (layer 2) content on properties of PE/PE-EVOH/PE multilayer films To evaluate the effect of PE/EVOH polyme blend layer content on the properties of the PE/PE-EVOH/PE multilayer film, PE/PE-EVOH/PE multilayer film with PE-g-MAH compatibilizer content layer 1 and layer 3 of 4%, PE/EVOH polymer blend content of 5 – 20% were prepared. 3.2.1.2.1. Effect of PE/EVOH polyme blend content on mechanical properties of PE/PE-EVOH/PE multuilayer films Effect of the content of PE/EVOH polyme blend on the mechanical properties of PE/PE-EVOH/PE multilayer films was summarized in table 3.9. Table 3.9. Mechanical properties of PE/PE-EVOH/PE multilayer films The content of PE/EVOH layer (%) Tensile strength (MPa) Elongation at break (%) 5 32.3 680.3 10 31.4 661.7 15 30.5 624.8 20 29.8 605.5 Mechanical properties measurement results showed that tensile strength and elongation at break of multilayer films decreased slightly when increasing the content of PE/EVOH polymer blend. This was due to the PE/EVOH polymer blend layer had much lower elongation at break than LLDPE resin. Especially, EVOH is a copolymers with high crystallinity (58- 70%), so it is quite brittle and low elongation, so increasing their content lead to reduce elongation at break of the multilayer film. 3.2.1.2.2. Effect of PE/EVOH polyme blend content on oxygen transmission rate (OTR), water vapor transmission rate (WVTR) of PE/PE-EVOH/PE multilayer films Results of measuring oxygen and water vapor transmission rate of multilayer films with different PE/EVOH polymer blend contents were presented in Table 3.10. The results showed that when the concent of PE/EVOH polymer blend layer increased, the oxygen transmission rate of the multilayer films decreased significantly. When the content of PE/EVOH polymer blend layer from 5 - 15%, oxygen transmission rate decreased sharply and then decreased insignificantly when the content of PE/EVOH polymer blend layer increased to 20%. The water vapor transmission rate of PE/PE-EVOH/PE films 15 increased with increasing content of PE/EVOH blend layer. This is explained by EVOH having -OH groups leading to its hydrophilic properties. Increasing concentration of blend layer PE/EVOH means an increase in EVOH content leads to an increase in the number of OH groups, making them more hydrophilic. Table 3.10. The oxygen and water vapor transmission of the PE/PE- EVOH/PE multilayer films (4% PE-g-MAH) Transmission rate The content of PE/EVOH polymer blend (%) 5 10 15 20 Oxygen transmission rate (ml/m 2 .ngày) 20.60 12.13 3.26 2.34 Water vapor transmission rate (g/m 2 .ngày) 4.78 5.34 6.89 9.58 3.2.2. Study on preparation of PE/PA-EVOH/PE gas barrier multilayer films 3.2.2.1. Effect of PE-g-MAH compatibilizer content on properties of PE/PA- EVOH/PE gas barrier multilayer films To evaluate the effect of PE-g-MAH compatibilizer content in layer 1 and layer 3 on the properties of the PE/PA-EVOH/PE multilayer film, PE/PA-EVOH/PE multilayer film with layer 2 (PA6/EVOH polymer blend) accounted for 10% in volume, layer 1 and layer 3 (LLDPE/PE-g-MAH polymer blend) accounted for 90% in volume were prepared. The PE-g-MAH compatibilizer contents in layer 1 and layer 3 were 0-10%. 3.2.2.1.1. Effect of PE-g-MAH compatibilizer content on surface morphology of PE/PA-EVOH/PE gas barrier multilayer films SEM image of fracture surface of the PE/PA-EVOH/PE three layer films with the PA6/EVOH polymer blend content of 15% with compatibilizer was shown in Figure 3.19. (a) Fracture surface of film (b) Fracture surface of LLDPE/PE-g-MAH polymer blend layer (c) Fracture surface of PA6/EVOH polymer blend layer Fig.3.19. SEM image of fracture surface of the PE/PA-EVOH/PE film with 4% PE-g-MAH compatibilizer Observing the fracture surface of film (Figure 3.19a), it can be seen that the interaction at the interface between the two phases is relatively good. This is because in the molten extrusion state, on the surface between the 16 membranes there is a covalent bond between the carbonyl group of MAH in PE-g-MAH and the amino group in PA6 and the hydroxyl group in EVOH. This strong interaction lead to increased adhesion between LLDPE/PE-g- MAH polymer blend layer and PA6/EVOH polymer blend layer. 3.2.2.1.2. Effect of PE-g-MAH compatibilizer content on mechanical properties of PE/PA-EVOH/PE multuilayer films Effect of the PE-g-MAH content on the mechanical properties of PE/PA-EVOH/PE mulitayler films was shown in figure 3.20. Fig.3.20. Effect of the PE-g-MAH content on the mechanical properties of mulitayler films The results showed that PE-g-MAH unsignificantly affected to the tensile strength of the PE/PA-EVOH/PE multilayer films. The results also showed that the elongation at break of the PE/PA-EVOH/PE multilayer films increased slightly with the addition of PE-g-MAH and the elongation at break increased when the PE-g-MAH content in film increased. 3.2.2.1.3. Effect of PE-g-MAH compatibilizer content on oxygen transmission rate (OTR), water vapor transmission rate (WVTR) of PE/PA- EVOH/PE multilayer films The influence of the PE-g-MAH content on the permeability of the PE/PA-EVOH/PE multilayer films is summarized in Table 3.11. Table 3.11. The oxygen and water vapor tranmisison rate of the PE/PA- EVOH/PE multilayer films with different PE-g-MAH content (10% of PA6/EVOH) Transmission rate The content of PE-g-MAH (%) 0 2.5 5 7.5 10 Oxygen transmission rate (ml/m 2 .ngày) 1.86 2.52 2.43 4.21 5.39 Water vapor transmission rate (g/m 2 .ngày) 6.70 6.69 6.72 6.79 6.75 The results showed that the presence of PE-g-MAH increased oxygen tranmisison rate. However, when the PE-g-MAH content increased from 2.5 to 5%, the oxygen tranmisison rate was almost unchanged. When the PE-g- MAH content was > 5%, the oxygen tranmisison rate increased. The results 400 450 500 550 600 650 700 10 15 20 25 30 35 0 2,5 5 7,5 10 E lo n g at io n a t b re ak (% ) T en si l st re n g th ( M P a) PE-g-MAH content Độ bền kéo đứt Độ dãn dài khi đứt Tensile stength Elongation at break 17 also showed a similar trend for the PE/PE-EVOH/PE multilayer films, PE-g- MAH did not affect the water vapor tranmisison rate of the PE/PA-EVOH/PE multilayer films. 3.2.2.2. Effect of PA6/EVOH polyme blend (layer 2) content on properties of PE/PE-EVOH/PE multilayer films To evaluate the effect of PA6/EVOH polyme blend layer content on the properties of the PE/PA-EVOH/PE multilayer film, PE/PA-EVOH/PE multilayer film with PE-g-MAH compatibilizer content layer 1 and layer 3 of 5%, PA6/EVOH polymer blend content of 5 – 20% were prepared. 3.2.2.2.1. Effect of PA6/EVOH polyme blend content on mechanical properties of PE/PE-EVOH/PE multuilayer films Effect of the content of PA6/EVOH polymer blend layer on the mechanical properties of mulayer films was presented in table 3.11. Table 3.11. The mechanical properties of multilayer films with different PA6/EVOH polymer blend layer contents The content of PA6/EVOH layer (%) Tensile strength (MPa) Elongation at break (%) 5 30.7 560.4 10 34.1 520.8 15 35.2 512.7 20 35.7 508.6 The results in table 3.11 showed that the tensile strength of films increased slightly when the polymer blend layer content increased from 10- 15%. When continuing to increase the content of polymer blend layer to 20%, the tensile strength is almost unchanged. 3.2.2.2.2. Effect of PA6/EVOH polyme blend content on oxygen transmission rate (OTR), water vapor transmission rate (WVTR) of PE/PA-EVOH/PE multilayer films Results of measuring oxygen and water vapor transmission rate of multilayer films with different PA6/EVOH polymer blend contents were presented in table 3.13. Table 3.13 The oxygen and water vapor transmission of the PE/PA- EVOH/PE multilayer films (5% PE-g-MAH) Transmission rate The content of PA6/EVOH blend layer (%) 5 10 15 20 Oxygen transmission rate (ml/m 2 .ngày) 4.54 2.43 1.69 1.32 Water vapor transmission rate (g/m 2 .ngày) 5.6 6.72 8.1 11.1 The results showed that, when the content of blend layer (middle layer thickness) increased, the O2 gas transmission rate decreased significantly. In terms of water vapor transmission rate (WVTR), when the content of blend 18 layer increased, the WVTR increased slightly. Compared with the PE/PE-EVOH/PE multilayer membrane with the same middle layer content, it was found that the oxygen barrier ability of the PE/PA-EVOH/PE films was better, or the oxygen transmission rate was lower. This can be explained by the fact that PA6 has a much higher barrier to oxygen than PE but less than EVOH. In contrast, the water vapor barrier ability of PE/PA-EVOH/PE multi-layer films was less than that of PE/PE- EVOH/PE films with the same middle layer content, because PA6 contains polar amide groups, which are hydrophilic so its water vapor transmission rate was higher. General comment: it can be seen that with the same content of the middle layer, the PE/PE-EVOH/PE multi-layer film has lower WVTR but higher OTR as compared with PE/PA-EVOH/PE multilayer film. So, depending on the purpose of use, choose the right film. According to some studies, to make the gas barrier film, the OTR of the film must be ≤ 5 ml/m 2 .day and the WVTR of the film must be ≤ 8 g/m2.day. The results showed that the PE/PE-EVOH/PE multilayer film with the PE/EVOH polymer blend content of 15% and the PE/PA-EVOH/PE multilayer film with the PA- EVOH polymer blend content of 5, 10 and 15% (signed PAEV-5, PAEV-10, and PAEV-15, respectively) were unsatisfactory as gas barrier film. 3.3. Study on application of gas barrier multilayer films in the preservation of some dry agricultural products 3.3.1. Study on application of gas barrier multilayer films in the preservation of maize grain Corn at 10.98% moisture content is packed into PAEV-10 bags, then vacuumed on BZQ 500 machine (Maize-CK) (vacuum pressure -0.08MPa). The control samples (without vacuum, Maize-T) were similarly conducted. 3.3.1.1. Effect of packaging conditions on maize quality The changes in quality of maize grain under packaging conditions were summarized in Table 3.15. Table 3.15. The quality of maize grain under packaging condition during storage Quality indicators Samples Time (months) 0 2 4 6 8 Moisture content (%) Maize-CK 10.98 10.96 11.04 11.09 11.18 Maize -T 10.98 11.30 11.64 11.95 12.05 Starch co