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acteria suitable for silage-making in tropical regions. JARQ. 29: 251-256. Okeke, B. C. and S.K.C., Obi. 1995. Saccharification of agro-waste materials by fungal cellulases and hemicellulases. Biores. Technol. 51: 23-27. Schimming, S., W.H. Schwarz and W.L. Staudenbauer. 1991. Properties of a thermoactive b-1,3-1,4-glucanase (lichenase) from Clostridium thermocellum express in Escherichia coli. Biochem. Biophysic. Res. Commun. 77: 447-452. Stefanie, J.W.H., O. Elferink, F. Driehuis, J.C. Gottschal and S.F. Spoelstra. 2000. Silage fermentation process and their manipulation. Eletronic Conference on Tropical Silage. Available. http://www.fao.org/waicent/ faoinfo/agricult/agp/gp/silage/contents. HTML. May 21, 2000. Kasetsart J. (Nat. Sci.) 40(1) 147 Stetälä, J. 1988. Enzymes in grass silage production. Food Biotechnol. 21: 211-225. Stokes, M.R. 1992. Nutrition, feeding, and calves : effects of an enzyme mixture, an inoculant, and their interaction on silage fermentation and dairy production. J. Dairy Sci. 75: 764- 773. Stulke, J., R. Hanschke, M. Hecker. 1993. Temporal activation of b-glucanase synthesisIn Bacillus subtilis is midiated by the GTP pool. J. Gen. Microbiol. 139: 2041- 2045. Tang, X.-J., G.-Q. He, Q.-H. Chen, X.-Y. Zhang and M.A.M. Ali. 2004. Medium Optimization for the production of thermal stable βglucanase by Bacillus subtilis ZJF-1A5 using response surface methodology. Bioresource Technol. 93: 175-181.
Kasetsart J. (Nat. Sci.) 40 : 148 - 157 (2006) Thermal Ageing of Thermoplastic Elastomeric Natural Rubber-Low Density Polyethylene Blends ABSTRACT Wiwat Suaysom and Wirunya Keawwattana* The effect of amount and type of antioxidants on the mechanical properties in the 65/35 NR/ LDPE blend was investigated using thermal aging both unstressed and under tensile elongation. The ageing of a family of thermoplastic elastomers from blends of natural rubber and low density polyethylene was studied using thermal treatments at 60°C for 3 days, and 70°C for 5 days. Thermal ageing of the blends of two polymers caused the tensile properties to deteriorate, especially at longer times or higher temperatures of ageing. When an antioxidant for rubber or heat or light stabilizer for polyethylene was added, thermo-oxidative stability was increased. Mechanical properties also indicated changes due to ageing. Samples were prepared with dicumyl peroxide crosslinking agent. The antioxidants used were (i) N, N’-diphenyl-1,4-phenylenediamine; DPPD, (ii) Tetrakis[methylene(3,5-di-tert-butyl hydroxyhydrocinnamate)]methane; Irganox, and (iii) Tris(2,4-di-tert-butylphenyl) phosphate; Irgafos. All of the antioxidants produced considerable improvement in the thermal-resistance. The most effective one was the combination of Irganox and Irgafos even though the continuous phase in these blends was low-density polyethylene. Key words: natural rubber, low-density polyethylene, thermal ageing INTRODUCTION Blending of two or more existing polymers or copolymers is nowadays a widely accepted method in order to respond to the demand of new materials. Blending of two polymers usually gives better properties than those of a single polymer. The emergence of thermoplastic elastomers (TPEs) is one of the important developments in the field of polymer science and technology in recent years. TPEs are a new class of materials which combine the properties of vulcanized rubbers with the ease of processability of thermoplastics. TPEs based on rubber-plastic Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10903. * correspondent author, e-mail : wirunyak@yahoo.com blends have potential for many applications in engineering and consumer goods (Walker, 1979 and Holed et al., 1996). The outdoor applications such as automotive window seals and footwear are necessary to develop satisfactory stabilization systems to ensure prolonged life. Stabilizers are required to protect the compounds from thermal degradation (at the elevated temperatures used in processing) and photo-degradation caused by the ultraviolet irradiation (UV) in sunlight (Adam et al., 1991 and Cataldo, 2001). Although some stabilizers have a wide application and can be used with many different polymers, some additives act as a stabilizer with one polymer and as a prodegradant for another. Therefore, when choosing Received date : 12/01/05 Accepted date : 09/01/06
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January - March 2006 Volume 40 Numb
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KASETSART JOURNAL NATURAL SCIENCE T
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In sacco Degradation Characteristic
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2 and management practices a sorghu
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4 the greater plant height was obta
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6 at Wolenchity (Figure 3) that led
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8 Stover and aboveground biomass Co
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10 Radford, B.J., A.J. Dry, L.N. Ro
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12 At present, new cultivars with h
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14 2000), grapevine (Lavee, 2000),
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16 repeatability of FW, FLT, FLW, S
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18 (Table 5) indicating that select
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Kasetsart J. (Nat. Sci.) 40 : 20 -
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22 measured to define fruit shape i
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24 for higher fruit number and yiel
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28 (Table 2). The numbers of flower
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30 to the color of fruit and seed c
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32 1999. Carrots and related vegeta
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34 MATERIALS AND METHODS Laboratory
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36 DISCUSSION Extensive studies hav
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38 from Gossypium hirsutum. J. Inse
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40 The natural resistance of plants
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42 4. Data collection and statistic
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44 was not significantly different
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46 showed the highest yield compare
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48 Kessmann, H., T. Staub, C. Hofma
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50 There are approximately 60 comme
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52 in PBST containing 2% ovalbumin
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54 Kasetsart J. (Nat. Sci.) 40(1) T
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56 Virus-free orchid plants show fa
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60 feed source was based on purchas
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62 intake of DM, CP, ether extract
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64 relatively slow and short. The p
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66 week 4. Milk composition was not
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68 Agricultural Experiment Station.
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70 et al., 2002). In contrast to ma
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72 level and showed marked polymorp
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76 loam (Eutric Fluvisol) soil and
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78 Eugenia caryophyllata, Echinops
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80 CONCLUSION In conclusion, out of
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82 of chromic acid titration method
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84 initials at the time of pinning
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86 vessels a point where the number
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88 Kasetsart J. (Nat. Sci.) 40(1) T
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90 CONCLUSIONS In the investigation
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92 1994; Strand et al., 1997). Now
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94 The clones were grown overnight
Page 101 and 102: 96 isozymes. The copy number for nu
Page 103 and 104: 98 Helianthus annuus. Theor. Appl.
Page 105 and 106: 100 MATERIALS AND METHODS Plant mat
Page 107 and 108: 102 The amount of Na + (%) 6 5 4 3
Page 109 and 110: 104 NGE, 7-16 folds). Finally, all
Page 111 and 112: 106 Anal. Biochem. 162: 156-159. Cr
Page 113 and 114: 108 grown for academic purpose at N
Page 115 and 116: 110 Cluster A was further separated
Page 117 and 118: 112 Table 2 Similarity index of 19
Page 119 and 120: 114 subjected to UPGMA and resultin
Page 121 and 122: 116 Tabel 3 The similarity index of
Page 123 and 124: 118 formation as seen from phylogen
Page 125 and 126: 120 Genet. 101: 860-864. Lerceteau,
Page 127 and 128: 122 INTRODUCTION Methylotrophic yea
Page 129 and 130: 124 RESULTS AND DISCUSSION Screenin
Page 131 and 132: 126 optimum temperature, insignific
Page 133 and 134: 128 medium of C. boidinii (Volfova
Page 135 and 136: 130 was observed soon after 24h cul
Page 137 and 138: 132 Kasetsart J. (Nat. Sci.) 40(1)
Page 139 and 140: 134 ACKNOWLEDGEMENTS This work was
Page 141 and 142: Kasetsart J. (Nat. Sci.) 40 : 136 -
Page 143 and 144: 138 Determination of enzyme activit
Page 145 and 146: 140 Table 1 Optimum and stability o
Page 147 and 148: 142 for example recombinant E. coli
Page 149 and 150: 144 were studied for β-1,3-1,4-glu
Page 151: 146 ACKNOWLEDGEMENT This work was s
Page 155 and 156: 150 vulcanization times were calcul
Page 157 and 158: 152 RESULTS AND DISCUSSION Mechanic
Page 159 and 160: 154 Kasetsart J. (Nat. Sci.) 40(1)
Page 161 and 162: 156 blend with 0.5 phr Irganox. How
Page 165 and 166: 160 (AA-680 ShiMADZU, Atomic Absorp
Page 167 and 168: 162 warm, relatively shallow and hi
Page 169 and 170: 164 cycle in crustacean (Chen et al
Page 171 and 172: 166 Salaenoi, J. 2004. Changes of e
Page 173 and 174: 168 MATERIALS AND METHODS This rese
Page 175 and 176: 170 DISCUSSION The average total am
Page 179 and 180: 174 repacked and scanned three time
Page 181 and 182: 176 found the most in the shrimp fe
Page 183 and 184: 178 PLS model The comparison betwee
Page 185 and 186: 180 brix value and dry matter of ma
Page 187 and 188: 182 approach to increase immunity t
Page 189 and 190: 184 higher (P
Page 191 and 192: 186 levels were significantly eleva
Page 195 and 196: 190 currents. Zone 4: River outlet
Page 197 and 198: 192 standing waters, thus the occur
Page 199 and 200: 194 and moving to 59%TL in juvenile
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198 thin membrane (Figure 1A, B). T
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200 were clearly seen. The presence
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202 could change to female at 6-12
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206 water until the water became cl
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208 reported by Thu and Preston (19
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210 cavalcade hay. The crude protei
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212 CONCLUSIONS Ruminal disappeared
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214 ∅rskov, E.R. and I. McDonald.
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216 is constrained mainly due to fa
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218 SNF and fat composition in raw
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220 in terms of both manual samplin
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222 Harding, F. 1995. Compositional
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224 proteins described by Barbut an
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226 starch/flour, shaken vigorously
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228 % Stress relaxation 54 49 44 39
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230 Kasetsart J. (Nat. Sci.) 40(1)
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234 categories including puffed sna
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236 Cohesiveness of mass Crispness
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238 Cohesiveness of mass Sweetness
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242 3. Physicochemical properties 3
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246 ACKNOWLEDGEMENTS This research
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248 are now becoming more and more
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250 downstream control. Lam Chae re
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254 Inflow (mcm.) Inflow (mcm.) Inf
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256 were above 0.70. The testing re
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258 1999-2000 could be used for tra
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262 we assume that r ≥ 2 and d r
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266 Figure 1 Prototype domains. num
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268 DISCUSSION Consequences indicat
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272 George, B. K. 1997. The GIS Boo
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discussed; and appropriateness of t
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LITERATURE CITED FORMAT Manuscripts
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