高分子複合材料的相關產物早已融入日常的生活之中，而為了應因石化能源枯竭和落實環保的概念，綠色高分子複合材料發展則日趨重視。竹纖維的低成本、生長期短、生物降解性高、機械性質良好、高經濟效益等，使得天然竹纖維是一個良好的補強材選擇，可以補強眾多的高分子材料，如:聚乳酸、聚丙烯、樹脂等高分子材料。
本研究選用台灣常見的在地竹種刺竹、孟宗竹、桂竹做測試，再使用機械法和鹼洗法萃取竹纖維，在比較兩法萃取的竹纖維拉伸強度和其橫截面變化。機械法是使用滾壓機直接滾壓竹片作物理萃取，鹼洗法則是調配了濃度0.3N的氫氧化鈉及100℃的滾沸水做萃取。在竹纖維的微拉伸測試方面利用線性負載量測平台做底座，再使用自行設計的夾頭做微拉伸測試，再將各竹種的數據整理出來並建立台灣竹種資料庫。

SUMMARY
Polymer composites has been used as consumer goods in our daily lives. The applications of green composites become important for reducing petroleum consumption and enhancing environmental protection. Natural bamboo fibers have many advantages such as low cost, fast growth, biodegradability, high strength, and ecologically, etc. In addition, bamboo fibers are considered suitable materials as reinforcement in polymeric composites.
The purpose of the study is to measure the tensile property of single bamboo fiber. The bamboo fibers were extracted by using mechanical method (Mec) or alkaline method (Alk). The tensile strengths of bamboo fibers extracted by two methods were compare. Mec was a mechanical separation method to harvest coarse bamboo fibers. Alk was a combination chemical and mechanical methods to extract bamboo fibers. In the chemical part, sodium hydroxide (NaOH) solution in concentration of 0.3N was prepared. The bamboo strips were boiled in solution in 100℃ to dissolve lignin and hemi-cellulose. After extracting bamboo fibers, tensile test was performed for the bamboo fiber at a home-made micro-tensile tester. The study selected Taiwan’s native bamboos like thorny bamboo, moso bamboo and makino bamboo as the testing samples.
INTRODUCTION
With gradual depletion of fossil fuel, green composite materials have gained much interest to be alternatives of the current composites. Usually, composite consists of matrix and reinforcement. Conventional fibers could be substituted by natural bamboo fiber as the reinforcement in composites. Bamboo fiber has the advantages as low cost and environment friendly. On top of that, it has inherent properties such as high tensile strength, high stiffness, and low elongation at break. These benefits show that bamboo fiber is an excellent candidate as reinforcements.
Bamboo fiber has hierarchical structures, distributed in the broad and narrow lamellae. There are many vascular bundles in lamellae like figure 2-7. The chemical constituents of bamboo are cellulose, hemi-cellulose, lignin and pectin etc. Cellulose is the primary content of plant cell wall, and that of bamboo is approximately 45%. Hemi-cellulose which presents along with cellulose in cell wall is easily hydrolyzed by dilute base. Lignin is insoluble in water but soluble in alkaline solutions. It supports bamboo to have a high strength. The studying purpose is to measure the tensile property of different bamboo fibers.
EXPERIMENTAL METHOD
First, raw bamboo was cut to short section with nodes and veneers removed. Then, it was longitudinal cleaved into bamboo segments with 40mm length. After that, there are methods used to extract bamboo fibers: mechanical method and alkaline method.
Mechanical method:
Bamboo segments were chopped to strips with 3mm thick. Bamboo strips were placed in a roller-mill machine to harvest rough bamboo fibers.
Alkaline method:
The bamboo strips were boiled in sodium hydroxide solution with 0.3N concentration for 12 hours. After that, the strips were washed under water to remove dissolved impurities. Then, they were placed inside a roller-mill machine for three times passes. Finally, fibers were dried in room temperature.

The extracted fibers were tested under a desktop tensile testing machine to measure the tensile properties. Test samples with fixtures as shown in figure 3-6 were prepared before the tensile test. A single bamboo fiber was attached on a paper with epoxy adhesive. Then, sample was dried under 120℃ for 2 hours to cure the epoxy adhesive and further dry the fiber. After tensile testing, the broken fiber was collected for cross section measurement. The broken fiber was emerged in epoxy in a pot and was cured together. The entire setup is shown in figure 3-14 and was cut across to observe the cross section after curing. The cross section area measurement and morphology observation were examined by scanning electron microscopy (SEM).
RESULT AND DISCUSSION
The mechanical extracting method derives bamboo fibers with the same mechanical properties as the original raw bamboo strips. On the other hand, sodium hydroxide solution treatment causes the lignin and hemi-cellulose to be dissolved. Alkali treated fibers appear smooth shape, lower strength and lighter color. In fiber cross area section, mechanical extracted fibers have many vascular bundles structure in cross area. Alkali treated fibers only show peripheral profile and have no vascular bundles in the cross area.
According to literatures, thorny bamboo is the strongest bamboo among studied species. Based on the stress-strain diagram from the test, the strength of mechanical extracted fibers has much wider distribution than that of alkali treated fibers. The strength of alkali treated fibers was centrally distributed between 100 to 200MPa. Raw bamboo contains complicated content. The obtained samples may be come from different part of the bamboo, which causes the measured strengths to scatter widely. With alkaline treatment, fibers remain much pure cellulose content. Thus, the measured strength may have less scattering. However, the alkali treated fibers have less average strength as compared to the original bamboo fibers.

CONCULSION
The study discuss on measurement of tensile properties of bamboo fiber extracted by mechanical and alkaline methods. In the experiment, the tensile strength and Young’s modulus of bamboo fiber extracted by mechanical method are better than that of alkali treated fibers. Alkali treated fibers appear less strength and stiffness because of the removing of lignin. With alkaline method treatment, thorny bamboo reduces 60% in strength. Moso and makino bamboo reduce about 50% in strength. For the Young’s modulus, thorny bamboo fiber reduces 40%. Moso and makino bamboo fibers reduce 55 to 60% in modulus. In conclusions, the measured raw bamboo’s tensile properties depend on adopting the samples obtained from different bamboo parts, which may vary a lot. Alkali treated fibers have less average strength as compared to original bamboo fibers, but the measure data has less scattering.

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