Dilek YAYLALI, Canan URAZ, Esat GÜMÜŞKAYA
method was used to determine the holocellulose content of the hemp bast fibres, and Kürschner–Hoffner’s approach was used to determine the cellulose content [Browning 1967]. The TAPPI T 222 om-11:2011 test method was t determine the amount of acid-soluble lignin in the hem bast fibres [TAPPI T 222:2011]. The hemp bast fibre ash content was determined using the TAPPI T 211 om-93:1993 test method [TAPPI T 211:1993]. The solubility of the hemp bast fibres was tested using the following TAPPI test methods: TAPPI T 204 cm-07:2007 [TAPPI T 204:2007] for solvent extractives of hemp bast fibres, TAPPI T 207 cm-08:2008 [TAPPI T 207:2008] for water solubility of hemp bast fibres and TAPPI T 212 om-12:2012 [TAPPI T 212:2012] for 1% sodium hydroxide solubility of hemp bast fibres. Table 2. The applied standard test methods for determination of carbohydrate components, solubility and ash content of hemp bast fibre Carbohydrate components tests Applied standard Holocellulose Wise's chlorite method Cellulose Kurschner-Hoffner method Lignin TAPPI T-211 om-88 Solubility and ash content tests Applied standard Hot water solubility TAPPI T-207 om-88 NaOH %1 solubility TAPPI T-212 om-88 Alcohol-benzene solubility TAPPI T-204 om-88 Ash content TAPPI T-207 om-88 X-ray diffraction (XRD) measurements The degree of crystallinity is determined by the crystallinity index (CrI), which is useful for grading the crystallinity of various cellulose types and observing the effects of physical and chemical treatments on crystallin ity [Gümüşkaya and Usta 2006]. The crystallisation behaviours of raw, beaten and cooked hemp bast fibres were analysed by XRD patterns, and the degree of crystallinity was calculated using the patterns. The patterns were captured using a Panalytical Empyrean XRD system with a Cu Kα radiation source running at 45 kV voltage and 40 mA current. The patterns were obtained in the 2θ = 3 –44° range. The CrI of the samples were calculated using the following equation, which was proposed by Segal et al. [1959] for native cellulose: ሺΨሻൌ୍ ଶି୍ ୟ୫ଶ୭୰୮୦୍ ݔ ͳͲͲ , (3) where I 002 represents crystalline and amorphous regions of cellulose (max intensity at 2θ = 22,7°) and I amorph represents the merely amorphous phase (intensity of the diffraction at 2θ = 14,8°). All experiments were repeated twice.
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