Influence of Different Retting on Hemp Stem and Fiber Characteristics Under the East of France Climate Conditions

ABSTRACT

Historically, for fiber extraction, the stems were immersed in water. However, this method proved far too polluting, leading to its substitution by the dew-retting method in the field. Different retting processes and durations can produce significant differences in hemp stems and fiber characteristics. Both dew- and water-retting methods were carried out on the Santhica 27 cultivar in Eastern France in 2020. An analysis of the stem chemical composition and characteristics has been performed to observe the stem degradation during retting for both methods. Secondly, the analyses of the fiber chemical composition, color, morphological and mechanical properties have been performed to evaluate the impact of retting on the fiber quality. The effect of the retting on the stem and the fiber is observed after 1 week for water-retting and after 4 weeks for dew-retting. For dew-retting, the percentages of fine fiber and cellulose in the fiber bundle increase after 1 week, while the stem chemical composition decreases. Unlike in the dew-retting, the percentage of fine fiber and cellulose in the fiber bundle increases after 4 weeks, while the potassium percentage in the stem, fiber brightness, and fiber tenacity and strain decrease. Finally, after 8 weeks, the fiber properties were found to be similar for both methods.

摘要

从历史上看，为了提取纤维，茎被浸泡在水中. 但事实证明，这种方法污染太大，在现场被露水脱胶法取代了. 不同的脱胶工艺和脱胶时间会导致大麻茎和纤维特性的显著差异.2020年，对法国东部的Santhica 27品种进行了露水和水浸处理. 已经对茎的化学成分和特性进行了分析，以观察两种方法在脱胶过程中的茎降解情况. 其次，对纤维的化学成分、颜色、形态和力学性能进行了分析，以评估脱胶对纤维质量的影响.在水脱胶一周后和露水脱胶四周后观察脱胶对茎和纤维的影响. 对于脱胶，纤维束中细纤维和纤维素的百分比在一周后增加，而茎的化学成分减少. 与露水脱胶不同的是，纤维束中细纤维和纤维素的百分比在四周后增加，而茎中钾的百分比、纤维亮度以及纤维韧性和应变降低. 最后，八周后，证明两种方法的纤维性能相似.

KEYWORDS:

• Hemp fiber
• dew-retting
• water-retting
• stem characterization
• mechanical properties

关键词:

• 大麻纤维
• 露水脱胶
• 水脱胶
• 茎特征
• 机械性能

Acknowledgment

This experimentation was carried out thanks to the financing of the European Union LEADER and the Région Grand-Est. The first author acknowledges the ANR CIFRE for financing her research work and PhD.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Confirmation of authors

The authors confirm that the work described has not been published before and is not under consideration for publication anywhere else. We can also say that the publication has been approved by all of us.

Highlights

• Dew- and water-retting methods are compared over 8 weeks in Eastern France.

• For both methods, the stem chemical composition changes during the retting.

• The fiber mechanical properties change during the retting, whatever the method.

• The optimal retting duration depends on the retting method.

• The water-retting was optimized and adapted for the textile industry.