Wood fibre insulation boards (WFIB) are typically made from softwood fibres. However, due to the rapid decrease in softwood stands in Germany, the industry will be forced to adapt to the wood market. Therefore, alternative approaches for the substitution of softwood with hardwood will be needed in the fibre industry. The objective of this paper is to address the characterisation of hardwood fibres regarding their availability for the WFIB industry. The physico-mechanical properties of WFIB are significantly determined by the length of the fibres. Longer softwood fibres usually generate higher strength properties and a lower thermal conductivity than shorter hardwood fibres. In this paper, the potential application of hardwood fibres (up to 20,500 μm long) produced in a refiner by thermo-mechanical pulping (TMP) to WFIB production was examined. The scanner-based system FibreShape was used for the automatic optical analysis of the geodesic length distribution of fibres. The analysed hardwood fibres contained significantly more dust and were shorter than respectively produced softwood fibres, limiting their applicability for WFIB production. Thus, two analytical approaches were chosen to receive longer fibres and less dust: (1) blending hardwood fibres with supporting softwood fibres (20%, 50 and 80% proportion of softwood), and (2) mathematical fractionation of hardwood fibres based on the fibre length to remove all particles smaller than 500 μm. It was concluded that the practical fractionation seems to be economically and ecologically challenging and that blending hardwood fibres with at least 50% softwood fibres offers a promising approach, which should be further studied.

木纤维绝缘板（WFIB）通常由软木纤维制成。但是，由于德国软木林分的迅速减少，该行业将被迫适应木材市场。因此，在纤维工业中将需要用软木代替硬木的替代方法。本文的目的是解决关于硬木纤维在WFIB工业中的可用性的表征。WFIB的物理机械性能明显取决于纤维的长度。与较短的硬木纤维相比，较长的软木纤维通常会产生较高的强度性能和较低的导热率。在本文中，研究了通过热机械制浆（TMP）在精制机中生产的硬木纤维（最长20,500μm长）在WFIB生产中的潜在应用。基于扫描仪的系统FibreShape用于对纤维的测地线长度分布进行自动光学分析。分析的硬木纤维比分别生产的软木纤维含有更多的灰尘，并且短得多，这限制了它们在WFIB生产中的适用性。因此，选择了两种分析方法来接收更长的纤维和更少的灰尘：（1）将硬木纤维与支持性软木纤维（软木的比例分别为20％，50和80％）混合，以及（2）基于纤维长度以去除所有小于500μm的颗粒。结论是，实际分级似乎在经济和生态上具有挑战性，并且将硬木纤维与至少50％的软木纤维混合提供了一种有前途的方法，应进一步研究。