Polycaprolactone (PCL) is a non-toxic and slowly biodegradable synthetic polymer, and is used in making biomaterial products such as surgical sutures, scaffolds, fibres and textile mesh for biomedical applications. Compared to materials of biological origin, PCL has no intrinsic biological capability to enhance healing of damaged cells or tissues. Therefore, a variety of bioactive agents such as proteins are incorporated into polymer matrices to improve biological interactions between the implanted device and cells or tissues. However, addition of structurally different proteins can greatly influence the key physicochemical characteristics of biomaterials, such as mechanical performance and surface morphology. In the present study, keratin extracted from wool was added to the PCL matrix and fibres were extruded using a melt-extrusion technique. Pure PCL fibre had an average tensile strength of 981 MPa, elongation of 19% and Young’s modulus of 5.8 GPa. The addition of keratin into the PCL matrix, imposed melt-processing difficulty and reduced tensile strength at higher loadings of keratin (e.g., 10 wt%). However, silane treatment improved the keratin/PCL interfacial adhesion as revealed by electron microscopy and consequently improved melt-spinning, and reduced mechanical stiffness of the material, a key characteristic of suture fibres.

The purpose of this paper is to show how the yarns used in chain stitch influenced the hand of knitted tapes for fasteners. For this purpose, we made experimental tapes that differed only in the yarn of chain stitch, and the hand of tapes was evaluated by the paired comparison method. Furthermore, we measured the mechanical properties of the tapes, and the relationship between the sensory values for hand and the mechanical properties was studied by correlation analysis. The results are as follows.
(1) As a result of the analysis of variance for mean preference scores of each adjective, it was found that the hand of tape with chain stitch made with different yarns was evaluated using the adjectives “shittori, smooth, flat, easy to slide, soft, and elastic”.
(2) As a result of correlation analysis between the thermal properties of the yarns used in chain stitch and the mechanical properties of the tapes, the mean of the bending rigidity (BM) and the mean of the bending hysteresis (2HBM) were positively correlated with the dry heating shrinkage tension at 170℃, and the surface roughness (SMD) was negatively correlated with the dry heating dimensional change ratio at 170℃.
(3) As a result of correlation analysis between mean preference scores of “shittori, smooth, flat, easy to slide, soft, and elastic” and the mechanical properties of tapes, “shittori” was negatively correlated with the mean deviation of the coefficient of friction (MMD), “smooth, flat, and easy to slide” were negatively correlated with the surface roughness (SMD), “soft” was negatively correlated with the mean of the bending rigidity (BM), and “elastic” was positively correlated with the mean of the bending hysteresis (2HBM).

There are few effective recycling systems for waste textiles because the material specifications are complex and mixed waste textiles are not easily separable. To improve this situation, we proposed the “ Colour Recycle System ”, which separates waste textiles by colour prior to recycling. Previously, we discussed a separation standard for shoddy of recycling materials and optimizing the colour combination in waste textiles collection. The proposed standard was based on the favorable ratings in a sensitive analysis. However, the optimum separation standard will also depend on the configuration of the fiber assembly. Therefore, this paper investigates the effect of fiber configuration such as grain and yarn on the favorable ratings. The threshold value for highly favorable ratings was identified as 80–105° interior angle on the Munsell color circle, regardless of configuration.

In order to make clear the mechanism of interlacing process, the equipment with a high-speed video camera was developed to observe filaments motion in a slit-type interlacer from the axial direction of yarn. Filaments motiont was analyzed by Particle Image Velocimetry (PIV). Results obtained are as follows: (1) Filaments motion is almost the same as numerical simulation results of airflow, thus the numerical simulation is considered to be one of the important methods to study interlacing process. (2) The mechanism of interlacing process is considered as follows: overall, symmetric twin vortex of air in the yarn passage makes the filaments move. The tangling filaments in the initial state separate into two groups and disperse near the stagnation point of the twin vortex. The dispersed filaments moving with the twin vortex change their relative positions and are mutually entangled on the symmetric plane, where the twin vortex collides and merges with each other. (3) The average value and deviation of the distance from the yarn center to each filament becomes an index to show tangling and opening parts. (4) The time spent to form the opening state was about eight times larger than the time of the tangling state. (5) The number of tangling parts in a unit length of the yarn counted from video images was almost the same as that measured in the interlaced yarn.