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Structure and properties of porous bulked tussah silk and its product
Tieling Xing1,a, Jiayong Sheng1,b, Guoqiang Chen1,c, Yongfa Yang2,d, Yaguang Liu2,e
1College of Textile and Clothing Engineering, Soochow University, Suzhou, China
2Liaoning Maylin Group Co. Ltd., Tieling, China
Keywords: Tussah silk; porous bulked silk; structure; property.
Abstract. Tussah silk is a special product of China, which has luxury, ecological and health care
advantages. Tussah silk is particularly suitable for the production of silk quilt, silk blanket, warm
clothing and other products. In this work, porous bulked tussah silk fibers could be obtained through
high temperature, high pressure, steaming explosion and puffing physical processing high-tech
without any chemicals and assistants during degumming process. The surface morphology, size,
porosity and mechanical property of the porous bulked tussah silk fibers were studied and compared
with the ordinary tussah silk fibers. SEM results indicated that the bulked tussah silk fibers had
porous structure. And the porous bulked tussah silk had higher elasticity and softness than the
ordinary tussah silk fibers. Porous bulked and high elasticity tussah silk quit was produced from the
ecotype porous bulked tussah silk fibers. The wearability of porous bulked tussah silk quilt was also
investigated. The results showed that the insulating property, elastic recovery percentage and
bulkiness of the porous bulked tussah silk quilt were all better than those of the ordinary silk quilt. As
a result of the high resilience and flexibility of porous bulked tussah silk, the tussah quilt can
effectively prevent the tangles and clumping of the silk fibers and is durable.
Introduction
Porous bulked tussah silk was developed by Liaoning Maylin Group Co. Ltd and Soochow
University. The porous bulked tussah silk fibers are obtained by putting tussah cocoon shells or silk
raw materials into the closed pressure vessel, and then the tussah silk fibers change into bulking state
from swelling state under the action of high temperature and high pressure. With abrupt reducing
pressure, the tussah silk fibers instantaneously undergo from high pressure to atmospheric pressure,
and the energy accumulated in the silk fibers suddenly release, which makes the silk fibers swell. At
the moment of the steaming explosion, the sticking points between silk fibroin and sericin of cocoon
filament completely separate and the degumming aim of cocoon filament can be obtained. Therefore
the degumming process of porous bulked tussah silk need no chemicals and chemical assitants, which
is favor to the recovery of silk sericin and preparation of high purity of sericin powder because of the
little impurity. Sericin can be applied in textile coating, food additives and novel biomaterials, which
greatly improves the comprehensive utilization value of silk sericin. Due to the sericin recycle from
the degumming wastewater of porous bulked tussah silk, the pollution to the environment of the
sericin sewage can effectively be prevented. The process of porous bulked tussah silk to its finished
product can achieve energy saving and emission reduction effect, the novel silk materials can
completely meet the requirements of ecological textiles, therefore porous bulked tussah silk is a new
green and environmental friendly silk material. In this work, the structure and the properties of the
porous bulked tussah silk fibers and its product were discussed.
Advanced Materials Research Vol. 796 (2013) pp 172-175Online available since 2013/Sep/18 at www.scientific.net© (2013) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.796.172
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,www.ttp.net. (ID: 130.15.241.167, Queen's University, Kingston, Canada-17/08/14,19:41:03)
Experimental
Materials. Ordinary tussah silk fibers, porous bulked tussah silk fibers and quilt were provided by
Liaoning Maylin Group Co. Ltd.
Measurements. The surface of the tussah silk fibers was examined, after gold coating, with a
Hitachi S-4700 scanning electron microscope (SEM) at an acceleration voltage of 3 kV. The single
fiber porosity was calculated by the following equation with the aid of computer image processing
technology on the SEM photo of tussah silk fibers:
100fiber single of area
fiber singlein micropores of area ) porosity(%fiber single ×= . (1)
The mechanical properties of the tussah silk yarns were measured by a Instron 1122 Electro
mechanical Test System. The gauge length of the sample was 10 cm, and the strain rate was 2 mm/
min. Ten samples were tested for each yarn. The warmth retention properties of tussah silk quilt were
measured according to the GB/T 11048-1989(Textiles--Testing method for warmth retention
property) at 0 ℃~ 50℃. The samples were placed under standard atmospheric conditions (20± 2 ℃,
65 ±2% ) for 24 h, the sample size 30 cm× 30 cm, preheating 30min to 60 min. The warmth retention
properties were indicated at follows:
%100×Q
Q-1 = Q
1
2 . (2)
Where Q is heat preservation rate, Q1 is the heat dissipating capacity without sample, Q2 is the heat
dissipating capacity at the presence of sample.
%100UU
UU U
21
21 ×−×= . (3)
Where U is the heat transfer coefficient of sample, U1 is the heat transfer coefficient of heat transfer
board at the absence of sample, U2 is the heat transfer coefficient of heat transfer board at the presence
of sample.
Warmth value, CLO value, was calculated as follows:
U155.0
1 CLO = . (4)
Results and Discussions
Morphology of porous bulked tussah silk fibers. Fig. 1 shows the SEM photos of tussah silk
fibers. It can be seen that the diameter of porous bulked tussah silk fiber is bigger than the ordinary
tussah silk. The cross-section structure of ordinary tussah silk and porous bulky tussah silk fiber are
both porous, however, the porous structure of porous bulked tussah silk are much more obvious than
ordinary tussah silk. In order to make a quantitative comparison of two kinds of cross section of
porous structure of tussah silk, the longitudinal SEM photos of tussah silk fibers were scanned,
processed, calculated and indicated by single fiber porosity. The diameter and single fiber porosity of
tussah silk fibers are listed in Table 1. The diameter and single fiber porosity of porous bulked tussah
silk fiber were both higher than the ordinary silk fiber, which further proved the more porous structure
of porous bulked tussah silk fibers.
Advanced Materials Research Vol. 796 173
Fig. 1 SEM photos of tussah silk fibers
a. c.: ordinaryl tussah silk; b. d.: porous bulked tussah silk
Table 1 Diameter and single fiber porosity of porous bulked tussah silk fiber
Diameter
(μm)
Single fiber porosity （%）
Porous bulked tussah silk fiber 35.82 15.80
Ordinary tussah silk fiber 30.52 8.94
Mechanical properties of porous bulked tussah silk fibers. Table 2 shows the mechanical
properties of porous bulked tussah silk fibers and ordinary tussah silk fibers. It can be seen from Table
2 that that the breaking strength of porous bulked tussah silk fiber was nearly unchanged comparing
with the ordinary tussah silk fiber . This was due to the appropriate control of the temperature and
saturated water vapor pressure in a sealed container and explosion at a certain moment, which caused
the interior porous structure of tussah silk fibers. This is also the key technology of development of
porous bulked tussah silk fibers. The breaking elongation of porous bulked tussah silk fiber was
higher than the ordinary tussah silk fiber, which endowed the porous bulked tussah silk fiber with
high elasticity. The initial modulus is an indirect index to measure fiber softness. The initial modulus
of porous bulked tussah silk was lower than the ordinary tussah silk, which indicated that the porous
bulked tussah silk fiber was easy to deform and had better softness than the ordinary tussah silk.
Table 2 Mechnical properties of porous bulked tussah silk fibers
Breaking strength
(CN/dtex)
Breaking elongation
( % )
Initial modulus
(CN/dtex)
Porous bulked tussah silk fiber 2.2 27.57 1.51
Ordinary tussah silk fiber 2.2 23.45 1.87
174 Silk, Protective Clothing and Eco-Textiles
Properties of porous bulked tussah silk quilt. High elastic porous bulked tussah silk quilt was
developed with the porous bulked tussah silk as raw materials. The insulating properties of the porous
bulked tussah silk quilt are listed in Table 3. The internal porous structure of micro porous bulked
tussah silk quilt fibers could form much tiny space, which could store large amounts of static air. Thus
the tussah silk quilt had good warm keeping property. The heat transfer coefficient of porous bulked
tussah silk quilt was smaller than that of the ordinary tussah silk quilt. And CLO value was inversely
proportional to the heat transfer coefficient. Generally speaking, the lower the heat transfer coefficient
is, the better the warm keeping property of textiles and the heat energy is not easy to transfer outward
through the textiles. Accordingly, the heat preservation rate of the porous bulked tussah silk quilt was
higher than that of the ordinary tussah silk quilt. Covering porous bulked tussah silk quilt could
isolate the intrusion of cold air from human body, and excellent efficacy in two-way adjustment of
warm keeping and cold proofing could be obtained.
Table 3 Insulating property of porous bulked tussah silk quilt
Heat transfer coefficient
(w/m2·℃)
CLO value
(CLO)
Heat
preservation rate
(%)
Porous bulked tussah silk quilt 1.720 3.755 87.04
Ordinary tussah silk quilt 2.299 2.812 81.95
The wearability of porous bulked tussah silk quilt is shown in Table 4. The elastic recovery rate of
porous bulked tussah silk quilt reached more than 97%, which was 21.3% higher than the index of
special class silk quilt establishing by the textile industry [1]. Because of the particular elasticity and
softness of porous bulked tussah silk quilt, it can effectively prevent the tangles and clumping of
tussah silk fibers. The softness, elasticity and warmth of the porous bulked tussah silk quilt would not
decrease, and the quilt could realize durable utilization.
Table 4 Wearability of porous bulked tussah silk quilt
Elastic recovery percentage
(%)
Bulking intensity
(cm3/g)
Porous bulked tussah silk quilt 97.6 30
Ordinary tussah silk quilt 89.2 26
Summary
The surface morphology, size, and porosity of the porous bulked tussah silk fibers were studied by
SEM, and the results indicated that the bulked tussah silk fibers had porous structure. The porous
bulked tussah silk had higher elasticity and softness than the ordinary tussah silk fibers. The product
of porous bulked tussah silk, tussah silk quit, had high elasticity, good insulating property and
bulkiness, which can effectively prevent the entanglement and clumping of the tussah silk fibers. And
the porous bulked tussah silk quilt could realize durable utilization.
Acknowledgement
The financial support by National Natural Science Foundation of China (No. 51203107) and PAPD
are greatly appreciated.
References
[1] GB/T 24252-2009 Silk Quilt Standard, China Standard (2009)
Advanced Materials Research Vol. 796 175
Silk, Protective Clothing and Eco-Textiles 10.4028/www.scientific.net/AMR.796 Structure and Properties of Porous Bulked Tussah Silk and its Product 10.4028/www.scientific.net/AMR.796.172
