Preparation and Performance Evaluation of PU Foam Composite Board
Jia-Horng Lin1, 2, 3, b, Yu-Chun Chuang1, Ching-Wen Lou4, Ting-Ting Li5 and
Chen-Hung Huang6, a
1
Laboratory of Fiber Application and Manufacturing, Department of Fiber and Composite Materials,
Feng Chia University, Taichung City 407, Taiwan.
2
School of Chinese Medicine, China Medical University, Taichung 40402, Taiwan.
3
Department of Fashion Design, Asia University, Taichung 41354, Taiwan.
4
Institute of Biomedical Engineering and Material Science, Central Taiwan University of Science and
Technology, Taichung 406, Taiwan.
5
School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China.
6
Department of Aerospace and Systems Engineering, Feng Chia University, Taichung City 407,
Taiwan.
*Corresponding author email: achhuang@fcu.edu.tw, bjhlin@fcu.edu.tw
Keyword: PU Foam; Polyol; Isocyanate; cushion; Puncture-resistance.
Abstract. As improvement of industry and society, some potential crisis happened in working and
living environment is taken into account by human people. Meanwhile, different kinds of protective
appliances develop rapidly, and composite boards with cushion and puncture-resistance property are
required consequently. This study aims to develop a cushion/puncture-resistance PU foam
protective composites. This paper used Polyol and Isocyanate to prepare porous PU foam composite
via foaming and curing process. By changing foam density and addition amount, cushion and
puncture-resistance property were tested and then evaluated to seek for PU foam composite with
cushion and puncture-resistance property. Result shows that, when density was 80 kg/m3, PU
foaming composite board had the optimum resilience rate of 44 %, lowest impact remaining load of
638 N and best puncture-resistance force of 138.3 N.
Introduction
Individual protective appliances mainly utilize engineering technology to eliminate possible
hazards in working environment of mechanical equipment, manufacturing process and materials
production. According to applied aspects, they are commonly classified into industrial,
farm-orientated, military, medical and sports protective textiles. And base on functionality, they
include thermal protection (heat prevention, thermal insulation), chemical proof, mechanical
impact-resistance (bullet resistance, puncture resistance), radioresistance, biological protection
(antibacterial, antivirus) and electrical protection (EMI, ESD) [1].Cushion concept derives from
impact-resistance package materials. It aims to lower damage for protective goods or personnel via
employing vibration-reducing and cushioning structure to reach stress and energy dispersion.
According to materials’ flexibility, puncture-resistance fabric and composites can divide into rigid,
half-soft and soft type, and their purpose is to prevent human body from sharp weapons injury [2].
In order to promote people’s dwelling environment, individual safety protection studies have been
on the way [3-4]. This study aims at developing technology of PU foam composite, mainly for
preparation of protective composite board with cushioning and puncture-resisting property and then
evaluation for its reliance rate, cushion property and puncture resistance.
Experimental
Material
Fire-retardant PET fiber in length of 64 mm was provided by Far Eastern New Century
Corporation, Taiwan. PU foam solvent is divided into foaming agent and hardener. Polyol foaming
agent and Isocyanate (MDI) hardener were both supplied by Zhongxing Chemical, Taiwan.
Vermiculite particles with diameter of 1.4 - 4 mm were purchased from Topcover co., Taiwan.
Samples Preparation and Characterization
Fire-retardant PET fibers were used to fabricate PET nonwoven after needle-punching process.
During PU foaming process, PET nonwoven were firstly put at the bottom of metal mold. Then PU
foaming solution composed of foaming agent, hardener and vermiculite was poured into the mold.
And then additional PET nonwoven was placed on the surface. Finally mold was sealed and cured
for 30 min at room temperature, forming PU foam composite. In this process, foam density was
changed from 40, 60 to 80 kg/m3, and vermiculite fraction was varied as 0 and 10 wt%. Foam
density was adjusted by volume of mold and amount of foaming solution. The cross area and cell of
PU foam composite board was observed by stereomicroscope (SMZ-10A, Nikon, Japan). Resilience
rate was measured based on ASTM D2632-08 using Vertical Rebound Resilience Tester (HT-8355V,
Hung Ta Instrument Co., Ltd, Taiwan). The sample size was 10 cm ×10 cm. Each group was
repeated for five times. Cushion property was assessed by Drop Tower impact tester (GuangNeng
mechanical factory, Taichung, Taiwan). The impact load was set as 9000 N and height was 2 cm
The sample size was 10 cm ×10 cm, and each group was also repeated for five times. Puncture
resistance property was tested according to ASTM F1342-05. Sample size was 100 mm × 100 mm,
and five samples were tested for each composite. During testing, samples were penetrated by
needles (4.5 mm diameter) at speed of 508 mm/min using Universal Testing Machine (5566, Instron,
USA).
Results and Discussion
Stereoscopic microscope observations
Figure 1 shows stereoscopic image of PU foam board, and Figure 1 (b) displays foam cell. Cell
presents closed type, similar to honey comb structure. When energy impact was imposed on PU
foam composite board, it would transmit through its surface layer and then disperse along cell of
core layer. Thus impact energy was absorbed by form of cell transformation. When energy
surpasses cell load, it would happen cell collapsing to consume energy gradually.
(b)
(a
)
Figure 1 stereoscopic observation of (a) PU foam composite board and (b) foam cell
Effects of foam density and additive content on resilience rate
Figure 1 shows resilience rate of PU foam composite board by changing foam density(40, 60 and
80 kg/m3) and vermiculite content (0, 10 wt %). With increase of foam density, resilience rate tends
to rise up. During emulsification foaming process, more gas was released out at higher foam density,
thus increasing pressure of PU foaming solvent on surface layer. Therefore, PU foam solution
entered into fire-retardant PET nonwoven, increasing thickness and rigid of surface layer. After
curing, surface layer of PU foam board becomes stiffer, and the foam density is larger and thus
resilience rate is better. In addition, after addition of vermiculite, PU foam board had higher
resilience rate. And vermiculite addition showed 44% higher resilience rate than without addition in
PU foam boards.
Table 1. Resilience rate of PU foam composite board with different foam density (40, 60and 80
kg/m3) and vermiculite addition (0, 10 wt%)
resilience
rate
density
40 kg/m3
60 kg/m3
80 kg/m3
0%
37
40
40
10 %
36.5
42
44
vermiculite
Effects of foam density and additive content on cushion property
Figure 2. Cushion property of PU foam composite board with different density (40, 60and 80 kg/m3)
and vermiculite addition (0, 10 wt%)
Figure 2 shows foam density and vermiculite content changing on cushion property of PU foam
composite board. It is found that foam density not significantly influenced on cushion property, but
residual load slightly increased after impact, revealing that cushion property of PU composite board
slightly decreases. After adding vermiculite, residual load becomes higher, meaning that absorbing
energy decreases after impact when 10 wt% of vermiculite was joined in PU foam composite.
This is because SiO2 in vermiculite bonds with polar group contained in PU foaming molecular
after adding vermiculite, producing hard and brittle cells that are easily collapsed after impact [5].
As a result, higher load was remained and cushion property was decreased correspondingly.
Effects of foam density and additive content on puncture resistance property
Figure 3 shows foam density and vermiculite content changing on puncture resistance property
of PU foam composite board. PU foam composite without vermiculite showed a higher puncture
resistance force, and puncture resistance reinforced with increase of foam density. Vermiculite not
only hindered PU foam solution flowing, but also changed cell uniform due to its opening. After
adding vermiculite, needle puncture becomes easier when penetrating through PU foam composite
board, and thus puncture resistance property of PU foam board decreased by 50 % comparing
without contacting vermiculite.
Figure 3. Static puncture resistance of PU foam composite board with different density (40, 60and
80 kg/m3) and vermiculite content (0, 10 wt%).
Conclusions
This study successfully prepared PU foam composite density with both cushion and puncture
resistance property. When foam density increased from 40 to 80 kg/m3, surface resilience rate of PU
foam board promoted from 36 % to 44 % after adding vermiculite. Under impact load of 9000 N,
PU foam composite board absorbed 95 % of impact energy; and static puncture resistance reached
50 N when penetrated by 4.5-mm-diameter needle.
Acknowledgement
This work would especially like to thank National Science Council of the Taiwan, for financially
supporting this research under Contract NSC 99-2622-E-035-008-cc3.
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