Biomedical Engineering Reference
In-Depth Information
production was approximate 2,000 g/m². For the needle felt production one part of
the multilayer webs was processed on an industrial machine to needle felts with an
approximate area weight per unit of 2,000 g/m². The multilayer web was pre-needled
with the needling density at the rate of 10 punches/cm² by a Heuer & Sohn (Tespe,
Germany) pre-needle machine (type ROV 12S/250/11/900; one needle board, 800
needles per m working width, 7 needle lines, 320 pinpricks per minute) with a work-
ing width of 2,600 mm. For the pre-needling process needles of the type 15 x 20 x 4
R333 G 1012 (Groz & Beckert KG, Gummersbach, Germany) were used. The main
needle felt production was carried out by a Fehrer (Linz, Austria) needle felt machine
type NL1226 with a working width of 2,600 mm (two needle boards, 312 needles per
line, 14 lines per needle board, feeding rate of 1.6, and 672 pinpricks per minute).
Needle-punching density in the main needle process was per throughput 74 punches/
cm². The roller carded webs were punched twice (from both sides, 148 punches/cm²).
For the needle-punching process needles from the type 15 x 16 x 36 x 3 R222 G 53437
(Groz & Beckert KG, Gummersbach, Germany) were used.
The influence of the compression moulding step was analysed using two different
compression moulding techniques:
CP-1
:
Ten minute pre-heating of the semi-finished product in the open press at
180°C (instead of a pre-drying step), 10 min compression moulding at 3.2 MPa (hy-
draulic press type KV 214.01 (Rucks Maschinenbau GmbH, Glauchau, Germany) and
cooling at room temperature (20-25°C) for at least 30 min (Graupner and Müssig,
2009).
CP-2
:
The semi-finished products were pre-dried for 2 hr at 105°C in a forced
air oven (Thermicon® (Heraeus GmbH, Hanau, Germany), compression molded at
180°C for 5 min at 5.8 MPa in a Joos hot press (hydraulic press type HP-S10, Joos,
Pfalzengrafenweiler, Germany) and cold pressed for 3 min at 25°C at 5.8 MPa in a
Joos cold press (hydraulic press type HP-S60, Joos, Pfalzengrafenweiler, Germany).
The treatment of one part of the multilayer webs with lignin was carried out by
using lignin of the plant
Eukalyptus globulus
(type Hardwood kraft eucalyptus; BFH,
Hamburg, Germany). One gram lignin was solved in 100 ml ethanol (96%) and the
lignin solution was sprayed on and between the single layers of the multilayer webs
by an aerosol can.
Composite Characteristics
From the resulting composite boards different test specimens were manufactured. The
investigation of the tensile characteristics of the composites was carried out with a
Zwick/Roell testing machine type Z 020 (Ulm, Germany) working with a load cell of
20 kN and pneumatic clamps according to DIN EN ISO 61. The testing speed was set
to 2 mm/min. Unnotched Charpy impact characteristics were analyzed using a Zwick
impact tester type 5,102 with a bearing distance of 40 mm, a pendulum length of 225
mm and a pendulum size ranging between 0.5 and 4 J according to DIN EN ISO 179.
Morphological examinations were carried out using a Zeiss DSM 940A scanning
electron microscope (SEM) manufactured by Zeiss (Jena, Germany). All specimens
were sputtered for 90 sec. with 56 mA with a layer of gold prior to SEM observations
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