Development of Natural Rubber (NR) and Ethylene-Propylene-Diene-Monomer (EPDM) Rubber Blend for Tie Down Strap Compound
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Date
2013
Journal Title
Journal ISSN
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
Tarpaulins or tarps are basically heavy duty waterproof covers that are used to secure loads in
pickup trucks, tractors, dump trucks, etc. preventing from any untoward incidences happening
during transportation. The tarps for trucks come with hooks or tie down straps to attach them
securely to the vehicle body. These tie down straps are mainly used to hold tarps securely in
place by providing high tensile strength and constant tension. Tie down strap is made out of
natural rubber (NR), ethylene propylene diene monomer rubber (EPDM) or a combination of
the both NR & EPDM by using cross-blending of two master batches method. Both NR and
EPDM rubber have unique properties inherent to each material. Strap material selection is based
on the climate they are used in. Natural rubber is ideal for cooler climates, as it will not crack
and split in colder conditions. EPDM rubber was designed for warmer climates as it stands up
better to extended sun exposure and hot UV rays (Anonymous, 2013).When concern the
properties, NR will stretch further than EPDM rubber and will return to its normal non-stretched
state quicker than EPDM rubber. To obtain the desired properties of both NR and EPDM,
blends of the NR & EPDM are being used. The development of blends of NR and EPDM will
deliver superior physical properties with the combination of excellent resistance to weathering
of EPDM, in particular to attack by ozone (Rattanasupa, 2007). The addition of compatibilizer
improves the compatibility of the NR/EPDM blends. It has been reported that graft copolymers
widely used as compatibilizing agents, usually to enhance interfacial interaction in polymer
blends, thus improving their mechanical properties (Arayapranee and Rempel, 2007). Based on
above literature, a study was conducted to identify the most promising NR/EPDM blend ratio
depend on cure characteristics and physical properties and to identify the effect of Methyl-
methacrylate-butadiene-styrene (MBS) as a compatibilizer on NR/EPDM blend for tie down
strap compound.
Methodology
The research study was carried out in a laboratory of Samson Compounds (Pvt) Ltd, Bataduwa,
Galle. Complete randomized design (CRD) was used as the experiment design and the
experiment was divided into two sub experiments as experiment 01 and experiment 02 aligning
with the objectives. Total mixing time and the ingredients were different for each experiment
but the blending procedure for both experiments was remained same.
In experiment 01, the different blend ratios of NR/EPDM (N90, N80, N70, N60, N50, N40,
N30, N20, N10) were prepared by mechanical blending and blend ratios were tested for cure
characteristics, physical properties and thermal aging characteristics aged at 70°C for 22 h in
respect of product specifications (Samson rubber products, 2012) of tie down strap. Replicates
of hardness and tearing were three and replicates of tensile strength, elongation at break and
tension set were arranged as four.
Description
Keywords
Agriculture, Export Agriculture, Rubber Production, Rubber Technology, Plantations, Natural Rubber