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INFLUENCE OF PHYSICAL AND MECHANICAL PROPERTIES OF POLYMER
COMPOSITS ON THE STRENGTH INDICATORS OF CAR PARTS
N.T. Almatayev,
Andijan State Technical Institute
Annotation.
In this article, the influence of the physical and mechanical properties of
polymer composite materials obtained by adding local fillers on the strength indicators of
automotive parts was studied.
Keywords:
Polymer, composite, physical-mechanical, part, strength, property, filler.
Introduction.
From the beginning of the 20th century, polymeric materials replaced
metallic and ceramic materials. Today, polymer parts are used in friction pairs as an alternative
material to metals or other materials [1-4]. Their normal tribological properties and low friction
are beneficial for their operation in various processes, including parts of vehicles, aircraft
components, and other machines and mechanisms.
Research [2-6] shows that the reason for the loss of operability of machines and
mechanisms is 80-90% wear due to friction. Around the world, 100 million tons of lubricants are
used annually to reduce friction. In developed countries, the failure of machine-building
equipment due to friction and wear accounts for 4-5% of the national income[5].
Most of the current research on polymer tribology [3-6] is focused on engineering
polymers. However, most of them are simple and simple tribo-systems, in which relatively less
load-bearing parts (bushing, shaft, pins, pulley) are involved. Until now, the tribological
properties of polymers and their compositions in these tribosystems have not been thoroughly
studied, but attention to these materials is increasing due to the emergence of problems.
Object and method of research
Research Method. The study of tribotechnical properties was carried out on the "Micron-
tribo
"
tribometer, operating in mini and nano sizes. For the experiment, a SHX steel ball with a
hardness of 38-40 was used. The diameter of the steel ball is 3-5 mm. The roughness of the
polypropylene sample with a diameter of 40-50 mm and a thickness of 4 mm was measured
using a profilometer
.
The experiments were conducted at a contact pressure of 1-20 N, a rotational speed of 0.5
and 1 m/s. Changes in the surface and surface parameters formed on the surface and in the
sample of a steel ball were observed and studied using a profilometer.
Results and their discussion.
The coefficient of friction and wear are significantly influenced not only by the type of
filler, but also by its content in the composite. For this, their optimal amounts are determined
experimentally. It is difficult to achieve the necessary properties by adding fillers to the polymer
composition separately, therefore a mixture of several fillers is used.
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Physical and mechanical properties of polypropylene
Table 1
No Properties
Trial methods Measure unit
JM 380 UZ
COR GAS
1. Elasticity modulus, 28 mm/min,
ASTM D 790
MPa
1682.53
2. Density
ASTM D 1505
g/cm
3
0.85-0.95
3. Relative elongation, min
ATSM D 638
%
30-50
4. Impact toughness IZOD (+23), min ASTM D 256
kg f cm/cm
2
6-9
Figure 1. Dependence of wear on average load
Wear is directly proportional to the normal load, i.e., the greater the load, the greater the
wear. The reason for this is that the increase in load brings the surfaces closer together, as a
result of which their mechanical (penetration) and molecular attraction increases (Fig. 1). It has
been shown that the degree of wear varies depending on the average load, the sliding speed is 0.5
l and 3.0 m/s. The maximum value of the degree of wear reaches 2-2.5 mg/min at a load of 5 N
at a speed of 3 m/s, for 1 m/s this value is 0.4-0.5 mg/min, the minimum value is 1.4; 0.35 and
0.25 mg/min. Relatively small changes were observed at a speed of 0.5 m/s. The higher the
material's velocity, the higher the temperature in the friction zone, resulting in softening of the
material's surface and increased wear. To reduce wear, the optimal values of surface roughness
for this pair are determined experimentally.
When a polypropylene sample is rubbed with a steel ball, it leaves a trace on the surface
of the sample due to the normal load and sliding speed, the size and value of which depend on
the friction modes and the type of material. These images are taken using a Micron-
tribo
"
microscope mounted on a tribometer and are calculated based on trace measurements.
RESULT
The friction and wear of composites are significantly influenced by the normal load and the
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sliding speed. The degree of wear varies depending on the average load. The maximum value of
the degree of wear reaches 2-2.5 mg/min at a load of 5 N at a speed of 3 m/s, for 1 m/s this value
is equal to 0.4-0.5 mg/min, the minimum value is 1.4; 0.35 and 0.25 mg/min at a load of 1 N.
Relatively small changes were observed at a speed of 0.5 m/s.
REFERENCES
1.
Tager A. A., Physicochemistry of Polymers, Moscow: Scientific World, 2007 - 573 pages.
2.
M.A. Askarov, I.I. Ismoilov. Chemistry and Physics of Plastics. Tashkent. 2004, 189
pages.
3.
Negmatov S.S. Fundamentals of Contact Interaction Processes of Composite Polymer
Materials with Fibrous Mass. - Tashkent: Fan, 1981, - 296 pages.
4.
Negmatov S.S., Almatayev T.A. and others. Improvement of Physico-mechanical
Properties of Thermoreactive and Thermoplastic Polymeric Coatings by Physical Methods
of Modification. /IVTN INTERNATIONAL CONFERENCE ON TIMES OF POLYMERS
(TOP) AND COMPOSITES. Italy 2008, 21-24 September, pp.67-69.
5.
V.V. Shapovalov et al. Tribotechnics. - Rostov-on-Don: FENIKS, 2017, - 348 pages.
6.
N.S. Penkin. Fundamentals of Tribology and Tribotechnics. - Moscow: Mashinostroenie,
2008, - 206 pages.
