STUDY ON TEXTILE REINFORCED COMPOSITE MATERIALS AND WOOD CHIPS

STUDY ON TEXTILE REINFORCED COMPOSITE MATERIALS AND WOOD CHIPS

LECTURER ADRIAN BUHU, PH. D, LECTURER LILIANA BUHU,

PH. D, LECTURER CRISTINA RACU, PH. D 1

1 FACULTY OF TEXTILE , LEATHER AND INDUSTRIAL MANAGEMENT, TECHNICAL UNIVERSITY GHEORGHE ASACHI FROM IASI, ROMANIA

Abstract: The composite materials have been designed to replace the increasing proportion, traditional

materials which have some drawbacks related to performance, processes of production and processing. Their

advantage consists in the modeling properties and obtains a variety of materials whose usage can be

extended in almost all fields of technical activity. These materials combine the components properties and

their quantity. This paper presents a composite of different layers placed into a structure ”sandwich” type, in

which the reinforcing elements are fabrics from natural fibers and a layer of a mixture of matrix polymer and

wood chips. This type of material can be used to ambient products where the impact is the main stress. The

composite absorbs impact energy in its structure due to the presence of layers of fabric and polymer mixture

of wood chips.

Key words: composite material, wood chips, mechanical work, impact

Corresponding author. E-mail address: e-mail: [email protected]

1. INTRODUCTION

Laminated composites are composed of

layers with different compositions, with a

thicker layer of material for filling. These

types of structures are used primarily to

obtain compliance materials, which must

simultaneously fulfill several conditions:

mechanical and good chemical resistance,

low specific weight, good thermal and

acoustic insulation, impermeability to gases

and water vapor.

The basic principle of the sandwich

structure, as material and properties, is to

separate the strength faces of the

lightweight and flexible core of the

composite. Materials used for the sides are

laminated composites and metals, while core

- metallic or non-metallic honeycombs,

cellular foams, wood soft and easily so.

Typically, the faces are glued with adhesive

by core. An important role is appearing in all

phases of composites in the border areas

between the basic and added materials,

significantly influencing the overall

performance and has an important role in

achieving effective material properties

considered for the final. It is therefore

necessary to know the nature and intensity

of interactions reinforced - the matrix and

the phenomena that occur at the interface.

The nature and the intensity of the

interface links are caused by the structure

and surface characteristics of the reinforcing

elements (the roughness, specific surface,

porosity, the possible presence of active

functional groups chemically) and of certain

structural characteristics of the matrix

(chemical composition, macro-molecular

conformation, etc.).

The interactions that established at

reinforcement-matrix interface fall into

three general mechanisms:

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| JOURNAL OF INVENTICS

mechanical coupling or

interpenetrate micromechanics of

those two components;

coupling through physical links (van

der Waals, dipole-dipole) or

electrostatic attractions;

covalent bonds that often involves

the participation of a coupling agent.

In order to improve the fibers wetting by

the matrix (default the phenomenon

increases the contact area between the two

phases), are used coupling agents. For

obtaining optimum properties, especially in

the mechanical strength, it is important how

the mechanical stress at the surface are

propagated matrix-fiber separation. A good

tensions transfer requires a large contact

area and very good adhesion. A low

adhesion between the matrix and fibers and

leads to rapid propagation the fissures

inside the composite. The paper analyzed

possibility to obtain a composite material

from woven and cellulose materials, wood

chips and the matrices of Polyvinyl acetate

(PVA) (cellulose material are compatible

with the reinforcement material).

Material and Methods

The samples were obtained by using a mold

with sizes of 175 x126 mm, the woven fabric

samples used has the same dimensions has

been made between the manual mixture of

PVA and wood chips as suggested in figure

1a. The pressure was achieved using weights

for 30 minutes in order to maintain constant

pressure value, after which the samples

were dried in an oven for 30 minutes at 700C

to prevent deterioration of the PVA matrix.

a.

b.

Figures 1. Composite material

a. the principle of obtaining the composite material: 1 - textile support (fabric), 2 - mixture of

wood chips and PVA matrix; 3 – mold; b. composite material

The aspect of sandwich composite

material is presented in figure 1 b. The fabric

layers characteristics used as

reinforcements are: the warp yarns count

Nm 5/2 and the weft yarns count Nm 5/1,

the warp density is 72 threads / cm, the weft

density is 62 threads/10cm and strength

between 833 and 2175 N.

The independent variables taken into

consideration has been: pressure for

achievement the composite material (p),

mass of wood chips (Mr) and mass of PVA

(Ma) - used as matrix, compatible with the

fabric used as outer layers and wood chips.

In table 1 are given values for the

corresponding experiment performed three

independent variables:

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Table 1

No.

Coded level

of variables

Real level

of variables

Dependent

variables

p Mr Ma p

(kPa)

Mr

(g)

Ma

(g)

(g/cm3)

L

(J)

1 + - - 65.610 10 70 0.605 4.560

2 + + + 65.610 40 150 0.720 5.510

3 + + - 65.610 40 70 0.566 5.210

4 - + - 16.760 40 70 0.490 4.780

5 - - - 16.760 10 70 0.405 4.620

6 0 0 0 41.185 25 110 0.590 5.031

7 - + + 16.760 40 150 0.640 5.020

8 + - + 65.610 10 150 0.538 5.310

9 - - + 16.760 10 150 0.508 4.950

Dependent variables studied were the

density of composite material and the

mechanical work of impact. Each composite

sample was measured and weighed so that

density can be calculated with the equation:

VM

(1)

The obtained composites panels can be

used as ambient products so that they were

main request are subject to the impact

resistance. The phenomenon of impact

depends on the velocity of the object with

the composite material comes into contact

(low (v <0.25 km / s), medium (v = 0.25 ... 2

km / s), ballistic (v = 2 ... 12 km / s) and

hyper-speed (v> 12 km / s)). In the case

studied used to create the phenomenon of

impact the object velocity was 0.00679 km

/s, its mass was 0.78 kg. Depending on the

strain produced by impact was calculated

mechanical work needed for deformation of

composite with 1 mm, results being shown

in the table 1.

The analysis of variances for dependent

variables was performed with the ANOVA

test; results are presented in tables 2 and 3.

Table 2

Analysis of Variance for (g/cm3)

Source DF Seq SS Adj SS Adj MS F P

Main Effects 3 0.0492745 0.0492745 0.0164248 19.23 0.166

2-Way Interactions 3 0.0131070 0.0131070 0.0043690 5.11 0.312


Residual Error 1 0.0008542 0.0008542 0.0008542

Curvature 1 0.0008542 0.0008542 0.0008542

Total 8 0.0670202

Table 3

Analysis of Variance for L (J) (coded units)

Source DF Seq SS Adj SS Adj MS F P

Main Effects 3 0.659900 0.659900 0.219967 190.94 0.053


REVISTA DE INVENTICA / Vol. 13, Nr. 70 / Septembrie 2010

35



Residual Error 1 0.001152 0.001152 0.001152

Curvature 1 0.001152 0.001152 0.001152

Total 8 0.790552

The estimated equation coefficients of variation of density and mechanical work are

presented in table 4.

Table 4

Term Coef.

( )

Coef.

(L)

Constant 0.152448 4.49440

p 0.00902422 -0.0142443

Mr 0.00462180 -0.00124794

Ma 0.00206948 0.00218414

p*Mr -1.88502E-04 0.000549301

p*Ma -5.83419E-05 0.000138178

Mr*Ma -5.29077E-06 1.39637E-05

p*Mr*Ma 1.48414E-06 -3.07062E-06

Significant coefficients are obtained by

plotting the normal plot of standardized

effects (figure 2), for density it comes

pressure p, mass of chips Mr, polymer mass

Ma and Mr - Ma interaction. The independent

variables that influence the mechanical work

impacts are pressure p, chips mass Mr ,

polymer mass Ma and interaction p - Mr. The

software allows recalculation of the

equation coefficients taking account the

independent variables and interactions

between them considered significant.

a. b.

Figure 2. Establishing of significant coefficients of the regression equation

In this regard consider by changing the terms the new coefficients are presented in Table 4.

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Table 4

Estimated Coefficients for (g/cm3)

using data in uncoded units

Estimated Coefficients for L (J)

using data in uncoded units

Term Coefficients Term Coefficients

Constant 0.439308 Constant 4.17778

p 0.00197544 p 0.00095531

Mr -0.00314167 Mr 0.00028806

Ma -3.33333E-04 Ma 0.00506250

Mr*Ma 5.58333E-05 p*Mr 0.000211532

Regression equations

arar MM00006.0M00033.0M00314.0p00198.43931.0

rar Mp00021.0M00506.0M00029.0p00096.01777.4L

In the graphic from figure 3 are presented

the effects of changing only the independent

variables on the density of the composite

material. Conclusion can be drawn from this

graph is that increasing the pressure, the

mass of wood chips the mass of polymer

increase the density of composite structure.

Effects of the three parameters are similar,

ranging between 0.6015 and 0.60725 g/cm3.

In the graphic from figure 4 are presented

the effects of changing only the independent

variables which affect mechanical work of

the composite material. Conclusion can be

drawn is that increasing the pressure, the

mass of polymer and the mass of chips

increases mechanical work (L) for necessary

deformation of the composite structure.

Effects of the three parameters are similar

ranging between 5.13 and 5.1975 J.

Figure 3. Effect of changes in each independent variable on the density


37


Figure 4. Effect of changes in each independent variable on the mechanical work

Figure 5. Effect of interaction of independent variables on the density

Figure 6. Effect of interaction of independent variables on the mechanical work

38

In the graphs from figures 5 and 6 are

shown the interactions between

independent variables that can modify the

influence of independent variables on the

behavior of the composite material.

Results and discussions:

It can be observed the following effects:

density increases to the growth of

all three variables;

the influence of pressure on the

density is greater than the influence

of other variables (0.643 g/cm3 and

0.629 g/cm3 to 0.565 g/cm3 (mass

of wood chips) or 0.574 g/cm3

(mass of matrix);

influence on density of mass of

wood chips is more important than

the polymer mass (0.68 g/cm3 to

0.523 g/cm3);

increased density can be achieved

by increasing pressure and mass of

wood chips;

the mechanical work increases for

damage the composite with

increases for all variables;

increasing is influenced more by

pressure 5,41 J for maximum

pressure, than by increasing chips

mass and polymer mass;

a small amount of wood chips

produced a greater increase of

mechanical work than the matrix

mass.

From the above data analysis it can be

shown that high values of density composite

material will lead to a higher resistance to its

impact. For this purpose have optimized

values of independent variables for which

density and mechanical work have the

highest value, figure 7. A higher adhesion of

the components of the material you take

proper the impact energy. Outer layer of

fabric was deformed without surface cracks

occur due to energy absorption capacity of

the structural elements fabric and the

matrix.

Global Solution

p = 65.61

Mr = 40

Ma = 150

Predicted Responses

(g/cm3) = 0.72825,

L (J) = 5.56650,

Figure 7. Optimal values of the density and mechanical work of impact

Conclusion

Layered composite materials from textile

(fabric from bast yarns), vinyl acetate and

wood chips combine’s characteristics of

fabrics with the polymer mixture of wood

chips achieving a material with particular

characteristics.

The destination of the composite material

is making decorative objects for plating at

which the stress taken under consideration

is the low speed impact.


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The mechanical work required to

deformation with a 1 mm composite

material has the highest value in the case

maximum values of independent variables.

This fact is confirmed by the material

density is highest at the same maximum

values of independent variables.

Acknowledgements

The authors would like to thank to the

Ministry of Education, Research, Youth and

Sports for the financial support (PN II

research grant no 72200/2008).

References [1] Padaki N. V., Alagirusany R.,. Deopera B. L,

Fangueiro R. – Low velocity impact behaviour of

texyile reinforced composites – Indian Journal of

Fibre & Textile Research, vol. 33, june 2008, pp. 189 –

202

[2] A. Lunguleasa – Cercetari privind consumul

de adeziv in tehnologia placilor din aschii de lemn –

Buletinul AGIR, nr. 1, 2009, ianuarie – martie

[3] *** - Design and manufacture of textile composites

– Edited by A. C. Long, The Textile Institute,

Woodhead Publishing Limited, Cambridge, England,

2005

[4] Meddahi Amer, Ait Tahar Kamal, Boukais S.,

Boumara Y. – Laminated reinforced with natural

fibers of dwarf palm tree (Doum) – Industria Textila,

vol. 60, nr. 3, 2009, pag. 119 - 123

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STUDY ON TEXTILE REINFORCED COMPOSITE MATERIALS AND WOOD CHIPS