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surface characteristics of untreated and modified hemp fibers. - characteristics of polyester

by:Cailong     2019-08-15
surface characteristics of untreated and modified hemp fibers.  -  characteristics of polyester
Introduction natural cellulose fibers are widely used as reinforcing materials in polymer substrates due to their high specificity, low cost, unlimited availability and renewable properties.
The composite materials made using them are applied in different fields such as auto parts, building materials and furniture [1, 2].
However, poor interface adhesion between fiber and synthetic resin leads to a decrease in mechanical properties of the composite [3-4]. Role of Acid-
The surface area of the base interaction material in adhesion can be described with the sum of the dispersed components and specific interactions.
The dispersion component refers to London dispersion, and the specific interaction refers to polarity, ions, electricity, metals and acids-
Basic interaction.
Fowkes and Mostafa recommend dispersion and acid resistance
Basic interaction is the main force to run on the [interface]5].
Therefore, the bonding work can be written [W. sub. a]= [W. sub. a. sup. d]+ [W. sub. a. sup. AB]where [W. sub. a], [W. sub. a. sup. d], and [W. sub. a. sup. AB]
Is the total work of adhesion, due to dispersion and adhesion due to acid
They are basic interactions.
Colleagues at Donnetand also said they were sour.
The substrate interaction is closely related to the interface shear strength at the shear strength between the single layer fiber sand layers of the composite [6]. Moreover,acid-
Basic interactions are also useful chemical interactions that can be used to modify [7].
Therefore, a new improvement method is designed to improve the fiber
Interpretation of the significance of matrix adhesion and existing adhesion, quantitative determination of surface acid
The basic properties of natural fibers are important.
The purpose of this study is to determine the dispersed components of surface energy and acid
Determination of basic properties of cannabis fiber using reverse gas chromatography (IGC)
The modification methods for improving the adhesion of the interface, such as alkalization, substitution radical, mixing agent and Halo treatment were reported [3, 8, 9].
But according to the author's knowledge, changes in the dispersion of surface energy and acid
Due to these surface treatments, the basic properties of various natural fibers have not been fully explored.
As a result, they have been tried.
Due to the wide application in the field of fiber chemistry, alkalization and B-chemical were selected [10]. Acid-
Fundamental interactions between fiber and non-saturated polyester substrates are also determined using specific interaction parameters defined by Schulz et al. [11].
Finally, the change of specific interaction parameters was compared with the improvement of the bending performance of resin transfer molding (RTM)composites.
Reverse gas chromatography IGC is a useful technique for measuring surface features of different types of materials.
Good reviews in the literature12-13].
In the infinitely Diluted IGC, the solid material is used as a stationary phase.
Inject a small amount of volatile probes into the column and study their interaction with the stationary phase using retention volume ([V. sub. n])
, Defined as the amount of carrying capacity required to extract volatile probes from column [14].
The relationship of use is [V. sub. n]= F([T. sub. r]-[T. sub. o])
Among them, F is the corrected traffic :[T. sub. r]
, The retention time of a specific probe; and [T. sub. o]
, Retention time of interaction probes (
Generally methane or air). Molar-
Free Energy of adsorption ([DELTA]G)
Related to the volume through the following relationships. [DELTA]G = RTln([V. sub. n])+ C (1)
Where R is the gas constant;
T, temperature;
The value of the OfC depends on the reference status.
According to Schulz and others.
The free energy of the adsorption is related to the adhesion work through the following relationships [11]. [DELTA]G = Na[W. sub. a](2)
Where N is the number of Avogadro;
A, surface area of A single probe; and [W. sub. a]
The work of adhesion.
According to Fowkes, the bonding work between the two materials is given by [only due to the dispersion force]15][W. sub. a. sup. d]= 2[square root of[[gamma]. sub. l. sup. d][[gamma]. sub. s. sup. d]](3)where [[gamma]. sub. l. sup. d]and [[gamma]. sub. s. sup. d]
They are dispersed components of the surface free energy of the interacting solids and liquids, respectively. Combining Eqs. (1)-(3), we get RTln([V. sub. n])= 2Na [square root of[[gamma]. sub. l. sup. d][[gamma]. sub. s. sup. d]]+ C. A plot of RTln([V. sub. n])versus a [square root of[[gamma]. sub. l. sup. d]]
A straight line should be produced in case it is possible to interact only due to the dispersed composition of the surface area.
From the perspective of a straight line [[gamma]. sub. s. sup. d]
Can be calculated. Acid-
In the case of a polar probe, dispersion and acid-
The interaction between the probe and the adsorption agent occurs.
Therefore, the critical volume measured using IGC is due to these two interactions.
However, Fowkes shows that these two interactions are independent of each other [15], i. e.
, The net retention volume of the polarized probe is the sum of the respective contributions of the two components.
Determine the contribution of acid-
In general, the distribution of dispersed interactions must be separated.
To achieve this goal, it is assumed that the dispersion component of the polar probe is equal to the dispersion component of a chain of considerable size.
Therefore, the contribution of acid to the polarized probe
Base interactions can be determined by subtracting the adsorption Free Energy estimated from the chain from the global free energy of the adsorption.
Free Energy of adsorption ([DELTA][G. sup. AB])
Related to adsorption enthalpy ([DELTA][H. sup. AB])by [DELTA][G. sup. AB]= [DELTA][H. sup. AB]-T[DELTA][S. sup. AB]where, [DELTA][S. sup. AB]
Because of the acid, the entropy of the adsorption is-
Basic interaction. A plot of [DELTA][G. sup. AB]versus T (temperature)
A straight line with a intercept equal to [should produceDELTA][H. sup. AB].
According to flour and Papirer [16][DELTA][H. sup. AB]= [K. sub. A]DN + [K. sub. B]
Where DN and AN are donor numbers and receptor numbers defined by guttmann [17], [K. sub. A]and [K. sub. B]
Describe the acidity and basic features of fibers [11].
Therefore, the plot [DELTA][H. sup. AB]
The relationship between/AN and DN/AN is expected to have a linear relationship with the slope and intercept equal [K. sub. A]and[K. sub. B]respectively.
According to Schulz and others.
Specific interaction parameters [11], I,for acid-
Basic interaction can be defined as I = [K. sub. A. sup. f][K. sub. B. sup. m]+ [K. sub. A. sup. m][K. sub. B. sup. f][
Figure 1 slightly]
Where f and m refer to the optical fiber and matrix respectively.
This parameter can be used to determine the acid-
Substrate interaction between fiber and resin.
The experimental materials used in this experiment, cannabis fiber, were provided by Hempline, Canada.
The polymer used is an unsaturated polyester resin provided by the progress plastic (Stypol 040-8086).
One-and-one peroxide was purchased from Sigma Aldrich.
The analytical reagent used is n-hexane,n-heptane, n-octane, n-
N-pentane, ch 2, ethyl acetate, B-base ether, Si-fluorine ether, acetone, sodium hydroxide, glacial acetic acid and B-thin.
Table 1 shows the properties of different probes for igc analysis.
Alkali-treated cannabis fiber was soaked in 6% w/v sodium hydroxide solution for 48 hours at room temperature.
Remove the fiber, thoroughly clean with distilled water and dry at room temperature.
Treat cannabis fiber with glacial acetic acid at room temperature for 1 hour.
The fiber is removed and further treated with acetate containing a small amount of concentrated sulfuric acid drops (catalyst)for 5 min.
The treated fibers are then thoroughly cleaned with distilledwater and dried at room temperature.
Column preparation and IGC program IGC measurement with Perkin-
Elmer 8500 gas chromatography with flame ionization detector.
To ensure rapid evaporation, the injection port remains at least 50 k above the boiling point of the probe.
Fill a column with 4 grams of hemp fiber with a length of 30 cm and an inner diameter of 4mm.
Helium is used as carrier gas.
The corrected flow rate of helium varies from 30 to 55 ml/min.
Inject a small number of probes into the column using a Hamilton syringe.
It is found that the peak is symmetrical and has nothing to do with the amount of injection.
With methane as a marker, an average of five measurements were taken to calculate the volume.
Fiber mats and composites make randomly oriented hemp fibers carefully spread over fiberglass woven materials.
Then cover with another woven fiberglass and press with a hot press at a temperature of 313 K for 30 minutes.
There are fiberglass mats on the top and bottom, and mixed composites with large hemp fibers in the middle are made using RTM with untreated, B-chemical and alkaline hemp fibers, respectively.
Unsaturated Polyester is used as a matrix material: hemp fiber holding 25 Weight % and glass fiber holding 11 Weight % in all composites.
The RTM process is described in an earlier article in our group [18].
Bending Strength and bending modulus are measured using the ASTM D790 standard.
[Results and discussion of dispersed components]
Figure 2:
Calculate the dispersion components of untreated, alkalized and ethyl Grass Hemp fibers from RTln fig ([V. sub. n])versus a[Square root][gamma]. sub. l. sup. d]].
The dispersed components of the resin are also calculated.
Figure 1 shows a diagram of 313 k untreated fibers.
Linear relationship in N-
This technology works well in the case of natural fibers.
The value of the dispersion component of the surface energy ([[gamma]. sub. s. sup. d])
Table 2 summarizes the situation at different temperatures.
Alkalization and ethanol increase the dispersion of cannabis fiber.
This may be due to low dissolution.
Surface exposure of energy surface impurities and relatively high energy cellulose. Acid-
Interaction of adsorption free energy bases ([DELTA][G. sup. AB])
Is drawn according to the temperature (T)
For all the probes in all four cases, Ie.
Untreated, alkalized, acetate hemp fibers and resin.
Adsorption enthalpy ([DELTA][H. sup. AB])
Each probe in all four cases is calculated from these graphs.
Figure 2 shows one of the graphs. Finally, [DELTA][H. sup. AB]
/AN draws the value of DN/AN for each case shown in figure 3, [K. sub. A]and [K. sub. B]
From it was identified.
These values are summarized in Table 2.
Cannabis fiber was found to be basic, which may be due to the presence of trisoryl ester of similar extracts with basic behavior.
Alkalization cleans the surface of the fiber by dissolving the extract and semi-cellulose.
This is expected to reduce the basic features of the surface and increase the acidic features due to exposure to cellulose, which is mainly acidic [20].
The study found that destarch can slightly reduce the basic properties of cannabis fiber.
This is because the dissolution of the extract is expected to reduce the salt base, and methylation can lead to an increase in the salt base, which is due to the nearby oh base in the [cell wall]21].
The size of the alkaline produced by the acetate depends on the degree of the reaction.
It is found that Unsaturated Polyester Resin is also basic. [
Figure 3 slightly]
Values of specific interaction parameters defined by Schulz et al. [11]
, The combination of fiber and resin of each type was calculated.
It can be clearly seen from Table 2 that acid-
The alkali interaction with unsaturated polyester increases the alkalization and acetate fibers.
The correlation of the mechanical properties of the composite made with alkalization and ethylation fibers indicates that the bending properties have been improved.
Table 3 shows the values of bending strength and bending modulus.
Highest improvement of acid
Fundamental interactions between fibers and substrates were observed in the case of alkali
The same is true for the mechanical properties of treated fibers to composite materials.
This shows the importance of acid.
Describes the fundamental interaction of the interface properties of natural fiber reinforced composites.
Conclusion * IGC under infinite dilution proved to be a convenient tool for measuring surface energy and acid
Basic properties of natural fibers.
Due to various modification methods, changes in the final performance of the composite can also be explained with this technique.
* Alkalization and B-chemical make cannabis fiber both sexual but alkaline dominant in the case of B-chemical fiber, which is due to the ester of oh-based. REFERENCES 1. T. G.
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Deepaksh Gulati, Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200
M5S 3E5 Toronto, Ontario, Canada
College of Forestry, University of Toronto, 33 Willcocks St.
M5S 3B3 Communications, Toronto, Ontario, Canada: M. Sain; e-mail: m. sain@utoronto.
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