Nitrile rubber is a common name for the emulsion copolymer of acrylonitrile and butadiene, and its best performance is superior to most oils and non-polar solvents.Compared with most conventional elastomers, NBR The polymers also provide better airtightness, abrasion resistance and thermal stability, and these properties come from their highly polar acrylonitrile, which determines the unique balance of polymer properties.
Figure 1, Mixing 1 to 4 at room temperature for 22 hours of compression permanent deformation
Nitrile rubber can be mixed with other elastomers and thermoplastics. The main thermoplastic blend with NBR is PVC. These two polymers form an easy-to-mix system upon melting, and NBR is added to PVC to exhibit ozone resistance, PVC alone is not possible. Visible PVC in the addition of nitrile polymer after the performance can be improved. The relationship is shown in Table 1.
Table 1, NBR and PVC performance characteristics
PVC changes can also be described as the ability of the PVC compound to impart a variety of applications when the nitrile polymer is added to the PVC in small amounts, for which the representative form of the nitrile polymer is in the form of agglomerates or powders So that it is easy to mix with PVC.
Figure 2, the mixture of 1 to 4 in 100 ℃ IRM903 oil soaking 70 hours after aging volume change
NBR acts as a polymeric plasticizer in place of ordinary monomolecular plasticizers for use in PVC compounds, which will help improve the resistance of the compounds to oil, flame retardant, tear resistance, abrasion resistance and bending resistance. The NBR is not removable because it is not extractable, it will remain after heat aging, oil and fuel immersion, resulting in better thermal aging and better post-aging low temperature performance. Low amount of monomer plasticizer Also reduce the adjacent thermoplastic plastic cracking, which is due to the migration of monomer plasticizer to the thermoplastic, resulting in plastic melt and produce cracks.
Table 2, formula formulations
This paper describes two basic studies, using a wide range of NBR composition on the PVC modification, the impact of the test.Firstly, the study was carried out with 120 parts of poly-crosslinked NBR polymer powder on PVC modification; followed by the study to assess the different range of NBR polymerization The purpose of these two studies was to explore the effect of NBR modified PVC compounds and to pay special attention to their performance improvement effects.
Figure 3, the hardness of the mixture 1 to 4
material
All ingredients used in this study were prepared from the market and the test recipes are listed in Table 2.
Table 3, NBR particle types in the mix
characteristic
The physical properties of the compounds were tested using standard ASTM test methods, including ASTM D412 for measuring tensile strength, tensile strength and modulus, ASTM D395 for determining compression permanent deformation properties.
Figure 4, the elongation of the mixes 1 to 4
Compounds are mixed
The compound was mixed with a laboratory using a Brabender mixer.
Effect of NBR - level Fluorescence on High - crosslinking Medium Viscosity on Mixture
The mixes 1 to 4 were gradually increased in the PVC resin by 32% BAN 50 Mooney viscosity of the crosslinked NBR to a maximum of 120 parts by weight. Overall, from the lower NBR amount to the NBR amount up to 120 parts by weight of the mixture 4 , It was observed that the compression set of permanent deformation and the volume change of aging in IRM903 oil were continuously improved.
Figure 5, the tensile strength values of the blends 1 to 4
Figure 1 shows the compressive permanent deformation measurements of the mix 1 to 4 series at room temperature for 22 hours.
Figure 6 shows the volume change of the mixes 1 to 4 after 70 hours at 23 ° C in fuel C
Figure 2 shows the volume change of the mixture 1 to 4 series after aging at 100 ° C in IRM 903 oil for 70 hours.
Figure 7, the tensile strength properties of the mixes A to I
The hardness, elongation and tensile properties also vary with the maximum amount of NBR in the amount of 120. This provides a very wide range of compound formulation design windows for optimizing NBR modified PVC properties.
Figure 8, 100% modulus of the mixes A to I
Figure 3 shows the hardness values of the mixes 1 to 4. Figure 4 shows the elongation of the blends 1 to 4, and Figure 5 shows the elongation values for the blends 1 to 4.
Figure 9, Compression of the mixes A to I (at 22 ° C for 22 hours)
In the fuel C exposure test, the mixture 2 exhibited an almost constant volume change, which contained 40 parts by weight of NBR.
Figure 10, the mixture A ~ I in 100 ℃ IRM903 oil placed 70 hours after the volume change
Figure 6 shows the volume change of the mixes 1 to 4 exposed to fuel C at 23 ° C for 70 hours.
With different linear and cross-linked NBR in 80 formulations of the compound results
There are several notable trends in the mixes A to I (Table 2 and Table 3.) In general, compared to the mix F to I (linear NBR polymer base), the mixtures A to E (cross-linking NBR-based) showed higher tensile and modulus, better compression and abrasion resistance, and higher BAN type NBR resulted in better oil resistance after IRM903 oil aging test at 100 ° C for 70 hours. It is also noted that the mixture A is based on a branched cross-linking type and the mixture D is based on a low amount of chemical crosslinking.
Figure 11, DIN A-I DIN abrasion resistance
Figure 7 shows the tensile properties of the mixes A to I; Figure 8 shows the 100% modulus properties of the mixes A to I; Figure 9 shows the compressive deformation of the mixes A to I (22 hours at 23 ° C) Figure 10 shows the volume change of the mixes A to I at 100 ° C IRM903 for 70 hours, varying with the amount of acrylonitrile in the NBR; Figure 11 shows the DIN wear properties of the mixes A to I.
to sum up
Nitrile rubber is a common rubber for PVC modification. In this study, cross-linked NBR polymers were used in the PVC blend series to provide a unique balance of properties, including excellent compression and oil resistance, NBR range. As a result, the performance of the mix can be optimized to be suitable for use in a variety of industries.