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略過巡覽連結Borica > Product & Industry > Tytan > Application > Coupling & Dispersing Agent > Performance Test

▶ Performance Test of Tytan Coupling Agent in CaCO3 Filled Polypropylene

Procedure



▶ CaCO3 pretreatment
The treatment was conducted at Borica lab with 1kg batch glassware
Dosage of titanate coupling agent: 1wt% based on CaCO3 weight

Procedure
1. Preheat CaCO3 at 100C for 1 hr
2. Dilute titanate with hexane at 1:25 ratio
3. Add titanate solution into CaCO3, stirring at around 60~70C
4. Strip off hexane then put dried CaCO3 at oven at 110C for 2hrs.

▶ Extrusion and Injection molding procedure
Loading of CaCO3: 50% in PP for all test groups.
Temperature profile of twin extruder: 210C for all sections
Screw rotation speed: 200~300 rpm with 400~600g/hr feeding rate
PP/CaCO3 was extruded twice to ensure the uniformity of the composite
The sample was then pelletized and injection molded into test specimen.

▶ Comparison between titanate coupling agents and stearic acid

Table 1. Performance of titanate couplings and stearic acid
Coupling agentPretreatmentDosage
(wt% on CaCO3)
Tensile strength
(MPa)
Stress at
break (MPa)
Elongation
at break (%)
N/AN/AN/A21.1417.39 163.69
Stearic acidYes2%24.1321.54305.93
CP-326Yes1%23.8922.07543.01
CP-317Yes1%23.8922.07543.01
CP-219Yes1%22.6621.43497.08
CP-318Yes1%24.7123.52424.59


Surface treatment of CaCO3 shows positive effect on mechanical properties of the composite. Elongation at break was improved significantly for all 5 groups without sacrificing the tensile strength or stress at break. Elongation for titanate treated composite was higher than stearic acid treated composite with lower dosage. One possible explanation is that titanate is a bulkier molecule than stearic acid. When CaCO3 is coated by titanate, the bulkier structure may exert more distance between CaCO3 particles, giving better dispersion in the polypropylene. Good dispersion means less CaCO3 agglomeration hence less voids are created in the composite. Another reason might be that the 3 long carbon chains attached on Ti provide higher extent of entanglement with polypropylene polymer chain than stearic acid, which contains only 1 carbon chain.


▶ Comparison between Titanate and Maleic anhydride grafted PE.
Maleic anhydride grafted PP/PE is another kind of coupling agent/adhesion promoter that used by compounders. A performance test of maleic anhydride grafted PE in PP/CaCO3 composite was also conducted. Mah-PE was premixed with CaCO3 and PP pellets then was direct co-extruded through twin screw extruder.

Table 2. Performance comparison of CP-318 vs Maleic anhydride grated PE (Mah-PE)
Coupling agentPretreatmentDosage
(wt% on CaCO3)
Tensile strength
(MPa)
Stress at
break (MPa)
Elongation
at break (%)
N/AN/AN/A21.1417.39 163.69
CP-318Yes1%24.7123.52424.59
Mah-PENo5% (on total weight)28.7721.3962.68


Mah-PE can greatly enhance the tensile strength of the composite but deteriorate the elongation property as we have expected in the comparison table. It makes the composite harder, but more brittle. We believe the combination of the two additives can further improve the properties since their working mechanisms are different and should not be interfered by one another.