Study On Modified Pelagic Calcareous Ooze Filled Polymer Composites

Since the 1930s,when marine resources became a new object of study,a lot of basic information and research results have been obtained on the deposition process,compositional characteristics,geological characteristics and environmental characteristics of oceanic sediments,but very little study has been done on their practical applications,and no study has been reported on the application of deep-sea calcareous clay(PCO).PCO is composed of granular minerals such as calcite,quartz,and layered minerals such as elysium/montmorillonite,and contains porous calcium algae,which has the characteristics of high rigidity,good stability and high activity,and it is necessary to explore its application potential as a filling material for enhanced organic matrix composites in the present era when similar resources on the surface are becoming depleted.In this study,we firstly started from the structure and composition of PCO,and proved that the crystalline part of it was mainly calcite by XRD and FT-IR.SEM images showed that there were also elysium/montmorillonite layer minerals and uniformly distributed algal remains in PCO,which were determined to be calcareous algae,mainly composed of calcium carbonate,under EDS analysis.A mixture of granular,lamellar and pore-like structures was formed.The morphology of calcareous algae can be classified into large,medium and small according to the particle size.The particle size analysis of PCO shows that large calcareous algae,medium calcareous algae and calcite,and small calcareous algae and elysium/montmorillonite mixed layer minerals are concentrated in three particle sizes of 30.1 μm,9.7 μm and 2.5 μm,forming a continuous open gradation composed,which proves that PCO has reasonable particle size characteristics.As a mixture of inorganic minerals as the main body,PCO is difficult to be naturally co MPatible and dispersed with organic matrix.In this paper,PCO was first modified before the preparation of composites.Stearic acid(SA),N,N’-ethylenedi(stearamide)(EBS),(3-Aminopropyl)triethoxysilane(KH-550)and 3-(2,3-Epoxypropoxy)propyltrimethoxysilane(KH-560)were selected as modifiers through sedimentation experiments,and the PCO modification process was completed by mechanical force chemical method.ABS,linear low density polyethylene(LLDPE)and polypropylene(PP),which are more representative among organic polymer plastics,were selected to be compounded with PCO to prepare a variety of new composites with improved mechanical properties.For the process conditions of preparing PCO composites,the process parameters of mixing time of 10 min,rotor speed of 30 r/min,molding time of 1 min and holding time of 24 hr were preferentially selected by orthogonal tests.Subsequently,three PCO-filled composites were obtained by following this condition for the mixing and molding process.The performance tests showed that the PCO/ABS composites achieved the highest tensile and flexural strengths of 56.1 MPa and 69.3 MPa,respectively,when filled with10.0 wt.% KH-550 modified PCO,which increased by 26.9 % and 6.6 %,respectively,co MPared with the control samples(i.e.,samples without PCO filling),while the hardness of the composites increased by The PCO/LLDPE composite reached the highest bending strength of 15.6 MPa when filled with 5.0 wt.% KH-550 modified PCO,which was 20.3 % higher than that of the control sample,and the highest tensile strength of 23.2 MPa when filled with 10.0 wt.% KH-550 modified PCO,which was 8.2 %higher than that of the control sample;the PCO/LLDPE composite reached the highest bending strength of 15.6 MPa when filled with 5.0 wt.% KH-550 modified PCO,which was 20.3 % higher than that of the control sample.The tensile and flexural strengths of the PCO/PP composites reached the highest when filled with 5.0 wt.% KH-550 modified PCO,28.73 MPa and 41.58 MPa,8.41% and 24.1% higher than the control group,and 7.57% higher hardness.The FT-IR test results showed that the molecular structure of PCO did not change during the composite process with the organic matrix.XRD tests showed that the crystallinity of PP could be increased during the PCO/PP composite process,leading to an increase in its mechanical properties.Meanwhile,the fracture SEM images of all three composite samples showed that PCO disperses and hinders the stress transfer on microscopic level when the material is stressed by embedding into the organization of crystalline lamellae or non-crystalline regions of the organic matrix,thus hindering the microscopic dislocation motion of the composite leading to its mechanical properties enhancement.