Nanoprecipitated Calcium Carbonate Research Articles

Water Absorption of Poly(lactic acid) Nanocomposites: Effects of Nanofillers and Maleated Rubbers

Injection-molded poly(lactic acid)/organo-montmorillonite (PLA/OMMT) and poly(lactic acid)/ nano-precipitated calcium carbonate (PLA/NPCC) were exposed to a water absorption test at 30°C for 70 days. The analysis was focused on the water diffusion kinetics and impact strength changes induced by the hydrolysis. The diffusion exponent (n) values of all the PLA samples are less than 0.5, indicating the Fickian diffusion model (case I) is obeyed. Adding nanofillers and maleated rubbers (SEBS-g-MAH or EPR-g-MAH) increased equilibrium moisture content but decreased diffusion coefficient values of PLA. The recoverability and retention-ability of the maleated rubbers toughened PLA/OMMT and PLA/NPCC after water absorption are excellent.

Effects of dynamic elongational flow on the dispersion and mechanical properties of low‐density polyethylene/nanoprecipitated calcium carbonate composites

Low‐density polyethylene (LDPE)/nanoprecipitated calcium carbonate (NPCC) nanocomposites were prepared with a self‐made vane extruder (VE) that generates global dynamic elongational flow and with a single‐screw extruder (SSE) that generates low shear flow. The mechanical properties, dispersed phase morphology, and thermal behavior of the nanocomposites were investigated to compare the different processing techniques. Scanning electron micrograph and transmission electron micrograph show that the elongational flow in the VE improves the dispersion of NPCC (5 wt%) particles in the LDPE matrix. The dimensional distribution of NPCC particles in the VE is significantly lower than that of the SSE. Differential scanning calorimetric curves indicate that dynamic elongational flow can enhance the crystallization ability of the LDPE/NPCC nanocomposites. The mechanical properties of the VE‐extruded samples are superior to those of the SSE‐extruded samples. When compared with that of SSE, morphology of tensile fracture surfaces suggests that the uniform and fine dispersion of NPCC particles in the LDPE matrix can successfully improve modulus and toughness of the LDPE/NPCC nanocomposites based on the novel VE. POLYM. COMPOS., 35:884–891, 2014. © 2013 Society of Plastics Engineers

Properties and Nonisothermal Crystallization Behavior of Nucleated Polylactide Biodegradable Composite Films

Polylactide biodegradable composite films were prepared via melt extrusion using a twin screw extruder. The effects of type and content of nucleating agent and cooling rate on the thermal and tensile properties of these films were investigated. Two types of nucleating agent, talc and nano precipitated calcium carbonate (NPCC), were studied at various contents from 0 to 2.0 phr. Nonisothermal crystallization behavior of composites was characterized by a differential scanning calorimetry (DSC). The cooling rate was varied from 1 to 10°C/min. The results indicated that the presence of nucleating agent significantly influenced on thermal and tensile properties of the PLA composite films. DSC thermograms revealed that the addition of nucleating agent on the PLA films led to an increase of crystallization temperature (Tc), crystallization rate, and degree of crystallization (χc) compared to the neat PLA. These behaviors could be noticed in both the nucleated PLA films with NPCC and talc. In contrast, the Tc and crystallization half-time (t 1/2) of these films significantly decreased when the cooling rate increased from 1 to 10°C/min. However, thermal stability of the films decreased when the nucleating agent content increased, especially that of the composites with NPCC.

Effect of Nano–Precipitated Calcium Carbonate on Mechanical Properties of PVC–U/Acrylic Blend

Perkembangan nanokomposit berasaskan polimer dan pengisi bersaiz nano telah menjadi pendekatan yang menarik untuk mencapai sifat komposit yang baik. Kesan nano–termendak kalsium karbonat (NPCC) terhadap sifat mekanikal matrik berlainan kemuluran telah dikaji. Poli(vinil klorida) tanpa pemplastik (PVC–U) dan PVC–U/akrilik telah digunakan sebagai matrik pada kajian ini. Untuk menghasilkan komposit, resin PVC, additif, akrilik dan NPCC pada mulanya diadun-kering menggunakan pencampur berkelajuan–tinggi berskala makmal sebelum diadun menjadi kepingan dengan menggunakan pengadun dua pengguling. Spesimen–spesimen ujian kemudiannya ditekan panas, selepas itu sifat mekanikal komposit dan morfologi permukaan patah komposit ditentukan. Modulus lenturan dan modulus Young meningkat dengan penambahan NPCC, tetapi telah menurunkan kekuatan regangan. NPCC telah menunjukkan kesan pengukuhan yang baik pada matrik PVC–U/ akrilik dan kesan kekakuan yang baik pada matrik PVC–U. Kekuatan lenturan kedua–dua komposit tidak dipengaruhi dengan penambahan NPCC. Kekuatan hentaman kedua–dua komposit telah mencapai nilai maksimum apabila 15 phr NPCC ditambah. Kata kunci: Poli(vinil klorida), nano–termendak kalsium karbonat, sifat–sifat mekanikal, akrilik Developing nanocomposites based upon polymers and nano–sized fillers has been an attractive approach to achieving good properties. Effects of nano–precipitated calcium carbonate (NPCC) on the mechanical properties of different ductile matrices were investigated. Unplasticised Poly(vinyl chloride) (PVC–U) and PVC–U/acrylic were used as the matrix in this study. To produce the composites, PVC resins, additives, acrylic and NPCC were first dry–blended using a laboratory high–speed mixer before being milled into sheets on a two–roll mill. Test specimens were then hot pressed, after that the mechanical properties and morphology of fracture surface of composites were determined. The flexural modulus and Young modulus of both the composites were enhanced after the addition of NPCC, but the tensile strength was decreased. The NPCC showed good toughening effect and stiffening effect on PVC–U/acrylic and PVC–U matrix, respectively. The flexural strength of both the composites was not significantly affected by the addition of NPCC. The impact strength of both the composites reached the maximum value when 15 phr NPCC was incorporated. Key words: Poly(vinyl chloride), nano–precipitated calcium carbonate, mechanical properties, acrylic

Effects of SEBS-g-MAH on the properties of injection moulded poly(lactic acid)/nano-calcium carbonate composites

Poly(lactic acid)/nano-precipitated calcium carbonate (PLA/NPCC) composites toughened with maleated styrene-ethylene/butylene-styrene (SEBS-g-MAH) were prepared by melt-compounding on a co-rotating twin-screw extruder followed by injection moulding. The mechanical properties of the PLA nanocomposites were characterized by ten- sile, flexural and impact tests, while their morphology were investigated using transmission electron microscopy (TEM). The thermal properties of the composites were examined with differential scanning calorimeter (DSC) and thermogravi- metric analyzer (TGA). The elongation at break and impact strength of the PLA/NPCC nanocomposites increased signifi- cantly after addition of SEBS-g-MAH. Both nano-dispersed NPCC and small NPCC clusters were found in PLA matrix. Also, some SEBS-g-MAH encapsulated NPCC can be observed. Thermal stability of PLA/NPCC was enhanced promi- nently by the addition of SEBS-g-MAH.

Facile surface modification of nanoprecipitated calcium carbonate by adsorption of sodium stearate in aqueous solution

A simple and solvent free two-step process for nanosized and surface-modified precipitated calcium carbonate (ns-PCC) synthesis has been proposed. Synthesized ns-PCC was thoroughly characterized by infra-red (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Langmuir adsorption study. Dynamic laser scattering (DLS) results on particle size showed a good correlation with those obtained by the proposed empirical model. Two aspects of nucleation and surface modification and the relationship of particle size on impact experimental parameters were also discussed.

Polypropylene/calcium carbonate nanocomposites – effects of processing techniques and maleated polypropylene compatibiliser

The mechanical properties and crystalline characteristics of polypropylene (PP) and nano precipitated calcium carbonate (NPCC) nanocomposites prepared via melt mixing in an internal mixer and melt extrusion in a twin screw extruder, were compared. The effect of maleic anhydride grafted PP (PP-g-MAH) as a compatibiliser was also studied using the internal mixer. At low filler concentration of 5 wt%, impact strength was better for the nanocomposites produced using the internal mixer. At higher filler loading of more than 10 wt%, the extrusion technique was more effective to dis- perse the nanofillers resulting in better impact properties. The impact results are consistent with the observations made from Scanning Electron Microscope (SEM) morphology study. As expected, the flexural modulus of the nanocomposites increased with filler concentration regardless of the techniques utilised. At a same filler loading, there was also no signifi- cant difference in the moduli for the two techniques. The tensile strength of the mixed nanocomposites were found to be inferior to the extruded nanocomposites. Introduction of PP-g-MAH improved the impact strength, tensile strength and modulus of the mixed nanocomposites. The improvements may be attributed to better interfacial adhesion, as evident from the SEM micrographs which displayed better dispersion of the NPCC in the presence of the compatibiliser. Though NPCC particles have weak nucleating effect on the crystallization of the PP, addition of PP-g-MAH into the mixed nanocompos- ites has induced significant crystallization of the PP.

Utilization of limestone dust waste as filler in natural rubber

The possibility of using limestone dust waste (LDW) as a filler in natural rubber (NR) was investigated. First, the basic properties of LDW were characterized; LDW was then incorporated into NR and the compound properties were determined. Comparison of the reinforcing effect of LDW and other commercial fillers such as light-precipitated calcium carbonate (PCC) and nanoprecipitated calcium carbonate (NPCC) was made. The results revealed that even though the addition of LDW has little effect on compound processability, it has a negative effect on most mechanical properties, e.g., tensile strength, tear strength, and abrasion resistance, of the vulcanizate. Among the three fillers, the degree of reinforcement could be placed in the following order: NPCC > PCC > LDW. Due to their relatively low specific surface area and thus low reinforcement ability, both LDW and PCC can be grouped as nonreinforcing fillers, whereas NPCC, the specific surface area of which is relatively high, could be grouped as a semi-reinforcing filler for rubber.

Study on the Functionality of Nano-Precipitated Calcium Carbonate as Filler in Thermoplastics

Study on the Functionality of Nano-Precipitated Calcium Carbonate as Filler in Thermoplastics