Papers by Keyword: Nucleating Agent

Abstract: The purpose of this research is to investigate the mechanical effects of polypropylene using sorghum fiber as nucleating agent. Alkalization, bleaching, and acid hydrolysis are all used to chemically modify sorghum fiber. This modified sorghum fiber was then mixed with polypropylene as a polymer matrix for 10 minutes in a rheomix at 100 rpm at 165°C and molded in a hot press. The results of this study suggest that acid hydrolysis can improve the crystallinity and compatibility of sorghum fiber. Furthermore, at 23.44 MPa, the optimum mechanical characteristics of a mixture of polypropylene and micro fibrillated cellulose (MFC) from sorghum fiber were achieved from 0.5% MFC resulting from acid hydrolysis.

Abstract: Impact Polypropylene Copolymer (IPC) is one of the PP type which is widely used. IPC was made with addition of ethylene in PP which decreases PP crystallinity. Many efforts have been made to improve the properties of PP crystallinity by addition of nucleating agents. In this study, we use Arenga Pinnata “Ijuk” fiber as PP nucleating agent. In order to determine the effect of “Ijuk” fiber as nucleating agents in kinetics aspect, we used DSC measurement based on Avrami equation. The results showed that the addition of ijuk decreases crystallizationhalf timeand dimension of crystal growth which indicate the effects of “Ijuk” fiber as a nucleating agent.

Abstract: Poly(L-lactic acid) (PLA) has good mechanical properties and is biodegradable. However, its crystallization rate is slow, crystallization period long, and its crystallization temperature high at 116 °C. Consequently, long processing cycles are required for the production of high crystallinity poly (L-lactic acid). Addition of nucleating agents is an efficient way to solve this problem. Aliphatic amide such as N,N-ethylenebis(12-hydroxystearamide) and ethylenebis-stearamide are reported as nucleating agents for poly (L-lactic acid). In this study, the effect of the aliphatic polyamide, poly (hexamethylene succinamide) on the crystallization behavior of PLA was investigated. Poly (hexamethylene succinamide) was synthesized by melt polymerization. Between one and ten weight percent poly (hexamethylene succinamide) was blended with poly (L-lactic acid) by melt extrusion. The crystallization temperature and crystallization period decreased with increasing poly (hexamethylene succinamide) content. The degree of crystallinity increased with the addition of poly (hexamethylene succinamide). A poly (hexamethylene succinamide) content of 5%wt provides optimum conditions for production of poly (L-lactic acid)-poly (hexamethylene succinamide) blend with good mechanical properties. The polymers obtained are entirely from renewable resources.

Abstract: Poly (lactic acid) (PLA) is a biopolymer derived from renewable resources and can be disposed of without creating harm to the environment. PLA can be formed by thermoplastic processes and has good mechanical properties. However, its disadvantages are a high crystallization temperature, slow crystallization rate, poor heat stability and low ductility. In the past, it was found that poly (D-lactic acid) (PDLA) can form complexes with poly (L-lactic acid) (PLLA) and the complexes could accelerate the crystallization and increase the degree of crystallinity of the PLA, but decrease the ductility. It is known that polyethylene glycol (PEG) can improve the ductility of PLLA. In this research, PDLA was copolymerized with PEG in an attempt to improve both crystallization behavior and ductility of PLLA. Poly (D-lactic acid)-co-polyethylene glycol (PDEG) was synthesized by ring opening polymerization using D-lactide and PEG at a D-lactide:PEG weight ratio of 10:3. The PDEG was blended with PLLA with a PDEG content of 0wt% to 50wt% by melt blending process. Fourier transform infrared spectrometry (FT-IR) and X-Ray diffractometry (XRD) confirmed the stereocomplex formation between PDEG and PLLA. Characterization by differential scanning calorimetry (DSC) revealed that crystallization temperatures of the blends were decreased in the presence of PDEG. Storage moduli and tan of the blends obtained from dynamic mechanical analysis (DMA) decreased as PDEG content increased. Polarized optical microscopy (POM) micrographs of blends with PDEG content of 1wt% to 5wt% obviously showed that crystallization rate was increased. PDEG has the potential to be an effective nucleating agent and efficient plasticizer for PLLA.

Abstract: Polypropylene (PP) membranes were respectively prepared using adipic acid (APA) and Sorbitol (NA-40) as nucleating agent via thermally induced phase separation (TIPS) method. The effects of nucleating agent content and cooling temperature on the structure and performance of membrane were investigated using scanning electron microscopy (SEM), wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). WAXD spectrogram indicates that three kinds of α, β and γ-form crystal were formed in this preparation process and the relative content of β-form crystal in membrane prepared by NA-40 system is higher than that of membrane formed by adipic acid. SEM images show that porous structure and cellular structure were observed on the surface and cross-section of membrane. The water flux, tensile strength and elongation increase with the addition of nucleating agent content and decrease with cooling temperature rising. This paper aims to choose proper nucleating agent NA-40 and coagulation temperature to improve the properties of PP membranes.

Abstract: In this study, silvergrass (SV) reinforced high density polyethylene (HDPE) composites were prepared. The effects of slivergrass fibers (SV) content on the mechanical properties, crystalline properties of wood plastic composites (WPCs) before and after water absorption were investigated. It was found that compared with the untreated WPCs after immersed into water, the tensile strength of PMDI treated composites were higher. Silvergrass can be the nucleating agent with treated by PMDI. The X_c of PMDI treated WPCs after immersed into water was also increased. However, this improved X_c has negative effect on mechanical properties.

Abstract: The foaming reaction so that all water-gel reaction and foaming reaction to reach equilibrium, the excellent thermal insulation material was prepared by the regulation of the catalyst, a nucleating agent and an isocyanate. By experiment we know that the amount of stannous octoate catalyst 6%, 4% of the amount of nucleating agent CaCO₃, and the case of 100% of the amount of isocyanate, the density of the foam material and the mechanical properties of the insulation material to achieve the best value.

Abstract: Due to the low transparency and poor gloss, the applications of ordinary opaque polypropylene are limited largely in the field of food, medicine, medical instrument and packaging. One of the ways to solve the defects mentioned above is to develop transparent polypropylene which is industrialized via polymerization and processing. The article introduces the progress of high transparent polypropylene (HTPP) all over the world.

Abstract: The crystallization behavior and crystalline structure of poly (lactic acid) (PLA) filled with a novel nucleating agent (TMC328), which is a kind of aromatic amide derivatives, were investigated using differential scanning calorimetry (DSC) and wide angle X-ray (XRD). In isothermal crystallization from the melt, the present of TMC328 remarkably affected the isothermal crystalline behaviors of PLA. PLA/0.5% TMC328 sample exhibited very short crystallization half-times at 90-130 °C. Furthermore, the Avrami theory was used to describe the isothermal crystallization kinetics of PLA/TMC328 samples. It is confirmed that TMC328 showed a significant heterogeneous nucleation effect on the crystallization of PLA matrix. Moreover, XRD measurement indicates that TMC328 is a kind of α-form nucleating agent for PLA.

Abstract: 2, 2'- methylene-bis (4,6-di-tert-butyl-phenyl) phosphate sodium (NA-11), a nucleator of polypropylene (PP) was high-efficiently prepared with homemade 2,2-methylene-bis (4,6-di-tert-butyl-phenyl) phosphorus oxychloride as raw materials by means of hydrolysis and neutralization, and the overall yield of the product was 95.9 %. The synthesized product was characterized by Fourier Transform Infrared spectroscopy (FTIR), thermogravimetry (TG), elemental analysis and ³¹P-NMR. Polypropylene was modified with the synthesized product as a nucleating agent. The results showed that the tensile strength, flexural strength, and the flexural modulus of composites increased by 12.1%, 30.2%, 41.0% respectively when the synthesized product is 0.1wt%, and the haze decreased form 42.9% to 17.3%.