Papers by Keyword: Interpenetrating Polymer Network

Abstract: In order to improve damping properties of polyurethane/vinyl ester resin interpenetrating polymer network (PU/VER IPN), a series of Lead Zirconate-Titanate/IPN (PZT/IPN) composites were prepared by adding PZT into PU/VER IPN by in-situ polymerization process and were polarized. The optimal polarization process is obtained. The influence of PZT contents on microstructure, damping performances, mechanical performances, relative dielectric constant and piezoelectric constant (d¬33) was studied. The results show that PZT particles disperse in composites uniformly. The optimal polarization parameters of PZT/IPN composites are as follows: polarization temperature 100°C, polarization field strength 6kV/mm and polarization time 40min. Mechanical loss tangent (tanδ) values of the optimal PZT/IPN composites with 75 wt.% PZT are higher than 0.3 from –31°C to higher than 120°C, which meets the requirement of damping materials with excellent performances.

Abstract: A series of interpenetrating polymer networks (IPN) spongy foams based on polyurethane (PU) and epoxy resin (EP) were prepared by a simultaneous polymerization technique. The PU/EP IPN spongy foams with different epoxy content were investigated. The results showed that initial adhesion increased with the increment of EP content, and gained the highest value when the content reached to 20%; FTIR suggested the formation of PU/EP IPN; the density also increased with the increasing content of epoxy; the highest degree of uniformity in bubbles were observed in foams with 20% content of epoxy resin.

Abstract: The acidfied sulfur-prevulcanized natural rubber (NR) latex was mixed with 1～20 parts per hundred rubber (phr) of a 2wt% solution of chitosan (CS) in 1wt% acetic acid, then cast to preapare a series of NR/CS semi-interpenetrating polymer network (semi-IPN) films; the NR/CS semi-IPN films were further treated with 0.5wt% glutaraldehyde（GA）solution for respectively 1, 3 and 6h to obtain NR/CS IPN films. The mechanical properties and swelling behavours in various media of water, toluene and reference olis of IRM901 and IRM 903 of these films were studied and compared with those pure sulfur-prevulcanized natural rubber latex (SNRL) film. Results showed that, NR/CS IPN films with better mechanical properties could be obained by treating the 24h-leached NR/CS semi-IPN films than by treating directly the unleached ones with 0.5wt% GA solution; the tear strength, 300% modulus, Shore A hardness, hydrophilicity and resistance to non-polar solvents and oil of the SNRL films increased with the incorporation of CS, while the NR/CS IPN films exhibited better than the NR/CS semi-IPN films, especially in tear strength enhancement; the tensile strength and elongation at break of NR/CS semi-IPN and IPN films gradually decreased with the increase in CS content. However, most of the elasticity of pure NR vulcanizate could be reserved, when the CS content was not greater than 15 phr.

Abstract: Konjac glucomannan with different molecular weights/poly(acrylic acid) hydrogels were prepared in this paper. The structure of the IPN hydrogels was characterized by FT-IR and SEM. The swelling ratio of these hydrogels showed they had pH-sensitive properties and the enzymatic degradation tests showed the hydrogels retain the enzymatic degradation character of KGM. Furthermore, hydrogel composed of native KGM degraded sharply in enzymatic degradation test and it had bigger swelling ratio and weight loss ratio than those hydrogels which composed of lower molecular weights KGM. Therefore, hydrogels composed of lower molecular weight might release drug more stable when they were used as drug carrier.

Abstract: High performance rigid cross-linked PVC foam has been prepared by molding process and boiling foam process with the main materials including polyvinyl chloride paste resin (PVC), liquefied methylene bis-phenyl diisocyanate (MDI-L) and methylhexahydrophthalic anhydride (MHHPA). The chemical structure, cellular structure and thermal properties were respectively characterized by fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), thermomechanical analyzer (TMA) and thermogravimetric analyzer (TGA). Results showed that the foam had a uniform cellular structure, and cell size was about 760μm. The glass transition temperature (Tg) was 81°C and 5% weight loss temperature (T_5d) was 252°C.

Abstract: Novel organic –inorganic nanocomposite hybrid materials have been prepared by a sol-gel process. Tetraethoxysilane (TEOS) was used as inorganic source. Polyurethane acrylate (PUA) was the organic segment. 3-(trimethoxysilyl)propyl methacrylate (KH-570) was used as both a secondary inorganic source and a silane coupling agent to improve the compatibility of the organic and inorganic phases. X-ray diffraction indicates that silica was equally dispersed in polymer matrix. Furthermore, silica and polymer formed interpenetrating polymer network. Thermal property of the hybrid materials were checked by TGA study.