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Polymer blends of PA6 and PPE compatibilized by poly[methylene(phenyleneisocyanate)] (PMPI) coupler
(1998-04-01)
Chiang, CR
;
Ju, MY
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
An oligomeric isocyanate, poly[methylene(phenylene isocyanate)] (PMPI), is demonstrated to be an efficient reactive compatibilizer for blends of polyamide-6 (PA6) and poly(2,6-dimethyl-1,4-phenylene ether)(PPE). Use of this compatibilizer results in substantial improvements in mechanical properties. The multiple functional isocyanate acts as a coupling agent and reacts with PA6 and PPE endgroups during melt processing to produce a PA6-co-PMPI-co-PPE mixed copolymer at the interface. This in situ-formed copolymer tends to reside at the interface to reduce the melt interfacial tension and enhance interface adhesion.
The kinetics, thermal and mechanical properties of epoxy-polycarbonate blends cured with aromatic amine
(1998-04-01)
Lu, MS
;
Chen, JL
;
Li, YS
;
Chang, FC
;
Li, MS
PC-DER331 blends are transparent and homogeneous due to the transesterification taking place during hot melting process. This transesterification reaction does not occur or occurs insignificantly during the preparation of PC-DER332 blends. PC is separated from the PC-DER332 melt mixture by slow cooling to room temperature but the mixture remains a single phase by quenching with an ice bath. Two systems of PC-epoxy blends, PC-DER331 blends and PCDER332 blends are cured by the m-phenylene diamine (MPDA) in a stoichiometric ratio. Curing kinetics have been carried out by differential scanning calorimeter (DSC). The presence of PC accelerates the curing reaction. Infrared spectroscopy (IR) indicates the occurrence of transesterification in the PC-DER331/MPDA blends during curing. The flexural modulus increases with the increase of the PC content while the notched Izod impact strength decreases with the increase of the PC content for all the blending systems. The fracture surfaces of the PC-DER331/MPDA blends are smooth, an indication of a homogeneous morphology. The fracture surfaces of the PC-DER332/MPDA blends are rough, an indication of a heterogeneous morphology.
Sequential distribution of copolyesters containing the phosphorus linking pendant groups characterized by H-1-NMR
(1998-06-01)
Chang, SJ
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
A series of phosphorus-containing copolyesters were synthesized by polycondensation of terephthalic acid (TPA), ethylene glycol (EG) and 9,10-dihydro-10-[2, 3-di(hydroxycarbonyl)propyl]-9-oxa-10-phosphaphenanthrene-10 -oxide (DDP). Chemical structures of these phosphorus-containing copolyesters were characterized by H-1-n.m.r.. Experimental results show that these methylene protons of the ethylene glycol unit resonate at lower field than those of the DDP aliphatic protons. The resonance intensity of DDP aliphatic protons increases with the increase of the phosphorus content. The H-1-n.m.r. spectrum of the DDP aliphatic protons contain three peaks since the proton in H-C-P has greater coupling constant than that of H-C-C. The chemical shifts of these methylene protons in the ethylene glycol unit vary with different sequences. The methylene protons in the ethylene glycol of the T-E-T unit resonate at lower field than those of P-E-T(T-E-P) and P-E-P units. The monomer molar fraction, sequential distribution and degree of randomness of the phosphorus-containing copolyester were determined through analyses of the resonances of methylene protons in the ethylene glycol unit. The molar fractions of the DDP comonomer determined by n.m.r. analyses are close to the charged values in synthetic step and the values determined by an UV method. Moreover, the copolyesters were found to be as random copolymers with a degree of randomness equal to about 1. (C) 1998 Elsevier Science Ltd. All rights reserved.
Polymer blends of polyamide-6 (PA6) and poly(phenylene ether) (PPE) compatibilized by a multifunctional epoxy coupler
(1998-08-01)
Chiang, CR
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
A tetrafunctional epoxy monomer, N,N,N'-N' -tetraglycidyl-4,4'-diaminodiphenyl methane (TGDDM),has demonstrated to be a highly efficient reactive compatibilizer in compatibilizing the immiscible and incompatible polymer blends of polyamide-6 (PA6) and poly(2,6-dimethyl-1,4-phenylene ether) (PPE). This epoxy coupler can react with both PA6 and PPE to form various PA6-co-TGDDM-co-PPE mixed copolymers. These interfacially formed PAG-co-TGDDM-co-PPE copolymers tend to anchor along the interface to reduce the interfacial tension and result in finer phase domains and enhanced interfacial adhesion. A simple one-step melt blending has demonstrated to be more efficient in producing a better compatibilized PA6/PPE blend than a two-step sequential blending. The mechanical property improvement of the compatibilized blend over the uncompatibilized counterpart is very drastic, by considering the addition of a very small amount, a few fractions of 1%, of this epoxy coupling agent. (C) 1998 John Wiley & Sons, Inc.
Characterizations for blends of phosphorus-containing copolyester with poly(ethylene terephthalate)
(1998-09-01)
Chang, SJ
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
High molecular weight phosphorus-containing copolyesters, poly(ethylene terephthalate)-co-poly(ethylene DDP) (PET-co-PEDDP)s, were prepared and characterized with the objective of producing a non-halogen flame retardant system for practical applications. The phosphorus-containing copolyester with 30 wt% phosphorus (P30 copolyester) was blended with PET to evaluate their characteristics and flame retardancy. Higher phosphorus content results in lower crystallinity and higher char formation after thermal degradation. The rheological behavior remains similar to that of PET. The P30/PET blend possesses higher crystallization rate than the corresponding phosphorus-containing copolyester containing equal phosphorus content. Thermal and rheological behaviors of P30/PET blends are similar to PET or the phosphorus-containing copolyesters. The P30/PET blends are miscible or compatible base on single T(g)s detected by DSC or DMA. The SEM/EDX phosphorus mapping image of the P30/PET blend shows uniform distribution of the phosphorus moieties within the P30/PET matrix, another indication of a compatible or miscible blend between the phosphorus-containing copolyester P30 and PET. Flame retardancy of the P30/PET blend is identical to that of the phosphorus-containing copolyester with identical phosphorus content. Blending of high phosphorus content copolyester with virgin PET provides a feasible method to obtain a flame resistant PET with LOI greater than 28.
Transesterification in homogeneous poly(epsilon-caprolactone)-epoxy blends
(1999-01-03)
Chen, JL
;
Huang, HM
;
Li, MS
;
Chang, FC
;
應用化學系
Transesterification has been investigated in poly(epsilon-caprolactone) (PCL)-epoxy blends. In the hot melt process, the hydroxyl on diglycidyl ether of bisphenol-il (DGEBA) monomers is too low to give a noticeable transesterification reaction. In the postcure process, model reactions reveal that the hydroxyls from a ring-opening reaction are able to react with the esters of PCL. In the meantime, the PCL molecular weight decrease and its distribution becomes broader. Nuclear magnetic resonance spectra reveal that fraction of the tertiary hydroxyls converts to secondary hydroxyls. In the cured DGEBA-3,3'-dimethylmethylene-di(cyclohexylamine)-PCL blend, a homogeneous morphology is achieved. PCL segments are grafted onto the epoxy network after postcuring and result in the lower T-g observed in the differential scanning calorimetry thermogram. A higher transesterification extent also results in broader transition peaks by dynamic mechanical analysis. (C) 1999 John Wiley & Sons, Inc.
Preparation and epoxy curing of novel dicyclopentadiene-derived Mannich amines
(1999-03-28)
Tseng, FP
;
Chang, FC
;
Lin, SF
;
Lin, JJ
;
應用化學系
Phenol/dicyclopentadiene (DCPD) adducts were prepared from the BF3-catalyzed reaction of p-nonylphenol and dicyclopentadiene at molar ratios of 2 : 1 and 3 : 2. The phenol-terminating adducts were consequently reacted with diethylenetriamine and formaldehyde using Mannich reaction conditions. These products containing phenol, amine and tricyclodecane functionalities in the same molecule can be used as epoxy curing agents. The diethylenetriamine was add to the phenol via Mannich reaction at approximately 50% theoretical equivalent. The multiple N-H soups in amines and the O-H groups in phenols provide crosslinking sites for epoxy resins. The cured epoxy resins show improvement in tensile strength and elongation in comparison with those cured by the poly(oxypropylene) diamine (400 molecular weight) or diethylenetriamine. (C) 1999 John Wiley & Sons, Inc.
Syntheses and characterizations of soft-segment ionic polyurethanes
(1999-04-15)
Wang, XL
;
Li, H
;
Tang, XZ
;
Chang, FC
;
應用化學系
Novel soft-segment ionic polyurethane (linear and crosslinking) have been prepared based up on sodium sulfonate-side chains poly(ethylene oxide) (SPEO). SPEO was synthesized by grafting the sodium sulfonate onto the chain of poly(ethylene oxide) with molecular weights of 400, 600, 800, and 1000. The SPEO and the ionic polyurethane were characterized by elemental analysis, IH;NMR, C-13-NMR, gel permeation chromatography, and impedance analysis. The effect of plasticizer on the ionic conductivity of the polyurethane was also investigated. These solid polymer electrolytes possess a higher ionic conductivity (about 10(-6) S/cm at room temperature) than the corresponding sulfonated hard-segment polyurethane electrolytes. The presence of the hydroxyl group in the electrolyte tends to lower the ionic conductivity. Crosslinking of polyurethane results in the enhancement of the dimensional stability, while maintaining the same level of the ionic conductivity. (C) 1999 John Wiley & Sons, Inc.
Synthesis and characterization of copolyesters containing the phosphorus linking pendent groups
(1999-04-04)
Chang, SJ
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
Poly(ethylene terephthalate)-co-poly(ethylene DDP)s [PET-co-poly(ethylene DDP)s], were synthesized by charging 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOP), itaconic acid, terephthalic acid, and ethylene glycol in one reactor to conduct the microaddition reaction (using H2PtCl6 as catalyst), esterification reaction, and polycondensation reaction. H2PtCl6 has demonstrated to be a highly efficient microaddition catalyst to improve the DDP conversion. The microaddition reaction of the phosphorus compound (DOP) with the itaconic acid can be proceeded at a significantly lower temperature (110 degrees C) and results in higher conversion (> 98%). The use of the H2PtCl6 catalyst makes it possible to charge all the reactants in one reactor to produce high molecular weight phosphorus-containing copolyesters without requiring the presynthesis of the DDP. These resulting copolyesters are identified by Fourier transform infrared spectroscopy, H-1-NMR, and differential scanning calorimetric analysis. Thermal characteristics, thermal stability, intrinsic viscosity, acid value, and rheological and mechanical properties of these copolyesters were also characterized. The presence of the bulky pendent phosphorus side groups in the copolyester tends to decrease the structural regularity and retards its crystallization. The formation of a protected char layer for the phosphorus-containing copolyester raises the decomposition temperature of the copolyester under an oxygen atmosphere higher than that of PET. The limiting oxygen index values of all phosphorus-containing copolyesters are all higher than 33. Higher phosphorus content results in decreasing crystallinity, lower melting temperature, lower decomposition temperature, as well as lower tensile strength, but increasing residual char after thermal degradation and higher limiting oxygen index value. The rheological behaviors of copolyesters remain similar to that of PET. The glass temperatures of copolyesters are all similar to 17 degrees C (76.8 degrees-77.2 degrees C). Incorporation of phosphorus moieties into its molecular chain has a significant effect on thermal and flame retardancy behavior. However, the crystal lattice of all copolyesters do not change with incorporation of the pendent phosphorus side group in the backbone of the copolyester. (C) 1999 John Wiley & Sons, Inc.
Effects of molecular structure of modifiers on the thermodynamics of phenolic blends: An entropic factor complementing PCAM
(1999-05-04)
Wu, HD
;
Chu, PP
;
Ma, CCM
;
Chang, FC
;
應用化學系
Different thermodynamics in phenolic blends with different polymeric modifiers, i.e., phenoxy, poly(decamethylene adipate), poly(ethylene oxide), and poly(vinyl alcohol), calculated by the Painter and Coleman association model (PCAM) are examined. The thermodynamics is calculated based upon the equilibrium constants derived experimentally from infrared spectroscopies of low molecular weight analogues with similar hydrogen-bonding formation. The discrepancies between the PCAM predictions and the experimentally observed T-g and free volume variation with blending composition are attributed to the additional entropic effects introduced by the long repeated units of modifiers. The structural characteristics and hydrogen-bonding heterogeneity as derived from solid-state NMR and IR spectra support the notion that the length and size of the modifier repeated unit are responsible for such discrepancies. These observed nonidealities can be interpreted as competition between inter- and intraassociations (Delta H-m favored), which depend on the entropy rise associated with the amount of increase of the breaking off of the self-association in phenolic and modifiers within blends. While PCAM is based on "true" miscibility, however, minor modification is required to better describe the thermodynamics for "real" blends where microdomain heterogeneity with size greater than that defined by thermodynamic criteria may be present.

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