Effect of Molecular Weight on Phase Diagram of Epoxy/Polyetherimide-Siloxane Blends

2011 ◽  
Vol 189-193 ◽  
pp. 1127-1131
Author(s):  
Xiao Yan Li ◽  
Wen Jun Gan ◽  
Yuan Ren ◽  
Zheng Xi ◽  
Ye Wen Tang ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Molecular Weight ◽  
Cloud Point ◽  
Epoxy Resins ◽  
Optical Microscope ◽  
Curing Agent ◽  
Curing Time ◽  
Point Curve ◽  
Cloud Points ◽  
Cloud Point Curve

The cloud points of blends epoxy/polyetherimide-siloxane (PEI-Siloxane) without or with curing agent methyl tetrahydrophthalic anhydride (Me-THPA) after different curing time (1min, 2min, 3min) at 150oC were determined by optical microscope. The cloud point curve for uncured and cured after different time was then obtained from the experimental results with different composition. The effects of molecular weight of epoxy on phase diagram were discussed. The miscibility of blends will be taken into account in the toughing of epoxy resins by thermoplastic PEI-Siloxane copolymer later.

scholarly journals Rheological Study on the Thermoreversible Gelation of Stereo-Controlled Poly(N-Isopropylacrylamide) in an Imidazolium Ionic Liquid

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 783 ◽  
Author(s):  
Zhi-Chao Yan ◽  
Chandra Sekhar Biswas ◽  
Florian J. Stadler
Keyword(s):  
Phase Diagram ◽  
Molecular Weight ◽  
Ionic Liquid ◽  
Phase Separation ◽  
Cloud Point ◽  
Imidazolium Ionic Liquid ◽  
Crossover Point ◽  
Partial Phase ◽  
Cloud Points ◽  
Point Line

The thermoreversible sol-gel transition for an ionic liquid (IL) solution of isotactic-rich poly (N-isopropylacrylamides) (PNIPAMs) is investigated by rheological technique. The meso-diad content of PNIPAMs ranges between 47% and 79%, and molecular weight (Mn) is ~35,000 and ~70,000 g/mol for two series of samples. PNIPAMs are soluble in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide ([BMIM][TFSI]) at high temperatures but undergo a gelation with decreasing temperatures. The transition temperature determined from G’-G” crossover increases with isotacticity, consistent with the previous cloud-point result at the same scanning rate, indicating imide groups along the same side of backbones are prone to be aggregated for formation of a gel. The transition point based on Winter-Chambon criterion is on average higher than that of the G’-G” crossover method and is insensitive to tacticity and molecular weight, since it correlates with percolation of globules rather than the further formation of elastic network (G’ > G”). For the first time, the phase diagram composed of both G’-G” crossover points for gelation and cloud points is established in PNIPAM/IL mixtures. For low-Mn PNIPAMs, the crossover-point line intersects the cloud-point line. Hence, from solution to opaque gel, the sample will experience two different transitional phases, either clear gel or opaque sol. A clear gel is formed due to partial phase separation of isotactic segments that could act as junctions of network. However, when the partial phase separation is not faster than the formation of globules, an opaque sol will be formed. For high-Mn PNIPAMs, crossover points are below cloud points at all concentrations, so their gelation only follows the opaque sol route. Such phase diagram is attributed to the poorer solubility of high-Mn polymers for entropic reasons. The phase diagram composed of Winter-Chambon melting points, crossover points for melting, and clear points is similar with the gelation phase diagram, confirming the mechanism above.

Effect of Various Curing Agents On the Chemical Stability of Epoxy Resins

CORROSION ◽  
1961 ◽  
Vol 17 (1) ◽  
pp. 11t-20t ◽  
Author(s):  
RONALD L. DeHOFF
Keyword(s):  
Molecular Weight ◽  
Chemical Stability ◽  
Epoxy Resins ◽  
Room Temperature ◽  
Low Molecular Weight ◽  
Curing Agent ◽  
Corrosion Prevention ◽  
Curing Agents ◽  
Outdoor Weathering ◽  
Better Than

Abstract The epoxy resins most widely used in corrosion prevention are liquids of low molecular weight which can be converted to hard, tough, chemically resistant polymers by the use of various curing agents. Unlike other thermosetting resins such as polyesters, the curing agents may produce chemical linkages in the final polymers that differ from those present in the uncured form. Hence, the properties of cured epoxy resins are likely dependent upon, and may even reflect the properties of the curing agent used. Some seven different epoxy resin systems were exposed to various chemical environments and evaluatd for changes in dimensional stability and flexural strengths over a six month period. From the data presented herein, only limited conclusions may be drawn. Heat cured systems fare better than room temperature cured systems in every case. Anhydride cured epoxy resins show greater resistance to outdoor weathering than amine cured systems. 5.4.5, 6.6.8

scholarly journals Epoxidized soybean oil modified using fatty acids as tougheners for thermosetting epoxy resins: Part 2—Effect of curing agent and epoxy molecular weight

2021 ◽  
Vol 138 (24) ◽  
pp. 50579
Author(s):  
Fengshuo Hu ◽  
John J. La Scala ◽  
Santosh Kumar Yadav ◽  
James Throckmorton ◽  
Giuseppe R. Palmese
Keyword(s):  
Fatty Acids ◽  
Molecular Weight ◽  
Soybean Oil ◽  
Epoxy Resins ◽  
Epoxidized Soybean Oil ◽  
Curing Agent ◽  
Thermosetting Epoxy

Is a “Cloud-Point Curve” in Aqueous Poly(N-isopropylacrylamide) Solution Binodal?

2009 ◽  
Vol 113 (16) ◽  
pp. 5440-5447 ◽  
Author(s):  
Tomoaki Kawaguchi ◽  
Kunihiko Kobayashi ◽  
Masashi Osa ◽  
Takenao Yoshizaki
Keyword(s):  
Cloud Point ◽  
Point Curve ◽  
Cloud Point Curve

Cloud-Point Curve

2016 ◽  
Author(s):  
W. J. Work ◽  
K. Horie ◽  
M. Hess ◽  
R. F. T. Stepto
Keyword(s):  
Cloud Point ◽  
Point Curve ◽  
Cloud Point Curve

Liquid-Liquid Phase Separation in Multicomponent Polymer Systems: Influence of Molar-Mass Distribution on Shadow Curve and Phase-Volume Ratio

1993 ◽  
Vol 58 (10) ◽  
pp. 2305-2320 ◽  
Author(s):  
Ron Koningsveld ◽  
Karel Šolc
Keyword(s):  
Liquid Phase ◽  
Cloud Point ◽  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution ◽  
Simple Relationship ◽  
Phase Volume ◽  
Constant Weight ◽  
Point Curve ◽  
Cloud Point Curve

The effect of the molar-mass distribution (MMD), in particular the effect of a few higher molar-mass averages, on liquid-liquid phase behaviour is studied with the aid of data based on the Flory-Huggis-Staverman model. The critical concentration and the critical slopes of the cloud-point curve and the shadow curve appear to be quite sensitive to mz and mz+1, and, theoretically, they could serve as a unique data source for estimating these averages. In practice, however, experimental difficulties and errors encountered, especially with the shadow-curve slope determination, are probably too great for these data to be of any use. Next, the entire cloud-point and shadow-curves, and phase-volume ratios are examined with respect to the possible use to supply information on the MMD. At constant weight- and number-average molar mass, the cloud-point curve does not appear to be overly sensitive to Mz-average in the studied range. As to the other curves, no simple relationship evolves either, higher averages and details of the MMD both determining shape and location of shadow and phase-volume curves. An alternative procedure is suggested which consists of fitting a set of delta functions to a series of data points.

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