The Molecular Weight of Polyvinyl Acetate

Sirianni, A. F.; Tremblay, Ronan; Puddington, I. E.

doi:10.1139/v58-076

Cited by 20 publications

(3 citation statements)

References 6 publications

(3 reference statements)

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“…It has been widely accepted that lignin as a dry powder mixed in a straightforward manner into rubber shows almost no reinforcing effects . This is believed to be a result of the lignin particles adhering together by hydrogen bonding and thus not being dispersed into the rubber through mixing at a normal temperatures.…”

Section: Resultsmentioning

confidence: 99%

Self‐crosslinkable lignin/epoxidized natural rubber composites

Jiang

Yao

et al. 2014

J of Applied Polymer Sci

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Self-crosslinkable lignin/epoxidized natural rubber composites (SLEs) were prepared through a high-temperature dynamic heat treatment procedure followed by a postcuring process. Because of the ring-opening reaction between lignin and epoxidized natural rubber (ENR), lignin as a crosslinker and reinforcing filler was uniformly dispersed into the ENR matrix and was highly compatible with the polymer matrix; this was confirmed by scanning electron microscopy. The curing behavior, mechanical properties, and dynamic mechanical properties of the SLEs were studied. The results show that the crosslinking degree, glass-transition temperature, modulus, and tensile properties of the SLEs substantially increased with the addition of lignin. A physical model was used to verify the strong interactions between lignin and ENR. Stress-strain curves and X-ray diffraction suggested that the reinforcement effect on the SLEs mainly originated from lignin itself rather than from strain-induced crystallization.

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Section: Resultsmentioning

confidence: 99%

Self‐crosslinkable lignin/epoxidized natural rubber composites

Jiang

Yao

et al. 2014

J of Applied Polymer Sci

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“…A similar phenomenon was observed previously with freshly prepared benzene solutions of a sample of polyvinyl acetate. When the solution was evaporated to dryness in a hard vacuum and a new solution was prepared under hermetically sealed conditions with fresh solvent, the effect disappeared and the molecular weight was dependent on concentration (14). Because the solution properties depend on delicately balanced lyophobic-lyophilic characteristics, small concentrations of extraneous materials can have an unexpectedly large influence.…”

Section: Resultsmentioning

confidence: 99%

The Solution Properties of Some Polyoxyethylated Nonionic Substances in Aqueous and in Nonaqueous Solvents

Sirianni¹,

Coleman²

1964

Can. J. Chem.

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Unlike sorbitan and glycerol monostearates, alkylphenol derivatives of polyoxytheylene appear to be monodisperse in benzene when the solutions were examined by vapor pressure lowering. I n addition, the existence of micelles was not detected by light-scattering measurements in benzene with a few representative samples. In agreement with light-scattering data, the number average micellar weight in water decreased with increasing nuinber of ethylene oxide units per molecule. A difference of about a factor of 8 between weight and number average molecular weight appears to exist for materials of similar con~position. IYTRODUCTIONNonionic detergents which derive their hydrophilic properties from ethylene oxide interact in aqueous solutions forming micelles above a critical concentration. The number of monomers clustering together to form micelles is dependent on the temperature (1, 2) and to some extent on the homogeneity of the polyoxyethylene chain lengths (3).Although a linear relationship appears to exist between aggregation number (n) and the reciprocal of the average number of ethylene oxide units for compounds containing more than 10 such units (4,5), the micellar weight of surfactants of lower solubility rises sharply in water with decreasing numbers of hydrophilic groups (6). Thus departures from linearity occur that became particularly apparent a t high ethylene oxide ratios when a wide range of ethylene oxide content is examined. Large differences in micellar weights were found between cryoscopic (7) and light-scattering measurements (8) of commercial isooctylphenol derivatives of nine ethylene oxide units. Since evidence for the existence of differences in number ( * ' , ) and weight (M,) average molecular weight appeared for other nonionic surface active agents in nonaqueous solvents (9, lo), it was of considerable interest t o assess the solution properties of some alkylphenol derivatives of ethylene oxide in both aqueous and nonaqueous media.In the present communication a number of octylphenol -ethylene oxide adducts (Tritons) were examined wherein the number of ethylene oxide units varied from 3 to 30 with the hydrophobic constituent of the molecule remaining constant. Two nonylphenols, Triton K128 and DowFax 9N9, were examined in benzene by vapor pressure lowering. Triton N128, DowFax 9x9, and Triton X-45 were also examined in benzene by lightscattering measurements and some vapor pressure measurements were carried out with DowFax 9N9 in alcohol. A variety of polyoxyethylated alkylphenols with cloud points above 50' C were examined in water using a vapor pressure "Osmometer".A lauryl alcohol derivative of 23 (po1y)oxyethylene units (Brij 35)* in which nonequilibrium states were found in water by light-scattering measurements (11) was examined in water and in benzene a t 37' C and in alcohol a t 44'. Some measurements were

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“…(3), as calculated from eq.(1). (3) where M: molecular weight of solute, c: concentration by weight of solute(g/c3).…”

Section: Introductionmentioning

confidence: 99%