A polyvinyl alcohol has a number-average molecular weight (Mn) from 4,400 to 440,000, a molecular weight distribution (Mw/Mn) from 1.05 to 1.70, a degree of saponification from 80 to 99.99 mol %, wherein the polyvinyl alcohol contains an end group represented by a formula (I) below, and a molar ratio (X) of the end group based on total monomer units and the number-average molecular weight (Mn) satisfy a formula (1) below. Such a polyvinyl alcohol has a narrow molecular weight distribution and a high number-average molecular weight with hue good. ##STR00001##
(In the formula, R.sup.1 denotes an optionally substituted aromatic group having a carbon number from 6 to 20, and R.sup.2 denotes a hydrogen atom, an alkyl group having a carbon number from 1 to 20, or an optionally substituted aromatic group having a carbon number from 6 to 20.)
X.Math.Mn/44≥0.5  (1)

A polyvinyl alcohol has a number-average molecular weight (Mn) from 4,400 to 440,000, a molecular weight distribution (Mw/Mn) from 1.05 to 1.70, a degree of saponification from 80 to 99.99 mol %, wherein the polyvinyl alcohol contains an end group represented by a formula (I) below, and a molar ratio (X) of the end group based on total monomer units and the number-average molecular weight (Mn) satisfy a formula (1) below. Such a polyvinyl alcohol has a narrow molecular weight distribution and a high number-average molecular weight with hue good. ##STR00001##
(In the formula, R.sup.1 denotes an optionally substituted aromatic group having a carbon number from 6 to 20, and R.sup.2 denotes a hydrogen atom, an alkyl group having a carbon number from 1 to 20, or an optionally substituted aromatic group having a carbon number from 6 to 20.)
X.Math.Mn/44≥0.5  (1)

The present disclosure provides a modified polyvinyl alcohol-based polymer, which comprises a modifying monomer unit represented by Formula ##STR00001## wherein, X is a moiety comprising an alkenyl group, and the modified polyvinyl alcohol-based polymer has a saponification degree of 67 mol % to 78 mol % and a modification rate of 0.02 mol % to 1.5 mol %. The modified polyvinyl alcohol-based polymer is suitable to be used as a dispersant for suspension polymerization, to make the obtained polyvinyl chloride-based resin have reduced particle diameter and few coarse particles.

The present disclosure provides a modified polyvinyl alcohol-based polymer, which comprises a modifying monomer unit represented by Formula ##STR00001## wherein, X is a moiety comprising an alkenyl group, and the modified polyvinyl alcohol-based polymer has a saponification degree of 67 mol % to 78 mol % and a modification rate of 0.02 mol % to 1.5 mol %. The modified polyvinyl alcohol-based polymer is suitable to be used as a dispersant for suspension polymerization, to make the obtained polyvinyl chloride-based resin have reduced particle diameter and few coarse particles.

Provided is a cell culture scaffold material having excellent cell adhesion. The cell culture scaffold material according to the present invention contains a peptide-conjugated polyvinyl alcohol derivative having a polyvinyl alcohol derivative portion and a peptide portion, and the peptide portion has a cyclic peptide skeleton.

A vinyl alcohol-based polymer according to one embodiment of the present invention has an integral value (e) of 0.8 to 20 in the case when a sum of the following integral value (a) to (e) is 100 in a .sup.1H-NMR spectrum.

(a) integral value of peak confirmed at 5.70 to 5.96 ppm
(b) integral value of peak confirmed at 5.97 to 6.63 ppm
(c) integral value of peak confirmed at 6.64 to 7.55 ppm
(d) integral value of peak confirmed at 7.56 to 7.81 ppm
(e) integral value of peak confirmed at 7.82 to 8.04 ppm

A vinyl alcohol-based polymer according to one embodiment of the present invention has an integral value (e) of 0.8 to 20 in the case when a sum of the following integral value (a) to (e) is 100 in a .sup.1H-NMR spectrum.

(a) integral value of peak confirmed at 5.70 to 5.96 ppm
(b) integral value of peak confirmed at 5.97 to 6.63 ppm
(c) integral value of peak confirmed at 6.64 to 7.55 ppm
(d) integral value of peak confirmed at 7.56 to 7.81 ppm
(e) integral value of peak confirmed at 7.82 to 8.04 ppm

A dispersion stabilizer for suspension polymerization of vinyl compounds comprising a vinyl alcohol polymer (A) which has a saponification degree of 30 mol % or more and less than 60 mol % and a viscosity-average polymerization degree (P) of more than 200 and less than 600, and has a terminal alkyl group having 6 to 18 carbon atoms, and in which a content of monomer units having an oxyalkylene group is 0.3 mol % or less and the relationship between the viscosity-average polymerization degree (P) and a modification rate (S) (mol %) of the alkyl group satisfies Formula (1). Thus, there can be provided a dispersion stabilizer for suspension polymerization with which, during suspension polymerization of vinyl compounds including vinyl chloride, even when it is used in a small amount, the absorbency of a plasticizer is high, resulting in easy processing and formation of coarse particles is little and the remaining monomer components can be easily removed.
50≦S×P/1.880<100  (1)

A polyolefin microporous membrane is disclosed. The membrane has a width of not less than 100 mm, and a variation range of an F25 value in a width direction is not greater than 1 MPa. The F25 value is a value obtained by dividing a load at 25% elongation of a sample of the laminated polyolefin microporous membrane as measured with a tensile testing machine by a cross-sectional area of the sample.

A polyolefin microporous membrane is disclosed. The membrane has a width of not less than 100 mm, and a variation range of an F25 value in a width direction is not greater than 1 MPa. The F25 value is a value obtained by dividing a load at 25% elongation of a sample of the laminated polyolefin microporous membrane as measured with a tensile testing machine by a cross-sectional area of the sample.