Recertification of the SRM 706a, a polystyrene

Abstract

Certain commercial materials and equipment are identified in this paper in order to specify adequately the experimental procedure. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply necessarily the best available for the purpose. According to ISO 31-8, the term "Molecular Weight" has been replaced by "Relative Molecular Mass," symbol M r Thus, if this nomenclature and notation were followed in this publication, one should write /W rw instead of the historically conventional M w for the weight average molecular weight with similar changes for M n , M z , and M v. M w would be called the "Mass Average Relative Molecular Mass." The conventional notation, rather than the ISO notation has been used in this publication.

NIST-Sponsored Interlaboratory Comparison of Polystyrene Molecular Mass Distribution Obtained by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry: Statistical Analysis

“…This preliminary comparison showed that polymer samples taken from all the vials produced identical chromatograms. A statistical analysis using methods of comparing chromatograms used in this laboratory for looking at bottle-to-bottle variation of NIST standard reference materials (SRMs) confirmed these observations . Details of that work are to be published as a NISTIR…”

Certification of the relative molecular mass and the intrinsic viscosity of SRM 2887, a polyethylene of narrow molecular mass distribution

“…For this purpose, we employ a scheme similar to that used in ref. [29] for the estimation of systematic uncertainties in SRM's 1482, 1483 and 1484 and ref [31] on the recertification of SRM 706a. These uncertainties are listed in Table 2 for SRM 2887.…”

Certification of the relative molecular mass and the intrinsic viscosity of SRM 2885, a polyethylene

“…(15) The coefficients in eq. (16) are related to the M w , molecular mean-square radius of gyration, R G 2 , the second viral coefficients, A 2 , and the third virial coefficients, A 3 , by [28,29]:…”

“…For this purpose, we employ a scheme similar to that used in ref. [28] for the estimation of systematic uncertainties in SRM's 1482, 1483 and 1484 and ref [29] on the recertification of SRM 706a. These uncertainties are listed in Table 2 for SRM 2885.…”