Method for analyzing molecular weight of the poly-p-phenylene terephthalamide

Abstract

A method for analyzing molecular weight of the poly-p-phenylene terephthalamide (PPTA) utilizing near infrared spectrum is provided for reducing the time required to analyze the molecular weight of PPTA. The method uses PPTA samples to build a spectrum-viscosity fitting curve. The molecular weight of an unknown PPTA is analyzed via a near infrared analysis software and the spectrum-viscosity fitting curve. The method is beneficial in that it has a short process time and high reliability.

Claims

1. A method for analyzing molecular weight of the poly-p-phenylene terephthalamide (PPTA) utilizing near infrared spectrum, comprising the following steps: (a) preparing 6090PPTA samples with different molecular weight, wherein the viscosity of said PPTA samples ranges from 1 to 9 dL/g; (b) dissolving respectively said PPTA samples in a concentrated sulfuric acid and detecting the viscosity thereof by an Ubbelohde viscometer; (c) scanning respectively each of said PPTA samples 110 times using a near infrared spectrometer to obtain corresponding spectral data thereof, and calculating an average spectral data of said spectral values; (d) extrapolating a spectrum data-viscosity fitting curve from said viscosity data of step (b) and said spectrum data of the step (c) via a near infrared analysis software; and (e) scanning an unknown PPTA resin using said near infrared spectrometer to obtain a near infrared spectrum data and calculating the viscosity of said unknown PPTA by said spectrum-viscosity fitting curve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a graph illustrating the raw data of PPTA near infrared spectrum.

(2) FIG. 2 is a graph of a contrast diagram, illustrating the presumable results based on the PPTA spectrum-weight regression equation (spot) and real results based on the Ubbelohde viscometer (circle).

(3) FIG. 3 is the flow chart of the claimed method to detect the molecular weight utilizing the near infrared spectrum.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(4) The following description is disclosed to enable any person skilled in the art to make and use the present invention. Preferred embodiments are provided in the following description only as examples and modifications will be apparent to those skilled in the art. The general principles defined in the following description would be applied to other embodiments, alternatives, modifications, equivalents, and applications without departing from the spirit and scope of the present invention.

(5) According to a first preferred embodiment of the present invention, a method for analyzing molecular weight of poly (p-phenylene terephthalamide) (PPTA) utilizing near infrared spectrum comprises the steps of:

(6) (a) choosing approximately 60 PPTA samples with viscosity ranging from 1 to 9 dL/g to build a fitting curve;

(7) (b) dissolving PPTA samples in concentrated sulfuric acid and detecting the viscosity by an Ubbelohde viscometer;

(8) (c) using a near infrared spectrometer to scan the PPTA samples 6 times to obtain an average spectrum;

(9) (d) extrapolating a spectrum-viscosity fitting curve from the viscosity data of step (b) and the spectrum of the step (c) via a near infrared analysis software; and

(10) (e) Using the near infrared spectrometer to scan an unknown PPTA resin to obtain a near infrared spectrum and calculating the viscosity of the unknown PPTA by the spectrum-viscosity fitting curve.

(11) It is worth mentioning that in the step (c), the model of the near infrared spectrometer is Luminar 5030; and in the step (d), the near infrared analysis software is SNAP 2.03.

(12) It is also worth mentioning that the method for analyzing molecular weight of poly (p-phenylene terephthalamide) (PPTA) can be implemented as an ongoing analysis process for a manufacturing line.

(13) According to a second embodiment of the present invention, a method for analyzing molecular weight of poly (p-phenylene terephthalamide) (PPTA) utilizing near infrared spectrum comprises the steps of:

(14) (a) choosing approximately 90 PPTA samples with viscosity ranging from 1 to 9 dL/g to build a fitting curve;

(15) (b) dissolving PPTA samples in concentrated sulfuric acid and detecting the viscosity by an Ubbelohde viscometer;

(16) (c) using a near infrared spectrometer to scan the PPTA samples 10 times to obtain an average spectrum;

(17) (d) extrapolating a spectrum-viscosity fitting curve from the viscosity data of step (b) and the spectrum of step (c) via a near infrared analysis software; and

(18) (e) using the near infrared spectrometer to scan an unknown PPTA resin to obtain a near infrared spectrum and calculating the viscosity of the unknown PPTA by the spectrum-viscosity fitting curve.

(19) According to a third embodiment of the present invention, a method for analyzing molecular weight of poly (p-phenylene terephthalamide) (PPTA) utilizing near infrared spectrum comprises the steps of:

(20) (a) choosing approximately 70 PPTA samples with viscosity ranging from 1 to 9 dL/g to build a fitting curve;

(21) (b) dissolving PPTA samples in concentrated sulfuric acid and detecting the viscosity by an Ubbelohde viscometer;

(22) (c) using a near infrared spectrometer to scan the PPTA samples 7 times to obtain an average spectrum;

(23) (d) extrapolating a spectrum-viscosity fitting curve from the viscosity data of step (b) and the spectrum of step (c) via a near infrared analysis software; and

(24) (e) using the near infrared spectrometer to scan an unknown PPTA resin to obtain a near infrared spectrum and calculating the viscosity of the unknown PPTA by the spectrum-viscosity fitting curve.

(25) According to a fourth embodiment of the present invention, a method for analyzing molecular weight of poly (p-phenylene terephthalamide) (PPTA) utilizing near infrared spectrum comprises the steps of:

(26) (a) choosing approximately 80 PPTA samples with viscosity ranging from 1 to 9 dL/g to build a fitting curve;

(27) (b) dissolving PPTA samples in concentrated sulfuric acid and detecting the viscosity by an Ubbelohde viscometer;

(28) (c) using a near infrared spectrometer to scan the PPTA samples 8 times to obtain an average spectrum;

(29) (d) extrapolating a spectrum-viscosity fitting curve from the viscosity data of step (b) and the spectrum of step (c) via a near infrared analysis software; and

(30) (e) using the near infrared spectrometer to scan an unknown PPTA resin to obtain a near infrared spectrum and calculating the viscosity of the unknown PPTA by the spectrum-viscosity fitting curve.

(31) The viscosity of four unknown PPTA groups calculated by said method of the first preferred embodiment of present invention and sulphuric acid viscosity was compared, and the specific as shown as the following table:

(32) TABLE-US-00001 Relative No. NIR viscosity H2SO4 viscosity deviation % 1 3.94 3.81 3.35 2 4.83 4.79 0.73 3 5.94 5.8 2.37 4 6.92 6.84 1.18 Relative deviation % 1.91

(33) One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting.

(34) It will thus be seen that the objects of the present invention have been fully and effectively accomplished. The embodiments have been shown and described for the purpose of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.