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CN-121994863-A - Test method for rapidly determining SSA analysis parameters of polyolefin materials

CN121994863ACN 121994863 ACN121994863 ACN 121994863ACN-121994863-A

Abstract

The invention relates to a test method for rapidly determining SSA analysis parameters of polyolefin materials, which comprises the steps of selecting a temperature point T 1 in a range of 0.005mW/° C≤f' (T) is less than or equal to 0.1mW/° C on a DSC melting curve first derivative curve of a polyolefin material to be tested, selecting a plurality of temperature points in [ T 1 -2K,T 1 )、(T 1 ,T 1 +2K ] to form a temperature point group, respectively taking the plurality of temperature points in the temperature point group as a first self-nucleation temperature, the temperature interval of 5K, the isothermal time of 5-10min and the temperature rise and fall rate of 5-20K/min, taking the first self-nucleation temperature T 1 -15K as an SSA temperature lower limit, obtaining a plurality of preliminary SSA melting curves, matching the plurality of preliminary SSA melting curves with the DSC melting curves one by one, finding a preliminary SSA melting curve with the highest matching degree, recording the corresponding first self-nucleation temperature T s , the temperature interval of 5K, the isothermal time of 5-10min and the temperature rise and fall rate of 5-20K/min, and finally detecting the SSA to obtain the SSA curve. The invention is used in the fields of polyolefin material crystallization property research, branched structure research, platelet thickness, crystallizable sequence length characterization and the like.

Inventors

  • ZHANG YUTIAN
  • CHEN ZHE
  • GU XIAOYAN
  • LIU ZHONGSHI
  • XIONG FENG
  • LIU HENGZHI

Assignees

  • 中石油(上海)新材料研究院有限公司
  • 中国石油天然气股份有限公司

Dates

Publication Date
20260508
Application Date
20241105

Claims (10)

  1. 1. A test method for rapidly determining SSA analysis parameters of polyolefin materials is characterized by comprising the following steps: step one, performing a DSC experiment of removing heat history once on a polyolefin material to be detected to obtain a DSC melting curve of the polyolefin material; step two, obtaining a first derivative of the DSC melting curve measured in the step one, and obtaining a first derivative curve of the DSC melting curve; Step three, selecting any temperature point from the first derivative curve in the step two within the range of 0.005mW/°C less than or equal to 0.1mW/°C of the first derivative value f' (T) at the high temperature end of the melting curve on the curve, marking as T 1 , and selecting a plurality of temperature points within the interval [ T 1 -2K,T 1 )、(T 1 ,T 1 +2K ] to form a temperature point group; Step four, respectively taking a plurality of temperature points in the temperature point group recorded in the step three as the first self-nucleation treatment temperature, taking the temperature interval as 5K, taking the isothermal time as 5-10min, taking the temperature rise and fall rate as 5-20K/min, recording the melting peak temperature of the DSC melting curve obtained in the step one as T p , and taking the temperature value of the difference between the range of T p -10K to T p -5K and the first self-nucleation treatment temperature T 1 as the SSA temperature lower limit to obtain a plurality of preliminary SSA melting curves; Step five, matching a plurality of preliminary SSA melting curves obtained in the step four with the DSC melting curve obtained in the step one by one, finding a preliminary SSA melting curve with highest matching degree, and recording a first self-nucleation treatment temperature T s corresponding to the curve; Taking T s in the step five as the temperature of the first self-nucleation treatment, taking the temperature interval as 5K, taking the isothermal time as 5-10min, taking the temperature rise and fall rate as 5-20K/min, and carrying out SSA detection to obtain a final SSA melting curve.
  2. 2. The method for rapidly determining SSA analysis parameters of polyolefin materials according to claim 1, wherein in the first step, the polyolefin materials to be measured are weighed 5-10mg.
  3. 3. The method for rapidly determining SSA analysis parameters of polyolefin materials according to claim 1, wherein in the first step, the polyolefin materials to be measured are weighed 5-8mg.
  4. 4. The method according to claim 1, wherein in the third step, T 1 is selected within a range of 0.01mW/° c≤f' (T). Ltoreq.0.02 mW/° C on the curve.
  5. 5. The method according to claim 1, wherein in the third step, T 1 is an integer after a rounding operation, and the rounding operation is any one of an up rounding operation, a down rounding operation, or a rounding operation.
  6. 6. The test method for rapidly determining SSA analysis parameters of polyolefin materials according to claim 5, the method is characterized in that the rounding operation is rounding operation.
  7. 7. The method for rapidly determining SSA analysis parameters of polyolefin materials according to claim 1, wherein in the third step, temperature points are symmetrically selected within the interval [ T 1 -2K,T 1 )、(T 1 ,T 1 +2k ], respectively.
  8. 8. The method according to claim 1, wherein in the third step, the set of temperature points is composed of a total of five temperature points of T 1 -2K、T 1 -1K、T 1 、T 1 +1K、T 1 +2k.
  9. 9. The method for rapidly determining SSA analysis parameters of polyolefin materials according to claim 1, wherein in the fourth step, the isothermal time is 5min, and the temperature rise and drop rate is 10K/min.
  10. 10. The method for rapidly determining SSA analysis parameters of polyolefin materials according to claim 1, wherein in the sixth step, the isothermal time is 5min, and the temperature rise and drop rate is 10K/min.

Description

Test method for rapidly determining SSA analysis parameters of polyolefin materials Technical Field The invention relates to the field of analysis and test of polyolefin materials, in particular to a test method for rapidly determining SSA analysis parameters of polyolefin materials, and particularly relates to a test method for rapidly determining the analysis parameters in the SSA analysis method, which can be used in the fields of research on crystallization performance, research on branched structure, characterization of platelet thickness and crystallizable sequence length and the like of polyolefin materials. Background The branched structure of polyolefin affects its material properties to a large extent, so that research on the chain structure of polyolefin is necessary in characterization test of polyolefin-based materials. In addition to molecular weight distribution, the branching length, branching content, branching distribution and other factors have influence on the material performance, so that research on branching structure has important significance in the aspects of product development, quality control and the like of polyolefin materials, and further research on crystallization performance, mechanical property, processing performance and the like of the materials is facilitated. The traditional FTIR or NMR method can detect the branched structure, but is mainly used for testing the average branching degree, TREF can give more detailed branching distribution information, but the problems of long testing time, large required sample amount, high cost, complex and tedious experimental process, high difficulty and the like limit the wide application of the method. After the continuous self-nucleation annealing (SSA) process has been proposed by Muller et al in 1997, this process plays an important role in the study of the crystallization properties and branched structure of polymeric materials, particularly polyolefin materials. SSA separates melting peaks according to the difference of crystallization behaviors of molecular chain segments, and through continuous self-nucleation annealing treatment on a polymer sample, a plurality of self-nucleation steps are accumulated, so that the polymer sample is fully crystallized from high to low according to the regularity of a molecular structure, a series of wafers with thickness from thick to thin are sequentially formed, and then heating scanning is carried out to obtain a final melting curve capable of reacting the distribution condition of the regularity of the molecular chain, thereby representing the chain structure of the polymer and obtaining the information such as the thickness of the wafer, the length of a crystallizable sequence and the like. The method can achieve the purpose of representing the microscopic chain segment structure of the sample by only one DSC (differential scanning calorimeter), and has the advantages of simple operation, small sample consumption and low cost, and can play a significant role in the research of branched structures and molecular chains. During the experimental process of SSA, the appropriateness of parameter selection will directly determine the quality of the results. In general, the key analysis parameters in SSA experiments are four of 1. The first self-nucleation temperature is that branching hinders crystallization, in most cases, the melting peak at the highest temperature end after SSA fractionation means the part with the lowest branching degree and the strongest crystallization capacity, so the initial temperature is not selected to be too low, the sample is not completely melted, crystallization is not complete and cannot be completely separated during annealing, and too high temperature is selected to cause no crystallization phenomenon in too high temperature area, thereby wasting detection time. The proper first treatment temperature needs to ensure that the melting peak at the highest temperature end has good and complete peak shape and accords with the trend of a DSC curve, but not incomplete low peak or shoulder peak, and 2, the interval between temperature steps is that the temperature interval is too small, so that the melting peaks are partially overlapped and cannot be completely separated, and the sufficient melting peak cannot be obtained when the temperature interval is too large, so that the thermal grading effect is poor. The isothermal time after each heating and cooling is equal to the heat classification result of Ar nal et al in JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSIC S, volume 40, 9, which is published in the study "Polydispersity of ethylene sequence length in metallocene ethylene/α-olefin copolymers.I.Characterized by thermal-fracti onation technique",, the temperature is constant for 5min and the temperature is not different from the heat classification result of Ar nal et al in 15min, the temperature of the melting peak at the constant temperature for 15min is l