JP2015206703A - Evaluation method of crosslinking degree of high molecule polymer - Google Patents
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本発明は、電気製品に汎用的に使用される高分子ポリマーであるポリエチレンや、ポリプロピレンなどのポリオレフィン樹脂の架橋度を評価するため方法で、安全、且つ簡便に評価することができる新規な高分子ポリマーの架橋度の評価方法に関する。 The present invention is a method for evaluating the degree of cross-linking of polyolefin resins such as polyethylene and polypropylene, which are polymer polymers generally used in electrical products, and is a novel polymer that can be safely and simply evaluated. The present invention relates to a method for evaluating the degree of crosslinking of a polymer.
電気特性に優れ、且つ耐熱性、耐溶剤性にも優れるので、従来からポリエチレン、ポリプロピレンなどのポリオレフィン樹脂が電気製品等には、さまざまな用途で使用されている。これらの高分子ポリマーは一般的に電子線・ガンマ線照射による放射線架橋や架橋剤、カップリング剤、過酸化物などによる化学反応（架橋反応）で架橋させることができる。
ここで、高分子ポリマーを架橋させることで耐熱性や高温での機械的特性が大きく向上することが知られている。すなわち、この架橋反応の進行状況により高分子ポリマーの性能が大きく変化するため、高分子ポリマーの架橋度を精度よく評価することは重要である。
一般的に、高分子ポリマーの架橋度は「ゲル分率」という試験方法で評価する（非特許文献１参照）。この方法を、簡単に示す。まず、毒性を有する有機溶剤であるキシレンを１１０℃に加熱し、評価対象の高分子ポリマーの試料を２４時間浸漬保持する。その後試料をキシレンから取り出し、温度１００℃、真空度１．３ｋＰａ以下で２４時間以上乾燥させる。
ここで、乾燥して得られた高分子ポリマー試料の質量Ｍ２を測定する。そしてキシレンに浸漬する前の高分子ポリマー試料の質量Ｍ１として、架橋度をＭ１とＭ２との比であるＭ２/Ｍ１×１００を「ゲル分率（単位％）」として表す。すなわち、高分子ポリマーを有機溶剤（キシレン）に浸漬した時に、溶かされずに残存する部分をゲル（架橋部分はゲルとして残る）として、このゲル部分の質量と溶剤で溶かす前の質量との比（百分率）を「ゲル分率」として算出することで、架橋の進行の程度を評価することができる。
上記の「ゲル分率」の評価方法は、有害な劇物及び有機溶剤であるキシレンを使用しなければならないうえに、測定に２日以上の時間がかかるという問題があった。
Because of its excellent electrical characteristics and excellent heat resistance and solvent resistance, polyolefin resins such as polyethylene and polypropylene have been used in various applications for electrical products. These high molecular polymers can generally be crosslinked by radiation crosslinking by electron beam / gamma ray irradiation or chemical reaction (crosslinking reaction) with a crosslinking agent, a coupling agent, a peroxide or the like.
Here, it is known that heat resistance and mechanical properties at high temperatures are greatly improved by crosslinking a polymer. That is, since the performance of the polymer polymer changes greatly depending on the progress of the crosslinking reaction, it is important to accurately evaluate the degree of crosslinking of the polymer polymer.
In general, the degree of crosslinking of a polymer is evaluated by a test method called “gel fraction” (see Non-Patent Document 1). This method is briefly described. First, xylene, which is a toxic organic solvent, is heated to 110 ° C., and a polymer polymer sample to be evaluated is immersed for 24 hours. Thereafter, the sample is taken out from xylene and dried at a temperature of 100 ° C. and a vacuum degree of 1.3 kPa or less for 24 hours or more.
Here, the mass M2 of the polymer sample obtained by drying is measured. Then, as the mass M1 of the polymer sample before being immersed in xylene, M2 / M1 × 100, which is the ratio of M1 and M2, is expressed as “gel fraction (unit%)”. That is, when the polymer is immersed in an organic solvent (xylene), the portion that remains without being dissolved is a gel (the cross-linked portion remains as a gel), and the ratio of the mass of this gel portion to the mass before dissolving with the solvent ( By calculating “percentage” as “gel fraction”, the degree of progress of crosslinking can be evaluated.
The above-mentioned method for evaluating the “gel fraction” has a problem that a harmful deleterious substance and xylene which is an organic solvent must be used, and the measurement takes two days or more.
電気製品に汎用的に使用される高分子ポリマーの架橋度を測定する方法として、従来法であるＪＩＳに規定されているゲル分率の試験方法の抱える問題点を解消し、安全且つ簡便に試験することができる高分子ポリマーの架橋度の評価方法が望まれていた。 As a method for measuring the degree of cross-linking of high-molecular polymers that are generally used in electrical products, it eliminates the problems associated with the gel fraction test method defined in JIS, which is a conventional method, and is a safe and simple test. There has been a demand for a method for evaluating the degree of cross-linking of a high molecular polymer.
本発明が提供する高分子ポリマーの評価方法は、放射線で架橋させた高分子ポリマーの架橋度の評価方法であって、第1ステップ：放射線吸収線量を複数の条件に設定した放射線照射処理することにより架橋度を変えた高分子ポリマー試料を複数作製する、
第２ステップ：得られた高分子ポリマー試料を示差熱走査熱量計（ＤＳＣ）を用いて、室温から１６０℃まで加熱させてから一旦室温まで冷却した後に、再度室温から１６０℃まで加熱し、この２回目の融解時の吸熱ピークの融解熱を測定する、
第３ステップ：第１ステップで得られた高分子ポリマー試料をＪＩＳ Ｃ ３００５：２０００ ４．２５ に規定されたゲル分率を測定する、
第４ステップ：第２ステップと第３ステップで得られた高分子ポリマー試料の融解熱とゲル分率の関係をプロットして検量線を作成する、
上記４ステップにより得られたゲル分率と融解熱の検量線を使用し、放射線架橋高分子ポリマーの架橋度を評価することを特徴とする高分子ポリマーの架橋度の評価方法が提供される。
The polymer polymer evaluation method provided by the present invention is a method for evaluating the degree of cross-linking of a polymer polymer cross-linked by radiation, and the first step is to perform a radiation irradiation treatment in which radiation absorbed doses are set in a plurality of conditions. Create multiple polymer samples with different degrees of cross-linking,
Second step: The obtained polymer sample was heated from room temperature to 160 ° C. using a differential thermal scanning calorimeter (DSC), then cooled to room temperature and then heated again from room temperature to 160 ° C. Measure the heat of fusion of the endothermic peak during the second melting,
Third step: The gel fraction defined in JIS C 3005: 2000 4.25 is measured on the polymer sample obtained in the first step.
Fourth step: Create a calibration curve by plotting the relationship between the heat of fusion of the polymer sample obtained in the second step and the third step and the gel fraction,
There is provided a method for evaluating the degree of crosslinking of a polymer, characterized in that the degree of crosslinking of the radiation-crosslinked polymer is evaluated using the calibration curve of gel fraction and heat of fusion obtained in the above four steps.
本発明によれば、電気製品で汎用的に使用される高分子ポリマーの架橋度を、安全かつ簡便に測定できる高分子ポリマーの架橋度の評価方法が提供される。 ADVANTAGE OF THE INVENTION According to this invention, the evaluation method of the crosslinking degree of the high molecular polymer which can measure the crosslinking degree of the high molecular polymer generally used with an electrical product safely and simply is provided.
本発明は、電子部品用途で、汎用的に使用されるポリエチレンやポリプロピレンなどの、従来から一般的に使用される高分子ポリマーの架橋度の測定方法であるゲル分率の前述した測定方法における問題点を解消するために、安全で且つ簡便に測定できる新規な高分子ポリマーの架橋度の評価方法を鋭意研究した。
その結果、汎用的に使用される示差熱走査熱量計（ＤＳＣ）を用いて、測定対象の高分子ポリマーの結晶サイズと結晶の融解熱との相関関係と、従来法のＪＩＳ Ｃ ３００５に規定された「ゲル分率」との相関関係が認められることから、従来法の「ゲル分率」に代わって示差熱捜査熱量計（ＤＳＣ）の融解熱量測定により高分子ポリマーの架橋度を評価することができることを見出し、本発明を完成するに至った。
本発明のこのＤＳＣを用いた高分子ポリマーの架橋度の評価方法についてその手順を具体的に説明する。
本発明の高分子ポリマーの架橋度の評価方法は第１から第４のステップで構成される。
すなわち、
（１）第1ステップは、放射線吸収線量を複数の条件に設定した放射線照射処理することにより架橋度を変えた高分子ポリマー試料を複数作製する。
（２）第２ステップは、第１ステップで得られた高分子ポリマー試料を示差熱走査熱量計（ＤＳＣ）を用いて、室温から１６０℃まで加熱させてから一旦室温まで冷却した後に、再度室温から１６０℃まで加熱し、この２回目の融解時の吸熱ピークの融解熱を測定する。
（３）第３ステップは、第２ステップにて測定に使用した第１ステップで作製した高分子ポリマー試料について、ＪＩＳ Ｃ ３００５：２０００ ４．２５ に規定されたゲル分率を測定する。
（４）第４ステップ：第２ステップと第３ステップで得られた高分子ポリマー試料の融解熱とゲル分率の関係をプロットして検量線を作成する。
以上の４ステップにより、高分子ポリマーの架橋度の検量線を作成し、以降は高分子ポリマーの架橋度を評価する場合には、示差熱走査熱量計（ＤＳＣ）を用いる第２ステップの測定を行うのみで、この検量線を用いて架橋度を評価することができる。
次に、示差熱走査熱量計（ＤＳＣ）について説明する。一般に、ＤＳＣは試料及び基準物質で構成される試料部の温度を、一定に変化させ、その試料と基準物質の温度差を測定する。そのとき試料の融解、ガラス転移、結晶化、硬化などの転移他、熱履歴を解析することで、比熱、純度など種々の測定が可能である。
ＤＳＣ測定では、室温（たとえば２０℃）から徐々に温度を上昇させていくと、ガラス転移温度になり放熱が起きる。さらに温度を上がると高分子ポリマーの融解が始まり、吸熱が起きる。さらに融点以上の温度１６０℃まで温度を上げて完全に溶融させたあとで、今度は室温まで温度を下げて、冷却していく。この降温過程で溶融していた高分子ポリマーが結晶化を始め、放熱し、再結晶化する。このときに高分子ポリマーの本来の配列の結晶が得られる。
再度、再結晶して得られた高分子ポリマーの試料を室温から融点以上の温度１６０℃まで上昇させる。その昇温過程で樹脂が再度、融解する。この時の吸熱量は、当該高分子ポリマー固有の融解熱を示すので、正確な架橋度を評価することができるわけである。ここで、結晶化する量が多いほど融解熱は大きく、また結晶サイズが大きいほど大きな融解熱を示す。逆に結晶サイズが小さいと融解熱は小さい。
この関係に注目して、高分子ポリマーの結晶サイズとその結晶の融解熱との相関関係が認められることが実験結果からわかり、高分子ポリマーの結晶サイズ、すなわち当該高分子ポリマーの架橋反応の進行度（架橋度）を知ることができるわけである。
一般に、架橋反応は高分子ポリマーの非結晶部で起こるため、融解後、非結晶部の架橋構造は保存される。このまま冷却すると結晶化時に架橋部による分子運動の制約により結晶は自由な成長ができず、その結果として、結晶サイズは融解前より小さくなり、融解熱も小さくなる。
よって、高分子ポリマーのＤＳＣ測定により得られた結晶サイズを架橋度と見なすことができ、この融解熱を測定することで結晶サイズが分り、放射線架橋する前の高分子ポリマー試料、複数の照射条件で放射線照射して架橋度の異なる試料において、融解熱を把握し、従来法のＪＩＳ Ｃ ３００５に規定された「ゲル分率」との相関関係をプロットして検量線を作成することで、これ以降にはＤＳＣ測定により融解熱を測定するだけで高分子ポリマーの架橋度を評価することができる。
なお、放射線照射の方式としては、電子線、ガンマ線などの放射線照射方式でも本発明を適用することができることは判明している。
The present invention is a problem in the above-described measurement method of gel fraction, which is a method for measuring the degree of crosslinking of high-molecular polymers generally used in the past, such as polyethylene and polypropylene, which are generally used for electronic parts. In order to solve this problem, we have intensively studied a method for evaluating the degree of crosslinking of a novel polymer that can be measured safely and simply.
As a result, using a differential thermal scanning calorimeter (DSC) that is widely used, the correlation between the crystal size of the macromolecular polymer to be measured and the heat of fusion of the crystal is defined in JIS C 3005 of the conventional method. Since the correlation with the “gel fraction” is recognized, the degree of cross-linking of the high molecular weight polymer should be evaluated by the differential calorimetry calorimeter (DSC) instead of the conventional “gel fraction”. As a result, the present invention has been completed.
The procedure of the method for evaluating the degree of crosslinking of a polymer using the DSC of the present invention will be specifically described.
The method for evaluating the degree of crosslinking of the polymer of the present invention comprises the first to fourth steps.
That is,
(1) In the first step, a plurality of polymer samples having different degrees of crosslinking are produced by performing radiation irradiation treatment with radiation absorbed doses set to a plurality of conditions.
(2) In the second step, the polymer sample obtained in the first step is heated from room temperature to 160 ° C. using a differential thermal scanning calorimeter (DSC), then cooled to room temperature, and then room temperature is again measured. To 160 ° C., and the heat of fusion of the endothermic peak during the second melting is measured.
(3) In the third step, the gel fraction defined in JIS C 3005: 2000 4.25 is measured for the polymer sample prepared in the first step used in the measurement in the second step.
(4) Fourth step: A calibration curve is created by plotting the relationship between the heat of fusion of the polymer sample obtained in the second step and the third step and the gel fraction.
A calibration curve for the degree of cross-linking of the polymer is prepared by the above four steps, and thereafter, when the degree of cross-linking of the polymer is evaluated, the second step measurement using a differential thermal scanning calorimeter (DSC) is performed. It is possible to evaluate the degree of cross-linking only by carrying out this calibration curve.
Next, a differential thermal scanning calorimeter (DSC) will be described. In general, DSC changes the temperature of a sample portion composed of a sample and a reference material to a constant value, and measures the temperature difference between the sample and the reference material. At that time, various measurements such as specific heat and purity can be performed by analyzing the thermal history in addition to the melting, glass transition, crystallization, and hardening transition of the sample.
In DSC measurement, when the temperature is gradually increased from room temperature (for example, 20 ° C.), the glass transition temperature is reached and heat dissipation occurs. When the temperature is further increased, melting of the polymer polymer starts and endotherm occurs. Further, after the temperature is raised to 160 ° C. above the melting point and completely melted, the temperature is lowered to room temperature and then cooled. The polymer melted in the temperature lowering process begins to crystallize, dissipates heat, and recrystallizes. At this time, crystals of the original arrangement of the polymer are obtained.
Again, the polymer sample obtained by recrystallization is raised from room temperature to 160 ° C. above the melting point. The resin melts again during the temperature raising process. Since the endothermic amount at this time indicates the heat of fusion inherent in the polymer, the degree of cross-linking can be accurately evaluated. Here, the greater the amount of crystallization, the greater the heat of fusion, and the larger the crystal size, the greater the heat of fusion. Conversely, if the crystal size is small, the heat of fusion is small.
Paying attention to this relationship, the experimental results show that there is a correlation between the crystal size of the polymer and the heat of fusion of the crystal, and the crystal size of the polymer, that is, the progress of the crosslinking reaction of the polymer The degree (crosslinking degree) can be known.
In general, since the crosslinking reaction occurs in the non-crystalline part of the polymer, the cross-linked structure of the non-crystalline part is preserved after melting. If it is cooled as it is, the crystal cannot grow freely due to the restriction of molecular motion due to the cross-linking part at the time of crystallization. As a result, the crystal size becomes smaller than that before melting and the heat of fusion also becomes smaller.
Therefore, the crystal size obtained by DSC measurement of the polymer can be regarded as the degree of crosslinking. By measuring the heat of fusion, the crystal size can be determined and the polymer polymer sample before radiation crosslinking, and a plurality of irradiation conditions. In this method, the heat of fusion is obtained for samples with different degrees of cross-linking after irradiation, and a calibration curve is created by plotting the correlation with the “gel fraction” defined in JIS C 3005 of the conventional method. Thereafter, the degree of crosslinking of the polymer can be evaluated only by measuring the heat of fusion by DSC measurement.
It has been found that the present invention can be applied to radiation irradiation methods such as electron beams and gamma rays.
以下に実施例を用いて、本発明をさらに詳しく説明する。 Hereinafter, the present invention will be described in more detail with reference to examples.
測定試料として、融点１３５℃の高密度ポリエチレン（密度 ９６０ｋｇ/ｍ3）を使用した。この試料を、１６０℃の熱プレス機にて厚さ０．６mmのシート状に成形した。
（実験例１）
架橋は電子線を用いる放射線架橋を選択した。
電子線加速器は、株式会社ＮＨＸコーポレーション社製、EPS-３０００を用いた。
放射線架橋条件として、加速電圧３０００ｋＶ、電流２０ｍAで１パスあたりの放射線吸収線量を３０ｋGy程度として試料に複数回照射して、４００ｋＧｙ，１０００ｋＧｙ，２０００ｋＧｙ照射した。
得られた試料を、示差熱走査熱量計（ＤＳＣ）マックサイエンス（株）社のＤＳＣ３１００Ｓを用い、窒素雰囲気中で融解熱を３水準の照射試料と未照射の試料について測定した。試料は３×３ｍｍ程度の大きさに切断し、試料重量は約４１ｍｇであった。
測定温度条件は、１回目の加熱は２０℃から１６０℃まで１℃／分の昇温速度で加熱した後に室温まで冷却して、２回目の加熱も室温から１６０℃までを１回目の同じ条件で加熱して、２回目の加熱時の融解熱を測定して、その試料の融解熱量とした。
上記のようにして得られた電子線照射試料の融解温度、融解熱は、４００ｋＧｙ照射試料（試料１）では、融解温度１２５．５℃、融解熱３．６９cal/gであった。１０００ｋＧｙ照射試料（試料２）では、融解温度１２５．７℃、融解熱３．２７cal/gであった。２０００ｋＧｙ照射試料（試料３）では、融解温度１２４．４℃、融解熱３．０７cal/gであった。
（実験例２）
次に、放射線架橋として、Ｃｏ６０を線源として、ガンマ線を照射した。試料は、実験例１で使用した試料を同じ試料を使用して、同じ条件となるように４００ｋＧｙ，１０００ｋＧｙ，２０００ｋＧｙ照射した試料を得た。
ＤＳＣ測定は、実験例１と同様にしてそれぞれの試料の溶融熱を測定した。
上記のようにして得られたγ線照射試料の融解温度、融解熱は、４００ｋＧｙ照射試料（試料４）では、融解温度１２５．３℃、融解熱３．４８cal/gであった。１０００ｋＧｙ照射試料（試料５）では、溶融温度１２５．６℃、融解熱３．２６cal/gであった。２０００ｋＧｙ照射試料（試料６）では、融解温度１２３．６℃、融解熱２．９０cal/gであった。
また、未照射試料（試料７）では、融解温度１３２．７℃、融解熱５．２０cal/gであった。
以上の結果を図１にまとめて示すと、電子線およびγ線による放射線吸収線量とＤＳＣ測定で得られた溶解熱量は、いずれの放射線でもほぼ同じ溶解熱量であり、また相関関係が認められた。
この結果から、高密度ポリエチレンに対して放射線照射の吸収線量の増加に伴って、高密度ポリエチレンの架橋反応が進行し、ポリエチレンの構造が絡み合い架橋度は増加し、架橋度の増加に比例して融解熱量が減少することが確認できる。
次に、実施例の試料１〜７で用いた高密度ポリエチレン試料をＪＩＳ Ｃ ３００５準拠のゲル分率で架橋度を測定した。
試料を１１０℃の有機溶剤のキシレン中に２４時間浸漬保持し、キシレンが揮発しないように容器に密閉して試料を保持した。２４時間後に換気ができるドラフト設備がある場所で試料を取り出し、さらに真空乾燥器を用い、１００℃、１．３ｋＰａ以下で２４時間乾燥させた。乾燥後試料の質量Ｍ２を測定し、キシレンに浸漬する前の質量Ｍ１との比を算出して、ゲル分率（％）とした。
その結果、試料１はゲル・分率７０％、試料２は９２％、試料３は９４％、試料４は８６％、試料５は９２％、試料６は９８％、試料７は２０％であった。
上記の「ゲル分率」の測定方法では、１試料測定するのに実質３日間を要した。以上の結果を、ＤＳＣ測定による溶融熱量とゲル分率の関係を示すと、図２に示すように、相関関係が認められた。この高密度ポリエチレンを十分架橋を進めるためには、ゲル分率が９０%以上となるためには、融解熱量が３．３cal/g以下である電子線照射量またはガンマ線照射量で１０００ｋＧｙ以上が必要であるということがわかる。
As a measurement sample, high-density polyethylene (density 960 kg / m 3 ) having a melting point of 135 ° C. was used. This sample was formed into a sheet having a thickness of 0.6 mm using a hot press at 160 ° C.
(Experimental example 1)
As the crosslinking, radiation crosslinking using an electron beam was selected.
As the electron beam accelerator, EPS-3000 manufactured by NHX Corporation was used.
As the radiation crosslinking conditions, the sample was irradiated several times with an acceleration voltage of 3000 kV, a current of 20 mA, and a radiation absorbed dose per pass of about 30 kGy, and irradiated with 400 kGy, 1000 kGy, and 2000 kGy.
Using the DSC3100S of the differential thermal scanning calorimeter (DSC) Mac Science Co., Ltd., the obtained sample was measured for the three levels of irradiated samples and unirradiated samples in a nitrogen atmosphere. The sample was cut into a size of about 3 × 3 mm, and the sample weight was about 41 mg.
The measurement temperature condition is that the first heating is from 20 ° C. to 160 ° C. at a heating rate of 1 ° C./min and then cooled to room temperature, and the second heating is the same as the first heating from room temperature to 160 ° C. And the heat of fusion at the second heating was measured and used as the heat of fusion of the sample.
The melting temperature and heat of fusion of the electron beam irradiated sample obtained as described above were 125.5 ° C. and heat of melting 3.69 cal / g for the 400 kGy irradiated sample (Sample 1). The 1000 kGy irradiated sample (Sample 2) had a melting temperature of 125.7 ° C. and a heat of fusion of 3.27 cal / g. The 2000 kGy irradiated sample (Sample 3) had a melting temperature of 124.4 ° C. and a heat of fusion of 3.07 cal / g.
(Experimental example 2)
Next, as radiation crosslinking, gamma rays were irradiated using Co60 as a radiation source. Samples obtained by irradiating 400 kGy, 1000 kGy, and 2000 kGy so as to satisfy the same conditions were obtained using the same sample as used in Experimental Example 1.
In DSC measurement, the heat of fusion of each sample was measured in the same manner as in Experimental Example 1.
The melting temperature and heat of fusion of the γ-irradiated sample obtained as described above were 125.3 ° C. and 3.48 cal / g of melting temperature for the 400 kGy irradiated sample (Sample 4). The 1000 kGy irradiated sample (Sample 5) had a melting temperature of 125.6 ° C. and a heat of fusion of 3.26 cal / g. The 2000 kGy irradiated sample (Sample 6) had a melting temperature of 123.6 ° C. and a heat of fusion of 2.90 cal / g.
The unirradiated sample (Sample 7) had a melting temperature of 132.7 ° C. and a heat of fusion of 5.20 cal / g.
When the above results are summarized in FIG. 1, the radiation absorbed dose by electron beam and γ-ray and the heat of dissolution obtained by DSC measurement are almost the same heat of dissolution for any radiation, and a correlation was recognized. .
From this result, the cross-linking reaction of high-density polyethylene proceeds with the increase in the absorbed dose of radiation irradiation to high-density polyethylene, the polyethylene structure is entangled and the degree of cross-linking increases, in proportion to the increase in the degree of cross-linking. It can be confirmed that the heat of fusion decreases.
Next, the degree of cross-linking of the high-density polyethylene samples used in Samples 1 to 7 of the Examples was measured with a gel fraction based on JIS C 3005.
The sample was immersed and held in xylene, an organic solvent at 110 ° C. for 24 hours, and the sample was held in a sealed container so that xylene did not volatilize. A sample was taken out in a place with a draft facility that can be ventilated after 24 hours, and further dried at 100 ° C. and 1.3 kPa or less using a vacuum dryer for 24 hours. After drying, the mass M2 of the sample was measured, and the ratio with the mass M1 before being immersed in xylene was calculated to obtain the gel fraction (%).
As a result, sample 1 had a gel fraction of 70%, sample 2 had 92%,
In the method of measuring the “gel fraction” described above, it took substantially 3 days to measure one sample. When the above results show the relationship between the heat of fusion measured by DSC measurement and the gel fraction, a correlation was recognized as shown in FIG. In order to sufficiently crosslink this high-density polyethylene, in order to achieve a gel fraction of 90% or more, an electron beam irradiation amount or a gamma ray irradiation amount of not more than 3.3 cal / g is required. It turns out that it is.
Claims (1)
第1ステップ：放射線吸収線量を複数の条件に設定した放射線照射処理することにより架橋度を変えた高分子ポリマー試料を複数作製する、
第２ステップ：得られた高分子ポリマー試料を示差熱走査熱量計（ＤＳＣ）を用いて、室温から１６０℃まで加熱させてから一旦室温まで冷却した後に、再度室温から１６０℃まで加熱し、この２回目の融解時の吸熱ピークの融解熱を測定する、
第３ステップ：第１ステップで得られた高分子ポリマー試料をＪＩＳ Ｃ ３００５：２０００ ４．２５ に規定されたゲル分率を測定する、
第４ステップ：第２ステップと第３ステップで得られた高分子ポリマー試料の融解熱とゲル分率の関係をプロットして検量線を作成する、
上記４ステップにより得られるゲル分率と融解熱の検量線を使用し、放射線架橋高分子ポリマーの架橋度を評価することを特徴とする高分子ポリマーの架橋度の評価方法。 A method for evaluating the degree of crosslinking of a polymer polymer crosslinked with radiation,
First step: Create multiple polymer samples with different degrees of cross-linking by performing radiation treatment with radiation absorbed dose set to multiple conditions.
Second step: The obtained polymer sample was heated from room temperature to 160 ° C. using a differential thermal scanning calorimeter (DSC), then cooled to room temperature and then heated again from room temperature to 160 ° C. Measure the heat of fusion of the endothermic peak during the second melting,
Third step: The gel fraction defined in JIS C 3005: 2000 4.25 is measured on the polymer sample obtained in the first step.
Fourth step: Create a calibration curve by plotting the relationship between the heat of fusion of the polymer sample obtained in the second step and the third step and the gel fraction,
A method for evaluating the degree of cross-linking of a polymer, characterized in that the degree of cross-linking of a radiation cross-linked polymer is evaluated using a calibration curve of gel fraction and heat of fusion obtained by the above four steps.
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| CN113075253A (en) * | 2021-03-08 | 2021-07-06 | 江苏斯尔邦石化有限公司 | Method for detecting residual peroxide in polyolefin |
| CN113466288A (en) * | 2021-07-09 | 2021-10-01 | 贵州茅台酒股份有限公司 | Method for evaluating sorghum by using peak gelatinization temperature |
| JP7458272B2 (en) | 2020-08-27 | 2024-03-29 | 旭化成株式会社 | Analysis method for polyolefin stretched film |
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| JP7458272B2 (en) | 2020-08-27 | 2024-03-29 | 旭化成株式会社 | Analysis method for polyolefin stretched film |
| CN113075253A (en) * | 2021-03-08 | 2021-07-06 | 江苏斯尔邦石化有限公司 | Method for detecting residual peroxide in polyolefin |
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