Tomoyuki Ishikawa

Effect of Perfluoroalkane Sulfonic Acid on the Flame Retardancy of Polycarbonate

Abstract The effect of perfluoroalkane sulfonic acid on the flame retardancy of polycarbonate (PC) has been studied. In particular, the very small amount of additives to restrain the combustion, as well as the thermal degradation path, was focused on. The flaming combustion times of PC blended with 100 ppm of the strong acid salts by the Underwriter Laboratory (UL)‐test were less than 5 sec, which satisfied the V‐0 level of the UL‐94 test. The ignition times of the UL test did not change remarkably, but those observed in a cone calorimeter test clearly got shorter. Referring to the results of thermal and elemental analyses, the process by which PC was shown excellent flame retardancy is not dehydration and subsequent char‐formation, but includes different scission routes. In particular, the flame retardancy strongly depends on the scission of the isopropylidene group on the main chain.

Thermal degradation and flame retardancy of ethylene-vinyl alcohol copolymer blended with ammonium polyphosphate

Abstract The thermal degradation and flame retardancy of ethylene-vinyl alcohol copolymer (EVOH) blended with ammonium polyphosphate (APP) have been studied. EVOH blended with 5 wt.% or more of APP showed excellent flame retardancy. The burn time in UL-94 test and the total released heat measured by cone calorimeter decreased with increasing APP content. In particular, blended-EVOH with 15 and 20 wt.% of APP did not ignite under UL-94 test. The thermal degradation properties were observed by TGA (thermal gravimetric analysis), Py/GC/MS (pyrolysis/gas chromatography/mass spectrometry) and EA (elemental analysis). TGA curves of blended-EVOH showed three points of inflection which were considered to be due to the reaction with APP. Although 20% of the degradation temperature fell with the blending of APP, 70% of the degradation temperature rose. The results of elemental analysis showed multiple degradation reactions, one of which was the reaction of APP with OH radicals on the polymer chain to form a crosslinked structure. The effect of APP on the flame retardancy of EVOH was considered to be caused by the crosslinking as well as the dehydrogenation.

STRUCTURAL DECAY AND FLAME RETARDANCY OF WOOD AS A NATURAL POLYMER

ABSTRACT The structural decay of wood (using “Obi” Japanese cedar) was studied by focusing on the effect of flame retardancy. The various flame retardants, including boron compound, used as one of the most popular flame retardants, were applied in this study. Thermogravimetric analysis, pyrolysis/gas chromatography/mass spectrometry, and elemental analysis were used to analyze the structural decay and thermal degradation. Flammability was observed via a vertical combustion test and a cone calorimeter. Woods to be alive was opened of pit for through the water. However, woods are independent and isolated each other by blockade of the pit at the end of their lives. Therefore, woods was prepared and destroy the pit under several conditions so as to be blended with flame retardants. After the flame retardants were impregnated, several thermal degradation tests were achieved. Boron showed an excellent effect on the flame retardancy and fluorocarbon acid salt and organic phosphate also showed a remarkable effect.

Deformation of PS, PPE, and their alloys during reversed tension–compression for study on fatigue behavior

Fatigue tests in reversed tension–compression were carried out on the sample of polystyrene (PS), poly(oxy-2,6-dimethyl-1,4-phenylene [poly(phenylene ether) (PPE)], and their alloys. The dynamic loss modulus, storage modulus, tan δ, and surface temperature of the specimens were continuously measured by a viscoelastometer during the fatigue tests. Fatigue lives and analysis of the samples by electron microscopy were also measured. The mechanical work, heat generated, and percent of work that appears as heat (PWAH) were calculated by the equations derived by viscoelastic equations and heat transfer. PWAH was in the range from 40 to 65%. The fatigue lives and PWAH were longer and larger for PPE and PPE-rich alloys than for PS and PS-rich alloys, respectively. The cleavage energy of the polymer chain calculated from the decrease of molecular weight before and after the fatigue test were much smaller compared to the total mechanical work. The entanglement densities observed before and after the test were the same. The majority of the work due to structural deformation is thought to be consumed by formation of striation and microscopically irreversible deformation.

Crystal Structure of Polyoxymethylene after Simultaneous and Successive Stretching

ポリオキシメチレンは機械的性質などが優れたエンジニアリングプラスチックであるが工業的に優れた延伸フィルムは得られていない. 本研究では延伸フィルムの工業化を目的として逐次二軸延伸を試みた. 基礎実験で得られたプレス延伸と同時二軸延伸における結果を参考にして, 本研究では最初に圧延処理を行い, 続いて逐次二軸延伸を行った. 圧延処理では微細結晶が方向性をもち力学的特性に異方性が見られたが, ラメラ構造が微細化されることによって構造の安定性をもたらすことができることを明らかにした. 延伸行程では温度制御が重要であるが, 実験は主として170℃において延伸倍率8倍以上の条件で行った. 延伸倍率が10倍を超えると配向が強くなり逐次延伸が困難であった. 工業化を目指した延伸実験で得られたフィルムの引張弾性率は基礎試験で得られたものより低かったが, これは結晶成長速度と延伸時間の関係, および微結晶の配向の不均一さに由来すると考えられた. 本研究によって結晶構造を制御できればポリオキシメチレンの延伸フィルムを工業的に得ることが可能であることを明らかにした.