Tetrafluoroethylene-propylene Copolymer Research Articles

Effects of MPBM on Crosslinking Density and Mechanical Properties of Tetrafluoroethylene-Propylene Copolymer

The composites of tetrafluoroethylene-propylene copolymer (TFE-P copolymer)/N, N'-metaphenylene-bis-maleimide (MPBM)/DCP were prepared by mill. The effects of MPBM on the crosslinking density and mechanical properties of TFE-P copolymer were investigated by equilibrium swelling method, MDR rheometer and electric tensile testing machine. The results show that MPBM can efficiently increase the crosslinking density of TFE-P copolymer cured with peroxide. There is a linear relationship between MPBM and the crosslinking density while MPBM is less than 5 phr.; due to the resinification and reinforcing effect of micro-zone of MPBM resin, the crosslinking degree and the modulus of the composite increase faster while MPBM is used more than 5 phr. Perfect network and mechanical properties could be obtained by regulating the amount of MPBM in peroxide curing system.

A 19F NMR Signal Assignment and a Detailed Structural Study of Alternating Tetrafluoroethylene-Propylene Copolymer by High Resolution 19F NMR Spectroscopy and Computational Chemistry

A 19 F NMR Signal Assignment and a Detailed Structural Study of Alternating Tetrafluoroethylene-Propylene Copolymer by High Resolution 19 F NMR Spectroscopy and Computational Chemistry

Regularities of organic solvents diffusion into fluoropolymer structure

Diffusion coefficients of organic solvents into tetrafluoroethylene-propylene copolymer structure may be generalized by multiparameter equations. Molar volume and cohesion energy of penetrating liquids are suggested to be determining their values and retarding the process.

テトラフルオロエチレン‐プロピレン共重合体の電線・ケーブルへの応用

テトラフルオロエチレン‐プロピレン共重合体の電線・ケーブルへの応用

Effect of hirudin on platelet deposition to an artificial surface during low-stress shear flow of whole blood

The effect of hirudin, a known inhibitor of thrombin, was evaluated for whole blood samples in terms of platelet deposition/adhesion to a non-biological test surface (tetrafluoroethylene-propylene copolymer), adenosine diphosphate (ADP) release and reduction in platelet count during laminar shear flow for a shear rate to 5680 s −1 (corresponding to a shear stress of about 150 dynes/cm 2). Experiments were done in a cone-and-plate viscometer for samples of whole blood with and without the addition of hirudin. Whole blood samples containing hirudin showed about a 50% reduction in platelet surface coverage compared with blood samples not containing hirudin. Results on low-stress, shear-induced release of ADP showed that for shear rates of 2860 s −1 and above there was an increase in ADP release for the blood samples not containing hirudin compared with the hirudin-treated samples. However, no differences in haemoglobin leakage from red blood cells as well as residual platelet count following shear were observed between both types of blood samples.

Application of TGA/FTIR to the thermal degradation mechanism of tetrafluoroethylene–propylene copolymers

Although the exact mechanism for the degradation of tetrafluoroethylene-propylene copolymer (Aflas TM ) has not been defined, comparative TGA/FTIR data have clearly shown that the main degradation products are mixed hydrocarbon/fluorocarbons similar to those observed with Tefzel rather than what one would expect if degradation occurred by unzipping to monomers

Artificial Surface Effect on Red Blood Cells and Platelets in Laminar Shear Flow

Red blood cell (RBC) effects on platelet adhesion to a nonbiologic test surface (tetrafluoroethylene propylene copolymer) and platelet aggregation during laminar shear flow for shear rates to 5,680 s-1 (corresponding to shear stress to 200 dyne/cm2) were investigated. Results on hemoglobin (Hb) and adenosine diphosphate (ADP) release from RBCs, percent decrease of single platelets in the bulk, and percent of test surface covered with platelets were obtained in a cone-and-plate (CP) viscometer for samples of whole blood, suspensions of RBC ghosts in platelet-rich plasma (PRP), and suspensions of RBCs in either PRP or platelet-poor plasma. Results obtained over the shear rate range studied for samples of normal hematocrit indicated that low-stress shearing led to ADP and Hb release from intact RBCs; shear-induced release of ADP from RBCs was about twice that of platelets, and of the total ADP released, the ADP released from RBCs contributed about six times that of the platelets to single platelet reduction in the bulk and about twice that of the platelets to platelet adhesion, ie, coverage of the test surface with platelets. Results obtained for various hematocrits showed that above a threshold hematocrit of about 25% to 35% the RBCs (suspended in PRP) had a greater contribution to ADP release, platelet adhesion, and platelet aggregation than the platelets themselves. Single platelet reduction for samples of RBC ghosts suspended in PRP correlated with shear rate level and not with shear stress.

Artificial surface effect on red blood cells and platelets in laminar shear flow

Red blood cell (RBC) effects on platelet adhesion to a nonbiologic test surface (tetrafluoroethylene propylene copolymer) and platelet aggregation during laminar shear flow for shear rates to 5,680 s-1 (corresponding to shear stress to 200 dyne/cm2) were investigated. Results on hemoglobin (Hb) and adenosine diphosphate (ADP) release from RBCs, percent decrease of single platelets in the bulk, and percent of test surface covered with platelets were obtained in a cone-and-plate (CP) viscometer for samples of whole blood, suspensions of RBC ghosts in platelet-rich plasma (PRP), and suspensions of RBCs in either PRP or platelet-poor plasma. Results obtained over the shear rate range studied for samples of normal hematocrit indicated that low-stress shearing led to ADP and Hb release from intact RBCs; shear-induced release of ADP from RBCs was about twice that of platelets, and of the total ADP released, the ADP released from RBCs contributed about six times that of the platelets to single platelet reduction in the bulk and about twice that of the platelets to platelet adhesion, ie, coverage of the test surface with platelets. Results obtained for various hematocrits showed that above a threshold hematocrit of about 25% to 35% the RBCs (suspended in PRP) had a greater contribution to ADP release, platelet adhesion, and platelet aggregation than the platelets themselves. Single platelet reduction for samples of RBC ghosts suspended in PRP correlated with shear rate level and not with shear stress.

Irradiation effect on the polytetrafluoroethylene-propylene copolymer solution

The solution of tetrafluoroethylene-propylene (TFEP) copolymer in tetrahydrofuran (THF) was irradiated by 60Co γ-rays in vacuum at room temperature, with total absorbed dose up to 500 kGy at constant absorbed dose rate of 10 kGy/h. The influence of polymer concentration on the radiation stability of TFEP copolymer in solution was investigated using three different solution concentrations: 1, 5 and 10%. The irradiation effect on these solutions was followed by the measurement of the gel fraction, molecular weight measurements (GPC), FTIR spectroscopy and gas chromatography. A plausible mechanism for radiation degradation and crosslinking in polymer solution was proposed.

Radiation-induced grafting of methyl-α,β,β- triflouroacrylate onto tetrafluoroethylene-propylene copolymer

Radiation-induced grafting of flourine-containing monomer,methyl—α,β,β—trifluoroacrylate (MTFA) onto tetrafluoroethylene-propylene copolymer (TFEP) has been studied. The grafting was performed in a homogeneous medium: the polymer solution was irradiated with 60Co gamma rays in the presence of monomer. The irradiation was carried out in vacuum at room temperature, with total absorbed dose up to 420 kGy at dose rates 5, 10, and 15 kGy/h. All of the total weight increase, the graft yield, and the homopolymer formation showed similar complex dependences on absorbed dose. After nonlinear increase, it reached maximum and then decreased. The maximum was higher and reached at lower absorbed dose when irradiation was performed at lower dose rate. The grafted samples were characterized by IR spectroscopy and were subjected to the molecular weight distribution measurement (GPC). Surface characterization using scanning electron microscope was also done. From these results a model for the grafting process was proposed.

Fast neutron irradiation effects on polymers-polyethylene, ethylene propylene rubber and tetrafluoroethylene propylene copolymer

A study of fast neutron irradiation effects on polymers has been carried out by using a fast neutron source reactor “YAYOI”. A combination of activation foil method and chemical dosimeter was used for the separation of the fast neutron component and the γ-ray component in the mixed-irradiation field. The effects of fast neutron irradiation on polyethylene, ethylene propylene copolymer, and tetrafluoroethylene propylene copolymer were compared with that of 60Co γ-rays by means of gel fraction and swelling ratio measurements. The difference in the effect between the two irradiations was not detected and the G- values of crosslink and chain scission for these polymers were determined.

Fast neutron irradiation effect—II. Crosslinking of polyethylene, ethylene-propylene copolymer, and tetrafluoroethylene-propylene copolymer

Effect of fast neutron irradiation on polyethylene, ethylene-propylene copolymer, and tetrafluoroethylene-propylene copolymer was compared with those of Co-60 γ-ray by the measurements of gel fraction and of swelling ratio after irradiation under vacuum. Difference in the effect between fast neutron and Co-60 γ-ray for the three polymers was not detected by those methods in spite of a large difference of linear energy transfer (LET). The G values of crosslink and chain scission determined from gel fraction data were the same for both fast neutron and Co-60 γ-ray for each polymer within the experimental error. It is thought that energy absorbed in a local region of polymer by fast neutron irradiation generates radicals in a more spread region and the radicals move in the polymer matrix until their recombination to form crosslink.

Molecular weight characteristics of tetrafluoroethylene–propylene copolymer produced by radiation-induced emulsion copolymerization

The alternating copolymers of tetrafluoroethylene and propylene produced in emulsion polymerization by radiation and by chemical initiators were fractionated and the fine structure of the molecules was examined. The correlation between Mn and [η] was obtained as for the fractionated samples. The molecular structure of the copolymers was not a complicated one, such as long-chain branching. There was no difference in molecular weight distribution and molecular structure between these copolymers. 19F NMR measurements showed that the copolymer by radiation had a large degree of the irregularity of alternation in the sequence than that by the chemical method; the irregularity increased with increasing molecular weight in the fractionated samples. The fluorine content in the fractionated samples determined with an fluoride ion-sensitive electrode was of similar tendency as that in the results of 19F NMR.

Radiation-Induced Cross-linking of a Tetrafluoroethylene-Propylene Copolymer

Abstract Radiation induced cross-linking of tetrafluoroethylene-propylene copolymer with γ-rays from a 60Co source and with electron beam from a Van de Graaff accelerator was investigated. The soluble fraction of the cross-linked copolymer in tetrahydrofuran was measured to determine the G value of the cross-linking and the probability ratio between cross-linking and chain scission. It was found that the tetrafluoroethylene-propylene copolymer can be cross-linked as well as polyethylene (i.e., G = 3). Moreover, it was also found that the copolymer could be cross-linked without chain scission under the absence of oxygen. The cross-linking occurs mainly by the abstraction of hydrogen fluoride from polymer chains. This was determined from the analysis of gases evolved from the copolymer by irradiation by means of fluorometric and mass spec-trometric measurements.