Professor: Cheng-Ho Chen

Student: Huang-Chi Hu

Reporting date: 2015 / 03 / 25

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Outline

IntroductionMaterialsExperimentalResults and discussionConclusions

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Introduction

1. Poly(ethylene terephthalate) (PET) is one of the most extensively used thermoplastic polyesters, which has assumed a role of primacy in fibres, films, packaging and molding materials .

2. Carbon nanotubes , which can be considered as thin long cylinders made up by rolling graphite sheets, have been evaluated in recent years as additives to polymers for imparting several properties such as mechanical reinforcement, electrical and thermal conductivity, as well as faster crystallization.

3. To our knowledge, there has been no report in literature that addresses the effect of carbon nanotubes on the rate of PET crystallization.

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Materials

Poly(ethylene terephthalate) pellets SWNTs (單壁奈米碳管 ) phenol/1,1,2,2-tetrachloroethane

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Experimental

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The polymer and the SWNTs were vacuum dried at 150 ℃for 12 h.

Haake kneader (model-HBI System-90) operating at 40 rpm for 4 min at 270 .℃

Preparation of PET–SWNT nanocomposites

Nanocomposites at different concentrations (0.0–3.0 wt%) of SWNTs were prepared.

Experimental

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Intrinsic viscosity measurements

Relative viscosities of solutions of PET or PET–SWNT samples in 1/1 mixture of phenol and 1,1,2,2-tetrachloroethane were determined using a Schott–Gerate viscometer at a constant temperature of 30 .℃

Experimental

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Weight : 4~5mg.Temperature : ambient temperature to 310 ℃Heating rate : 20 /min℃And held for 10 min to remove the thermal historyThen cooling to 50 at a rate of 20 /min℃ ℃

The samples were subsequently reheated to 310 at a ℃rate of 20 /min, held at 310 for 2 min, and then ℃ ℃cooled rapidly (60 /min) to the desired temperature ℃for isothermal crystallization (210, 215, 220 or 225 ).℃

(DSC)

Isothermal crystallization

Results and discussion

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Results and discussion

It is found that the nanocomposite sample containing SWNTs at a concentration as low as 0.03 wt% crystallizes 10 earlier than neat PET.℃

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Results and discussion

Fig. 1 shows the DSC cooling scans of PET–SWNT nanocomposite samples. During cooling from the melt, the SWNT containing samples show crystallization exotherms earlier than neat PET, as also seen from the corresponding Tc values indicated in Table 1.

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Results and discussion

The time corresponding to the maximum in the heat flow rate (exotherm) was taken as peak time of crystallization(tpeak).

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Results and discussion

We notice that the tpeak values for the nanocomposite samples reduce to less than 50% as compared to neat PET due to the presence of SWNTs at concentrations as low as 0.03 wt%

Conclusions

1. Melt compounded SWNTs have been shown to act as effective nucleating agents for PET crystallization.

2. The SWNTs at a concentration as low as 300 ppm enhance the crystallization temperature during melt cooling by 10 , or reduce the melt’s isothermal ℃crystallization time by more than 50 %.

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