theoretical influence of polyester molecular weight distribution variation on melt viscosity during injection molding and extrusion as influenced by ester-ester interchange.

In the past few decades, some polyester polymers have been commercially applied, such as polybendiester)PET, poly(hexam-
Ethylene trimethamine), poly(
Ding Diester)PBT, poly(carbonate)PC, etc.
Although these individual polymers have interesting and useful properties, some researchers (1, 2)
It was found that the mixture of these different polyester could significantly improve the physical properties.
The range of properties that can be developed from these blends has also been found to depend on the viscosity properties of these different polyester blends (1-4).
In turn, the blending properties of these mixtures are often strongly influenced by the processing history of these mixtures.
Therefore, the physical properties of these mixtures due to the processing history are not always predictable.
According to Porter (5)and Kotliar (6)
By mellow, acid or ester transfer, the molecular weight distribution of polyester mixture can be changed without changing the number of end groups.
However, Porter (5)and Kotliar (6)
It is also noted that the number of polyester end groups, so the molecular weight distribution can also be changed by the degradation of acid end groups to remove carbon dioxide gas, or to hydrolysis ester groups by introducing unwanted water.
In this study, degradation of the number of end-bases will be considered negligible.
As noted elsewhere, this is especially true if the mixed polymer has been properly dried before processing (7)
To prevent diarrhea
By properly drying polyester fiber, it can be considered that the degradation of hydrolysis can be ignored.
Therefore, the focus of this study is to address the predictive modification of the molecular weight distribution of polyester in meltstate, mainly subject to Ester-
Ester exchange of mixture with different molecular weight distribution.
The modification of the molecular weight distribution of polyester by acid and alcohol solutions was considered insignificant in this study.
The analysis in this study assumes that the primary modification of molecular weight distribution in existing polyester polymer mixtures is made by Ester-
Ester exchange in a molten state. Flory (8-12)
Is the first person to determine the correct mathematical method to characterize the molecular weight distribution in polyester polymerization. Flory (9-12)
It is also the first person to address the effect of Ester exchange on molecular weight distribution, which in turn relates to the melt viscosity of the polyester mixture. Some authors(13, 14)
Expanded Flory\'s original work to address improved understanding of molecular weight distribution mathematics during ester
Ester exchange. Other authors (15, 16)
The change of Flory polyester MWD in the process of intermittent and continuous polyester polymerization was solved.
However, it is not obvious in the literature that any author has attempted to extend Flory\'s original work to better understand some of the processing complications of the currently available polyester mixture.
Since the original mathematical description of MWD developed by Flory understands both polyester polymerization and Ester-
Esterinterchange has developed so well that he has only made limited but noteworthy improvements in his initial theoretical considerations.
However, some authors have produced a lot of experimental work (17-29)
In order to understand Ester better-
Ester exchange of two or more polyester molecular weight mixtures.
In a review of polyester compatibility and processing, Porter (5)
Several authors found out.
The ester exchange is very slow, or it is almost negligible below the temperature of the highest melting temperature of the two blendedpolyesters.
Because most of the polymer processing used for injection molding or extrusion is carried out at a temperature of 10 [degrees]C to 50[degrees]
C above the melting point, then the rate at which the ester is transferred under these conditions may be significant, but it may also slow down if there is not enough mixing.
The results of the experiments published by Kimura, Porter and Salee are very clear about the importance of viscosity changes (29). Kimura et al. (29)
The addition of the mixture and the addition of the mixture were evaluated in the polymerization (
Ding Diester)(PBT)
Poly (PAR)
A specific composition was found, creating the largest viscosity difference between these different types of mixtures.
This theme is also particularly appropriate today, as several polymer products on the market are a mixture of polyester, composite on a single polymer
Screw extruder or doublescrew extruder. Utracki (30)and Hold (31, 32)
I have pointed out that the single screw extruder is a poor mixer with relatively long dwell time, including a wide distribution of residence time, which is difficult to enlarge compared to the double screw extruderScrew extruder.
In works not yet published (33)
In addition, polyester mixtures of different molecular weights were found in single-
The screw extruder usually has a higher average melt viscosity than the mixture compounded on the twinsscrew extruder.
In addition, it is also found that for incomplete mixing of polyester, injection molding of very small molding parts on the molding machine will produce a lens without filling the mold (short shot)
Then, after only four shots, the mold can be filled (flashthe mold).
Well, one of the goals of this study is that t o extendFlory involves ester-
Trying to find a possible explanation for the viscosity difference in the polyester mix found by Kimura, Porter and Salee (29).
The second goal is to look at this theoretical explanation of the results by Kimura et al. (29)
As mentioned above, it can be applied to accidental injection molding of composite bad polyester mixture.
Extend the most likely distribution of Flori to a mixture of two polyester for the addition of mixture and complete ester-
Original analysis of ESTERINTERCHANGE blended Flory (8)
In polyester polymerization, it is assumed that the loss of moisture in the polymerization process is negligible, thus causing the total weight of the monomer of the polymer to remain unchanged during the polymerization process, [W. sub. T]= [N. sub. O][M. sub. M]= [N. sub. T][M. sub. N](1)where [M. sub. M]
= Molecular weight of monomer [M. sub. N]
= Average molecular weight of numbers [N. sub. O]
= Total number of AllXmers [initial Polyester Unit]N. sub. T]
= Total number of polyester molecules for all Xmers [W. sub. T]
= With this assumption Flory, the total weight of polyester, then the most likely distribution [N. sub. x]
And show how it leads to the aggregation averaging ,[X. sub. N], as [N. sub. T]= [N. sub. O](1-p)(2)[N. sub. x]= [N. sub. O][(1-P). sup. 2][P. sup. x-1](3)[X. sub. N]= [Sum up (n/x=1)]X [N. sub. x]/[summation over(n/x=1)][N. sub. x]= 1 -[P. sup. n](1 + n(1 -P))/(1 -P)(1 -[P. sup. n])(4)If P < 1 as n [right arrow][infinity]then [X. sub. N][right arrow]1/(1 -P)(5)or P = 1 -(1/[X. sub. N](6)
Where P = probability of single unit reaction or probability of Function group reaction [X. sub. N]
= Polyester X = the average degree of polymerization of the number of polyester for the length of X single unit [N. sub. x]
= For the polyester mixture, the number of polyester molecules that are X single, then Equation 1 can be used to produce the weight fraction f1 for each polyester in the mixture, [f. sub. 1]= [N. sub. T1][M. sub. N1]/([N. sub. T1][M. sub. N1]+[N. sub. T2][M. sub. N2])(7)
Combined with Eqs 1 and 7, the weight fraction ratio of [can be generated]f. sub. 1]/[f. sub. 2]as [f. sub. 1]/[f. sub. 2]= [N. sub. 01][M. sub. M1]/[N. sub. 02][M. sub. M2](8)or [N. sub. 01]/[N. sub. 02]= [f. sub. 1][M. sub. M2]/[f. sub. 2][M. sub. M1]=[f. sub. 1]/[M. sub. M1]/[f. sub. 2]/[M. sub. M2](9)
The average molecular weight of the number of two polyester will be considered in two main cases: 1)Prior to ester-
The molecular weight distribution of Ester exchange can be assumed as the most likely distribution of each polyester, and the new molecular weight distribution can be obtained by simply adding molecular weight distribution. 2)
The second case assumes that the average molecular weight of the number remains unchanged due to the non-change of the end of the chain, but the new molecular weight distribution is determined by Ester-
Ester exchange.
An add mixture of two molecular weights can be obtained using the following equation [N. sub. XA]= [N. sub. X1]+ [N. sub. X2](10)[X. sub. NA]= [Sum up (n/x=1)]X ([N. sub. X1]+[N. sub. X2])/[Sum up (n/x=1)]([N. sub. X1]+ [N. sub. X2])=[Sum up (n/x=1)]X [N. sub. X1]+ [Sum up (n/x=1)]X[N. sub. X2]/[Sum up (n/x=1)][N. sub. X1]+ [summation over(n/x=1)][N. sub. X2](11)[X. sub. NA]= [N. sub. 01]+ [N. sub. 02]/[N. sub. 01](1 -[P. sub. 1])+[N. sub. 02](1 -[P. sub. 2])(12)
However, due to the add mixture and Ester-
Assuming that the ester exchange mixture has the same number of chain ends, the average molecular weight is equivalent [X. sub. NA]= [X. sub. NE]= 1/(1 -[P. sub. E])(13)
Combine the production of Eqs 8, 12 and 13P. sub. E]= [N. sub. 01][P. sub. 1]+ [N. sub. 02][P. sub. 2]/[N. sub. 01]+[N. sub. 02]= ([M. sub. M2]/[M. sub. M1])[P. sub. 1]+([f. sub. 2]/[f. sub. 1])[P. sub. 2]/([M. sub. M2]/[M. sub. M1])+([f. sub. 2]/[f. sub. 1])(14)Where [f. sub. 1], [f. sub. 2]
= Weight fraction of molecular weight 1 and 2 in mixture [M. sub. M1], [M. sub. M2]
= Molecular weight of unit units of molecular weight 1 and 2 [P. sub. E]
= Fraction of functional groups of Ester reaction-
Esterinterchange blend [P. sub. 1], [P. sub. 2]
= Fraction reactions of functional groups form molecular weights 1 and 2 [N. sub. 01], [N. sub. 02]
= The number of initial polyester monomer units in molecular weight 1 and 2 can then be calculated [f. sub. XA]= X [N. sub. XA]/[Sum up (n/x=1)]X [N. sub. XA]= X[N. sub. X1]+ X [N. sub. X2]/[Sum up (n/x=1)]X [N. sub. X1]+[Sum up (n/x=1)]X [N. sub. X2](15)[f. sub. XA]= X [N. sub. X1]+ X [N. sub. x2]/[N. sub. 01]+ [N. sub. 02]= X [N. sub. 01][(1 -[P. sub. 1]). sup. 2][P. sup. x-1. sub. 1]+ X[N. sub. 02][(1 -[P. sub. 2]). sup. 2][P. sup. x-1. sub. 2]/[N. sub. 01]+[N. sub. 02](16)[f. sub. XA]= X ([f. sub. 1]/[M. sub. M1])[(1 -[P. sub. 1]). sup. 2][P. sup. x-1. sub. 1]+X ([f. sub. 2]/[M. sub. M2])[(1 -[P. sub. 2]). sup. 2][P. sup. x-1. sub. 2]/([f. sub. 1]/[M. sub. M1])+ ([f. sub. 2]/[M. sub. M2])(17)[f. sub. XE]= X [N. sub. XE]/[Sum up (n/x=1)]X [N. sub. XE]= X [N. sub. OE][(1 -[P. sub. E]). sup. 2][P. sup. x-1. sub. E]/[N. sub. OE]=X[(1 -[P. sub. E]). sup. 2][P. sup. x-1. sub. E](18)Where [f. sub. XA]
= Add the weight score of Xmers in the mixture [f. sub. XE]
= Weight fraction of Xmers in ester-
Esterinterchange blend [P. sub. 1], [P. sub. 2]
= Fraction reactions of functional groups form molecular weights 1 and 2 [P. sub. E]
= Fraction of functional groups of Ester reaction-
Esterinterchange blend [N. sub. 01], [N. sub. 02]
= Number of initial polyester monomer units with molecular weight of 1 and 2 [N. sub. OE]
= Number of initial polyester unit in ester-
The ester exchange mixing diagram plots some sample distributions described by the above equation1.
Two kinds of polyester (PBT)
The picture is polyester.
1 has the following features. If [M. sub. M1]= [M. sub. M2]= 220 {
Polydingone (PBT)monomer}[M. sub. N1]= 60,000 and [M. sub. N2]= 20,000 with [f. sub. 1]=[f. sub. 2]= . 50 then [X. sub. N1]
= 60000/220 = 2727 [X. sub. N2]
= 20000/220 = 909 [P. sub. 1]= 272. 1 -1/272. 7 = . 9963 [P. sub. 2]= 90. 9 -1/90. 9 =.
989 distribution of Xmers weight fractions of these two separated pet (PBT)
Polyester has been drawn in the figure.
1 Use Eq 18 [P. sub. 1]and [P. sub. 2]replacing [P. sub. E].
These 50 d mixtures of the same two molecular weight distributions are also plotted in Fig. 1 using Eq 17.
For the 50% mixture in the figure
Note that the add mixture is exactly between the weight distribution of these two separated molecules.
Also, add mix and theester-
The ester exchange mixture has been compared in figure 1
Two polyester. The ester-
Ester exchange mixture in Fig.
Generate 2 using Eq 18, where the score of the function group reacts [P. sub. E]
Determined from [P. sub. 1]and [P. sub. 2]using Eq 14. Note in Fig.
2, although the peak molecular weight of the added mixture is lower than that of Ester-
Ester exchange mixture, the add mixture has a larger weight fraction of higher molecular weight species, which will result in a higher average molecular weight.
The expansion of Flory\'s most likely distribution analysis to the weight average molecular weight of the ADD mixture and Ester
Ester exchange mixture and its effect on melt viscosity, at the same time, the average molecular weight of the number needs to be solved to obtain ester-
Limit molecular weight distribution of Ester exchange, Flory (10)
Obviously, the average molecular weight of weight has the greatest impact on viscosity.
Recently, Ravindranath and others. (16)and Elias (34)
The importance of the average molecular weight distribution as a major influence on the melt viscosity of the polyester mixture was also noted.
More importantly, the average molecular weight of the add mixture and Ester
It is found that there is a big difference in the ester exchange device.
This is expected to have a significant impact on the melt viscosity.
By the following analysis, the average molecular weight distribution of the added mixed weight of two different polyester can be obtained. [X. sub. WA]= [Sum up (n/x=1)][X. sup. 2][N. sub. XA]/[Sum up (n/x=1)]X [N. sub. XA]= [N. sub. 01](1 +[P. sub. 1]/1 -[P. sub. 1])+ [N. sub. 02](1 + [P. sub. 2]/1 -[P. sub. 2])/[N. sub. 01]+ [N. sub. 02](19)[X. sub. WA]= ([M. sub. M2]/[M. sub. M1])(1 + [P. sub. 1]/1 -[P. sub. 1])+ ([f. sub. 2]/[f. sub. 1])(1 + [P. sub. 2]/1 -[P. sub. 2])/([M. sub. M2]/[M. sub. M1])+ ([f. sub. 2]/[f. sub. 1])(20)For the ester-
The most likely distribution form of the ester exchange mixture is [N. sub. XE]= [N. sub. 0E][(1 -[P. sub. E]). sub. 2][P. sup. x-1. sub. E](21)
The substitution of this most likely distribution into the following equation will result in ester-
The average molecular weight distribution polymerization degree of Ester exchange weight. [X. sub. WE]= [Sum up (n/x=1)][X. sup. 2][N. sub. XE]/[Sum up (n/x=1)]X [N. sub. XE]= (1 + [P. sub. E]/1 -[P. sub. E])(22)
Replace Eq 14 with yield 22 [X. sub. WE]= (1 + [P. sub. 1])([M. sub. M2]/[M. sub. M1])+ (1 +[P. sub. 2])([f. sub. 2]/[f. sub. 1])/(1 -[P. sub. 1])([M. sub. M2]/[M. sub. M1])+(1 -[P. sub. 2])([f. sub. 2]/[f. sub. 1])(23)Where [X. sub. WA]
= Weight average degree of polymerization of the added mixture [X. sub. WE]
= Average polymerization degree of weight of Ester-
At this point, we go back to the same example where two Poly N-Ding ether (PBT)
The molecular weight of the results drawn by the previously described graph. 1 and 2.
For this example [M. sub. N1]=60,000 and [M. sub. N2]= 20,000 with [f. sub. 1]= [f. sub. 2]= 0.
50 is substituted into Eqs 20 and 23 【X. sub. WA]= (1/2)(1 + [P. sub. 1]/1 -[P. sub. 1])+ (1/2)(1 +[P. sub. 2]/1 -[P. sub. 2])= 362. 6 [X. sub. WE]= 2 + [P. sub. 1]+ [P. sub. 2]/2 -[P. sub. 1]-[P. sub. 2]=271. 7 ([X. sub. WA]/[X. sub. WE])= 362. 6/271. 7 = 1. 335 Flory (10)
Others recently (16, 34)
It has been shown that not only the melt viscosity ,[[eta]. sub. 0]
, Mainly related to the average molecular weight of the weight, but the viscosity is also proportional to the power [epsilon]
The average molecular weight of weight is as follows :[[eta]. sub. 0]= [K. sub. V][M. sup. [epsilon]. sub. W](24)
Generally speaking, for low molecular weight below the molecular weight of entanglement ,[epsilon][congruent to]
1. in the molecular weight of entanglement ,[epsilon][congruent to]3. 4.
For the above case, the melt viscosity is expected to be reduced from 25% to 63%-from the addition of the mixed weight average molecular weight to the complete ester-
Weight average molecular weight of Ester.
This is a viscosity change that can significantly affect the melting processing of polyester in injection molding machines or extruder.
Based on the above example, it can be estimated that the molecular weight drop from the addition of the mixture to the ester
To mix [by simply taking the ratio of Eqs 20 and 23]
Mathematical expressions that cannot be reproduced in ASCII]The ratio of ([X. sub. WA]/[X. sub. WE])
The Eq beenplotted chart of the month shows that.
3 for a mixture of two polyester with the same molecular weight of the monomer (PBT)
When the mean molecular weight of the maximum number is maintained at [as a function of the weight fraction of the low molecular weight polymer]M. sub. N1]= 60,000.
As shown in the figure.
3, for the binary mixture of polyester, the ratio of the average molecular weight of this weight has experienced the maximum.
The maximum value of blendsevalue evaluated using equation 25 can be easily found by derivation and solving the weight fraction ratio ,([f. sub. 2]/[f. sub. 1])
, In the production :([f. sub. 2]/[f. sub. 1])= ([M. sub. M2]/[M. sub. M1])[Square root ()1 +[P. sub. 1]/1 + [P. sub. 2])](26)When [M. sub. M1]= [M. sub. M2], [P. sub. 1]= 1 and [P. sub. 2]= 0 ([f. sub. 2]/[f. sub. 1])= 1. 414 and [f. sub. 1]= . 4142 = 41. 42% When [M. sub. M1]= [M. sub. M2], [P. sub. 1]= 1 and [P. sub. 2]= 1 ([f. sub. 2]/[f. sub. 1])= 1. 0 and [f. sub. 1]= .
5 = 50% therefore, when [M. sub. M1]= [M. sub. M2]
Maximum ratio ([X. sub. WA]/[X. sub. WE])
It mainly occurs in a mixture of two Polyester\'s basically 50%.
As shown in the figure, the size of this maximum
3, it is found that the smaller the average molecular weight of the number of second polyester added to the mixture.
For the 50% mixture with the lowest molecular weight ([M. sub. M2]= 500)
As shown in figure shown in
3 ,([X. sub. WA]/X. sub. WE])
It is estimated to be about 35 years old.
For such a mixture, melted ester-
The viscosity of Ester decreased by 0. 001% to 2.
Add 9% of the mixed viscosity.
Such a 97% to 99.
A 999% drop in melt viscosity is expected to have a disastrous effect on the processing of this mixture.
The results shown in Figure 1.
The description in Figure 3 is slightly different4. In Fig.
The proportion of 4 is ([X. sub. WA/[X. sub. WE])
The same large molecular weight has been used [calculated]M. sub. N1]
= 60,000, but the molecular weight is different, and a constant weight fraction ratio is drawn.
In both numbers, it is clear that the smaller the molecular weight used in all mixtures (
But especially for a mixture of a50 %)
, Because from the mixture added to the ester, the greater the decrease in the melt viscosity-
Ester exchange mixture.
If the molecular weight of the monomer of the two polyester is significantly different, then the position of this maximum value will also change significantly, as shown in the figure. 5.
Figure 1 calculation results
5 used [average molecular weight of numbers]M. sub. N1]= 60,000and [M. sub. N2]
= 20,000, just change the single molecular weight of the smaller molecular weight polyester.
Similarly, the change in the ratio of the addition mixture to the ester --
In addition to maximizing the movement to a significantly different location, the ester exchange mixture is still notable.
Because the position of this maximum value can be expressed in equation 26, then, replacing this weight fraction with equation 25 can be used to estimate the possible decline in the mean molecular weight of the weight added from the addition of the ester blendto
Ester exchange mixture.
The calculation results in the influence diagram of incomplete deterioration of BLENDSUSING melt processing using extrusion and injection molding. 3-
5 indicates that if two or more mixtures of different polyester molecular weights are processed in standard processing techniques such as injection molding or extrusion, if incomplete ester-
Treat the ester exchange mixture.
Mondragon and Nazar (2)
The change in the melt viscosity of polyaromatic Ester and polycarbonate polyester mixture was evaluated as a function of the mixing time on the Brabender mixing head.
These authors make it clear that, as complete Ester, the melt viscosity of these mixtures decreases over time
The ester exchange mixture is generated.
Overall, they found that if two [T. sub. g]
S was found, which indicates that there are two separate polymer phases on the DSC and the exchange is incomplete. Ester-
Ester exchange is considered complete only when one person [s]T. sub. g]was obtained.
While these authors did evaluate the different weight fractions of these mixtures, they did not specifically evaluate the comparison of these mixtures to the initial viscosity of the ester
Ester exchange mixture at completion of viscosity evaluation.
However, they did evaluate the ester
Change of Ester exchange viscosity at three different temperatures (i. e. , 250[degrees]C, 270[degrees]C and290[degrees]C)
Time to find an effective completion rate
Ester exchange is nearly twice as long as 250 [degrees]C as at290[degrees]C.
Usually, the ester is reached-
At290 [Ester exchange mixturedegrees]
C takes about 18 minutes while at 250 [degrees]
C. It takes about 36 minutes.
Overall, the results of mondragon et al.
Consistent with the results calculated in the figure. 3-5.
Results of experiments published by Kimura, Porter and Salee (29)
It may be best to confirm the forecast shown in Fig. 3-
Mathematical exposition in this study. Kimura et al. (34)
Full range of properties/rubber blends collapse of Twin Towers
()(PBT)
Poly (PAR)
Whether it is adding a mixture or purifying the mixture.
The polyaromatic Ester used in this study is D-
100, provided by United carbide. The Ardel D-
100 is described as co-polyester of bisphenol a and 50% pairs of acid/50% o phthal acid, with an average molecular weight of 18,600 gm/gm moles and a characteristic viscosity of 0. 71 dL/g.
This is aValox product provided by GE with an average molecular weight of 42,800 gm/gm Moore and an intrinsic viscosity of 1. 26 dL/g.
The molecular weight of the polymerization ester (PAR)
The number of 8gm/gm moles is 358, and the molecular weight of the monomer is 220gm/gm moles.
Using Eq 26, it is easy to show th at the maximum difference between adding mixed molecular weight and transfer Ester mixed molecular weight, which is expected to be about 38% in volume fraction (62% by weight) the weight of the standard Rod
Data from Kimura and others. (29)in Fig.
6 indicates that at a position close to 50%, they do achieve the maximum difference between these mixtures.
Most likely, with the production of additional data, the true maximum does show up on 38 wt % tb.
In works not yet published (33)
It is also found that the polyester mixture of different molecular weights is in a single-
The average melt viscosity of the screw extruder is usually higher than that of the blendscompounded compound on the twinsscrew extruder. Utracki (30)and Hold (31, 32)
Has shown that single
The screw extruder is a poor mixer with relatively long dwell time, including a wide distribution of residence time, which is difficult to enlarge compared with the screw extruder.
According to the calculation results summarized in the figure. 3-
Month strong indicatedthat the high viscosity produces a composite of two differentpolyesters with two single with different molecular weights
The screw extruder will be the result of incomplete ester
Ester exchange.
Similarly, the low viscosity obtained when compounding the same polyester mixture on the twins
The screw extruder is likely to be the result of almost complete ester transfer.
If the polyester mixture is compounded on both
Twin Screw Extruder
The screw extruder processes some very small parts in the injection molding machine and then causes serious complications.
For a single composite mixture
Screw Extruder, it can be very difficult to make consistent forming parts.
In particular, a part may not fill the mold (short shot)
After only a few photos, you can prepare a part to fill the mold (flash the mold).
This observation is not necessarily explained by an improperly adjusted injection molding machine.
One of the most reasonable explanations for such observations is that in single-
Screw extruder is a poor mixing with two types of microdomains.
One of the Micro
The domain may be an almost pure mixture of the initial polyester molecular weight and the second trace polyester
Domain may be characterized by almost complete cross-mixing.
For such a micro
Then, the first molded lens is likely to be made by micro-
Adding a mixed mixture, which will result in a high viscosity, resulting in the polymer not filling the mold (short shot).
Later, I took a few more photos.
The amount of almost complete ester-
The ester exchange may be injected into the mold with a very low viscosity, resulting in the mold filling (
The mold flashed).
For professionals with very different micro combinations
In areas with very different viscosity, it is impossible for the operator to make such small parts consistently on the injection molding machine.
According to the analysis discussed in this study, it is clear that the change in the melt viscosity of binary mixtures of different molecular weight polyester may be catastrophic if it is not effectively controlled.
However, some authors (3, 35)
A mixture of polyester and incomplete ester
Ester exchange can form two-phase polymer compounds with unique physical properties.
Tribenzene phosphate (3)
Is a proposed ester-
Ester exchange of these applications.
The patent states that this reaction is suppressed with the addition of the ester transfer inhibitor and that the melting point of the mixture does not change (35, 37)
To produce a stable mixture (38).
Some other compounds, especially those containing phosphorus, have been shown to inhibit this reaction.
It is speculated that the phosphate complex is a residual trace metal capable of catalytic conversion reaction (39-43).
On the other hand, Potter (5)
It also shows that,
It is well known that metal catalysts, such as tungsten compounds other than acid or alkali, can activate polymerization and ester transfer reactions.
Because there are several kinds of commercial polyester resin can be used for injection molding, extrusion, etc.
In fact, it is a mixture of different molecular weight polyester and different types of polyester, and it is often difficult to indicate whether a commercial product has been partially certified or whether the polyester mixture has been fully certified.
Only closely observed in the course of treatment can potential complications be found and properly treated.
As mentioned earlier, the ester transfer rate in the melting state is strongly affected by the temperature.
So if too much later
Ester transfer has been identified as a potential problem during processing, and then before addressing the potential new material for the application, lowering the processing temperature is found to be one of the easiest ways to minimize this problem.
Conclusion The initial molecular weight derivation of Flory involves polyester polymerization and Ester-
This study extends the ester exchange to make possible explanations for some unusual polyester mixing conditions that may be encountered during injection molding and extrusion.
The effects of the two types of mixture relative to the average molecular weight of the quantity and the average molecular weight of the weight were considered.
Add a mix first (
Comparable to dry mix)
All molecules of the same length in the mixture are simply added together to calculate the new combination number average molecular weight and the new weight average molecular weight.
The second polyester mixture involves the calculation of the full ester transfer, assuming that the most likely distribution of Flory can describe this blendo.
The average molecular weight of the number of this ester transfer mixture is considered to be the same as the determination of the add mixture, but has a very different average molecular weight of the most likely weight.
In theory, it is found that the weight average molecular weight of add blendall should always be greater than that of the ester transfer mixture.
In addition, if the initial mixing molecular weight is significantly different from each other, it is found that the weight average molecular weight ratio of adding the mixture to the ester transfer mixture is much larger.
It was also found that if the two different molecular weights had about the same single molecular weight, the ratio would also experience a maximum of about 50%.
However, if the individual molecular weight of polyester is significantly different, the position of this maximum may be significantly different from the weight of 50%.
It was also found that a very large proportion between the weight average molecular weight of the addition mixture and the weight average molecular weight of the transfer ester mixture also had a significant effect on the melt viscosity.
Generally, meltvisity is known to be proportional to the average molecular weight of the weight to 1 to 3.
4 power depends on whether the molecular weight is lower or higher than the molecular weight of entanglement.
Therefore, if the anadd mixture of the molecular weight of both polyester is characterized by incomplete ester transfer and further processing can induce more complete ester-
Ester exchange will lead to a significant reduction in viscosity.
Experimental data from Kimura et al. (29)
It can be well confirmed from the literature that for mixed polyester with a similar monomer molecular weight of about 50%, the viscosity ratio of this additive mixture/tacky mixture does actually exist.
Experimental results of Kimura et al. (29)
Very satisfied with the theoretical predictions derived from this study.
An important purpose of this study is to produce a possible explanation of why polyester mixtures of different molecular weights are present in a single
The average melt viscosity of the screw extruder may be higher than the mixture compound on the twinsscrew extruder.
Also, one would like to have an explanation of why injection molding of very small molded parts using a poor composite polyester mixture may produce short shots without filling the mold, then it is possible to mold or flash after a few shots.
The concept of the Add mixture and the ester transfer mixture can be developed at the micro level
The explanation of these two phenomena seems to be most satisfactory.
If a specific polyester mixture is found to be characterized-
Almost pure domain of molecular weight of mixed polyester with little or no transfer Ester and second trace
An area characterized by a mixture that is almost completely solidified, and then can undergo a dramatic change in viscosity in a very short period of time.
The injection molding complications described above can be from Micro
The amount of added mixture almost pure, which will result in a high viscosity, resulting in the polymer not filling the mold (short shot).
Then after a few shots, a gun covered the mold (
The mold flashed)
Probably by a micro
Number of early complete ester-
Ester exchange mixture.
For sucha materials with very different micro combinations
Very different micro-fields
Viscosity, it is impossible for the operator to make such small parts consistently on the injection molding machine.
While the literature has described additives that reduce the ester transfer, it is not clear whether these additives will minimize the complexity of the very small moles described in this study.
However, it is believed that this study provides at least a credible explanation for the above phenomena. [
Figure 1 slightly][
Figure 2:[
Figure 3 slightly][
Figure 4 slightly][
Figure 5 Slightly][
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