Fig.  6  Effect  of  vibration  frequency  on  product  strength  for
various blends and frequencies
 
Fig.  7 Effect  of  vibration  frequency  on  pressure  profile: ( a )100/0, (b)  75/25, and( c) 50/ 50

however,  for  both  the  50/50  and  75/25  material  blends  the  actual frequency  at  which  the  vibration  was  applied  did  not  appear  to have  a  dramatic  effect.  Some  frequency  dependence  was  found with  the  100%  new  material,  which  exhibited  a  slight  peak  in strength  enhancement  at  6  Hz.  Thus,  based  on  these  findings   the effect of vibration frequency appears to be less critical for virgin/recycled  PS  blends  than  for  pure  virgin  materials.
Figures 7 (a) –7 (c) compare the effect of vibration frequency on the  pressure-difference  profiles ~pressure  difference  between  P1 and P2! for a 0.4 s period, approximately 6 s after the cycle started (during  the  packing  stage ) for  100/0,  75/25,  and  50/50  virgin/recycled PS blends, respectively. These resultant pressure difference-profiles  correspond to the tensile strength results shown
 
Fig.  8 Effect  of  vibration  duty  cycle  on  product  strength  for
50 /50 virgin / recycled blend
in  Fig.  6.  The  significant   difference  in  the  pressure  profiles   was the amplitude of the pressure-difference curves. As the frequency increased,  the  amplitude  decreased.
in  Fig.  6.  The  significant   difference  in  the  pressure  profiles   was the amplitude of the pressure-difference curves. As the frequency increased,  the  amplitude  decreased.The  observed  effects  of  the  fourth  vibration-related  parameter duty cycle, on product tensile strength are illustrated in Fig. 8. The results  shown  are  for  the  50/50  blend  processed  at  a  number  of vibration  frequencies.  The  delay  time  to  begin  vibration  and  vibration  duration  levels  were  kept  constant  for  each  frequency.  It should be noted, however, that under such conditions changing the duty  cycle  causes  a  corresponding  change  in  the  actual  stroke amplitude  of  the  oscillating  injection  screw.  Nevertheless,  from Fig. 8 it is clear that the product strength decreases as duty cycle increases. This was uniformly observed with each of the materials and  blends  tested.
A final  vibration-related parameter that deserves some attention is vibration amplitude, which during the present study was monitored  in  the  form  of  the  oscillating  injection  screw  stroke  amplitude.  Figure  9  illustrates  the  effect  of  this  variable  on  tensile strength, again with data presented for the 50/50 blend processed at  a  number  of  vibration  frequencies.  The x-axis  of  the  figure   is labeled  in  a  relative  scale,  where  a  1.0  corresponds  to  the  maximum stroke amplitude achievable with a duty cycle of 1.0 at each frequency. The  other  vibration  parameters  were  kept  constant  for the  data  presented.  From  the  Fig.  9,  it  is  clearly  seen  that  larger screw stroke amplitudes uniformly produced stronger products. As was observed with other effects, this same trend was observed for both  the  75/25  blend  and  the  100%  virgin  PS  material. 回收塑料材料注射成型英文文献和中文翻译(8):http://www.youerw.com/fanyi/lunwen_17270.html